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fs/dcache.c
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// SPDX-License-Identifier: GPL-2.0-only |
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/* * fs/dcache.c * * Complete reimplementation * (C) 1997 Thomas Schoebel-Theuer, * with heavy changes by Linus Torvalds */ /* * Notes on the allocation strategy: * * The dcache is a master of the icache - whenever a dcache entry * exists, the inode will always exist. "iput()" is done either when * the dcache entry is deleted or garbage collected. */ |
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#include <linux/ratelimit.h> |
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#include <linux/string.h> #include <linux/mm.h> #include <linux/fs.h> |
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#include <linux/fscrypt.h> |
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#include <linux/fsnotify.h> |
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#include <linux/slab.h> #include <linux/init.h> |
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#include <linux/hash.h> #include <linux/cache.h> |
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#include <linux/export.h> |
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#include <linux/security.h> #include <linux/seqlock.h> |
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#include <linux/memblock.h> |
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#include <linux/bit_spinlock.h> #include <linux/rculist_bl.h> |
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#include <linux/list_lru.h> |
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#include "internal.h" |
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#include "mount.h" |
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/* * Usage: |
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* dcache->d_inode->i_lock protects: |
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* - i_dentry, d_u.d_alias, d_inode of aliases |
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* dcache_hash_bucket lock protects: * - the dcache hash table |
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* s_roots bl list spinlock protects: * - the s_roots list (see __d_drop) |
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* dentry->d_sb->s_dentry_lru_lock protects: |
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* - the dcache lru lists and counters * d_lock protects: * - d_flags * - d_name * - d_lru |
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* - d_count |
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* - d_unhashed() |
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* - d_parent and d_subdirs * - childrens' d_child and d_parent |
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* - d_u.d_alias, d_inode |
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* * Ordering: |
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* dentry->d_inode->i_lock |
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* dentry->d_lock |
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* dentry->d_sb->s_dentry_lru_lock |
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* dcache_hash_bucket lock |
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* s_roots lock |
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* |
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* If there is an ancestor relationship: * dentry->d_parent->...->d_parent->d_lock * ... * dentry->d_parent->d_lock * dentry->d_lock * * If no ancestor relationship: |
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* arbitrary, since it's serialized on rename_lock |
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*/ |
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int sysctl_vfs_cache_pressure __read_mostly = 100; |
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EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure); |
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__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock); |
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EXPORT_SYMBOL(rename_lock); |
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static struct kmem_cache *dentry_cache __read_mostly; |
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const struct qstr empty_name = QSTR_INIT("", 0); EXPORT_SYMBOL(empty_name); const struct qstr slash_name = QSTR_INIT("/", 1); EXPORT_SYMBOL(slash_name); |
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/* * This is the single most critical data structure when it comes * to the dcache: the hashtable for lookups. Somebody should try * to make this good - I've just made it work. * * This hash-function tries to avoid losing too many bits of hash * information, yet avoid using a prime hash-size or similar. */ |
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static unsigned int d_hash_shift __read_mostly; |
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static struct hlist_bl_head *dentry_hashtable __read_mostly; |
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static inline struct hlist_bl_head *d_hash(unsigned int hash) |
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{ |
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return dentry_hashtable + (hash >> d_hash_shift); |
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} |
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#define IN_LOOKUP_SHIFT 10 static struct hlist_bl_head in_lookup_hashtable[1 << IN_LOOKUP_SHIFT]; static inline struct hlist_bl_head *in_lookup_hash(const struct dentry *parent, unsigned int hash) { hash += (unsigned long) parent / L1_CACHE_BYTES; return in_lookup_hashtable + hash_32(hash, IN_LOOKUP_SHIFT); } |
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/* Statistics gathering. */ struct dentry_stat_t dentry_stat = { .age_limit = 45, }; |
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static DEFINE_PER_CPU(long, nr_dentry); |
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static DEFINE_PER_CPU(long, nr_dentry_unused); |
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static DEFINE_PER_CPU(long, nr_dentry_negative); |
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#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS) |
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/* * Here we resort to our own counters instead of using generic per-cpu counters * for consistency with what the vfs inode code does. We are expected to harvest * better code and performance by having our own specialized counters. * * Please note that the loop is done over all possible CPUs, not over all online * CPUs. The reason for this is that we don't want to play games with CPUs going * on and off. If one of them goes off, we will just keep their counters. * * glommer: See cffbc8a for details, and if you ever intend to change this, * please update all vfs counters to match. */ |
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static long get_nr_dentry(void) |
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{ int i; |
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long sum = 0; |
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for_each_possible_cpu(i) sum += per_cpu(nr_dentry, i); return sum < 0 ? 0 : sum; } |
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static long get_nr_dentry_unused(void) { int i; long sum = 0; for_each_possible_cpu(i) sum += per_cpu(nr_dentry_unused, i); return sum < 0 ? 0 : sum; } |
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static long get_nr_dentry_negative(void) { int i; long sum = 0; for_each_possible_cpu(i) sum += per_cpu(nr_dentry_negative, i); return sum < 0 ? 0 : sum; } |
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int proc_nr_dentry(struct ctl_table *table, int write, void *buffer, |
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size_t *lenp, loff_t *ppos) { |
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dentry_stat.nr_dentry = get_nr_dentry(); |
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dentry_stat.nr_unused = get_nr_dentry_unused(); |
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dentry_stat.nr_negative = get_nr_dentry_negative(); |
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return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
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} #endif |
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/* * Compare 2 name strings, return 0 if they match, otherwise non-zero. * The strings are both count bytes long, and count is non-zero. */ |
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#ifdef CONFIG_DCACHE_WORD_ACCESS #include <asm/word-at-a-time.h> /* * NOTE! 'cs' and 'scount' come from a dentry, so it has a * aligned allocation for this particular component. We don't * strictly need the load_unaligned_zeropad() safety, but it * doesn't hurt either. * * In contrast, 'ct' and 'tcount' can be from a pathname, and do * need the careful unaligned handling. */ |
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static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
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{ |
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unsigned long a,b,mask; |
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for (;;) { |
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a = read_word_at_a_time(cs); |
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b = load_unaligned_zeropad(ct); |
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if (tcount < sizeof(unsigned long)) break; if (unlikely(a != b)) return 1; cs += sizeof(unsigned long); ct += sizeof(unsigned long); tcount -= sizeof(unsigned long); if (!tcount) return 0; } |
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mask = bytemask_from_count(tcount); |
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return unlikely(!!((a ^ b) & mask)); |
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} |
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#else |
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static inline int dentry_string_cmp(const unsigned char *cs, const unsigned char *ct, unsigned tcount) |
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{ |
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do { if (*cs != *ct) return 1; cs++; ct++; tcount--; } while (tcount); return 0; } |
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#endif |
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static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *ct, unsigned tcount) { |
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/* * Be careful about RCU walk racing with rename: |
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* use 'READ_ONCE' to fetch the name pointer. |
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* * NOTE! Even if a rename will mean that the length * was not loaded atomically, we don't care. The * RCU walk will check the sequence count eventually, * and catch it. And we won't overrun the buffer, * because we're reading the name pointer atomically, * and a dentry name is guaranteed to be properly * terminated with a NUL byte. * * End result: even if 'len' is wrong, we'll exit * early because the data cannot match (there can * be no NUL in the ct/tcount data) */ |
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const unsigned char *cs = READ_ONCE(dentry->d_name.name); |
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return dentry_string_cmp(cs, ct, tcount); |
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} |
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struct external_name { union { atomic_t count; struct rcu_head head; } u; unsigned char name[]; }; static inline struct external_name *external_name(struct dentry *dentry) { return container_of(dentry->d_name.name, struct external_name, name[0]); } |
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static void __d_free(struct rcu_head *head) |
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{ |
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struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
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kmem_cache_free(dentry_cache, dentry); } static void __d_free_external(struct rcu_head *head) { struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu); |
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kfree(external_name(dentry)); |
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kmem_cache_free(dentry_cache, dentry); |
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} |
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static inline int dname_external(const struct dentry *dentry) { return dentry->d_name.name != dentry->d_iname; } |
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void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry) { spin_lock(&dentry->d_lock); |
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name->name = dentry->d_name; |
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if (unlikely(dname_external(dentry))) { |
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atomic_inc(&external_name(dentry)->u.count); |
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} else { |
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memcpy(name->inline_name, dentry->d_iname, dentry->d_name.len + 1); |
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name->name.name = name->inline_name; |
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} |
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spin_unlock(&dentry->d_lock); |
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} EXPORT_SYMBOL(take_dentry_name_snapshot); void release_dentry_name_snapshot(struct name_snapshot *name) { |
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if (unlikely(name->name.name != name->inline_name)) { |
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struct external_name *p; |
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p = container_of(name->name.name, struct external_name, name[0]); |
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if (unlikely(atomic_dec_and_test(&p->u.count))) |
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kfree_rcu(p, u.head); |
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} } EXPORT_SYMBOL(release_dentry_name_snapshot); |
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static inline void __d_set_inode_and_type(struct dentry *dentry, struct inode *inode, unsigned type_flags) { unsigned flags; dentry->d_inode = inode; |
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flags = READ_ONCE(dentry->d_flags); flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); flags |= type_flags; |
