/*

   * linux/fs/ext4/xattr.c

   *
   * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   *
   * Fix by Harrison Xing <harrison@mountainviewdata.com>.

   * Ext4 code with a lot of help from Eric Jarman <ejarman@acm.org>.

   * Extended attributes for symlinks and special files added per
   *  suggestion of Luka Renko <luka.renko@hermes.si>.
   * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>,
   *  Red Hat Inc.
   * ea-in-inode support by Alex Tomas <alex@clusterfs.com> aka bzzz
   *  and Andreas Gruenbacher <agruen@suse.de>.
   */
  
  /*
   * Extended attributes are stored directly in inodes (on file systems with
   * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
   * field contains the block number if an inode uses an additional block. All
   * attributes must fit in the inode and one additional block. Blocks that
   * contain the identical set of attributes may be shared among several inodes.
   * Identical blocks are detected by keeping a cache of blocks that have
   * recently been accessed.
   *
   * The attributes in inodes and on blocks have a different header; the entries
   * are stored in the same format:
   *
   *   +------------------+
   *   | header           |
   *   | entry 1          | |
   *   | entry 2          | | growing downwards
   *   | entry 3          | v
   *   | four null bytes  |
   *   | . . .            |
   *   | value 1          | ^
   *   | value 3          | | growing upwards
   *   | value 2          | |
   *   +------------------+
   *
   * The header is followed by multiple entry descriptors. In disk blocks, the
   * entry descriptors are kept sorted. In inodes, they are unsorted. The
   * attribute values are aligned to the end of the block in no specific order.
   *
   * Locking strategy
   * ----------------

   * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.

   * EA blocks are only changed if they are exclusive to an inode, so
   * holding xattr_sem also means that nothing but the EA block's reference
   * count can change. Multiple writers to the same block are synchronized
   * by the buffer lock.
   */
  
  #include <linux/init.h>
  #include <linux/fs.h>
  #include <linux/slab.h>

  #include <linux/mbcache.h>
  #include <linux/quotaops.h>
  #include <linux/rwsem.h>

  #include "ext4_jbd2.h"
  #include "ext4.h"

  #include "xattr.h"
  #include "acl.h"

  #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
  #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))

  #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)

  #ifdef EXT4_XATTR_DEBUG

  # define ea_idebug(inode, f...) do { \
  		printk(KERN_DEBUG "inode %s:%lu: ", \
  			inode->i_sb->s_id, inode->i_ino); \
  		printk(f); \
  		printk("
  "); \
  	} while (0)
  # define ea_bdebug(bh, f...) do { \
  		char b[BDEVNAME_SIZE]; \
  		printk(KERN_DEBUG "block %s:%lu: ", \
  			bdevname(bh->b_bdev, b), \
  			(unsigned long) bh->b_blocknr); \
  		printk(f); \
  		printk("
  "); \
  	} while (0)
  #else
  # define ea_idebug(f...)
  # define ea_bdebug(f...)
  #endif

  static void ext4_xattr_cache_insert(struct buffer_head *);
  static struct buffer_head *ext4_xattr_cache_find(struct inode *,
  						 struct ext4_xattr_header *,

  						 struct mb_cache_entry **);

  static void ext4_xattr_rehash(struct ext4_xattr_header *,
  			      struct ext4_xattr_entry *);

  static int ext4_xattr_list(struct dentry *dentry, char *buffer,

  			   size_t buffer_size);

  static struct mb_cache *ext4_xattr_cache;

  static const struct xattr_handler *ext4_xattr_handler_map[] = {

  	[EXT4_XATTR_INDEX_USER]		     = &ext4_xattr_user_handler,

  #ifdef CONFIG_EXT4_FS_POSIX_ACL

  	[EXT4_XATTR_INDEX_POSIX_ACL_ACCESS]  = &ext4_xattr_acl_access_handler,
  	[EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT] = &ext4_xattr_acl_default_handler,

  #endif

  	[EXT4_XATTR_INDEX_TRUSTED]	     = &ext4_xattr_trusted_handler,

  #ifdef CONFIG_EXT4_FS_SECURITY

  	[EXT4_XATTR_INDEX_SECURITY]	     = &ext4_xattr_security_handler,

  #endif
  };

  const struct xattr_handler *ext4_xattr_handlers[] = {

  	&ext4_xattr_user_handler,
  	&ext4_xattr_trusted_handler,

  #ifdef CONFIG_EXT4_FS_POSIX_ACL

  	&ext4_xattr_acl_access_handler,
  	&ext4_xattr_acl_default_handler,

  #endif

  #ifdef CONFIG_EXT4_FS_SECURITY

  	&ext4_xattr_security_handler,

  #endif
  	NULL
  };

  static inline const struct xattr_handler *

  ext4_xattr_handler(int name_index)

  {

  	const struct xattr_handler *handler = NULL;

  	if (name_index > 0 && name_index < ARRAY_SIZE(ext4_xattr_handler_map))
  		handler = ext4_xattr_handler_map[name_index];

  	return handler;
  }
  
  /*
   * Inode operation listxattr()
   *
   * dentry->d_inode->i_mutex: don't care
   */
  ssize_t

  ext4_listxattr(struct dentry *dentry, char *buffer, size_t size)

  {

  	return ext4_xattr_list(dentry, buffer, size);

  }
  
  static int

  ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)

  {
  	while (!IS_LAST_ENTRY(entry)) {

  		struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);

  		if ((void *)next >= end)
  			return -EIO;
  		entry = next;
  	}
  	return 0;
  }
  
  static inline int

  ext4_xattr_check_block(struct buffer_head *bh)

  {
  	int error;

  	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||

  	    BHDR(bh)->h_blocks != cpu_to_le32(1))
  		return -EIO;

  	error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);

  	return error;
  }
  
  static inline int

  ext4_xattr_check_entry(struct ext4_xattr_entry *entry, size_t size)

  {
  	size_t value_size = le32_to_cpu(entry->e_value_size);
  
  	if (entry->e_value_block != 0 || value_size > size ||
  	    le16_to_cpu(entry->e_value_offs) + value_size > size)
  		return -EIO;
  	return 0;
  }
  
  static int

  ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,

  		      const char *name, size_t size, int sorted)
  {

  	struct ext4_xattr_entry *entry;

  	size_t name_len;
  	int cmp = 1;
  
  	if (name == NULL)
  		return -EINVAL;
  	name_len = strlen(name);
  	entry = *pentry;

  	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {

  		cmp = name_index - entry->e_name_index;
  		if (!cmp)
  			cmp = name_len - entry->e_name_len;
  		if (!cmp)
  			cmp = memcmp(name, entry->e_name, name_len);
  		if (cmp <= 0 && (sorted || cmp == 0))
  			break;
  	}
  	*pentry = entry;

  	if (!cmp && ext4_xattr_check_entry(entry, size))

  			return -EIO;
  	return cmp ? -ENODATA : 0;
  }
  
  static int

  ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,

  		     void *buffer, size_t buffer_size)
  {
  	struct buffer_head *bh = NULL;

  	struct ext4_xattr_entry *entry;

  	size_t size;
  	int error;
  
  	ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
  		  name_index, name, buffer, (long)buffer_size);
  
  	error = -ENODATA;

  	if (!EXT4_I(inode)->i_file_acl)

  		goto cleanup;

  	ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
  	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);

  	if (!bh)
  		goto cleanup;
  	ea_bdebug(bh, "b_count=%d, refcount=%d",
  		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));

  	if (ext4_xattr_check_block(bh)) {

  bad_block:

  		EXT4_ERROR_INODE(inode, "bad block %llu",
  				 EXT4_I(inode)->i_file_acl);

  		error = -EIO;
  		goto cleanup;
  	}

  	ext4_xattr_cache_insert(bh);

  	entry = BFIRST(bh);

  	error = ext4_xattr_find_entry(&entry, name_index, name, bh->b_size, 1);

  	if (error == -EIO)
  		goto bad_block;
  	if (error)
  		goto cleanup;
  	size = le32_to_cpu(entry->e_value_size);
  	if (buffer) {
  		error = -ERANGE;
  		if (size > buffer_size)
  			goto cleanup;
  		memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs),
  		       size);
  	}
  	error = size;
  
  cleanup:
  	brelse(bh);
  	return error;
  }
  
  static int

  ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,

  		     void *buffer, size_t buffer_size)
  {

  	struct ext4_xattr_ibody_header *header;
  	struct ext4_xattr_entry *entry;
  	struct ext4_inode *raw_inode;
  	struct ext4_iloc iloc;

  	size_t size;
  	void *end;
  	int error;

  	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))

  		return -ENODATA;

  	error = ext4_get_inode_loc(inode, &iloc);

  	if (error)
  		return error;

  	raw_inode = ext4_raw_inode(&iloc);

  	header = IHDR(inode, raw_inode);
  	entry = IFIRST(header);

  	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
  	error = ext4_xattr_check_names(entry, end);

  	if (error)
  		goto cleanup;

  	error = ext4_xattr_find_entry(&entry, name_index, name,

  				      end - (void *)entry, 0);
  	if (error)
  		goto cleanup;
  	size = le32_to_cpu(entry->e_value_size);
  	if (buffer) {
  		error = -ERANGE;
  		if (size > buffer_size)
  			goto cleanup;
  		memcpy(buffer, (void *)IFIRST(header) +
  		       le16_to_cpu(entry->e_value_offs), size);
  	}
  	error = size;
  
  cleanup:
  	brelse(iloc.bh);
  	return error;
  }
  
  /*

   * ext4_xattr_get()

   *
   * Copy an extended attribute into the buffer
   * provided, or compute the buffer size required.
   * Buffer is NULL to compute the size of the buffer required.
   *
   * Returns a negative error number on failure, or the number of bytes
   * used / required on success.
   */
  int

  ext4_xattr_get(struct inode *inode, int name_index, const char *name,

  	       void *buffer, size_t buffer_size)
  {
  	int error;

  	down_read(&EXT4_I(inode)->xattr_sem);
  	error = ext4_xattr_ibody_get(inode, name_index, name, buffer,

  				     buffer_size);
  	if (error == -ENODATA)

  		error = ext4_xattr_block_get(inode, name_index, name, buffer,

  					     buffer_size);

  	up_read(&EXT4_I(inode)->xattr_sem);

  	return error;
  }
  
  static int

  ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,

  			char *buffer, size_t buffer_size)
  {
  	size_t rest = buffer_size;

  	for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {

  		const struct xattr_handler *handler =

  			ext4_xattr_handler(entry->e_name_index);

  
  		if (handler) {

  			size_t size = handler->list(dentry, buffer, rest,

  						    entry->e_name,

  						    entry->e_name_len,
  						    handler->flags);

  			if (buffer) {
  				if (size > rest)
  					return -ERANGE;
  				buffer += size;
  			}
  			rest -= size;
  		}
  	}
  	return buffer_size - rest;
  }
  
  static int

  ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)