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smp_store_release(&dentry->d_flags, flags); |
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} |
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static inline void __d_clear_type_and_inode(struct dentry *dentry) { unsigned flags = READ_ONCE(dentry->d_flags); flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU); WRITE_ONCE(dentry->d_flags, flags); |
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dentry->d_inode = NULL; |
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if (dentry->d_flags & DCACHE_LRU_LIST) this_cpu_inc(nr_dentry_negative); |
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} |
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static void dentry_free(struct dentry *dentry) { |
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WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias)); |
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if (unlikely(dname_external(dentry))) { struct external_name *p = external_name(dentry); if (likely(atomic_dec_and_test(&p->u.count))) { call_rcu(&dentry->d_u.d_rcu, __d_free_external); return; } } |
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/* if dentry was never visible to RCU, immediate free is OK */ |
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if (dentry->d_flags & DCACHE_NORCU) |
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__d_free(&dentry->d_u.d_rcu); else call_rcu(&dentry->d_u.d_rcu, __d_free); } |
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/* * Release the dentry's inode, using the filesystem |
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* d_iput() operation if defined. |
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*/ static void dentry_unlink_inode(struct dentry * dentry) __releases(dentry->d_lock) |
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__releases(dentry->d_inode->i_lock) |
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{ struct inode *inode = dentry->d_inode; |
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raw_write_seqcount_begin(&dentry->d_seq); |
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__d_clear_type_and_inode(dentry); |
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hlist_del_init(&dentry->d_u.d_alias); |
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raw_write_seqcount_end(&dentry->d_seq); |
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spin_unlock(&dentry->d_lock); |
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spin_unlock(&inode->i_lock); |
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if (!inode->i_nlink) fsnotify_inoderemove(inode); if (dentry->d_op && dentry->d_op->d_iput) dentry->d_op->d_iput(dentry, inode); else iput(inode); } /* |
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* The DCACHE_LRU_LIST bit is set whenever the 'd_lru' entry * is in use - which includes both the "real" per-superblock * LRU list _and_ the DCACHE_SHRINK_LIST use. * * The DCACHE_SHRINK_LIST bit is set whenever the dentry is * on the shrink list (ie not on the superblock LRU list). * * The per-cpu "nr_dentry_unused" counters are updated with * the DCACHE_LRU_LIST bit. * |
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* The per-cpu "nr_dentry_negative" counters are only updated * when deleted from or added to the per-superblock LRU list, not * from/to the shrink list. That is to avoid an unneeded dec/inc * pair when moving from LRU to shrink list in select_collect(). * |
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* These helper functions make sure we always follow the * rules. d_lock must be held by the caller. */ #define D_FLAG_VERIFY(dentry,x) WARN_ON_ONCE(((dentry)->d_flags & (DCACHE_LRU_LIST | DCACHE_SHRINK_LIST)) != (x)) static void d_lru_add(struct dentry *dentry) { D_FLAG_VERIFY(dentry, 0); dentry->d_flags |= DCACHE_LRU_LIST; this_cpu_inc(nr_dentry_unused); |
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if (d_is_negative(dentry)) this_cpu_inc(nr_dentry_negative); |
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WARN_ON_ONCE(!list_lru_add(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); } static void d_lru_del(struct dentry *dentry) { D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); dentry->d_flags &= ~DCACHE_LRU_LIST; this_cpu_dec(nr_dentry_unused); |
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if (d_is_negative(dentry)) this_cpu_dec(nr_dentry_negative); |
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WARN_ON_ONCE(!list_lru_del(&dentry->d_sb->s_dentry_lru, &dentry->d_lru)); } static void d_shrink_del(struct dentry *dentry) { D_FLAG_VERIFY(dentry, DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); list_del_init(&dentry->d_lru); dentry->d_flags &= ~(DCACHE_SHRINK_LIST | DCACHE_LRU_LIST); this_cpu_dec(nr_dentry_unused); } static void d_shrink_add(struct dentry *dentry, struct list_head *list) { D_FLAG_VERIFY(dentry, 0); list_add(&dentry->d_lru, list); dentry->d_flags |= DCACHE_SHRINK_LIST | DCACHE_LRU_LIST; this_cpu_inc(nr_dentry_unused); } /* * These can only be called under the global LRU lock, ie during the * callback for freeing the LRU list. "isolate" removes it from the * LRU lists entirely, while shrink_move moves it to the indicated * private list. */ |
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static void d_lru_isolate(struct list_lru_one *lru, struct dentry *dentry) |
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{ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); dentry->d_flags &= ~DCACHE_LRU_LIST; this_cpu_dec(nr_dentry_unused); |
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if (d_is_negative(dentry)) this_cpu_dec(nr_dentry_negative); |
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list_lru_isolate(lru, &dentry->d_lru); |
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} |
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static void d_lru_shrink_move(struct list_lru_one *lru, struct dentry *dentry, struct list_head *list) |
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{ D_FLAG_VERIFY(dentry, DCACHE_LRU_LIST); dentry->d_flags |= DCACHE_SHRINK_LIST; |
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if (d_is_negative(dentry)) this_cpu_dec(nr_dentry_negative); |
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list_lru_isolate_move(lru, &dentry->d_lru, list); |
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} |
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/** |
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* d_drop - drop a dentry * @dentry: dentry to drop * * d_drop() unhashes the entry from the parent dentry hashes, so that it won't * be found through a VFS lookup any more. Note that this is different from * deleting the dentry - d_delete will try to mark the dentry negative if * possible, giving a successful _negative_ lookup, while d_drop will * just make the cache lookup fail. * * d_drop() is used mainly for stuff that wants to invalidate a dentry for some * reason (NFS timeouts or autofs deletes). * |
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* __d_drop requires dentry->d_lock * ___d_drop doesn't mark dentry as "unhashed" * (dentry->d_hash.pprev will be LIST_POISON2, not NULL). |
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*/ |
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static void ___d_drop(struct dentry *dentry) |
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{ |
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struct hlist_bl_head *b; /* * Hashed dentries are normally on the dentry hashtable, * with the exception of those newly allocated by * d_obtain_root, which are always IS_ROOT: */ if (unlikely(IS_ROOT(dentry))) b = &dentry->d_sb->s_roots; else b = d_hash(dentry->d_name.hash); |
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hlist_bl_lock(b); __hlist_bl_del(&dentry->d_hash); hlist_bl_unlock(b); |
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} |
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void __d_drop(struct dentry *dentry) { |
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if (!d_unhashed(dentry)) { ___d_drop(dentry); dentry->d_hash.pprev = NULL; write_seqcount_invalidate(&dentry->d_seq); } |
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} |
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|
477 478 479 480 |
EXPORT_SYMBOL(__d_drop); void d_drop(struct dentry *dentry) { |
789680d1e
|
481 482 483 |
spin_lock(&dentry->d_lock); __d_drop(dentry); spin_unlock(&dentry->d_lock); |
789680d1e
|
484 485 |
} EXPORT_SYMBOL(d_drop); |
ba65dc5ef
|
486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 |
static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent) { struct dentry *next; /* * Inform d_walk() and shrink_dentry_list() that we are no longer * attached to the dentry tree */ dentry->d_flags |= DCACHE_DENTRY_KILLED; if (unlikely(list_empty(&dentry->d_child))) return; __list_del_entry(&dentry->d_child); /* * Cursors can move around the list of children. While we'd been * a normal list member, it didn't matter - ->d_child.next would've * been updated. However, from now on it won't be and for the * things like d_walk() it might end up with a nasty surprise. * Normally d_walk() doesn't care about cursors moving around - * ->d_lock on parent prevents that and since a cursor has no children * of its own, we get through it without ever unlocking the parent. * There is one exception, though - if we ascend from a child that * gets killed as soon as we unlock it, the next sibling is found * using the value left in its ->d_child.next. And if _that_ * pointed to a cursor, and cursor got moved (e.g. by lseek()) * before d_walk() regains parent->d_lock, we'll end up skipping * everything the cursor had been moved past. * * Solution: make sure that the pointer left behind in ->d_child.next * points to something that won't be moving around. I.e. skip the * cursors. */ while (dentry->d_child.next != &parent->d_subdirs) { next = list_entry(dentry->d_child.next, struct dentry, d_child); if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR))) break; dentry->d_child.next = next->d_child.next; } } |
e55fd0115
|
523 |
static void __dentry_kill(struct dentry *dentry) |
77812a1ef
|
524 |
{ |
41edf278f
|
525 526 |
struct dentry *parent = NULL; bool can_free = true; |
41edf278f
|
527 |
if (!IS_ROOT(dentry)) |
77812a1ef
|
528 |
parent = dentry->d_parent; |
31e6b01f4
|
529 |
|
0d98439ea
|
530 531 532 533 |
/* * The dentry is now unrecoverably dead to the world. */ lockref_mark_dead(&dentry->d_lockref); |
f0023bc61
|
534 |
/* |
f0023bc61
|
535 536 537 |
* inform the fs via d_prune that this dentry is about to be * unhashed and destroyed. */ |
292662014
|
538 |
if (dentry->d_flags & DCACHE_OP_PRUNE) |
61572bb1f
|
539 |
dentry->d_op->d_prune(dentry); |
01b603519
|
540 541 542 |
if (dentry->d_flags & DCACHE_LRU_LIST) { if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) d_lru_del(dentry); |
01b603519
|
543 |
} |
77812a1ef
|
544 545 |
/* if it was on the hash then remove it */ __d_drop(dentry); |
ba65dc5ef
|
546 |
dentry_unlist(dentry, parent); |
03b3b889e
|
547 548 |
if (parent) spin_unlock(&parent->d_lock); |
550dce01d
|
549 550 551 552 |
if (dentry->d_inode) dentry_unlink_inode(dentry); else spin_unlock(&dentry->d_lock); |
03b3b889e
|
553 554 555 |
this_cpu_dec(nr_dentry); if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); |
41edf278f
|
556 557 558 559 560 561 |
spin_lock(&dentry->d_lock); if (dentry->d_flags & DCACHE_SHRINK_LIST) { dentry->d_flags |= DCACHE_MAY_FREE; can_free = false; } spin_unlock(&dentry->d_lock); |
41edf278f
|
562 563 |
if (likely(can_free)) dentry_free(dentry); |
9c5f1d301
|
564 |
cond_resched(); |
e55fd0115
|
565 |
} |
8b987a46a
|
566 |
static struct dentry *__lock_parent(struct dentry *dentry) |
046b961b4
|
567 |
{ |
8b987a46a
|
568 |
struct dentry *parent; |
046b961b4
|
569 |
rcu_read_lock(); |
c2338f2dc
|
570 |
spin_unlock(&dentry->d_lock); |
046b961b4
|
571 |
again: |
66702eb59
|
572 |
parent = READ_ONCE(dentry->d_parent); |
046b961b4
|
573 574 575 576 577 578 579 580 581 582 583 584 585 |
spin_lock(&parent->d_lock); /* * We can't blindly lock dentry until we are sure * that we won't violate the locking order. * Any changes of dentry->d_parent must have * been done with parent->d_lock held, so * spin_lock() above is enough of a barrier * for checking if it's still our child. */ if (unlikely(parent != dentry->d_parent)) { spin_unlock(&parent->d_lock); goto again; } |
65d8eb5a8
|
586 587 |
rcu_read_unlock(); if (parent != dentry) |
9f12600fe
|
588 |
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
65d8eb5a8
|
589 |
else |
046b961b4
|
590 591 592 |
parent = NULL; return parent; } |
8b987a46a
|
593 594 595 596 597 598 599 600 601 |
static inline struct dentry *lock_parent(struct dentry *dentry) { struct dentry *parent = dentry->d_parent; if (IS_ROOT(dentry)) return NULL; if (likely(spin_trylock(&parent->d_lock))) return parent; return __lock_parent(dentry); } |
a338579f2
|
602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 |
static inline bool retain_dentry(struct dentry *dentry) { WARN_ON(d_in_lookup(dentry)); /* Unreachable? Get rid of it */ if (unlikely(d_unhashed(dentry))) return false; if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED)) return false; if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) { if (dentry->d_op->d_delete(dentry)) return false; } |
2c567af41
|
617 618 619 |
if (unlikely(dentry->d_flags & DCACHE_DONTCACHE)) return false; |
62d9956ce
|
620 621 622 623 624 625 |
/* retain; LRU fodder */ dentry->d_lockref.count--; if (unlikely(!(dentry->d_flags & DCACHE_LRU_LIST))) d_lru_add(dentry); else if (unlikely(!(dentry->d_flags & DCACHE_REFERENCED))) dentry->d_flags |= DCACHE_REFERENCED; |
a338579f2
|
626 627 |
return true; } |
2c567af41
|
628 629 630 631 632 633 634 635 636 637 638 639 640 641 |
void d_mark_dontcache(struct inode *inode) { struct dentry *de; spin_lock(&inode->i_lock); hlist_for_each_entry(de, &inode->i_dentry, d_u.d_alias) { spin_lock(&de->d_lock); de->d_flags |= DCACHE_DONTCACHE; spin_unlock(&de->d_lock); } inode->i_state |= I_DONTCACHE; spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(d_mark_dontcache); |
360f54796
|
642 |
/* |
c1d0c1a2b
|
643 644 645 646 647 648 649 650 651 652 653 |
* Finish off a dentry we've decided to kill. * dentry->d_lock must be held, returns with it unlocked. * Returns dentry requiring refcount drop, or NULL if we're done. */ static struct dentry *dentry_kill(struct dentry *dentry) __releases(dentry->d_lock) { struct inode *inode = dentry->d_inode; struct dentry *parent = NULL; if (inode && unlikely(!spin_trylock(&inode->i_lock))) |
f657a666f
|
654 |
goto slow_positive; |
c1d0c1a2b
|
655 656 657 658 |
if (!IS_ROOT(dentry)) { parent = dentry->d_parent; if (unlikely(!spin_trylock(&parent->d_lock))) { |
f657a666f
|
659 660 661 662 663 664 665 666 |
parent = __lock_parent(dentry); if (likely(inode || !dentry->d_inode)) goto got_locks; /* negative that became positive */ if (parent) spin_unlock(&parent->d_lock); inode = dentry->d_inode; goto slow_positive; |
c1d0c1a2b
|
667 668 |
} } |
c1d0c1a2b
|
669 670 |
__dentry_kill(dentry); return parent; |
f657a666f
|
671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 |
slow_positive: spin_unlock(&dentry->d_lock); spin_lock(&inode->i_lock); spin_lock(&dentry->d_lock); parent = lock_parent(dentry); got_locks: if (unlikely(dentry->d_lockref.count != 1)) { dentry->d_lockref.count--; } else if (likely(!retain_dentry(dentry))) { __dentry_kill(dentry); return parent; } /* we are keeping it, after all */ if (inode) spin_unlock(&inode->i_lock); if (parent) spin_unlock(&parent->d_lock); |
c1d0c1a2b
|
688 |
spin_unlock(&dentry->d_lock); |
f657a666f
|
689 |
return NULL; |
c1d0c1a2b
|
690 691 692 |
} /* |
360f54796
|
693 694 695 696 697 698 699 700 701 702 703 704 705 706 |
* Try to do a lockless dput(), and return whether that was successful. * * If unsuccessful, we return false, having already taken the dentry lock. * * The caller needs to hold the RCU read lock, so that the dentry is * guaranteed to stay around even if the refcount goes down to zero! */ static inline bool fast_dput(struct dentry *dentry) { int ret; unsigned int d_flags; /* * If we have a d_op->d_delete() operation, we sould not |
75a6f82a0
|
707 |
* let the dentry count go to zero, so use "put_or_lock". |
360f54796
|
708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 |
*/ if (unlikely(dentry->d_flags & DCACHE_OP_DELETE)) return lockref_put_or_lock(&dentry->d_lockref); /* * .. otherwise, we can try to just decrement the * lockref optimistically. */ ret = lockref_put_return(&dentry->d_lockref); /* * If the lockref_put_return() failed due to the lock being held * by somebody else, the fast path has failed. We will need to * get the lock, and then check the count again. */ if (unlikely(ret < 0)) { spin_lock(&dentry->d_lock); if (dentry->d_lockref.count > 1) { dentry->d_lockref.count--; spin_unlock(&dentry->d_lock); |
7964410fc
|
728 |
return true; |
360f54796
|
729 |
} |
7964410fc
|
730 |
return false; |
360f54796
|
731 732 733 734 735 736 |
} /* * If we weren't the last ref, we're done. */ if (ret) |
7964410fc
|
737 |
return true; |
360f54796
|
738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 |
/* * Careful, careful. The reference count went down * to zero, but we don't hold the dentry lock, so * somebody else could get it again, and do another * dput(), and we need to not race with that. * * However, there is a very special and common case * where we don't care, because there is nothing to * do: the dentry is still hashed, it does not have * a 'delete' op, and it's referenced and already on * the LRU list. * * NOTE! Since we aren't locked, these values are * not "stable". However, it is sufficient that at * some point after we dropped the reference the * dentry was hashed and the flags had the proper * value. Other dentry users may have re-gotten * a reference to the dentry and change that, but * our work is done - we can leave the dentry * around with a zero refcount. */ smp_rmb(); |
66702eb59
|
761 |
d_flags = READ_ONCE(dentry->d_flags); |
75a6f82a0
|
762 |
d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST | DCACHE_DISCONNECTED; |
360f54796
|
763 764 765 |
/* Nothing to do? Dropping the reference was all we needed? */ if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry)) |
7964410fc
|
766 |
return true; |
360f54796
|
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 |
/* * Not the fast normal case? Get the lock. We've already decremented * the refcount, but we'll need to re-check the situation after * getting the lock. */ spin_lock(&dentry->d_lock); /* * Did somebody else grab a reference to it in the meantime, and * we're no longer the last user after all? Alternatively, somebody * else could have killed it and marked it dead. Either way, we * don't need to do anything else. */ if (dentry->d_lockref.count) { spin_unlock(&dentry->d_lock); |
7964410fc
|
783 |
return true; |
360f54796
|
784 785 786 787 788 789 790 791 |
} /* * Re-get the reference we optimistically dropped. We hold the * lock, and we just tested that it was zero, so we can just * set it to 1. */ dentry->d_lockref.count = 1; |
7964410fc
|
792 |
return false; |
360f54796
|
793 |
} |
1da177e4c
|
794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 |
/* * This is dput * * This is complicated by the fact that we do not want to put * dentries that are no longer on any hash chain on the unused * list: we'd much rather just get rid of them immediately. * * However, that implies that we have to traverse the dentry * tree upwards to the parents which might _also_ now be * scheduled for deletion (it may have been only waiting for * its last child to go away). * * This tail recursion is done by hand as we don't want to depend * on the compiler to always get this right (gcc generally doesn't). * Real recursion would eat up our stack space. */ /* * dput - release a dentry * @dentry: dentry to release * * Release a dentry. This will drop the usage count and if appropriate * call the dentry unlink method as well as removing it from the queues and * releasing its resources. If the parent dentries were scheduled for release * they too may now get deleted. |
1da177e4c
|
819 |
*/ |
1da177e4c
|
820 821 |
void dput(struct dentry *dentry) { |
1088a6408
|
822 823 |
while (dentry) { might_sleep(); |
1da177e4c
|
824 |
|
1088a6408
|
825 826 827 828 829 |
rcu_read_lock(); if (likely(fast_dput(dentry))) { rcu_read_unlock(); return; } |
47be61845
|
830 |
|
1088a6408
|
831 |
/* Slow case: now with the dentry lock held */ |
360f54796
|
832 |
rcu_read_unlock(); |
360f54796
|
833 |
|
1088a6408
|
834 835 836 837 |
if (likely(retain_dentry(dentry))) { spin_unlock(&dentry->d_lock); return; } |
265ac9023
|
838 |
|
1088a6408
|
839 |
dentry = dentry_kill(dentry); |
47be61845
|
840 |
} |
1da177e4c
|
841 |
} |
ec4f86059
|
842 |
EXPORT_SYMBOL(dput); |
1da177e4c
|
843 |
|
9bdebc2bd
|
844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 |
static void __dput_to_list(struct dentry *dentry, struct list_head *list) __must_hold(&dentry->d_lock) { if (dentry->d_flags & DCACHE_SHRINK_LIST) { /* let the owner of the list it's on deal with it */ --dentry->d_lockref.count; } else { if (dentry->d_flags & DCACHE_LRU_LIST) d_lru_del(dentry); if (!--dentry->d_lockref.count) d_shrink_add(dentry, list); } } void dput_to_list(struct dentry *dentry, struct list_head *list) { rcu_read_lock(); if (likely(fast_dput(dentry))) { rcu_read_unlock(); return; } rcu_read_unlock(); if (!retain_dentry(dentry)) __dput_to_list(dentry, list); spin_unlock(&dentry->d_lock); } |
1da177e4c
|
870 |
|
b5c84bf6f
|
871 |
/* This must be called with d_lock held */ |
dc0474be3
|
872 |
static inline void __dget_dlock(struct dentry *dentry) |
230445078
|
873 |
{ |
98474236f
|
874 |
dentry->d_lockref.count++; |
230445078
|
875 |
} |
dc0474be3
|
876 |
static inline void __dget(struct dentry *dentry) |
1da177e4c
|
877 |
{ |
98474236f
|
878 |
lockref_get(&dentry->d_lockref); |
1da177e4c
|
879 |
} |
b7ab39f63
|
880 881 |
struct dentry *dget_parent(struct dentry *dentry) { |
df3d0bbcd
|
882 |
int gotref; |
b7ab39f63
|
883 |
struct dentry *ret; |
e84009336
|
884 |
unsigned seq; |
b7ab39f63
|
885 |
|
df3d0bbcd
|
886 887 888 889 890 |
/* * Do optimistic parent lookup without any * locking. */ rcu_read_lock(); |
e84009336
|
891 |
seq = raw_seqcount_begin(&dentry->d_seq); |
66702eb59
|
892 |
ret = READ_ONCE(dentry->d_parent); |
df3d0bbcd
|
893 894 895 |
gotref = lockref_get_not_zero(&ret->d_lockref); rcu_read_unlock(); if (likely(gotref)) { |
e84009336
|
896 |
if (!read_seqcount_retry(&dentry->d_seq, seq)) |
df3d0bbcd
|
897 898 899 |
return ret; dput(ret); } |
b7ab39f63
|
900 |
repeat: |
a734eb458
|
901 902 903 904 905 |
/* * Don't need rcu_dereference because we re-check it was correct under * the lock. */ rcu_read_lock(); |
b7ab39f63
|
906 |
ret = dentry->d_parent; |
a734eb458
|
907 908 909 910 |
spin_lock(&ret->d_lock); if (unlikely(ret != dentry->d_parent)) { spin_unlock(&ret->d_lock); rcu_read_unlock(); |
b7ab39f63
|
911 912 |
goto repeat; } |
a734eb458
|
913 |
rcu_read_unlock(); |
98474236f
|
914 915 |
BUG_ON(!ret->d_lockref.count); ret->d_lockref.count++; |
b7ab39f63
|
916 |
spin_unlock(&ret->d_lock); |
b7ab39f63
|
917 918 919 |
return ret; } EXPORT_SYMBOL(dget_parent); |
61fec493c
|
920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 |
static struct dentry * __d_find_any_alias(struct inode *inode) { struct dentry *alias; if (hlist_empty(&inode->i_dentry)) return NULL; alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); __dget(alias); return alias; } /** * d_find_any_alias - find any alias for a given inode * @inode: inode to find an alias for * * If any aliases exist for the given inode, take and return a * reference for one of them. If no aliases exist, return %NULL. */ struct dentry *d_find_any_alias(struct inode *inode) { struct dentry *de; spin_lock(&inode->i_lock); de = __d_find_any_alias(inode); spin_unlock(&inode->i_lock); return de; } EXPORT_SYMBOL(d_find_any_alias); |
1da177e4c
|
948 949 950 |
/** * d_find_alias - grab a hashed alias of inode * @inode: inode in question |
1da177e4c
|
951 952 953 954 955 |
* * If inode has a hashed alias, or is a directory and has any alias, * acquire the reference to alias and return it. Otherwise return NULL. * Notice that if inode is a directory there can be only one alias and * it can be unhashed only if it has no children, or if it is the root |
3ccb354d6
|
956 957 |
* of a filesystem, or if the directory was renamed and d_revalidate * was the first vfs operation to notice. |
1da177e4c
|
958 |
* |
21c0d8fdd
|
959 |
* If the inode has an IS_ROOT, DCACHE_DISCONNECTED alias, then prefer |
52ed46f0f
|
960 |
* any other hashed alias over that one. |
1da177e4c
|
961 |
*/ |
52ed46f0f
|
962 |
static struct dentry *__d_find_alias(struct inode *inode) |
1da177e4c
|
963 |
{ |
61fec493c
|
964 965 966 967 |
struct dentry *alias; if (S_ISDIR(inode->i_mode)) return __d_find_any_alias(inode); |
1da177e4c
|
968 |
|
946e51f2b
|
969 |
hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { |
da5029563
|
970 |
spin_lock(&alias->d_lock); |
61fec493c
|
971 |
if (!d_unhashed(alias)) { |
8d80d7dab
|
972 973 974 |
__dget_dlock(alias); spin_unlock(&alias->d_lock); return alias; |
1da177e4c
|
975 |
} |
da5029563
|
976 |
spin_unlock(&alias->d_lock); |
1da177e4c
|
977 |
} |
da5029563
|
978 |
return NULL; |
1da177e4c
|
979 |
} |
da5029563
|
980 |
struct dentry *d_find_alias(struct inode *inode) |
1da177e4c
|
981 |
{ |
214fda1f6
|
982 |
struct dentry *de = NULL; |
b3d9b7a3c
|
983 |
if (!hlist_empty(&inode->i_dentry)) { |
873feea09
|
984 |
spin_lock(&inode->i_lock); |
52ed46f0f
|
985 |
de = __d_find_alias(inode); |
873feea09
|
986 |
spin_unlock(&inode->i_lock); |
214fda1f6
|
987 |
} |
1da177e4c
|
988 989 |
return de; } |
ec4f86059
|
990 |
EXPORT_SYMBOL(d_find_alias); |
1da177e4c
|
991 992 993 994 995 996 997 |
/* * Try to kill dentries associated with this inode. * WARNING: you must own a reference to inode. */ void d_prune_aliases(struct inode *inode) { |
0cdca3f98
|
998 |
struct dentry *dentry; |
1da177e4c
|
999 |
restart: |
873feea09
|
1000 |
spin_lock(&inode->i_lock); |
946e51f2b
|
1001 |
hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) { |
1da177e4c
|
1002 |
spin_lock(&dentry->d_lock); |
98474236f
|
1003 |
if (!dentry->d_lockref.count) { |
29355c390
|
1004 1005 1006 |
struct dentry *parent = lock_parent(dentry); if (likely(!dentry->d_lockref.count)) { __dentry_kill(dentry); |
4a7795d35
|
1007 |
dput(parent); |
29355c390
|
1008 1009 1010 1011 |
goto restart; } if (parent) spin_unlock(&parent->d_lock); |
1da177e4c
|
1012 1013 1014 |
} spin_unlock(&dentry->d_lock); } |
873feea09
|
1015 |
spin_unlock(&inode->i_lock); |
1da177e4c
|
1016 |
} |
ec4f86059
|
1017 |
EXPORT_SYMBOL(d_prune_aliases); |
1da177e4c
|
1018 |
|
3b3f09f48
|
1019 1020 |
/* * Lock a dentry from shrink list. |
8f04da2ad
|
1021 1022 |
* Called under rcu_read_lock() and dentry->d_lock; the former * guarantees that nothing we access will be freed under us. |
3b3f09f48
|
1023 |
* Note that dentry is *not* protected from concurrent dentry_kill(), |
8f04da2ad
|
1024 1025 |
* d_delete(), etc. * |
3b3f09f48
|
1026 1027 1028 1029 1030 |
* Return false if dentry has been disrupted or grabbed, leaving * the caller to kick it off-list. Otherwise, return true and have * that dentry's inode and parent both locked. */ static bool shrink_lock_dentry(struct dentry *dentry) |
1da177e4c
|
1031 |
{ |
3b3f09f48
|
1032 1033 |
struct inode *inode; struct dentry *parent; |
da3bbdd46
|
1034 |
|
3b3f09f48
|
1035 1036 1037 1038 1039 |
if (dentry->d_lockref.count) return false; inode = dentry->d_inode; if (inode && unlikely(!spin_trylock(&inode->i_lock))) { |
3b3f09f48
|
1040 1041 |
spin_unlock(&dentry->d_lock); spin_lock(&inode->i_lock); |
ec33679d7
|
1042 |
spin_lock(&dentry->d_lock); |
3b3f09f48
|
1043 1044 1045 1046 1047 |
if (unlikely(dentry->d_lockref.count)) goto out; /* changed inode means that somebody had grabbed it */ if (unlikely(inode != dentry->d_inode)) goto out; |
3b3f09f48
|
1048 |
} |
046b961b4
|
1049 |
|
3b3f09f48
|
1050 1051 1052 |
parent = dentry->d_parent; if (IS_ROOT(dentry) || likely(spin_trylock(&parent->d_lock))) return true; |
dd1f6b2e4
|
1053 |
|
3b3f09f48
|
1054 |
spin_unlock(&dentry->d_lock); |
3b3f09f48
|
1055 1056 1057 1058 1059 1060 1061 |
spin_lock(&parent->d_lock); if (unlikely(parent != dentry->d_parent)) { spin_unlock(&parent->d_lock); spin_lock(&dentry->d_lock); goto out; } spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
8f04da2ad
|
1062 |
if (likely(!dentry->d_lockref.count)) |
3b3f09f48
|
1063 |
return true; |
3b3f09f48
|
1064 1065 1066 1067 |
spin_unlock(&parent->d_lock); out: if (inode) spin_unlock(&inode->i_lock); |
3b3f09f48
|
1068 1069 |
return false; } |
77812a1ef
|
1070 |
|
9bdebc2bd
|
1071 |
void shrink_dentry_list(struct list_head *list) |
3b3f09f48
|
1072 1073 1074 |
{ while (!list_empty(list)) { struct dentry *dentry, *parent; |
64fd72e0a
|
1075 |
|
3b3f09f48
|
1076 1077 |
dentry = list_entry(list->prev, struct dentry, d_lru); spin_lock(&dentry->d_lock); |
8f04da2ad
|
1078 |
rcu_read_lock(); |
3b3f09f48
|
1079 1080 |
if (!shrink_lock_dentry(dentry)) { bool can_free = false; |
8f04da2ad
|
1081 |
rcu_read_unlock(); |
3b3f09f48
|
1082 1083 1084 |
d_shrink_del(dentry); if (dentry->d_lockref.count < 0) can_free = dentry->d_flags & DCACHE_MAY_FREE; |
64fd72e0a
|
1085 1086 1087 1088 1089 |
spin_unlock(&dentry->d_lock); if (can_free) dentry_free(dentry); continue; } |
8f04da2ad
|
1090 |
rcu_read_unlock(); |