  {

  	struct inode *inode = dentry->d_inode;

  	struct buffer_head *bh = NULL;
  	int error;
  
  	ea_idebug(inode, "buffer=%p, buffer_size=%ld",
  		  buffer, (long)buffer_size);
  
  	error = 0;

  	if (!EXT4_I(inode)->i_file_acl)

  		goto cleanup;

  	ea_idebug(inode, "reading block %u", EXT4_I(inode)->i_file_acl);
  	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);

  	error = -EIO;
  	if (!bh)
  		goto cleanup;
  	ea_bdebug(bh, "b_count=%d, refcount=%d",
  		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));

  	if (ext4_xattr_check_block(bh)) {

  		EXT4_ERROR_INODE(inode, "bad block %llu",
  				 EXT4_I(inode)->i_file_acl);

  		error = -EIO;
  		goto cleanup;
  	}

  	ext4_xattr_cache_insert(bh);

  	error = ext4_xattr_list_entries(dentry, BFIRST(bh), buffer, buffer_size);

  
  cleanup:
  	brelse(bh);
  
  	return error;
  }
  
  static int

  ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)

  {

  	struct inode *inode = dentry->d_inode;

  	struct ext4_xattr_ibody_header *header;
  	struct ext4_inode *raw_inode;
  	struct ext4_iloc iloc;

  	void *end;
  	int error;

  	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR))

  		return 0;

  	error = ext4_get_inode_loc(inode, &iloc);

  	if (error)
  		return error;

  	raw_inode = ext4_raw_inode(&iloc);

  	header = IHDR(inode, raw_inode);

  	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
  	error = ext4_xattr_check_names(IFIRST(header), end);

  	if (error)
  		goto cleanup;

  	error = ext4_xattr_list_entries(dentry, IFIRST(header),

  					buffer, buffer_size);
  
  cleanup:
  	brelse(iloc.bh);
  	return error;
  }
  
  /*

   * ext4_xattr_list()

   *
   * Copy a list of attribute names into the buffer
   * provided, or compute the buffer size required.
   * Buffer is NULL to compute the size of the buffer required.
   *
   * Returns a negative error number on failure, or the number of bytes
   * used / required on success.
   */

  static int

  ext4_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)

  {

  	int ret, ret2;

  	down_read(&EXT4_I(dentry->d_inode)->xattr_sem);

  	ret = ret2 = ext4_xattr_ibody_list(dentry, buffer, buffer_size);
  	if (ret < 0)
  		goto errout;
  	if (buffer) {
  		buffer += ret;
  		buffer_size -= ret;

  	}

  	ret = ext4_xattr_block_list(dentry, buffer, buffer_size);
  	if (ret < 0)
  		goto errout;
  	ret += ret2;
  errout:

  	up_read(&EXT4_I(dentry->d_inode)->xattr_sem);

  	return ret;

  }
  
  /*

   * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is

   * not set, set it.
   */

  static void ext4_xattr_update_super_block(handle_t *handle,

  					  struct super_block *sb)
  {

  	if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR))

  		return;

  	if (ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh) == 0) {

  		EXT4_SET_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_EXT_ATTR);

  		ext4_handle_dirty_super(handle, sb);

  	}

  }
  
  /*
   * Release the xattr block BH: If the reference count is > 1, decrement
   * it; otherwise free the block.
   */
  static void

  ext4_xattr_release_block(handle_t *handle, struct inode *inode,

  			 struct buffer_head *bh)
  {
  	struct mb_cache_entry *ce = NULL;

  	int error = 0;

  	ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);

  	error = ext4_journal_get_write_access(handle, bh);
  	if (error)
  		goto out;
  
  	lock_buffer(bh);

  	if (BHDR(bh)->h_refcount == cpu_to_le32(1)) {
  		ea_bdebug(bh, "refcount now=0; freeing");
  		if (ce)
  			mb_cache_entry_free(ce);

  		get_bh(bh);

  		ext4_free_blocks(handle, inode, bh, 0, 1,
  				 EXT4_FREE_BLOCKS_METADATA |
  				 EXT4_FREE_BLOCKS_FORGET);

  	} else {

  		le32_add_cpu(&BHDR(bh)->h_refcount, -1);

  		error = ext4_handle_dirty_metadata(handle, inode, bh);

  		if (IS_SYNC(inode))

  			ext4_handle_sync(handle);

  		dquot_free_block(inode, 1);

  		ea_bdebug(bh, "refcount now=%d; releasing",
  			  le32_to_cpu(BHDR(bh)->h_refcount));

  		if (ce)
  			mb_cache_entry_release(ce);
  	}

  	unlock_buffer(bh);
  out:
  	ext4_std_error(inode->i_sb, error);
  	return;

  }

  /*
   * Find the available free space for EAs. This also returns the total number of
   * bytes used by EA entries.
   */
  static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
  				    size_t *min_offs, void *base, int *total)
  {
  	for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
  		*total += EXT4_XATTR_LEN(last->e_name_len);
  		if (!last->e_value_block && last->e_value_size) {
  			size_t offs = le16_to_cpu(last->e_value_offs);
  			if (offs < *min_offs)
  				*min_offs = offs;
  		}
  	}
  	return (*min_offs - ((void *)last - base) - sizeof(__u32));
  }

  struct ext4_xattr_info {

  	int name_index;
  	const char *name;
  	const void *value;
  	size_t value_len;
  };

  struct ext4_xattr_search {
  	struct ext4_xattr_entry *first;

  	void *base;
  	void *end;

  	struct ext4_xattr_entry *here;

  	int not_found;
  };
  
  static int

  ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s)

  {

  	struct ext4_xattr_entry *last;

  	size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
  
  	/* Compute min_offs and last. */
  	last = s->first;

  	for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {

  		if (!last->e_value_block && last->e_value_size) {
  			size_t offs = le16_to_cpu(last->e_value_offs);
  			if (offs < min_offs)
  				min_offs = offs;
  		}
  	}
  	free = min_offs - ((void *)last - s->base) - sizeof(__u32);
  	if (!s->not_found) {
  		if (!s->here->e_value_block && s->here->e_value_size) {
  			size_t size = le32_to_cpu(s->here->e_value_size);

  			free += EXT4_XATTR_SIZE(size);

  		}

  		free += EXT4_XATTR_LEN(name_len);

  	}
  	if (i->value) {

  		if (free < EXT4_XATTR_SIZE(i->value_len) ||
  		    free < EXT4_XATTR_LEN(name_len) +
  			   EXT4_XATTR_SIZE(i->value_len))

  			return -ENOSPC;
  	}
  
  	if (i->value && s->not_found) {
  		/* Insert the new name. */

  		size_t size = EXT4_XATTR_LEN(name_len);

  		size_t rest = (void *)last - (void *)s->here + sizeof(__u32);
  		memmove((void *)s->here + size, s->here, rest);
  		memset(s->here, 0, size);
  		s->here->e_name_index = i->name_index;
  		s->here->e_name_len = name_len;
  		memcpy(s->here->e_name, i->name, name_len);
  	} else {
  		if (!s->here->e_value_block && s->here->e_value_size) {
  			void *first_val = s->base + min_offs;
  			size_t offs = le16_to_cpu(s->here->e_value_offs);
  			void *val = s->base + offs;

  			size_t size = EXT4_XATTR_SIZE(

  				le32_to_cpu(s->here->e_value_size));

  			if (i->value && size == EXT4_XATTR_SIZE(i->value_len)) {

  				/* The old and the new value have the same
  				   size. Just replace. */
  				s->here->e_value_size =
  					cpu_to_le32(i->value_len);

  				memset(val + size - EXT4_XATTR_PAD, 0,
  				       EXT4_XATTR_PAD); /* Clear pad bytes. */

  				memcpy(val, i->value, i->value_len);
  				return 0;
  			}
  
  			/* Remove the old value. */
  			memmove(first_val + size, first_val, val - first_val);
  			memset(first_val, 0, size);
  			s->here->e_value_size = 0;
  			s->here->e_value_offs = 0;
  			min_offs += size;
  
  			/* Adjust all value offsets. */
  			last = s->first;
  			while (!IS_LAST_ENTRY(last)) {
  				size_t o = le16_to_cpu(last->e_value_offs);
  				if (!last->e_value_block &&
  				    last->e_value_size && o < offs)
  					last->e_value_offs =
  						cpu_to_le16(o + size);

  				last = EXT4_XATTR_NEXT(last);

  			}
  		}
  		if (!i->value) {
  			/* Remove the old name. */

  			size_t size = EXT4_XATTR_LEN(name_len);

  			last = ENTRY((void *)last - size);
  			memmove(s->here, (void *)s->here + size,
  				(void *)last - (void *)s->here + sizeof(__u32));
  			memset(last, 0, size);
  		}
  	}
  
  	if (i->value) {
  		/* Insert the new value. */
  		s->here->e_value_size = cpu_to_le32(i->value_len);
  		if (i->value_len) {

  			size_t size = EXT4_XATTR_SIZE(i->value_len);

  			void *val = s->base + min_offs - size;
  			s->here->e_value_offs = cpu_to_le16(min_offs - size);

  			memset(val + size - EXT4_XATTR_PAD, 0,
  			       EXT4_XATTR_PAD); /* Clear the pad bytes. */

  			memcpy(val, i->value, i->value_len);
  		}
  	}
  	return 0;
  }

  struct ext4_xattr_block_find {
  	struct ext4_xattr_search s;

  	struct buffer_head *bh;
  };
  
  static int

  ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
  		      struct ext4_xattr_block_find *bs)

  {
  	struct super_block *sb = inode->i_sb;
  	int error;
  
  	ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld",
  		  i->name_index, i->name, i->value, (long)i->value_len);

  	if (EXT4_I(inode)->i_file_acl) {

  		/* The inode already has an extended attribute block. */

  		bs->bh = sb_bread(sb, EXT4_I(inode)->i_file_acl);

  		error = -EIO;
  		if (!bs->bh)
  			goto cleanup;
  		ea_bdebug(bs->bh, "b_count=%d, refcount=%d",
  			atomic_read(&(bs->bh->b_count)),
  			le32_to_cpu(BHDR(bs->bh)->h_refcount));

  		if (ext4_xattr_check_block(bs->bh)) {

  			EXT4_ERROR_INODE(inode, "bad block %llu",
  					 EXT4_I(inode)->i_file_acl);

  			error = -EIO;
  			goto cleanup;
  		}
  		/* Find the named attribute. */
  		bs->s.base = BHDR(bs->bh);
  		bs->s.first = BFIRST(bs->bh);
  		bs->s.end = bs->bh->b_data + bs->bh->b_size;
  		bs->s.here = bs->s.first;

  		error = ext4_xattr_find_entry(&bs->s.here, i->name_index,

  					      i->name, bs->bh->b_size, 1);
  		if (error && error != -ENODATA)
  			goto cleanup;
  		bs->s.not_found = error;
  	}
  	error = 0;
  
  cleanup:
  	return error;
  }
  
  static int

  ext4_xattr_block_set(handle_t *handle, struct inode *inode,
  		     struct ext4_xattr_info *i,
  		     struct ext4_xattr_block_find *bs)