3b3f09f48
|
1091 1092 |
d_shrink_del(dentry); parent = dentry->d_parent; |
9bdebc2bd
|
1093 1094 |
if (parent != dentry) __dput_to_list(parent, list); |
ff2fde992
|
1095 |
__dentry_kill(dentry); |
da3bbdd46
|
1096 |
} |
3049cfe24
|
1097 |
} |
3f97b1632
|
1098 1099 |
static enum lru_status dentry_lru_isolate(struct list_head *item, struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
f60415675
|
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 |
{ struct list_head *freeable = arg; struct dentry *dentry = container_of(item, struct dentry, d_lru); /* * we are inverting the lru lock/dentry->d_lock here, * so use a trylock. If we fail to get the lock, just skip * it */ if (!spin_trylock(&dentry->d_lock)) return LRU_SKIP; /* * Referenced dentries are still in use. If they have active * counts, just remove them from the LRU. Otherwise give them * another pass through the LRU. */ if (dentry->d_lockref.count) { |
3f97b1632
|
1119 |
d_lru_isolate(lru, dentry); |
f60415675
|
1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 |
spin_unlock(&dentry->d_lock); return LRU_REMOVED; } if (dentry->d_flags & DCACHE_REFERENCED) { dentry->d_flags &= ~DCACHE_REFERENCED; spin_unlock(&dentry->d_lock); /* * The list move itself will be made by the common LRU code. At * this point, we've dropped the dentry->d_lock but keep the * lru lock. This is safe to do, since every list movement is * protected by the lru lock even if both locks are held. * * This is guaranteed by the fact that all LRU management * functions are intermediated by the LRU API calls like * list_lru_add and list_lru_del. List movement in this file * only ever occur through this functions or through callbacks * like this one, that are called from the LRU API. * * The only exceptions to this are functions like * shrink_dentry_list, and code that first checks for the * DCACHE_SHRINK_LIST flag. Those are guaranteed to be * operating only with stack provided lists after they are * properly isolated from the main list. It is thus, always a * local access. */ return LRU_ROTATE; } |
3f97b1632
|
1149 |
d_lru_shrink_move(lru, dentry, freeable); |
f60415675
|
1150 1151 1152 1153 |
spin_unlock(&dentry->d_lock); return LRU_REMOVED; } |
3049cfe24
|
1154 |
/** |
b48f03b31
|
1155 1156 |
* prune_dcache_sb - shrink the dcache * @sb: superblock |
503c358cf
|
1157 |
* @sc: shrink control, passed to list_lru_shrink_walk() |
b48f03b31
|
1158 |
* |
503c358cf
|
1159 1160 |
* Attempt to shrink the superblock dcache LRU by @sc->nr_to_scan entries. This * is done when we need more memory and called from the superblock shrinker |
b48f03b31
|
1161 |
* function. |
3049cfe24
|
1162 |
* |
b48f03b31
|
1163 1164 |
* This function may fail to free any resources if all the dentries are in * use. |
3049cfe24
|
1165 |
*/ |
503c358cf
|
1166 |
long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc) |
3049cfe24
|
1167 |
{ |
f60415675
|
1168 1169 |
LIST_HEAD(dispose); long freed; |
3049cfe24
|
1170 |
|
503c358cf
|
1171 1172 |
freed = list_lru_shrink_walk(&sb->s_dentry_lru, sc, dentry_lru_isolate, &dispose); |
f60415675
|
1173 |
shrink_dentry_list(&dispose); |
0a234c6dc
|
1174 |
return freed; |
da3bbdd46
|
1175 |
} |
230445078
|
1176 |
|
4e717f5c1
|
1177 |
static enum lru_status dentry_lru_isolate_shrink(struct list_head *item, |
3f97b1632
|
1178 |
struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) |
dd1f6b2e4
|
1179 |
{ |
4e717f5c1
|
1180 1181 |
struct list_head *freeable = arg; struct dentry *dentry = container_of(item, struct dentry, d_lru); |
dd1f6b2e4
|
1182 |
|
4e717f5c1
|
1183 1184 1185 1186 1187 1188 1189 |
/* * we are inverting the lru lock/dentry->d_lock here, * so use a trylock. If we fail to get the lock, just skip * it */ if (!spin_trylock(&dentry->d_lock)) return LRU_SKIP; |
3f97b1632
|
1190 |
d_lru_shrink_move(lru, dentry, freeable); |
4e717f5c1
|
1191 |
spin_unlock(&dentry->d_lock); |
ec33679d7
|
1192 |
|
4e717f5c1
|
1193 |
return LRU_REMOVED; |
da3bbdd46
|
1194 |
} |
4e717f5c1
|
1195 |
|
da3bbdd46
|
1196 |
/** |
1da177e4c
|
1197 1198 1199 |
* shrink_dcache_sb - shrink dcache for a superblock * @sb: superblock * |
3049cfe24
|
1200 1201 |
* Shrink the dcache for the specified super block. This is used to free * the dcache before unmounting a file system. |
1da177e4c
|
1202 |
*/ |
3049cfe24
|
1203 |
void shrink_dcache_sb(struct super_block *sb) |
1da177e4c
|
1204 |
{ |
4e717f5c1
|
1205 1206 |
do { LIST_HEAD(dispose); |
1dbd449c9
|
1207 |
list_lru_walk(&sb->s_dentry_lru, |
b17c070fb
|
1208 |
dentry_lru_isolate_shrink, &dispose, 1024); |
4e717f5c1
|
1209 |
shrink_dentry_list(&dispose); |
b17c070fb
|
1210 |
} while (list_lru_count(&sb->s_dentry_lru) > 0); |
1da177e4c
|
1211 |
} |
ec4f86059
|
1212 |
EXPORT_SYMBOL(shrink_dcache_sb); |
1da177e4c
|
1213 |
|
db14fc3ab
|
1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 |
/** * enum d_walk_ret - action to talke during tree walk * @D_WALK_CONTINUE: contrinue walk * @D_WALK_QUIT: quit walk * @D_WALK_NORETRY: quit when retry is needed * @D_WALK_SKIP: skip this dentry and its children */ enum d_walk_ret { D_WALK_CONTINUE, D_WALK_QUIT, D_WALK_NORETRY, D_WALK_SKIP, }; |
c826cb7df
|
1227 |
|
1da177e4c
|
1228 |
/** |
db14fc3ab
|
1229 1230 1231 1232 |
* d_walk - walk the dentry tree * @parent: start of walk * @data: data passed to @enter() and @finish() * @enter: callback when first entering the dentry |
1da177e4c
|
1233 |
* |
3a8e3611e
|
1234 |
* The @enter() callbacks are called with d_lock held. |
1da177e4c
|
1235 |
*/ |
db14fc3ab
|
1236 |
static void d_walk(struct dentry *parent, void *data, |
3a8e3611e
|
1237 |
enum d_walk_ret (*enter)(void *, struct dentry *)) |
1da177e4c
|
1238 |
{ |
949854d02
|
1239 |
struct dentry *this_parent; |
1da177e4c
|
1240 |
struct list_head *next; |
48f5ec21d
|
1241 |
unsigned seq = 0; |
db14fc3ab
|
1242 1243 |
enum d_walk_ret ret; bool retry = true; |
949854d02
|
1244 |
|
58db63d08
|
1245 |
again: |
48f5ec21d
|
1246 |
read_seqbegin_or_lock(&rename_lock, &seq); |
58db63d08
|
1247 |
this_parent = parent; |
2fd6b7f50
|
1248 |
spin_lock(&this_parent->d_lock); |
db14fc3ab
|
1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 |
ret = enter(data, this_parent); switch (ret) { case D_WALK_CONTINUE: break; case D_WALK_QUIT: case D_WALK_SKIP: goto out_unlock; case D_WALK_NORETRY: retry = false; break; } |
1da177e4c
|
1261 1262 1263 1264 1265 |
repeat: next = this_parent->d_subdirs.next; resume: while (next != &this_parent->d_subdirs) { struct list_head *tmp = next; |
946e51f2b
|
1266 |
struct dentry *dentry = list_entry(tmp, struct dentry, d_child); |
1da177e4c
|
1267 |
next = tmp->next; |
2fd6b7f50
|
1268 |
|
ba65dc5ef
|
1269 1270 |
if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR)) continue; |
2fd6b7f50
|
1271 |
spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
db14fc3ab
|
1272 1273 1274 1275 1276 1277 |
ret = enter(data, dentry); switch (ret) { case D_WALK_CONTINUE: break; case D_WALK_QUIT: |
2fd6b7f50
|
1278 |
spin_unlock(&dentry->d_lock); |
db14fc3ab
|
1279 1280 1281 1282 1283 1284 1285 |
goto out_unlock; case D_WALK_NORETRY: retry = false; break; case D_WALK_SKIP: spin_unlock(&dentry->d_lock); continue; |
2fd6b7f50
|
1286 |
} |
db14fc3ab
|
1287 |
|
1da177e4c
|
1288 |
if (!list_empty(&dentry->d_subdirs)) { |
2fd6b7f50
|
1289 |
spin_unlock(&this_parent->d_lock); |
5facae4f3
|
1290 |
spin_release(&dentry->d_lock.dep_map, _RET_IP_); |
1da177e4c
|
1291 |
this_parent = dentry; |
2fd6b7f50
|
1292 |
spin_acquire(&this_parent->d_lock.dep_map, 0, 1, _RET_IP_); |
1da177e4c
|
1293 1294 |
goto repeat; } |
2fd6b7f50
|
1295 |
spin_unlock(&dentry->d_lock); |
1da177e4c
|
1296 1297 1298 1299 |
} /* * All done at this level ... ascend and resume the search. */ |
ca5358ef7
|
1300 1301 |
rcu_read_lock(); ascend: |
1da177e4c
|
1302 |
if (this_parent != parent) { |
c826cb7df
|
1303 |
struct dentry *child = this_parent; |
31dec1327
|
1304 |
this_parent = child->d_parent; |
31dec1327
|
1305 1306 |
spin_unlock(&child->d_lock); spin_lock(&this_parent->d_lock); |
ca5358ef7
|
1307 1308 |
/* might go back up the wrong parent if we have had a rename. */ if (need_seqretry(&rename_lock, seq)) |
949854d02
|
1309 |
goto rename_retry; |
2159184ea
|
1310 1311 1312 |
/* go into the first sibling still alive */ do { next = child->d_child.next; |
ca5358ef7
|
1313 1314 1315 |
if (next == &this_parent->d_subdirs) goto ascend; child = list_entry(next, struct dentry, d_child); |
2159184ea
|
1316 |
} while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)); |
31dec1327
|
1317 |
rcu_read_unlock(); |
1da177e4c
|
1318 1319 |
goto resume; } |
ca5358ef7
|
1320 |
if (need_seqretry(&rename_lock, seq)) |
949854d02
|
1321 |
goto rename_retry; |
ca5358ef7
|
1322 |
rcu_read_unlock(); |
db14fc3ab
|
1323 1324 1325 |
out_unlock: spin_unlock(&this_parent->d_lock); |
48f5ec21d
|
1326 |
done_seqretry(&rename_lock, seq); |
db14fc3ab
|
1327 |
return; |
58db63d08
|
1328 1329 |
rename_retry: |
ca5358ef7
|
1330 1331 1332 |
spin_unlock(&this_parent->d_lock); rcu_read_unlock(); BUG_ON(seq & 1); |
db14fc3ab
|
1333 1334 |
if (!retry) return; |
48f5ec21d
|
1335 |
seq = 1; |
58db63d08
|
1336 |
goto again; |
1da177e4c
|
1337 |
} |
db14fc3ab
|
1338 |
|
01619491a
|
1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 |
struct check_mount { struct vfsmount *mnt; unsigned int mounted; }; static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry) { struct check_mount *info = data; struct path path = { .mnt = info->mnt, .dentry = dentry }; if (likely(!d_mountpoint(dentry))) return D_WALK_CONTINUE; if (__path_is_mountpoint(&path)) { info->mounted = 1; return D_WALK_QUIT; } return D_WALK_CONTINUE; } /** * path_has_submounts - check for mounts over a dentry in the * current namespace. * @parent: path to check. * * Return true if the parent or its subdirectories contain * a mount point in the current namespace. */ int path_has_submounts(const struct path *parent) { struct check_mount data = { .mnt = parent->mnt, .mounted = 0 }; read_seqlock_excl(&mount_lock); |
3a8e3611e
|
1371 |
d_walk(parent->dentry, &data, path_check_mount); |
01619491a
|
1372 1373 1374 1375 1376 |
read_sequnlock_excl(&mount_lock); return data.mounted; } EXPORT_SYMBOL(path_has_submounts); |
1da177e4c
|
1377 |
/* |
eed810076
|
1378 1379 1380 1381 |
* Called by mount code to set a mountpoint and check if the mountpoint is * reachable (e.g. NFS can unhash a directory dentry and then the complete * subtree can become unreachable). * |
1ffe46d11
|
1382 |
* Only one of d_invalidate() and d_set_mounted() must succeed. For |
eed810076
|
1383 1384 1385 1386 1387 1388 1389 1390 |
* this reason take rename_lock and d_lock on dentry and ancestors. */ int d_set_mounted(struct dentry *dentry) { struct dentry *p; int ret = -ENOENT; write_seqlock(&rename_lock); for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) { |
1ffe46d11
|
1391 |
/* Need exclusion wrt. d_invalidate() */ |
eed810076
|
1392 1393 1394 1395 1396 1397 1398 1399 1400 |
spin_lock(&p->d_lock); if (unlikely(d_unhashed(p))) { spin_unlock(&p->d_lock); goto out; } spin_unlock(&p->d_lock); } spin_lock(&dentry->d_lock); if (!d_unlinked(dentry)) { |
3895dbf89
|
1401 1402 1403 1404 1405 |
ret = -EBUSY; if (!d_mountpoint(dentry)) { dentry->d_flags |= DCACHE_MOUNTED; ret = 0; } |
eed810076
|
1406 1407 1408 1409 1410 1411 1412 1413 |
} spin_unlock(&dentry->d_lock); out: write_sequnlock(&rename_lock); return ret; } /* |
fd5179094
|
1414 |
* Search the dentry child list of the specified parent, |
1da177e4c
|
1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 |
* and move any unused dentries to the end of the unused * list for prune_dcache(). We descend to the next level * whenever the d_subdirs list is non-empty and continue * searching. * * It returns zero iff there are no unused children, * otherwise it returns the number of children moved to * the end of the unused list. This may not be the total * number of unused children, because select_parent can * drop the lock and return early due to latency * constraints. */ |
1da177e4c
|
1427 |
|
db14fc3ab
|
1428 1429 |
struct select_data { struct dentry *start; |
9bdebc2bd
|
1430 1431 1432 1433 |
union { long found; struct dentry *victim; }; |
db14fc3ab
|
1434 |
struct list_head dispose; |
db14fc3ab
|
1435 |
}; |
230445078
|
1436 |
|
db14fc3ab
|
1437 1438 1439 1440 |
static enum d_walk_ret select_collect(void *_data, struct dentry *dentry) { struct select_data *data = _data; enum d_walk_ret ret = D_WALK_CONTINUE; |
1da177e4c
|
1441 |
|
db14fc3ab
|
1442 1443 |
if (data->start == dentry) goto out; |
2fd6b7f50
|
1444 |
|
fe91522a7
|
1445 |
if (dentry->d_flags & DCACHE_SHRINK_LIST) { |
db14fc3ab
|
1446 |
data->found++; |
fe91522a7
|
1447 1448 1449 1450 1451 1452 1453 |
} else { if (dentry->d_flags & DCACHE_LRU_LIST) d_lru_del(dentry); if (!dentry->d_lockref.count) { d_shrink_add(dentry, &data->dispose); data->found++; } |
1da177e4c
|
1454 |
} |
db14fc3ab
|
1455 1456 1457 1458 1459 |
/* * We can return to the caller if we have found some (this * ensures forward progress). We'll be coming back to find * the rest. */ |
fe91522a7
|
1460 1461 |
if (!list_empty(&data->dispose)) ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; |
1da177e4c
|
1462 |
out: |
db14fc3ab
|
1463 |
return ret; |
1da177e4c
|
1464 |
} |
9bdebc2bd
|
1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 |
static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry) { struct select_data *data = _data; enum d_walk_ret ret = D_WALK_CONTINUE; if (data->start == dentry) goto out; if (dentry->d_flags & DCACHE_SHRINK_LIST) { if (!dentry->d_lockref.count) { rcu_read_lock(); data->victim = dentry; return D_WALK_QUIT; } } else { if (dentry->d_flags & DCACHE_LRU_LIST) d_lru_del(dentry); if (!dentry->d_lockref.count) d_shrink_add(dentry, &data->dispose); } /* * We can return to the caller if we have found some (this * ensures forward progress). We'll be coming back to find * the rest. */ if (!list_empty(&data->dispose)) ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY; out: return ret; } |
1da177e4c
|
1495 1496 1497 1498 1499 1500 |
/** * shrink_dcache_parent - prune dcache * @parent: parent of entries to prune * * Prune the dcache to remove unused children of the parent dentry. */ |
db14fc3ab
|
1501 |
void shrink_dcache_parent(struct dentry *parent) |
1da177e4c
|
1502 |
{ |
db14fc3ab
|
1503 |
for (;;) { |
9bdebc2bd
|
1504 |
struct select_data data = {.start = parent}; |
1da177e4c
|
1505 |
|
db14fc3ab
|
1506 |
INIT_LIST_HEAD(&data.dispose); |
3a8e3611e
|
1507 |
d_walk(parent, &data, select_collect); |
4fb488714
|
1508 1509 1510 1511 1512 1513 1514 |
if (!list_empty(&data.dispose)) { shrink_dentry_list(&data.dispose); continue; } cond_resched(); |
db14fc3ab
|
1515 1516 |
if (!data.found) break; |
9bdebc2bd
|
1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 |