  {
  	struct super_block *sb = inode->i_sb;
  	struct buffer_head *new_bh = NULL;

  	struct ext4_xattr_search *s = &bs->s;

  	struct mb_cache_entry *ce = NULL;

  	int error = 0;

  #define header(x) ((struct ext4_xattr_header *)(x))

  
  	if (i->value && i->value_len > sb->s_blocksize)
  		return -ENOSPC;
  	if (s->base) {

  		ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,

  					bs->bh->b_blocknr);

  		error = ext4_journal_get_write_access(handle, bs->bh);
  		if (error)
  			goto cleanup;
  		lock_buffer(bs->bh);

  		if (header(s->base)->h_refcount == cpu_to_le32(1)) {
  			if (ce) {
  				mb_cache_entry_free(ce);
  				ce = NULL;
  			}
  			ea_bdebug(bs->bh, "modifying in-place");

  			error = ext4_xattr_set_entry(i, s);

  			if (!error) {
  				if (!IS_LAST_ENTRY(s->first))

  					ext4_xattr_rehash(header(s->base),

  							  s->here);

  				ext4_xattr_cache_insert(bs->bh);

  			}
  			unlock_buffer(bs->bh);
  			if (error == -EIO)
  				goto bad_block;
  			if (!error)

  				error = ext4_handle_dirty_metadata(handle,
  								   inode,
  								   bs->bh);

  			if (error)
  				goto cleanup;
  			goto inserted;
  		} else {
  			int offset = (char *)s->here - bs->bh->b_data;

  			unlock_buffer(bs->bh);

  			ext4_handle_release_buffer(handle, bs->bh);

  			if (ce) {
  				mb_cache_entry_release(ce);
  				ce = NULL;
  			}
  			ea_bdebug(bs->bh, "cloning");

  			s->base = kmalloc(bs->bh->b_size, GFP_NOFS);

  			error = -ENOMEM;
  			if (s->base == NULL)
  				goto cleanup;
  			memcpy(s->base, BHDR(bs->bh), bs->bh->b_size);
  			s->first = ENTRY(header(s->base)+1);
  			header(s->base)->h_refcount = cpu_to_le32(1);
  			s->here = ENTRY(s->base + offset);
  			s->end = s->base + bs->bh->b_size;
  		}
  	} else {
  		/* Allocate a buffer where we construct the new block. */

  		s->base = kzalloc(sb->s_blocksize, GFP_NOFS);

  		/* assert(header == s->base) */
  		error = -ENOMEM;
  		if (s->base == NULL)
  			goto cleanup;

  		header(s->base)->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);

  		header(s->base)->h_blocks = cpu_to_le32(1);
  		header(s->base)->h_refcount = cpu_to_le32(1);
  		s->first = ENTRY(header(s->base)+1);
  		s->here = ENTRY(header(s->base)+1);
  		s->end = s->base + sb->s_blocksize;
  	}

  	error = ext4_xattr_set_entry(i, s);

  	if (error == -EIO)
  		goto bad_block;
  	if (error)
  		goto cleanup;
  	if (!IS_LAST_ENTRY(s->first))

  		ext4_xattr_rehash(header(s->base), s->here);

  
  inserted:
  	if (!IS_LAST_ENTRY(s->first)) {

  		new_bh = ext4_xattr_cache_find(inode, header(s->base), &ce);

  		if (new_bh) {
  			/* We found an identical block in the cache. */
  			if (new_bh == bs->bh)
  				ea_bdebug(new_bh, "keeping");
  			else {
  				/* The old block is released after updating
  				   the inode. */

  				error = dquot_alloc_block(inode, 1);
  				if (error)

  					goto cleanup;

  				error = ext4_journal_get_write_access(handle,

  								      new_bh);
  				if (error)
  					goto cleanup_dquot;
  				lock_buffer(new_bh);

  				le32_add_cpu(&BHDR(new_bh)->h_refcount, 1);

  				ea_bdebug(new_bh, "reusing; refcount now=%d",
  					le32_to_cpu(BHDR(new_bh)->h_refcount));
  				unlock_buffer(new_bh);

  				error = ext4_handle_dirty_metadata(handle,
  								   inode,
  								   new_bh);

  				if (error)
  					goto cleanup_dquot;
  			}
  			mb_cache_entry_release(ce);
  			ce = NULL;
  		} else if (bs->bh && s->base == bs->bh->b_data) {
  			/* We were modifying this block in-place. */
  			ea_bdebug(bs->bh, "keeping this block");
  			new_bh = bs->bh;
  			get_bh(new_bh);
  		} else {
  			/* We need to allocate a new block */

  			ext4_fsblk_t goal, block;
  
  			goal = ext4_group_first_block_no(sb,

  						EXT4_I(inode)->i_block_group);

  
  			/* non-extent files can't have physical blocks past 2^32 */

  			if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))

  				goal = goal & EXT4_MAX_BLOCK_FILE_PHYS;

  			/*
  			 * take i_data_sem because we will test
  			 * i_delalloc_reserved_flag in ext4_mb_new_blocks
  			 */
  			down_read((&EXT4_I(inode)->i_data_sem));

  			block = ext4_new_meta_blocks(handle, inode, goal, 0,
  						     NULL, &error);

  			up_read((&EXT4_I(inode)->i_data_sem));

  			if (error)
  				goto cleanup;

  			if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))

  				BUG_ON(block > EXT4_MAX_BLOCK_FILE_PHYS);

  			ea_idebug(inode, "creating block %d", block);
  
  			new_bh = sb_getblk(sb, block);
  			if (!new_bh) {
  getblk_failed:

  				ext4_free_blocks(handle, inode, NULL, block, 1,

  						 EXT4_FREE_BLOCKS_METADATA);

  				error = -EIO;
  				goto cleanup;
  			}
  			lock_buffer(new_bh);

  			error = ext4_journal_get_create_access(handle, new_bh);

  			if (error) {
  				unlock_buffer(new_bh);
  				goto getblk_failed;
  			}
  			memcpy(new_bh->b_data, s->base, new_bh->b_size);
  			set_buffer_uptodate(new_bh);
  			unlock_buffer(new_bh);

  			ext4_xattr_cache_insert(new_bh);

  			error = ext4_handle_dirty_metadata(handle,
  							   inode, new_bh);

  			if (error)
  				goto cleanup;
  		}
  	}
  
  	/* Update the inode. */

  	EXT4_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;

  
  	/* Drop the previous xattr block. */
  	if (bs->bh && bs->bh != new_bh)

  		ext4_xattr_release_block(handle, inode, bs->bh);

  	error = 0;
  
  cleanup:
  	if (ce)
  		mb_cache_entry_release(ce);
  	brelse(new_bh);
  	if (!(bs->bh && s->base == bs->bh->b_data))
  		kfree(s->base);
  
  	return error;
  
  cleanup_dquot:

  	dquot_free_block(inode, 1);

  	goto cleanup;
  
  bad_block:

  	EXT4_ERROR_INODE(inode, "bad block %llu",
  			 EXT4_I(inode)->i_file_acl);

  	goto cleanup;
  
  #undef header
  }

  struct ext4_xattr_ibody_find {
  	struct ext4_xattr_search s;
  	struct ext4_iloc iloc;

  };
  
  static int

  ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
  		      struct ext4_xattr_ibody_find *is)

  {

  	struct ext4_xattr_ibody_header *header;
  	struct ext4_inode *raw_inode;

  	int error;

  	if (EXT4_I(inode)->i_extra_isize == 0)

  		return 0;

  	raw_inode = ext4_raw_inode(&is->iloc);

  	header = IHDR(inode, raw_inode);
  	is->s.base = is->s.first = IFIRST(header);
  	is->s.here = is->s.first;

  	is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;

  	if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {

  		error = ext4_xattr_check_names(IFIRST(header), is->s.end);

  		if (error)
  			return error;
  		/* Find the named attribute. */

  		error = ext4_xattr_find_entry(&is->s.here, i->name_index,

  					      i->name, is->s.end -
  					      (void *)is->s.base, 0);
  		if (error && error != -ENODATA)
  			return error;
  		is->s.not_found = error;
  	}
  	return 0;
  }
  
  static int

  ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
  		     struct ext4_xattr_info *i,
  		     struct ext4_xattr_ibody_find *is)

  {

  	struct ext4_xattr_ibody_header *header;
  	struct ext4_xattr_search *s = &is->s;

  	int error;

  	if (EXT4_I(inode)->i_extra_isize == 0)

  		return -ENOSPC;

  	error = ext4_xattr_set_entry(i, s);

  	if (error)
  		return error;

  	header = IHDR(inode, ext4_raw_inode(&is->iloc));

  	if (!IS_LAST_ENTRY(s->first)) {

  		header->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);

  		ext4_set_inode_state(inode, EXT4_STATE_XATTR);

  	} else {
  		header->h_magic = cpu_to_le32(0);

  		ext4_clear_inode_state(inode, EXT4_STATE_XATTR);

  	}
  	return 0;
  }
  
  /*

   * ext4_xattr_set_handle()

   *

   * Create, replace or remove an extended attribute for this inode.  Value

   * is NULL to remove an existing extended attribute, and non-NULL to
   * either replace an existing extended attribute, or create a new extended
   * attribute. The flags XATTR_REPLACE and XATTR_CREATE
   * specify that an extended attribute must exist and must not exist
   * previous to the call, respectively.
   *
   * Returns 0, or a negative error number on failure.
   */
  int

  ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,

  		      const char *name, const void *value, size_t value_len,
  		      int flags)
  {

  	struct ext4_xattr_info i = {

  		.name_index = name_index,
  		.name = name,
  		.value = value,
  		.value_len = value_len,
  
  	};

  	struct ext4_xattr_ibody_find is = {

  		.s = { .not_found = -ENODATA, },
  	};

  	struct ext4_xattr_block_find bs = {

  		.s = { .not_found = -ENODATA, },
  	};

  	unsigned long no_expand;

  	int error;
  
  	if (!name)
  		return -EINVAL;
  	if (strlen(name) > 255)
  		return -ERANGE;

  	down_write(&EXT4_I(inode)->xattr_sem);

  	no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
  	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);

  	error = ext4_reserve_inode_write(handle, inode, &is.iloc);

  	if (error)
  		goto cleanup;

  	if (ext4_test_inode_state(inode, EXT4_STATE_NEW)) {

  		struct ext4_inode *raw_inode = ext4_raw_inode(&is.iloc);
  		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);

  		ext4_clear_inode_state(inode, EXT4_STATE_NEW);

  	}

  	error = ext4_xattr_ibody_find(inode, &i, &is);

  	if (error)
  		goto cleanup;
  	if (is.s.not_found)

  		error = ext4_xattr_block_find(inode, &i, &bs);

  	if (error)
  		goto cleanup;
  	if (is.s.not_found && bs.s.not_found) {
  		error = -ENODATA;
  		if (flags & XATTR_REPLACE)
  			goto cleanup;
  		error = 0;
  		if (!value)
  			goto cleanup;
  	} else {
  		error = -EEXIST;
  		if (flags & XATTR_CREATE)
  			goto cleanup;
  	}

  	if (!value) {
  		if (!is.s.not_found)

  			error = ext4_xattr_ibody_set(handle, inode, &i, &is);

  		else if (!bs.s.not_found)

  			error = ext4_xattr_block_set(handle, inode, &i, &bs);