data.victim = NULL; d_walk(parent, &data, select_collect2); if (data.victim) { struct dentry *parent; spin_lock(&data.victim->d_lock); if (!shrink_lock_dentry(data.victim)) { spin_unlock(&data.victim->d_lock); rcu_read_unlock(); } else { rcu_read_unlock(); parent = data.victim->d_parent; if (parent != data.victim) __dput_to_list(parent, &data.dispose); __dentry_kill(data.victim); } } if (!list_empty(&data.dispose)) shrink_dentry_list(&data.dispose); |
421348f1c
|
1535 |
} |
1da177e4c
|
1536 |
} |
ec4f86059
|
1537 |
EXPORT_SYMBOL(shrink_dcache_parent); |
1da177e4c
|
1538 |
|
9c8c10e26
|
1539 |
static enum d_walk_ret umount_check(void *_data, struct dentry *dentry) |
42c326082
|
1540 |
{ |
9c8c10e26
|
1541 1542 1543 |
/* it has busy descendents; complain about those instead */ if (!list_empty(&dentry->d_subdirs)) return D_WALK_CONTINUE; |
42c326082
|
1544 |
|
9c8c10e26
|
1545 1546 1547 1548 1549 1550 1551 |
/* root with refcount 1 is fine */ if (dentry == _data && dentry->d_lockref.count == 1) return D_WALK_CONTINUE; printk(KERN_ERR "BUG: Dentry %p{i=%lx,n=%pd} " " still in use (%d) [unmount of %s %s] ", |
42c326082
|
1552 1553 1554 |
dentry, dentry->d_inode ? dentry->d_inode->i_ino : 0UL, |
9c8c10e26
|
1555 |
dentry, |
42c326082
|
1556 1557 1558 |
dentry->d_lockref.count, dentry->d_sb->s_type->name, dentry->d_sb->s_id); |
9c8c10e26
|
1559 1560 1561 1562 1563 1564 1565 |
WARN_ON(1); return D_WALK_CONTINUE; } static void do_one_tree(struct dentry *dentry) { shrink_dcache_parent(dentry); |
3a8e3611e
|
1566 |
d_walk(dentry, dentry, umount_check); |
9c8c10e26
|
1567 1568 |
d_drop(dentry); dput(dentry); |
42c326082
|
1569 1570 1571 1572 1573 1574 1575 1576 |
} /* * destroy the dentries attached to a superblock on unmounting */ void shrink_dcache_for_umount(struct super_block *sb) { struct dentry *dentry; |
9c8c10e26
|
1577 |
WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked"); |
42c326082
|
1578 1579 1580 |
dentry = sb->s_root; sb->s_root = NULL; |
9c8c10e26
|
1581 |
do_one_tree(dentry); |
42c326082
|
1582 |
|
f1ee61621
|
1583 1584 |
while (!hlist_bl_empty(&sb->s_roots)) { dentry = dget(hlist_bl_entry(hlist_bl_first(&sb->s_roots), struct dentry, d_hash)); |
9c8c10e26
|
1585 |
do_one_tree(dentry); |
42c326082
|
1586 1587 |
} } |
ff17fa561
|
1588 |
static enum d_walk_ret find_submount(void *_data, struct dentry *dentry) |
848ac114e
|
1589 |
{ |
ff17fa561
|
1590 |
struct dentry **victim = _data; |
848ac114e
|
1591 |
if (d_mountpoint(dentry)) { |
8ed936b56
|
1592 |
__dget_dlock(dentry); |
ff17fa561
|
1593 |
*victim = dentry; |
848ac114e
|
1594 1595 |
return D_WALK_QUIT; } |
ff17fa561
|
1596 |
return D_WALK_CONTINUE; |
848ac114e
|
1597 1598 1599 |
} /** |
1ffe46d11
|
1600 1601 |
* d_invalidate - detach submounts, prune dcache, and drop * @dentry: dentry to invalidate (aka detach, prune and drop) |
848ac114e
|
1602 |
*/ |
5542aa2fa
|
1603 |
void d_invalidate(struct dentry *dentry) |
848ac114e
|
1604 |
{ |
ff17fa561
|
1605 |
bool had_submounts = false; |
1ffe46d11
|
1606 1607 1608 |
spin_lock(&dentry->d_lock); if (d_unhashed(dentry)) { spin_unlock(&dentry->d_lock); |
5542aa2fa
|
1609 |
return; |
1ffe46d11
|
1610 |
} |
ff17fa561
|
1611 |
__d_drop(dentry); |
1ffe46d11
|
1612 |
spin_unlock(&dentry->d_lock); |
848ac114e
|
1613 |
/* Negative dentries can be dropped without further checks */ |
ff17fa561
|
1614 |
if (!dentry->d_inode) |
5542aa2fa
|
1615 |
return; |
848ac114e
|
1616 |
|
ff17fa561
|
1617 |
shrink_dcache_parent(dentry); |
848ac114e
|
1618 |
for (;;) { |
ff17fa561
|
1619 |
struct dentry *victim = NULL; |
3a8e3611e
|
1620 |
d_walk(dentry, &victim, find_submount); |
ff17fa561
|
1621 1622 1623 |
if (!victim) { if (had_submounts) shrink_dcache_parent(dentry); |
81be24d26
|
1624 |
return; |
8ed936b56
|
1625 |
} |
ff17fa561
|
1626 1627 1628 |
had_submounts = true; detach_mounts(victim); dput(victim); |
848ac114e
|
1629 |
} |
848ac114e
|
1630 |
} |
1ffe46d11
|
1631 |
EXPORT_SYMBOL(d_invalidate); |
848ac114e
|
1632 |
|
1da177e4c
|
1633 |
/** |
a4464dbc0
|
1634 1635 |
* __d_alloc - allocate a dcache entry * @sb: filesystem it will belong to |
1da177e4c
|
1636 1637 1638 1639 1640 1641 1642 |
* @name: qstr of the name * * Allocates a dentry. It returns %NULL if there is insufficient memory * available. On a success the dentry is returned. The name passed in is * copied and the copy passed in may be reused after this call. */ |
5c8b0dfc6
|
1643 |
static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name) |
1da177e4c
|
1644 1645 1646 |
{ struct dentry *dentry; char *dname; |
285b102d3
|
1647 |
int err; |
1da177e4c
|
1648 |
|
e12ba74d8
|
1649 |
dentry = kmem_cache_alloc(dentry_cache, GFP_KERNEL); |
1da177e4c
|
1650 1651 |
if (!dentry) return NULL; |
6326c71fd
|
1652 1653 1654 1655 1656 1657 1658 |
/* * We guarantee that the inline name is always NUL-terminated. * This way the memcpy() done by the name switching in rename * will still always have a NUL at the end, even if we might * be overwriting an internal NUL character */ dentry->d_iname[DNAME_INLINE_LEN-1] = 0; |
798434bda
|
1659 |
if (unlikely(!name)) { |
cdf01226b
|
1660 |
name = &slash_name; |
798434bda
|
1661 1662 |
dname = dentry->d_iname; } else if (name->len > DNAME_INLINE_LEN-1) { |
8d85b4845
|
1663 |
size_t size = offsetof(struct external_name, name[1]); |
2e03b4bc4
|
1664 1665 1666 1667 |
struct external_name *p = kmalloc(size + name->len, GFP_KERNEL_ACCOUNT | __GFP_RECLAIMABLE); if (!p) { |
1da177e4c
|
1668 1669 1670 |
kmem_cache_free(dentry_cache, dentry); return NULL; } |
2e03b4bc4
|
1671 1672 |
atomic_set(&p->u.count, 1); dname = p->name; |
1da177e4c
|
1673 1674 1675 |
} else { dname = dentry->d_iname; } |
1da177e4c
|
1676 1677 1678 1679 1680 |
dentry->d_name.len = name->len; dentry->d_name.hash = name->hash; memcpy(dname, name->name, name->len); dname[name->len] = 0; |
6326c71fd
|
1681 |
/* Make sure we always see the terminating NUL character */ |
7088efa91
|
1682 |
smp_store_release(&dentry->d_name.name, dname); /* ^^^ */ |
6326c71fd
|
1683 |
|
98474236f
|
1684 |
dentry->d_lockref.count = 1; |
dea3667bc
|
1685 |
dentry->d_flags = 0; |
1da177e4c
|
1686 |
spin_lock_init(&dentry->d_lock); |
264753719
|
1687 |
seqcount_spinlock_init(&dentry->d_seq, &dentry->d_lock); |
1da177e4c
|
1688 |
dentry->d_inode = NULL; |
a4464dbc0
|
1689 1690 |
dentry->d_parent = dentry; dentry->d_sb = sb; |
1da177e4c
|
1691 1692 |
dentry->d_op = NULL; dentry->d_fsdata = NULL; |
ceb5bdc2d
|
1693 |
INIT_HLIST_BL_NODE(&dentry->d_hash); |
1da177e4c
|
1694 1695 |
INIT_LIST_HEAD(&dentry->d_lru); INIT_LIST_HEAD(&dentry->d_subdirs); |
946e51f2b
|
1696 1697 |
INIT_HLIST_NODE(&dentry->d_u.d_alias); INIT_LIST_HEAD(&dentry->d_child); |
a4464dbc0
|
1698 |
d_set_d_op(dentry, dentry->d_sb->s_d_op); |
1da177e4c
|
1699 |
|
285b102d3
|
1700 1701 1702 1703 1704 1705 1706 1707 1708 |
if (dentry->d_op && dentry->d_op->d_init) { err = dentry->d_op->d_init(dentry); if (err) { if (dname_external(dentry)) kfree(external_name(dentry)); kmem_cache_free(dentry_cache, dentry); return NULL; } } |
3e880fb5e
|
1709 |
this_cpu_inc(nr_dentry); |
312d3ca85
|
1710 |
|
1da177e4c
|
1711 1712 |
return dentry; } |
a4464dbc0
|
1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 |
/** * d_alloc - allocate a dcache entry * @parent: parent of entry to allocate * @name: qstr of the name * * Allocates a dentry. It returns %NULL if there is insufficient memory * available. On a success the dentry is returned. The name passed in is * copied and the copy passed in may be reused after this call. */ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name) { struct dentry *dentry = __d_alloc(parent->d_sb, name); if (!dentry) return NULL; |
a4464dbc0
|
1728 1729 1730 1731 1732 1733 1734 |
spin_lock(&parent->d_lock); /* * don't need child lock because it is not subject * to concurrency here */ __dget_dlock(parent); dentry->d_parent = parent; |
946e51f2b
|
1735 |
list_add(&dentry->d_child, &parent->d_subdirs); |
a4464dbc0
|
1736 1737 1738 1739 |
spin_unlock(&parent->d_lock); return dentry; } |
ec4f86059
|
1740 |
EXPORT_SYMBOL(d_alloc); |
1da177e4c
|
1741 |
|
f9c34674b
|
1742 1743 1744 1745 1746 |
struct dentry *d_alloc_anon(struct super_block *sb) { return __d_alloc(sb, NULL); } EXPORT_SYMBOL(d_alloc_anon); |
ba65dc5ef
|
1747 1748 |
struct dentry *d_alloc_cursor(struct dentry * parent) { |
f9c34674b
|
1749 |
struct dentry *dentry = d_alloc_anon(parent->d_sb); |
ba65dc5ef
|
1750 |
if (dentry) { |
5467a68cb
|
1751 |
dentry->d_flags |= DCACHE_DENTRY_CURSOR; |
ba65dc5ef
|
1752 1753 1754 1755 |
dentry->d_parent = dget(parent); } return dentry; } |
e1a24bb0a
|
1756 1757 1758 1759 1760 1761 1762 |
/** * d_alloc_pseudo - allocate a dentry (for lookup-less filesystems) * @sb: the superblock * @name: qstr of the name * * For a filesystem that just pins its dentries in memory and never * performs lookups at all, return an unhashed IS_ROOT dentry. |
5467a68cb
|
1763 1764 1765 1766 |
* This is used for pipes, sockets et.al. - the stuff that should * never be anyone's children or parents. Unlike all other * dentries, these will not have RCU delay between dropping the * last reference and freeing them. |
ab1152dd5
|
1767 1768 1769 |
* * The only user is alloc_file_pseudo() and that's what should * be considered a public interface. Don't use directly. |
e1a24bb0a
|
1770 |
*/ |
4b936885a
|
1771 1772 |
struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name) { |
5467a68cb
|
1773 1774 1775 1776 |
struct dentry *dentry = __d_alloc(sb, name); if (likely(dentry)) dentry->d_flags |= DCACHE_NORCU; return dentry; |
4b936885a
|
1777 |
} |
4b936885a
|
1778 |
|
1da177e4c
|
1779 1780 1781 1782 1783 |
struct dentry *d_alloc_name(struct dentry *parent, const char *name) { struct qstr q; q.name = name; |
8387ff257
|
1784 |
q.hash_len = hashlen_string(parent, name); |
1da177e4c
|
1785 1786 |
return d_alloc(parent, &q); } |
ef26ca97e
|
1787 |
EXPORT_SYMBOL(d_alloc_name); |
1da177e4c
|
1788 |
|
fb045adb9
|
1789 1790 |
void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op) { |
6f7f7caab
|
1791 1792 |
WARN_ON_ONCE(dentry->d_op); WARN_ON_ONCE(dentry->d_flags & (DCACHE_OP_HASH | |
fb045adb9
|
1793 1794 |
DCACHE_OP_COMPARE | DCACHE_OP_REVALIDATE | |
ecf3d1f1a
|
1795 |
DCACHE_OP_WEAK_REVALIDATE | |
4bacc9c92
|
1796 |
DCACHE_OP_DELETE | |
d101a1259
|
1797 |
DCACHE_OP_REAL)); |
fb045adb9
|
1798 1799 1800 1801 1802 1803 1804 1805 1806 |
dentry->d_op = op; if (!op) return; if (op->d_hash) dentry->d_flags |= DCACHE_OP_HASH; if (op->d_compare) dentry->d_flags |= DCACHE_OP_COMPARE; if (op->d_revalidate) dentry->d_flags |= DCACHE_OP_REVALIDATE; |
ecf3d1f1a
|
1807 1808 |
if (op->d_weak_revalidate) dentry->d_flags |= DCACHE_OP_WEAK_REVALIDATE; |
fb045adb9
|
1809 1810 |
if (op->d_delete) dentry->d_flags |= DCACHE_OP_DELETE; |
f0023bc61
|
1811 1812 |
if (op->d_prune) dentry->d_flags |= DCACHE_OP_PRUNE; |
d101a1259
|
1813 1814 |
if (op->d_real) dentry->d_flags |= DCACHE_OP_REAL; |
fb045adb9
|
1815 1816 1817 |
} EXPORT_SYMBOL(d_set_d_op); |
df1a085af
|
1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 |
/* * d_set_fallthru - Mark a dentry as falling through to a lower layer * @dentry - The dentry to mark * * Mark a dentry as falling through to the lower layer (as set with * d_pin_lower()). This flag may be recorded on the medium. */ void d_set_fallthru(struct dentry *dentry) { spin_lock(&dentry->d_lock); dentry->d_flags |= DCACHE_FALLTHRU; spin_unlock(&dentry->d_lock); } EXPORT_SYMBOL(d_set_fallthru); |
b18825a7c
|
1833 1834 |
static unsigned d_flags_for_inode(struct inode *inode) { |
44bdb5e5f
|
1835 |
unsigned add_flags = DCACHE_REGULAR_TYPE; |
b18825a7c
|
1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 |
if (!inode) return DCACHE_MISS_TYPE; if (S_ISDIR(inode->i_mode)) { add_flags = DCACHE_DIRECTORY_TYPE; if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) { if (unlikely(!inode->i_op->lookup)) add_flags = DCACHE_AUTODIR_TYPE; else inode->i_opflags |= IOP_LOOKUP; } |
44bdb5e5f
|
1848 1849 1850 1851 |
goto type_determined; } if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { |
6b2553918
|
1852 |
if (unlikely(inode->i_op->get_link)) { |
b18825a7c
|
1853 |
add_flags = DCACHE_SYMLINK_TYPE; |
44bdb5e5f
|
1854 1855 1856 |
goto type_determined; } inode->i_opflags |= IOP_NOFOLLOW; |
b18825a7c
|
1857 |
} |
44bdb5e5f
|
1858 1859 1860 1861 |
if (unlikely(!S_ISREG(inode->i_mode))) add_flags = DCACHE_SPECIAL_TYPE; type_determined: |
b18825a7c
|
1862 1863 1864 1865 |
if (unlikely(IS_AUTOMOUNT(inode))) add_flags |= DCACHE_NEED_AUTOMOUNT; return add_flags; } |
360da9002
|
1866 1867 |
static void __d_instantiate(struct dentry *dentry, struct inode *inode) { |
b18825a7c
|
1868 |
unsigned add_flags = d_flags_for_inode(inode); |
85c7f8104
|
1869 |
WARN_ON(d_in_lookup(dentry)); |
b18825a7c
|
1870 |
|
b23fb0a60
|
1871 |
spin_lock(&dentry->d_lock); |
af0c9af1b
|
1872 1873 1874 1875 1876 |
/* * Decrement negative dentry count if it was in the LRU list. */ if (dentry->d_flags & DCACHE_LRU_LIST) this_cpu_dec(nr_dentry_negative); |
de689f5e3
|
1877 |
hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
a528aca7f
|
1878 |
raw_write_seqcount_begin(&dentry->d_seq); |
4bf46a272
|
1879 |
__d_set_inode_and_type(dentry, inode, add_flags); |
a528aca7f
|
1880 |
raw_write_seqcount_end(&dentry->d_seq); |
affda4841
|
1881 |
fsnotify_update_flags(dentry); |
b23fb0a60
|
1882 |
spin_unlock(&dentry->d_lock); |
360da9002
|
1883 |
} |
1da177e4c
|
1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 |
/** * d_instantiate - fill in inode information for a dentry * @entry: dentry to complete * @inode: inode to attach to this dentry * * Fill in inode information in the entry. * * This turns negative dentries into productive full members * of society. * * NOTE! This assumes that the inode count has been incremented * (or otherwise set) by the caller to indicate that it is now * in use by the dcache. */ void d_instantiate(struct dentry *entry, struct inode * inode) { |
946e51f2b
|
1901 |
BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); |
de689f5e3
|
1902 |
if (inode) { |
b96809173
|
1903 |
security_d_instantiate(entry, inode); |
873feea09
|
1904 |
spin_lock(&inode->i_lock); |
de689f5e3
|
1905 |
__d_instantiate(entry, inode); |
873feea09
|
1906 |
spin_unlock(&inode->i_lock); |
de689f5e3
|
1907 |
} |
1da177e4c
|
1908 |
} |
ec4f86059
|
1909 |
EXPORT_SYMBOL(d_instantiate); |
1da177e4c
|
1910 |
|
1e2e547a9
|
1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 |
/* * This should be equivalent to d_instantiate() + unlock_new_inode(), * with lockdep-related part of unlock_new_inode() done before * anything else. Use that instead of open-coding d_instantiate()/ * unlock_new_inode() combinations. */ void d_instantiate_new(struct dentry *entry, struct inode *inode) { BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); BUG_ON(!inode); lockdep_annotate_inode_mutex_key(inode); security_d_instantiate(entry, inode); spin_lock(&inode->i_lock); __d_instantiate(entry, inode); WARN_ON(!(inode->i_state & I_NEW)); |
c2b6d621c
|
1926 |
inode->i_state &= ~I_NEW & ~I_CREATING; |
1e2e547a9
|
1927 1928 1929 1930 1931 |
smp_mb(); wake_up_bit(&inode->i_state, __I_NEW); spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(d_instantiate_new); |
adc0e91ab
|
1932 1933 1934 1935 1936 |
struct dentry *d_make_root(struct inode *root_inode) { struct dentry *res = NULL; if (root_inode) { |
f9c34674b
|
1937 |
res = d_alloc_anon(root_inode->i_sb); |
5467a68cb
|
1938 |
if (res) |
adc0e91ab
|
1939 |
d_instantiate(res, root_inode); |
5467a68cb
|
1940 |
else |
adc0e91ab
|
1941 1942 1943 1944 1945 |
iput(root_inode); } return res; } EXPORT_SYMBOL(d_make_root); |
f9c34674b
|
1946 1947 1948 |
static struct dentry *__d_instantiate_anon(struct dentry *dentry, struct inode *inode, bool disconnected) |
4ea3ada29
|
1949 |
{ |
9308a6128
|
1950 |
struct dentry *res; |
b18825a7c
|
1951 |
unsigned add_flags; |
4ea3ada29
|
1952 |
|
f9c34674b
|
1953 |
security_d_instantiate(dentry, inode); |
873feea09
|
1954 |
spin_lock(&inode->i_lock); |
d891eedbc
|
1955 |
res = __d_find_any_alias(inode); |
9308a6128
|
1956 |
if (res) { |
873feea09
|
1957 |
spin_unlock(&inode->i_lock); |
f9c34674b
|
1958 |
dput(dentry); |
9308a6128
|
1959 1960 1961 1962 |
goto out_iput; } /* attach a disconnected dentry */ |
1a0a397e4
|
1963 1964 1965 1966 |
add_flags = d_flags_for_inode(inode); if (disconnected) add_flags |= DCACHE_DISCONNECTED; |
b18825a7c
|
1967 |
|
f9c34674b
|
1968 1969 1970 |
spin_lock(&dentry->d_lock); __d_set_inode_and_type(dentry, inode, add_flags); hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); |
f1ee61621
|
1971 |
if (!disconnected) { |
139351f1f
|
1972 1973 1974 |
hlist_bl_lock(&dentry->d_sb->s_roots); hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots); hlist_bl_unlock(&dentry->d_sb->s_roots); |
f1ee61621
|
1975 |
} |
f9c34674b
|
1976 |
spin_unlock(&dentry->d_lock); |
873feea09
|
1977 |
spin_unlock(&inode->i_lock); |
9308a6128
|
1978 |
|
f9c34674b
|
1979 |
return dentry; |
9308a6128
|
1980 1981 1982 1983 |
out_iput: iput(inode); return res; |
4ea3ada29
|
1984 |
} |
1a0a397e4
|
1985 |
|
f9c34674b
|
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 |
struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode) { return __d_instantiate_anon(dentry, inode, true); } EXPORT_SYMBOL(d_instantiate_anon); static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected) { struct dentry *tmp; struct dentry *res; if (!inode) return ERR_PTR(-ESTALE); if (IS_ERR(inode)) return ERR_CAST(inode); res = d_find_any_alias(inode); if (res) goto out_iput; tmp = d_alloc_anon(inode->i_sb); if (!tmp) { res = ERR_PTR(-ENOMEM); goto out_iput; } return __d_instantiate_anon(tmp, inode, disconnected); out_iput: iput(inode); return res; } |
1a0a397e4
|
2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 |
/** * d_obtain_alias - find or allocate a DISCONNECTED dentry for a given inode * @inode: inode to allocate the dentry for * * Obtain a dentry for an inode resulting from NFS filehandle conversion or * similar open by handle operations. The returned dentry may be anonymous, * or may have a full name (if the inode was already in the cache). * * When called on a directory inode, we must ensure that the inode only ever * has one dentry. If a dentry is found, that is returned instead of * allocating a new one. * * On successful return, the reference to the inode has been transferred * to the dentry. In case of an error the reference on the inode is released. * To make it easier to use in export operations a %NULL or IS_ERR inode may * be passed in and the error will be propagated to the return value, * with a %NULL @inode replaced by ERR_PTR(-ESTALE). */ struct dentry *d_obtain_alias(struct inode *inode) { |
f9c34674b
|
2038 |
return __d_obtain_alias(inode, true); |
1a0a397e4
|
2039 |
} |
adc487204
|
2040 |
EXPORT_SYMBOL(d_obtain_alias); |
1da177e4c
|
2041 2042 |
/** |
1a0a397e4
|
2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 |
* d_obtain_root - find or allocate a dentry for a given inode * @inode: inode to allocate the dentry for * * Obtain an IS_ROOT dentry for the root of a filesystem. * * We must ensure that directory inodes only ever have one dentry. If a * dentry is found, that is returned instead of allocating a new one. * * On successful return, the reference to the inode has been transferred * to the dentry. In case of an error the reference on the inode is * released. A %NULL or IS_ERR inode may be passed in and will be the * error will be propagate to the return value, with a %NULL @inode * replaced by ERR_PTR(-ESTALE). */ struct dentry *d_obtain_root(struct inode *inode) { |
f9c34674b
|
2059 |
return __d_obtain_alias(inode, false); |
1a0a397e4
|
2060 2061 2062 2063 |
} EXPORT_SYMBOL(d_obtain_root); /** |
9403540c0
|
2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 |
* d_add_ci - lookup or allocate new dentry with case-exact name * @inode: the inode case-insensitive lookup has found * @dentry: the negative dentry that was passed to the parent's lookup func * @name: the case-exact name to be associated with the returned dentry * * This is to avoid filling the dcache with case-insensitive names to the * same inode, only the actual correct case is stored in the dcache for * case-insensitive filesystems. * * For a case-insensitive lookup match and if the the case-exact dentry * already exists in in the dcache, use it and return it. * * If no entry exists with the exact case name, allocate new dentry with * the exact case, and return the spliced entry. */ |
e45b590b9
|
2079 |
struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode, |
9403540c0
|
2080 2081 |
struct qstr *name) { |
d9171b934
|
2082 |
struct dentry *found, *res; |
9403540c0
|
2083 |
|
b6520c819
|
2084 2085 2086 2087 |
/* * First check if a dentry matching the name already exists, * if not go ahead and create it now. */ |
9403540c0
|
2088 |
found = d_hash_and_lookup(dentry->d_parent, name); |
d9171b934
|
2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 |
if (found) { iput(inode); return found; } if (d_in_lookup(dentry)) { found = d_alloc_parallel(dentry->d_parent, name, dentry->d_wait); if (IS_ERR(found) || !d_in_lookup(found)) { iput(inode); return found; |
9403540c0
|
2099 |
} |
d9171b934
|
2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 |
} else { found = d_alloc(dentry->d_parent, name); if (!found) { iput(inode); return ERR_PTR(-ENOMEM); } } res = d_splice_alias(inode, found); if (res) { dput(found); return res; |
9403540c0
|
2111 |
} |
4f522a247
|
2112 |
return found; |
9403540c0
|
2113 |
} |
ec4f86059
|
2114 |
EXPORT_SYMBOL(d_add_ci); |
1da177e4c
|
2115 |
|
12f8ad4b0
|
2116 |
|
d4c91a8f7
|
2117 2118 2119 |
static inline bool d_same_name(const struct dentry *dentry, const struct dentry *parent, const struct qstr *name) |
12f8ad4b0
|
2120 |
{ |
d4c91a8f7
|
2121 2122 2123 2124 |
if (likely(!(parent->d_flags & DCACHE_OP_COMPARE))) { if (dentry->d_name.len != name->len) return false; return dentry_cmp(dentry, name->name, name->len) == 0; |
12f8ad4b0
|
2125 |
} |
6fa67e707
|
2126 |
return parent->d_op->d_compare(dentry, |
d4c91a8f7
|
2127 2128 |
dentry->d_name.len, dentry->d_name.name, name) == 0; |
12f8ad4b0
|
2129 |
} |
1da177e4c
|
2130 |
/** |
31e6b01f4
|
2131 2132 2133 |
* __d_lookup_rcu - search for a dentry (racy, store-free) * @parent: parent dentry * @name: qstr of name we wish to find |
1f1e6e523
|
2134 |
* @seqp: returns d_seq value at the point where the dentry was found |
31e6b01f4
|
2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 |
* Returns: dentry, or NULL * * __d_lookup_rcu is the dcache lookup function for rcu-walk name * resolution (store-free path walking) design described in * Documentation/filesystems/path-lookup.txt. * * This is not to be used outside core vfs. * * __d_lookup_rcu must only be used in rcu-walk mode, ie. with vfsmount lock * held, and rcu_read_lock held. The returned dentry must not be stored into * without taking d_lock and checking d_seq sequence count against @seq * returned here. * |
15570086b
|
2148 |
* A refcount may be taken on the found dentry with the d_rcu_to_refcount |
31e6b01f4
|
2149 2150 2151 2152 2153 2154 |
* function. * * Alternatively, __d_lookup_rcu may be called again to look up the child of * the returned dentry, so long as its parent's seqlock is checked after the * child is looked up. Thus, an interlocking stepping of sequence lock checks * is formed, giving integrity down the path walk. |
12f8ad4b0
|
2155 2156 2157 |
* * NOTE! The caller *has* to check the resulting dentry against the sequence * number we've returned before using any of the resulting dentry state! |
31e6b01f4
|
2158 |
*/ |
8966be903
|
2159 2160 |
struct dentry *__d_lookup_rcu(const struct dentry *parent, const struct qstr *name, |
da53be12b
|
2161 |
unsigned *seqp) |
31e6b01f4
|
2162 |
{ |
26fe57502
|
2163 |
u64 hashlen = name->hash_len; |
31e6b01f4
|
2164 |
const unsigned char *str = name->name; |
8387ff257
|
2165 |
struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen)); |
ceb5bdc2d
|
2166 |
struct hlist_bl_node *node; |
31e6b01f4
|
2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 |
struct dentry *dentry; /* * Note: There is significant duplication with __d_lookup_rcu which is * required to prevent single threaded performance regressions * especially on architectures where smp_rmb (in seqcounts) are costly. * Keep the two functions in sync. */ /* * The hash list is protected using RCU. * * Carefully use d_seq when comparing a candidate dentry, to avoid * races with d_move(). * * It is possible that concurrent renames can mess up our list * walk here and result in missing our dentry, resulting in the * false-negative result. d_lookup() protects against concurrent * renames using rename_lock seqlock. * |
b0a4bb830
|
2187 |
* See Documentation/filesystems/path-lookup.txt for more details. |
31e6b01f4
|
2188 |
*/ |
b07ad9967
|
2189 |
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
8966be903
|
2190 |
unsigned seq; |
31e6b01f4
|
2191 |
|
31e6b01f4
|
2192 |
seqretry: |
12f8ad4b0
|
2193 2194 |
/* * The dentry sequence count protects us from concurrent |
da53be12b
|
2195 |
* renames, and thus protects parent and name fields. |
12f8ad4b0
|
2196 2197 |
* * The caller must perform a seqcount check in order |
da53be12b
|
2198 |
* to do anything useful with the returned dentry. |
12f8ad4b0
|
2199 2200 2201 2202 2203 2204 2205 |
* * NOTE! We do a "raw" seqcount_begin here. That means that * we don't wait for the sequence count to stabilize if it * is in the middle of a sequence change. If we do the slow * dentry compare, we will do seqretries until it is stable, * and if we end up with a successful lookup, we actually * want to exit RCU lookup anyway. |
d4c91a8f7
|
2206 2207 2208 |
* * Note that raw_seqcount_begin still *does* smp_rmb(), so * we are still guaranteed NUL-termination of ->d_name.name. |
12f8ad4b0
|
2209 2210 |
*/ seq = raw_seqcount_begin(&dentry->d_seq); |
31e6b01f4
|
2211 2212 |
if (dentry->d_parent != parent) continue; |
2e321806b
|
2213 2214 |
if (d_unhashed(dentry)) continue; |
12f8ad4b0
|
2215 |
|
830c0f0ed
|
2216 |
if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) { |
d4c91a8f7
|
2217 2218 |
int tlen; const char *tname; |
26fe57502
|
2219 2220 |
if (dentry->d_name.hash != hashlen_hash(hashlen)) continue; |
d4c91a8f7
|
2221 2222 2223 2224 2225 |
tlen = dentry->d_name.len; tname = dentry->d_name.name; /* we want a consistent (name,len) pair */ if (read_seqcount_retry(&dentry->d_seq, seq)) { cpu_relax(); |
12f8ad4b0
|
2226 2227 |
goto seqretry; } |
6fa67e707
|
2228 |
if (parent->d_op->d_compare(dentry, |
d4c91a8f7
|
2229 2230 2231 2232 2233 2234 2235 |
tlen, tname, name) != 0) continue; } else { if (dentry->d_name.hash_len != hashlen) continue; if (dentry_cmp(dentry, str, hashlen_len(hashlen)) != 0) continue; |
31e6b01f4
|
2236 |
} |
da53be12b
|
2237 |
*seqp = seq; |
d4c91a8f7
|
2238 |
return dentry; |
31e6b01f4
|
2239 2240 2241 2242 2243 |
} return NULL; } /** |
1da177e4c
|
2244 2245 2246 |
* d_lookup - search for a dentry * @parent: parent dentry * @name: qstr of name we wish to find |
b04f784e5
|
2247 |
* Returns: dentry, or NULL |
1da177e4c
|
2248 |
* |
b04f784e5
|
2249 2250 2251 2252 |
* d_lookup searches the children of the parent dentry for the name in * question. If the dentry is found its reference count is incremented and the * dentry is returned. The caller must use dput to free the entry when it has * finished using it. %NULL is returned if the dentry does not exist. |
1da177e4c
|
2253 |
*/ |
da2d8455e
|
2254 |
struct dentry *d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4c
|
2255 |
{ |
31e6b01f4
|
2256 |
struct dentry *dentry; |
949854d02
|
2257 |
unsigned seq; |
1da177e4c
|
2258 |
|
b8314f930
|
2259 2260 2261 2262 |
do { seq = read_seqbegin(&rename_lock); dentry = __d_lookup(parent, name); if (dentry) |
1da177e4c
|
2263 2264 2265 2266 |
break; } while (read_seqretry(&rename_lock, seq)); return dentry; } |
ec4f86059
|
2267 |
EXPORT_SYMBOL(d_lookup); |
1da177e4c
|
2268 |
|
31e6b01f4
|
2269 |
/** |
b04f784e5
|
2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 |
* __d_lookup - search for a dentry (racy) * @parent: parent dentry * @name: qstr of name we wish to find * Returns: dentry, or NULL * * __d_lookup is like d_lookup, however it may (rarely) return a * false-negative result due to unrelated rename activity. * * __d_lookup is slightly faster by avoiding rename_lock read seqlock, * however it must be used carefully, eg. with a following d_lookup in * the case of failure. * * __d_lookup callers must be commented. */ |
a713ca2ab
|
2284 |
struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name) |
1da177e4c
|
2285 |
{ |
1da177e4c
|
2286 |
unsigned int hash = name->hash; |
8387ff257
|
2287 |
struct hlist_bl_head *b = d_hash(hash); |
ceb5bdc2d
|
2288 |
struct hlist_bl_node *node; |
31e6b01f4
|
2289 |
struct dentry *found = NULL; |
665a7583f
|
2290 |
struct dentry *dentry; |
1da177e4c
|
2291 |
|
b04f784e5
|
2292 |
/* |
31e6b01f4
|
2293 2294 2295 2296 2297 2298 2299 |
* Note: There is significant duplication with __d_lookup_rcu which is * required to prevent single threaded performance regressions * especially on architectures where smp_rmb (in seqcounts) are costly. * Keep the two functions in sync. */ /* |
b04f784e5
|
2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 |
* The hash list is protected using RCU. * * Take d_lock when comparing a candidate dentry, to avoid races * with d_move(). * * It is possible that concurrent renames can mess up our list * walk here and result in missing our dentry, resulting in the * false-negative result. d_lookup() protects against concurrent * renames using rename_lock seqlock. * |