  	} else {

  		error = ext4_xattr_ibody_set(handle, inode, &i, &is);

  		if (!error && !bs.s.not_found) {
  			i.value = NULL;

  			error = ext4_xattr_block_set(handle, inode, &i, &bs);

  		} else if (error == -ENOSPC) {

  			if (EXT4_I(inode)->i_file_acl && !bs.s.base) {
  				error = ext4_xattr_block_find(inode, &i, &bs);
  				if (error)
  					goto cleanup;
  			}

  			error = ext4_xattr_block_set(handle, inode, &i, &bs);

  			if (error)
  				goto cleanup;
  			if (!is.s.not_found) {
  				i.value = NULL;

  				error = ext4_xattr_ibody_set(handle, inode, &i,

  							     &is);
  			}
  		}
  	}
  	if (!error) {

  		ext4_xattr_update_super_block(handle, inode->i_sb);

  		inode->i_ctime = ext4_current_time(inode);

  		if (!value)

  			ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);

  		error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);

  		/*

  		 * The bh is consumed by ext4_mark_iloc_dirty, even with

  		 * error != 0.
  		 */
  		is.iloc.bh = NULL;
  		if (IS_SYNC(inode))

  			ext4_handle_sync(handle);

  	}
  
  cleanup:
  	brelse(is.iloc.bh);
  	brelse(bs.bh);

  	if (no_expand == 0)

  		ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);

  	up_write(&EXT4_I(inode)->xattr_sem);

  	return error;
  }
  
  /*

   * ext4_xattr_set()

   *

   * Like ext4_xattr_set_handle, but start from an inode. This extended

   * attribute modification is a filesystem transaction by itself.
   *
   * Returns 0, or a negative error number on failure.
   */
  int

  ext4_xattr_set(struct inode *inode, int name_index, const char *name,

  	       const void *value, size_t value_len, int flags)
  {
  	handle_t *handle;
  	int error, retries = 0;
  
  retry:

  	handle = ext4_journal_start(inode, EXT4_DATA_TRANS_BLOCKS(inode->i_sb));

  	if (IS_ERR(handle)) {
  		error = PTR_ERR(handle);
  	} else {
  		int error2;

  		error = ext4_xattr_set_handle(handle, inode, name_index, name,

  					      value, value_len, flags);

  		error2 = ext4_journal_stop(handle);

  		if (error == -ENOSPC &&

  		    ext4_should_retry_alloc(inode->i_sb, &retries))

  			goto retry;
  		if (error == 0)
  			error = error2;
  	}
  
  	return error;
  }
  
  /*

   * Shift the EA entries in the inode to create space for the increased
   * i_extra_isize.
   */
  static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
  				     int value_offs_shift, void *to,
  				     void *from, size_t n, int blocksize)
  {
  	struct ext4_xattr_entry *last = entry;
  	int new_offs;
  
  	/* Adjust the value offsets of the entries */
  	for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
  		if (!last->e_value_block && last->e_value_size) {
  			new_offs = le16_to_cpu(last->e_value_offs) +
  							value_offs_shift;
  			BUG_ON(new_offs + le32_to_cpu(last->e_value_size)
  				 > blocksize);
  			last->e_value_offs = cpu_to_le16(new_offs);
  		}
  	}
  	/* Shift the entries by n bytes */
  	memmove(to, from, n);
  }
  
  /*
   * Expand an inode by new_extra_isize bytes when EAs are present.
   * Returns 0 on success or negative error number on failure.
   */
  int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
  			       struct ext4_inode *raw_inode, handle_t *handle)
  {
  	struct ext4_xattr_ibody_header *header;
  	struct ext4_xattr_entry *entry, *last, *first;
  	struct buffer_head *bh = NULL;
  	struct ext4_xattr_ibody_find *is = NULL;
  	struct ext4_xattr_block_find *bs = NULL;
  	char *buffer = NULL, *b_entry_name = NULL;
  	size_t min_offs, free;
  	int total_ino, total_blk;
  	void *base, *start, *end;
  	int extra_isize = 0, error = 0, tried_min_extra_isize = 0;

  	int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);

  
  	down_write(&EXT4_I(inode)->xattr_sem);
  retry:
  	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
  		up_write(&EXT4_I(inode)->xattr_sem);
  		return 0;
  	}
  
  	header = IHDR(inode, raw_inode);
  	entry = IFIRST(header);
  
  	/*
  	 * Check if enough free space is available in the inode to shift the
  	 * entries ahead by new_extra_isize.
  	 */
  
  	base = start = entry;
  	end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
  	min_offs = end - base;
  	last = entry;
  	total_ino = sizeof(struct ext4_xattr_ibody_header);
  
  	free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
  	if (free >= new_extra_isize) {
  		entry = IFIRST(header);
  		ext4_xattr_shift_entries(entry,	EXT4_I(inode)->i_extra_isize
  				- new_extra_isize, (void *)raw_inode +
  				EXT4_GOOD_OLD_INODE_SIZE + new_extra_isize,
  				(void *)header, total_ino,
  				inode->i_sb->s_blocksize);
  		EXT4_I(inode)->i_extra_isize = new_extra_isize;
  		error = 0;
  		goto cleanup;
  	}
  