b0a4bb830
|
2310 |
* See Documentation/filesystems/path-lookup.txt for more details. |
b04f784e5
|
2311 |
*/ |
1da177e4c
|
2312 2313 |
rcu_read_lock(); |
b07ad9967
|
2314 |
hlist_bl_for_each_entry_rcu(dentry, node, b, d_hash) { |
1da177e4c
|
2315 |
|
1da177e4c
|
2316 2317 |
if (dentry->d_name.hash != hash) continue; |
1da177e4c
|
2318 2319 |
spin_lock(&dentry->d_lock); |
1da177e4c
|
2320 2321 |
if (dentry->d_parent != parent) goto next; |
d0185c088
|
2322 2323 |
if (d_unhashed(dentry)) goto next; |
d4c91a8f7
|
2324 2325 |
if (!d_same_name(dentry, parent, name)) goto next; |
1da177e4c
|
2326 |
|
98474236f
|
2327 |
dentry->d_lockref.count++; |
d0185c088
|
2328 |
found = dentry; |
1da177e4c
|
2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 |
spin_unlock(&dentry->d_lock); break; next: spin_unlock(&dentry->d_lock); } rcu_read_unlock(); return found; } /** |
3e7e241f8
|
2340 2341 2342 2343 |
* d_hash_and_lookup - hash the qstr then search for a dentry * @dir: Directory to search in * @name: qstr of name we wish to find * |
4f522a247
|
2344 |
* On lookup failure NULL is returned; on bad name - ERR_PTR(-error) |
3e7e241f8
|
2345 2346 2347 |
*/ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name) { |
3e7e241f8
|
2348 2349 2350 2351 2352 |
/* * Check for a fs-specific hash function. Note that we must * calculate the standard hash first, as the d_op->d_hash() * routine may choose to leave the hash value unchanged. */ |
8387ff257
|
2353 |
name->hash = full_name_hash(dir, name->name, name->len); |
fb045adb9
|
2354 |
if (dir->d_flags & DCACHE_OP_HASH) { |
da53be12b
|
2355 |
int err = dir->d_op->d_hash(dir, name); |
4f522a247
|
2356 2357 |
if (unlikely(err < 0)) return ERR_PTR(err); |
3e7e241f8
|
2358 |
} |
4f522a247
|
2359 |
return d_lookup(dir, name); |
3e7e241f8
|
2360 |
} |
4f522a247
|
2361 |
EXPORT_SYMBOL(d_hash_and_lookup); |
3e7e241f8
|
2362 |
|
1da177e4c
|
2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 |
/* * When a file is deleted, we have two options: * - turn this dentry into a negative dentry * - unhash this dentry and free it. * * Usually, we want to just turn this into * a negative dentry, but if anybody else is * currently using the dentry or the inode * we can't do that and we fall back on removing * it from the hash queues and waiting for * it to be deleted later when it has no users */ /** * d_delete - delete a dentry * @dentry: The dentry to delete * * Turn the dentry into a negative dentry if possible, otherwise * remove it from the hash queues so it can be deleted later */ void d_delete(struct dentry * dentry) { |
c19457f0a
|
2386 |
struct inode *inode = dentry->d_inode; |
c19457f0a
|
2387 2388 2389 |
spin_lock(&inode->i_lock); spin_lock(&dentry->d_lock); |
1da177e4c
|
2390 2391 2392 |
/* * Are we the only user? */ |
98474236f
|
2393 |
if (dentry->d_lockref.count == 1) { |
13e3c5e5b
|
2394 |
dentry->d_flags &= ~DCACHE_CANT_MOUNT; |
31e6b01f4
|
2395 |
dentry_unlink_inode(dentry); |
c19457f0a
|
2396 |
} else { |
1da177e4c
|
2397 |
__d_drop(dentry); |
c19457f0a
|
2398 2399 2400 |
spin_unlock(&dentry->d_lock); spin_unlock(&inode->i_lock); } |
1da177e4c
|
2401 |
} |
ec4f86059
|
2402 |
EXPORT_SYMBOL(d_delete); |
1da177e4c
|
2403 |
|
15d3c589f
|
2404 |
static void __d_rehash(struct dentry *entry) |
1da177e4c
|
2405 |
{ |
15d3c589f
|
2406 |
struct hlist_bl_head *b = d_hash(entry->d_name.hash); |
61647823a
|
2407 |
|
1879fd6a2
|
2408 |
hlist_bl_lock(b); |
b07ad9967
|
2409 |
hlist_bl_add_head_rcu(&entry->d_hash, b); |
1879fd6a2
|
2410 |
hlist_bl_unlock(b); |
1da177e4c
|
2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 |
} /** * d_rehash - add an entry back to the hash * @entry: dentry to add to the hash * * Adds a dentry to the hash according to its name. */ void d_rehash(struct dentry * entry) { |
1da177e4c
|
2422 |
spin_lock(&entry->d_lock); |
15d3c589f
|
2423 |
__d_rehash(entry); |
1da177e4c
|
2424 |
spin_unlock(&entry->d_lock); |
1da177e4c
|
2425 |
} |
ec4f86059
|
2426 |
EXPORT_SYMBOL(d_rehash); |
1da177e4c
|
2427 |
|
84e710da2
|
2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 |
static inline unsigned start_dir_add(struct inode *dir) { for (;;) { unsigned n = dir->i_dir_seq; if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n) return n; cpu_relax(); } } static inline void end_dir_add(struct inode *dir, unsigned n) { smp_store_release(&dir->i_dir_seq, n + 2); } |
d9171b934
|
2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 |
static void d_wait_lookup(struct dentry *dentry) { if (d_in_lookup(dentry)) { DECLARE_WAITQUEUE(wait, current); add_wait_queue(dentry->d_wait, &wait); do { set_current_state(TASK_UNINTERRUPTIBLE); spin_unlock(&dentry->d_lock); schedule(); spin_lock(&dentry->d_lock); } while (d_in_lookup(dentry)); } } |
94bdd655c
|
2456 |
struct dentry *d_alloc_parallel(struct dentry *parent, |
d9171b934
|
2457 2458 |
const struct qstr *name, wait_queue_head_t *wq) |
94bdd655c
|
2459 |
{ |
94bdd655c
|
2460 |
unsigned int hash = name->hash; |
94bdd655c
|
2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 |
struct hlist_bl_head *b = in_lookup_hash(parent, hash); struct hlist_bl_node *node; struct dentry *new = d_alloc(parent, name); struct dentry *dentry; unsigned seq, r_seq, d_seq; if (unlikely(!new)) return ERR_PTR(-ENOMEM); retry: rcu_read_lock(); |
015555fd4
|
2472 |
seq = smp_load_acquire(&parent->d_inode->i_dir_seq); |
94bdd655c
|
2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 |
r_seq = read_seqbegin(&rename_lock); dentry = __d_lookup_rcu(parent, name, &d_seq); if (unlikely(dentry)) { if (!lockref_get_not_dead(&dentry->d_lockref)) { rcu_read_unlock(); goto retry; } if (read_seqcount_retry(&dentry->d_seq, d_seq)) { rcu_read_unlock(); dput(dentry); goto retry; } rcu_read_unlock(); dput(new); return dentry; } if (unlikely(read_seqretry(&rename_lock, r_seq))) { rcu_read_unlock(); goto retry; } |
015555fd4
|
2493 2494 2495 2496 2497 |
if (unlikely(seq & 1)) { rcu_read_unlock(); goto retry; } |
94bdd655c
|
2498 |
hlist_bl_lock(b); |
8cc07c808
|
2499 |
if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) { |
94bdd655c
|
2500 2501 2502 2503 |
hlist_bl_unlock(b); rcu_read_unlock(); goto retry; } |
94bdd655c
|
2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 |
/* * No changes for the parent since the beginning of d_lookup(). * Since all removals from the chain happen with hlist_bl_lock(), * any potential in-lookup matches are going to stay here until * we unlock the chain. All fields are stable in everything * we encounter. */ hlist_bl_for_each_entry(dentry, node, b, d_u.d_in_lookup_hash) { if (dentry->d_name.hash != hash) continue; if (dentry->d_parent != parent) continue; |
d4c91a8f7
|
2516 2517 |
if (!d_same_name(dentry, parent, name)) continue; |
94bdd655c
|
2518 |
hlist_bl_unlock(b); |
e7d6ef979
|
2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 |
/* now we can try to grab a reference */ if (!lockref_get_not_dead(&dentry->d_lockref)) { rcu_read_unlock(); goto retry; } rcu_read_unlock(); /* * somebody is likely to be still doing lookup for it; * wait for them to finish */ |
d9171b934
|
2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 |
spin_lock(&dentry->d_lock); d_wait_lookup(dentry); /* * it's not in-lookup anymore; in principle we should repeat * everything from dcache lookup, but it's likely to be what * d_lookup() would've found anyway. If it is, just return it; * otherwise we really have to repeat the whole thing. */ if (unlikely(dentry->d_name.hash != hash)) goto mismatch; if (unlikely(dentry->d_parent != parent)) goto mismatch; if (unlikely(d_unhashed(dentry))) goto mismatch; |
d4c91a8f7
|
2544 2545 |
if (unlikely(!d_same_name(dentry, parent, name))) goto mismatch; |
d9171b934
|
2546 2547 |
/* OK, it *is* a hashed match; return it */ spin_unlock(&dentry->d_lock); |
94bdd655c
|
2548 2549 2550 |
dput(new); return dentry; } |
e7d6ef979
|
2551 |
rcu_read_unlock(); |
94bdd655c
|
2552 2553 |
/* we can't take ->d_lock here; it's OK, though. */ new->d_flags |= DCACHE_PAR_LOOKUP; |
d9171b934
|
2554 |
new->d_wait = wq; |
94bdd655c
|
2555 2556 2557 |
hlist_bl_add_head_rcu(&new->d_u.d_in_lookup_hash, b); hlist_bl_unlock(b); return new; |
d9171b934
|
2558 2559 2560 2561 |
mismatch: spin_unlock(&dentry->d_lock); dput(dentry); goto retry; |
94bdd655c
|
2562 2563 |
} EXPORT_SYMBOL(d_alloc_parallel); |
85c7f8104
|
2564 2565 |
void __d_lookup_done(struct dentry *dentry) { |
94bdd655c
|
2566 2567 2568 |
struct hlist_bl_head *b = in_lookup_hash(dentry->d_parent, dentry->d_name.hash); hlist_bl_lock(b); |
85c7f8104
|
2569 |
dentry->d_flags &= ~DCACHE_PAR_LOOKUP; |
94bdd655c
|
2570 |
__hlist_bl_del(&dentry->d_u.d_in_lookup_hash); |
d9171b934
|
2571 2572 |
wake_up_all(dentry->d_wait); dentry->d_wait = NULL; |
94bdd655c
|
2573 2574 |
hlist_bl_unlock(b); INIT_HLIST_NODE(&dentry->d_u.d_alias); |
d9171b934
|
2575 |
INIT_LIST_HEAD(&dentry->d_lru); |
85c7f8104
|
2576 2577 |
} EXPORT_SYMBOL(__d_lookup_done); |
ed782b5a7
|
2578 2579 2580 2581 2582 |
/* inode->i_lock held if inode is non-NULL */ static inline void __d_add(struct dentry *dentry, struct inode *inode) { |
84e710da2
|
2583 2584 |
struct inode *dir = NULL; unsigned n; |
0568d705b
|
2585 |
spin_lock(&dentry->d_lock); |
84e710da2
|
2586 2587 2588 |
if (unlikely(d_in_lookup(dentry))) { dir = dentry->d_parent->d_inode; n = start_dir_add(dir); |
85c7f8104
|
2589 |
__d_lookup_done(dentry); |
84e710da2
|
2590 |
} |
ed782b5a7
|
2591 |
if (inode) { |
0568d705b
|
2592 2593 2594 2595 2596 |
unsigned add_flags = d_flags_for_inode(inode); hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry); raw_write_seqcount_begin(&dentry->d_seq); __d_set_inode_and_type(dentry, inode, add_flags); raw_write_seqcount_end(&dentry->d_seq); |
affda4841
|
2597 |
fsnotify_update_flags(dentry); |
ed782b5a7
|
2598 |
} |
15d3c589f
|
2599 |
__d_rehash(dentry); |
84e710da2
|
2600 2601 |
if (dir) end_dir_add(dir, n); |
0568d705b
|
2602 2603 2604 |
spin_unlock(&dentry->d_lock); if (inode) spin_unlock(&inode->i_lock); |
ed782b5a7
|
2605 |
} |
fb2d5b86a
|
2606 |
/** |
34d0d19dc
|
2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 |
* d_add - add dentry to hash queues * @entry: dentry to add * @inode: The inode to attach to this dentry * * This adds the entry to the hash queues and initializes @inode. * The entry was actually filled in earlier during d_alloc(). */ void d_add(struct dentry *entry, struct inode *inode) { |
b96809173
|
2617 2618 |
if (inode) { security_d_instantiate(entry, inode); |
ed782b5a7
|
2619 |
spin_lock(&inode->i_lock); |
b96809173
|
2620 |
} |
ed782b5a7
|
2621 |
__d_add(entry, inode); |
34d0d19dc
|
2622 2623 2624 2625 |
} EXPORT_SYMBOL(d_add); /** |
668d0cd56
|
2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 |
* d_exact_alias - find and hash an exact unhashed alias * @entry: dentry to add * @inode: The inode to go with this dentry * * If an unhashed dentry with the same name/parent and desired * inode already exists, hash and return it. Otherwise, return * NULL. * * Parent directory should be locked. */ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode) { struct dentry *alias; |
668d0cd56
|
2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 |
unsigned int hash = entry->d_name.hash; spin_lock(&inode->i_lock); hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { /* * Don't need alias->d_lock here, because aliases with * d_parent == entry->d_parent are not subject to name or * parent changes, because the parent inode i_mutex is held. */ if (alias->d_name.hash != hash) continue; if (alias->d_parent != entry->d_parent) continue; |
d4c91a8f7
|
2652 |
if (!d_same_name(alias, entry->d_parent, &entry->d_name)) |
668d0cd56
|
2653 2654 2655 2656 2657 2658 2659 |
continue; spin_lock(&alias->d_lock); if (!d_unhashed(alias)) { spin_unlock(&alias->d_lock); alias = NULL; } else { __dget_dlock(alias); |
15d3c589f
|
2660 |
__d_rehash(alias); |
668d0cd56
|
2661 2662 2663 2664 2665 2666 2667 2668 2669 |
spin_unlock(&alias->d_lock); } spin_unlock(&inode->i_lock); return alias; } spin_unlock(&inode->i_lock); return NULL; } EXPORT_SYMBOL(d_exact_alias); |
8d85b4845
|
2670 |
static void swap_names(struct dentry *dentry, struct dentry *target) |
1da177e4c
|
2671 |
{ |
8d85b4845
|
2672 2673 |
if (unlikely(dname_external(target))) { if (unlikely(dname_external(dentry))) { |
1da177e4c
|
2674 2675 2676 |
/* * Both external: swap the pointers */ |
9a8d5bb4a
|
2677 |
swap(target->d_name.name, dentry->d_name.name); |
1da177e4c
|
2678 2679 2680 2681 2682 |
} else { /* * dentry:internal, target:external. Steal target's * storage and make target internal. */ |
321bcf921
|
2683 2684 |
memcpy(target->d_iname, dentry->d_name.name, dentry->d_name.len + 1); |
1da177e4c
|
2685 2686 2687 2688 |
dentry->d_name.name = target->d_name.name; target->d_name.name = target->d_iname; } } else { |
8d85b4845
|
2689 |
if (unlikely(dname_external(dentry))) { |
1da177e4c
|
2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 |
/* * dentry:external, target:internal. Give dentry's * storage to target and make dentry internal */ memcpy(dentry->d_iname, target->d_name.name, target->d_name.len + 1); target->d_name.name = dentry->d_name.name; dentry->d_name.name = dentry->d_iname; } else { /* |
da1ce0670
|
2700 |
* Both are internal. |
1da177e4c
|
2701 |
*/ |
da1ce0670
|
2702 2703 2704 2705 2706 2707 |
unsigned int i; BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long))); for (i = 0; i < DNAME_INLINE_LEN / sizeof(long); i++) { swap(((long *) &dentry->d_iname)[i], ((long *) &target->d_iname)[i]); } |
1da177e4c
|
2708 2709 |
} } |
a28ddb87c
|
2710 |
swap(dentry->d_name.hash_len, target->d_name.hash_len); |
1da177e4c
|
2711 |
} |
8d85b4845
|
2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 |
static void copy_name(struct dentry *dentry, struct dentry *target) { struct external_name *old_name = NULL; if (unlikely(dname_external(dentry))) old_name = external_name(dentry); if (unlikely(dname_external(target))) { atomic_inc(&external_name(target)->u.count); dentry->d_name = target->d_name; } else { memcpy(dentry->d_iname, target->d_name.name, target->d_name.len + 1); dentry->d_name.name = dentry->d_iname; dentry->d_name.hash_len = target->d_name.hash_len; } if (old_name && likely(atomic_dec_and_test(&old_name->u.count))) |
2e03b4bc4
|
2727 |
kfree_rcu(old_name, u.head); |
8d85b4845
|
2728 |
} |
1da177e4c
|
2729 |
/* |
183675011
|
2730 |
* __d_move - move a dentry |
1da177e4c
|
2731 2732 |
* @dentry: entry to move * @target: new dentry |
da1ce0670
|
2733 |
* @exchange: exchange the two dentries |
1da177e4c
|
2734 2735 |
* * Update the dcache to reflect the move of a file name. Negative |
c46c88774
|
2736 2737 2738 |
* dcache entries should not be moved in this way. Caller must hold * rename_lock, the i_mutex of the source and target directories, * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). |
1da177e4c
|
2739 |
*/ |
da1ce0670
|
2740 2741 |
static void __d_move(struct dentry *dentry, struct dentry *target, bool exchange) |
1da177e4c
|
2742 |
{ |
42177007a
|
2743 |
struct dentry *old_parent, *p; |
84e710da2
|
2744 2745 |
struct inode *dir = NULL; unsigned n; |
1da177e4c
|
2746 |
|
42177007a
|
2747 2748 2749 |
WARN_ON(!dentry->d_inode); if (WARN_ON(dentry == target)) return; |
2fd6b7f50
|
2750 |
BUG_ON(d_ancestor(target, dentry)); |
42177007a
|
2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 |
old_parent = dentry->d_parent; p = d_ancestor(old_parent, target); if (IS_ROOT(dentry)) { BUG_ON(p); spin_lock(&target->d_parent->d_lock); } else if (!p) { /* target is not a descendent of dentry->d_parent */ spin_lock(&target->d_parent->d_lock); spin_lock_nested(&old_parent->d_lock, DENTRY_D_LOCK_NESTED); } else { BUG_ON(p == dentry); spin_lock(&old_parent->d_lock); if (p != target) spin_lock_nested(&target->d_parent->d_lock, DENTRY_D_LOCK_NESTED); } spin_lock_nested(&dentry->d_lock, 2); spin_lock_nested(&target->d_lock, 3); |
2fd6b7f50
|
2769 |
|
84e710da2
|
2770 2771 2772 |
if (unlikely(d_in_lookup(target))) { dir = target->d_parent->d_inode; n = start_dir_add(dir); |
85c7f8104
|
2773 |
__d_lookup_done(target); |
84e710da2
|
2774 |
} |
1da177e4c
|
2775 |
|
31e6b01f4
|
2776 |
write_seqcount_begin(&dentry->d_seq); |
1ca7d67cf
|
2777 |
write_seqcount_begin_nested(&target->d_seq, DENTRY_D_LOCK_NESTED); |
31e6b01f4
|
2778 |
|
15d3c589f
|
2779 |
/* unhash both */ |
0632a9ac7
|
2780 2781 2782 2783 |
if (!d_unhashed(dentry)) ___d_drop(dentry); if (!d_unhashed(target)) ___d_drop(target); |
1da177e4c
|
2784 |
|
076515fc9
|
2785 2786 2787 |
/* ... and switch them in the tree */ dentry->d_parent = target->d_parent; if (!exchange) { |
8d85b4845
|
2788 |
copy_name(dentry, target); |
61647823a
|
2789 |
target->d_hash.pprev = NULL; |
076515fc9
|
2790 |
dentry->d_parent->d_lockref.count++; |
5467a68cb
|
2791 |
if (dentry != old_parent) /* wasn't IS_ROOT */ |
076515fc9
|
2792 |
WARN_ON(!--old_parent->d_lockref.count); |
1da177e4c
|
2793 |
} else { |
076515fc9
|
2794 2795 |
target->d_parent = old_parent; swap_names(dentry, target); |
946e51f2b
|
2796 |
list_move(&target->d_child, &target->d_parent->d_subdirs); |
076515fc9
|
2797 2798 |
__d_rehash(target); fsnotify_update_flags(target); |
1da177e4c
|
2799 |
} |
076515fc9
|
2800 2801 2802 |
list_move(&dentry->d_child, &dentry->d_parent->d_subdirs); __d_rehash(dentry); fsnotify_update_flags(dentry); |
0bf3d5c16
|
2803 |
fscrypt_handle_d_move(dentry); |
1da177e4c
|
2804 |
|
31e6b01f4
|
2805 2806 |
write_seqcount_end(&target->d_seq); write_seqcount_end(&dentry->d_seq); |
84e710da2
|
2807 2808 |
if (dir) end_dir_add(dir, n); |
076515fc9
|
2809 2810 2811 2812 2813 2814 2815 |
if (dentry->d_parent != old_parent) spin_unlock(&dentry->d_parent->d_lock); if (dentry != old_parent) spin_unlock(&old_parent->d_lock); spin_unlock(&target->d_lock); spin_unlock(&dentry->d_lock); |
183675011
|
2816 2817 2818 2819 2820 2821 2822 2823 |
} /* * d_move - move a dentry * @dentry: entry to move * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative |
c46c88774
|
2824 2825 |
* dcache entries should not be moved in this way. See the locking * requirements for __d_move. |
183675011
|
2826 2827 2828 2829 |
*/ void d_move(struct dentry *dentry, struct dentry *target) { write_seqlock(&rename_lock); |
da1ce0670
|
2830 |
__d_move(dentry, target, false); |
1da177e4c
|
2831 |
write_sequnlock(&rename_lock); |
9eaef27b3
|
2832 |
} |
ec4f86059
|
2833 |
EXPORT_SYMBOL(d_move); |
1da177e4c
|
2834 |
|
da1ce0670
|
2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 |
/* * d_exchange - exchange two dentries * @dentry1: first dentry * @dentry2: second dentry */ void d_exchange(struct dentry *dentry1, struct dentry *dentry2) { write_seqlock(&rename_lock); WARN_ON(!dentry1->d_inode); WARN_ON(!dentry2->d_inode); WARN_ON(IS_ROOT(dentry1)); WARN_ON(IS_ROOT(dentry2)); __d_move(dentry1, dentry2, true); write_sequnlock(&rename_lock); } |
e2761a116
|
2853 2854 2855 2856 2857 2858 2859 |
/** * d_ancestor - search for an ancestor * @p1: ancestor dentry * @p2: child dentry * * Returns the ancestor dentry of p2 which is a child of p1, if p1 is * an ancestor of p2, else NULL. |
9eaef27b3
|
2860 |
*/ |
e2761a116
|
2861 |
struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2) |
9eaef27b3
|
2862 2863 |
{ struct dentry *p; |
871c0067d
|
2864 |
for (p = p2; !IS_ROOT(p); p = p->d_parent) { |
9eaef27b3
|
2865 |
if (p->d_parent == p1) |
e2761a116
|
2866 |
return p; |
9eaef27b3
|
2867 |
} |
e2761a116
|
2868 |
return NULL; |
9eaef27b3
|
2869 2870 2871 2872 2873 2874 |
} /* * This helper attempts to cope with remotely renamed directories * * It assumes that the caller is already holding |
a03e283bf
|
2875 |
* dentry->d_parent->d_inode->i_mutex, and rename_lock |
9eaef27b3
|
2876 2877 2878 |
* * Note: If ever the locking in lock_rename() changes, then please * remember to update this too... |
9eaef27b3
|
2879 |
*/ |
b5ae6b15b
|
2880 |
static int __d_unalias(struct inode *inode, |
873feea09
|
2881 |
struct dentry *dentry, struct dentry *alias) |
9eaef27b3
|
2882 |
{ |
9902af79c
|
2883 2884 |
struct mutex *m1 = NULL; struct rw_semaphore *m2 = NULL; |
3d330dc17
|
2885 |
int ret = -ESTALE; |
9eaef27b3
|
2886 2887 2888 2889 |
/* If alias and dentry share a parent, then no extra locks required */ if (alias->d_parent == dentry->d_parent) goto out_unalias; |
9eaef27b3
|
2890 |
/* See lock_rename() */ |
9eaef27b3
|
2891 2892 2893 |
if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) goto out_err; m1 = &dentry->d_sb->s_vfs_rename_mutex; |
9902af79c
|
2894 |
if (!inode_trylock_shared(alias->d_parent->d_inode)) |
9eaef27b3
|
2895 |
goto out_err; |
9902af79c
|
2896 |
m2 = &alias->d_parent->d_inode->i_rwsem; |
9eaef27b3
|
2897 |
out_unalias: |
8ed936b56
|
2898 |
__d_move(alias, dentry, false); |
b5ae6b15b
|
2899 |
ret = 0; |
9eaef27b3
|
2900 |
out_err: |
9eaef27b3
|
2901 |
if (m2) |
9902af79c
|
2902 |
up_read(m2); |
9eaef27b3
|
2903 2904 2905 2906 |
if (m1) mutex_unlock(m1); return ret; } |
770bfad84
|
2907 |
/** |
3f70bd51c
|
2908 2909 2910 2911 |
* d_splice_alias - splice a disconnected dentry into the tree if one exists * @inode: the inode which may have a disconnected dentry * @dentry: a negative dentry which we want to point to the inode. * |
da093a9b7
|
2912 2913 2914 |
* If inode is a directory and has an IS_ROOT alias, then d_move that in * place of the given dentry and return it, else simply d_add the inode * to the dentry and return NULL. |
3f70bd51c
|
2915 |
* |
908790fa3
|
2916 2917 2918 |
* If a non-IS_ROOT directory is found, the filesystem is corrupt, and * we should error out: directories can't have multiple aliases. * |
3f70bd51c
|
2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 |
* This is needed in the lookup routine of any filesystem that is exportable * (via knfsd) so that we can build dcache paths to directories effectively. * * If a dentry was found and moved, then it is returned. Otherwise NULL * is returned. This matches the expected return value of ->lookup. * * Cluster filesystems may call this function with a negative, hashed dentry. * In that case, we know that the inode will be a regular file, and also this * will only occur during atomic_open. So we need to check for the dentry * being already hashed only in the final case. */ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry) { |
3f70bd51c
|
2932 2933 |
if (IS_ERR(inode)) return ERR_CAST(inode); |
770bfad84
|
2934 |
BUG_ON(!d_unhashed(dentry)); |
de689f5e3
|
2935 |
if (!inode) |
b5ae6b15b
|
2936 |
goto out; |
de689f5e3
|
2937 |
|
b96809173
|
2938 |
security_d_instantiate(dentry, inode); |
873feea09
|
2939 |
spin_lock(&inode->i_lock); |
9eaef27b3
|
2940 |
if (S_ISDIR(inode->i_mode)) { |
b5ae6b15b
|
2941 2942 |
struct dentry *new = __d_find_any_alias(inode); if (unlikely(new)) { |
a03e283bf
|
2943 2944 |
/* The reference to new ensures it remains an alias */ spin_unlock(&inode->i_lock); |
183675011
|
2945 |
write_seqlock(&rename_lock); |
b5ae6b15b
|
2946 2947 |
if (unlikely(d_ancestor(new, dentry))) { write_sequnlock(&rename_lock); |
b5ae6b15b
|
2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 |
dput(new); new = ERR_PTR(-ELOOP); pr_warn_ratelimited( "VFS: Lookup of '%s' in %s %s" " would have caused loop ", dentry->d_name.name, inode->i_sb->s_type->name, inode->i_sb->s_id); } else if (!IS_ROOT(new)) { |
076515fc9
|
2958 |
struct dentry *old_parent = dget(new->d_parent); |
b5ae6b15b
|
2959 |
int err = __d_unalias(inode, dentry, new); |
183675011
|
2960 |
write_sequnlock(&rename_lock); |
b5ae6b15b
|
2961 2962 2963 2964 |
if (err) { dput(new); new = ERR_PTR(err); } |
076515fc9
|
2965 |
dput(old_parent); |
183675011
|
2966 |
} else { |
b5ae6b15b
|
2967 2968 |
__d_move(new, dentry, false); write_sequnlock(&rename_lock); |
dd179946d
|
2969 |
} |
b5ae6b15b
|
2970 2971 |
iput(inode); return new; |
9eaef27b3
|
2972 |
} |
770bfad84
|
2973 |
} |
b5ae6b15b
|
2974 |
out: |
ed782b5a7
|
2975 |
__d_add(dentry, inode); |
b5ae6b15b
|
2976 |
return NULL; |
770bfad84
|
2977 |
} |
b5ae6b15b
|
2978 |
EXPORT_SYMBOL(d_splice_alias); |
770bfad84
|
2979 |
|
1da177e4c
|
2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 |
/* * Test whether new_dentry is a subdirectory of old_dentry. * * Trivially implemented using the dcache structure */ /** * is_subdir - is new dentry a subdirectory of old_dentry * @new_dentry: new dentry * @old_dentry: old dentry * |
a6e5787fc
|
2991 2992 |
* Returns true if new_dentry is a subdirectory of the parent (at any depth). * Returns false otherwise. |
1da177e4c
|
2993 2994 2995 |
* Caller must ensure that "new_dentry" is pinned before calling is_subdir() */ |
a6e5787fc
|
2996 |
bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry) |
1da177e4c
|
2997 |
{ |
a6e5787fc
|
2998 |
bool result; |
949854d02
|
2999 |
unsigned seq; |
1da177e4c
|
3000 |
|
e2761a116
|
3001 |
if (new_dentry == old_dentry) |
a6e5787fc
|
3002 |
return true; |
e2761a116
|
3003 |
|
e2761a116
|
3004 |
do { |
1da177e4c
|
3005 |
/* for restarting inner loop in case of seq retry */ |
1da177e4c
|
3006 |
seq = read_seqbegin(&rename_lock); |
949854d02
|
3007 3008 3009 3010 3011 |
/* * Need rcu_readlock to protect against the d_parent trashing * due to d_move */ rcu_read_lock(); |
e2761a116
|
3012 |
if (d_ancestor(old_dentry, new_dentry)) |
a6e5787fc
|
3013 |
result = true; |
e2761a116
|
3014 |
else |
a6e5787fc
|
3015 |
result = false; |
949854d02
|
3016 |
rcu_read_unlock(); |
1da177e4c
|
3017 |
} while (read_seqretry(&rename_lock, seq)); |
1da177e4c
|
3018 3019 3020 |
return result; } |
e8f9e5b78
|
3021 |
EXPORT_SYMBOL(is_subdir); |
1da177e4c
|
3022 |
|
db14fc3ab
|
3023 |
static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry) |
1da177e4c
|
3024 |
{ |
db14fc3ab
|
3025 3026 3027 3028 |
struct dentry *root = data; if (dentry != root) { if (d_unhashed(dentry) || !dentry->d_inode) return D_WALK_SKIP; |
1da177e4c
|
3029 |
|
01ddc4ede
|
3030 3031 3032 3033 |
if (!(dentry->d_flags & DCACHE_GENOCIDE)) { dentry->d_flags |= DCACHE_GENOCIDE; dentry->d_lockref.count--; } |
1da177e4c
|
3034 |
} |
db14fc3ab
|
3035 3036 |
return D_WALK_CONTINUE; } |
58db63d08
|
3037 |
|
db14fc3ab
|
3038 3039 |
void d_genocide(struct dentry *parent) { |
3a8e3611e
|
3040 |
d_walk(parent, parent, d_genocide_kill); |
1da177e4c
|
3041 |
} |
cbd4a5bcb
|
3042 |
EXPORT_SYMBOL(d_genocide); |
60545d0d4
|
3043 |
void d_tmpfile(struct dentry *dentry, struct inode *inode) |
1da177e4c
|
3044 |
{ |
60545d0d4
|
3045 3046 |
inode_dec_link_count(inode); BUG_ON(dentry->d_name.name != dentry->d_iname || |
946e51f2b
|
3047 |
!hlist_unhashed(&dentry->d_u.d_alias) || |
60545d0d4
|
3048 3049 3050 3051 3052 3053 3054 3055 |
!d_unlinked(dentry)); spin_lock(&dentry->d_parent->d_lock); spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", (unsigned long long)inode->i_ino); spin_unlock(&dentry->d_lock); spin_unlock(&dentry->d_parent->d_lock); d_instantiate(dentry, inode); |
1da177e4c
|
3056 |
} |
60545d0d4
|
3057 |
EXPORT_SYMBOL(d_tmpfile); |
1da177e4c
|
3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 |
static __initdata unsigned long dhash_entries; static int __init set_dhash_entries(char *str) { if (!str) return 0; dhash_entries = simple_strtoul(str, &str, 0); return 1; } __setup("dhash_entries=", set_dhash_entries); static void __init dcache_init_early(void) { |
1da177e4c
|
3071 3072 3073 3074 3075 3076 3077 3078 |
/* If hashes are distributed across NUMA nodes, defer * hash allocation until vmalloc space is available. */ if (hashdist) return; dentry_hashtable = alloc_large_system_hash("Dentry cache", |
b07ad9967
|
3079 |
sizeof(struct hlist_bl_head), |
1da177e4c
|
3080 3081 |
dhash_entries, 13, |
3d375d785
|
3082 |
HASH_EARLY | HASH_ZERO, |
1da177e4c
|
3083 |
&d_hash_shift, |
b35d786b6
|
3084 |
NULL, |
31fe62b95
|
3085 |
0, |
1da177e4c
|
3086 |
0); |
854d3e634
|
3087 |
d_hash_shift = 32 - d_hash_shift; |
1da177e4c
|
3088 |
} |
74bf17cff
|
3089 |
static void __init dcache_init(void) |
1da177e4c
|
3090 |
{ |
3d375d785
|
3091 |
/* |
1da177e4c
|
3092 3093 |
* A constructor could be added for stable state like the lists, * but it is probably not worth it because of the cache nature |
3d375d785
|
3094 |
* of the dcache. |
1da177e4c
|
3095 |
*/ |
80344266c
|
3096 3097 3098 |
dentry_cache = KMEM_CACHE_USERCOPY(dentry, SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD|SLAB_ACCOUNT, d_iname); |
1da177e4c
|
3099 3100 3101 3102 3103 3104 3105 |
/* Hash may have been set up in dcache_init_early */ if (!hashdist) return; dentry_hashtable = alloc_large_system_hash("Dentry cache", |
b07ad9967
|
3106 |
sizeof(struct hlist_bl_head), |
1da177e4c
|
3107 3108 |
dhash_entries, 13, |
3d375d785
|
3109 |
HASH_ZERO, |
1da177e4c
|
3110 |
&d_hash_shift, |
b35d786b6
|
3111 |
NULL, |
31fe62b95
|
3112 |
0, |
1da177e4c
|
3113 |
0); |
854d3e634
|
3114 |
d_hash_shift = 32 - d_hash_shift; |
1da177e4c
|
3115 3116 3117 |
} /* SLAB cache for __getname() consumers */ |
e18b890bb
|
3118 |
struct kmem_cache *names_cachep __read_mostly; |
ec4f86059
|
3119 |
EXPORT_SYMBOL(names_cachep); |
1da177e4c
|
3120 |
|
1da177e4c
|
3121 3122 |
void __init vfs_caches_init_early(void) { |
6916363f3
|
3123 3124 3125 3126 |
int i; for (i = 0; i < ARRAY_SIZE(in_lookup_hashtable); i++) INIT_HLIST_BL_HEAD(&in_lookup_hashtable[i]); |
1da177e4c
|
3127 3128 3129 |
dcache_init_early(); inode_init_early(); } |
4248b0da4
|
3130 |
void __init vfs_caches_init(void) |
1da177e4c
|
3131 |
{ |
6a9b88204
|
3132 3133 |
names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, 0, PATH_MAX, NULL); |
1da177e4c
|
3134 |
|
74bf17cff
|
3135 3136 |
dcache_init(); inode_init(); |
4248b0da4
|
3137 3138 |
files_init(); files_maxfiles_init(); |
74bf17cff
|
3139 |
mnt_init(); |
1da177e4c
|
3140 3141 3142 |
bdev_cache_init(); chrdev_init(); } |