  	/*
  	 * Enough free space isn't available in the inode, check if
  	 * EA block can hold new_extra_isize bytes.
  	 */
  	if (EXT4_I(inode)->i_file_acl) {
  		bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);
  		error = -EIO;
  		if (!bh)
  			goto cleanup;
  		if (ext4_xattr_check_block(bh)) {

  			EXT4_ERROR_INODE(inode, "bad block %llu",
  					 EXT4_I(inode)->i_file_acl);

  			error = -EIO;
  			goto cleanup;
  		}
  		base = BHDR(bh);
  		first = BFIRST(bh);
  		end = bh->b_data + bh->b_size;
  		min_offs = end - base;
  		free = ext4_xattr_free_space(first, &min_offs, base,
  					     &total_blk);
  		if (free < new_extra_isize) {
  			if (!tried_min_extra_isize && s_min_extra_isize) {
  				tried_min_extra_isize++;
  				new_extra_isize = s_min_extra_isize;
  				brelse(bh);
  				goto retry;
  			}
  			error = -1;
  			goto cleanup;
  		}
  	} else {
  		free = inode->i_sb->s_blocksize;
  	}
  
  	while (new_extra_isize > 0) {
  		size_t offs, size, entry_size;
  		struct ext4_xattr_entry *small_entry = NULL;
  		struct ext4_xattr_info i = {
  			.value = NULL,
  			.value_len = 0,
  		};
  		unsigned int total_size;  /* EA entry size + value size */
  		unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
  		unsigned int min_total_size = ~0U;
  
  		is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
  		bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
  		if (!is || !bs) {
  			error = -ENOMEM;
  			goto cleanup;
  		}
  
  		is->s.not_found = -ENODATA;
  		bs->s.not_found = -ENODATA;
  		is->iloc.bh = NULL;
  		bs->bh = NULL;
  
  		last = IFIRST(header);
  		/* Find the entry best suited to be pushed into EA block */
  		entry = NULL;
  		for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
  			total_size =
  			EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
  					EXT4_XATTR_LEN(last->e_name_len);
  			if (total_size <= free && total_size < min_total_size) {
  				if (total_size < new_extra_isize) {
  					small_entry = last;
  				} else {
  					entry = last;
  					min_total_size = total_size;
  				}
  			}
  		}
  
  		if (entry == NULL) {
  			if (small_entry) {
  				entry = small_entry;
  			} else {
  				if (!tried_min_extra_isize &&
  				    s_min_extra_isize) {
  					tried_min_extra_isize++;
  					new_extra_isize = s_min_extra_isize;
  					goto retry;
  				}
  				error = -1;
  				goto cleanup;
  			}
  		}
  		offs = le16_to_cpu(entry->e_value_offs);
  		size = le32_to_cpu(entry->e_value_size);
  		entry_size = EXT4_XATTR_LEN(entry->e_name_len);
  		i.name_index = entry->e_name_index,
  		buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
  		b_entry_name = kmalloc(entry->e_name_len + 1, GFP_NOFS);
  		if (!buffer || !b_entry_name) {
  			error = -ENOMEM;
  			goto cleanup;
  		}
  		/* Save the entry name and the entry value */
  		memcpy(buffer, (void *)IFIRST(header) + offs,
  		       EXT4_XATTR_SIZE(size));
  		memcpy(b_entry_name, entry->e_name, entry->e_name_len);
  		b_entry_name[entry->e_name_len] = '\0';
  		i.name = b_entry_name;
  
  		error = ext4_get_inode_loc(inode, &is->iloc);
  		if (error)
  			goto cleanup;
  
  		error = ext4_xattr_ibody_find(inode, &i, is);
  		if (error)
  			goto cleanup;
  
  		/* Remove the chosen entry from the inode */
  		error = ext4_xattr_ibody_set(handle, inode, &i, is);

  		if (error)
  			goto cleanup;

  
  		entry = IFIRST(header);
  		if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
  			shift_bytes = new_extra_isize;
  		else
  			shift_bytes = entry_size + size;
  		/* Adjust the offsets and shift the remaining entries ahead */
  		ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
  			shift_bytes, (void *)raw_inode +
  			EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
  			(void *)header, total_ino - entry_size,
  			inode->i_sb->s_blocksize);
  
  		extra_isize += shift_bytes;
  		new_extra_isize -= shift_bytes;
  		EXT4_I(inode)->i_extra_isize = extra_isize;
  
  		i.name = b_entry_name;
  		i.value = buffer;

  		i.value_len = size;

  		error = ext4_xattr_block_find(inode, &i, bs);
  		if (error)
  			goto cleanup;
  
  		/* Add entry which was removed from the inode into the block */
  		error = ext4_xattr_block_set(handle, inode, &i, bs);
  		if (error)
  			goto cleanup;
  		kfree(b_entry_name);
  		kfree(buffer);

  		b_entry_name = NULL;
  		buffer = NULL;

  		brelse(is->iloc.bh);
  		kfree(is);
  		kfree(bs);
  	}
  	brelse(bh);
  	up_write(&EXT4_I(inode)->xattr_sem);
  	return 0;
  
  cleanup:
  	kfree(b_entry_name);
  	kfree(buffer);
  	if (is)
  		brelse(is->iloc.bh);
  	kfree(is);
  	kfree(bs);
  	brelse(bh);
  	up_write(&EXT4_I(inode)->xattr_sem);
  	return error;
  }
  
  
  
  /*

   * ext4_xattr_delete_inode()

   *
   * Free extended attribute resources associated with this inode. This
   * is called immediately before an inode is freed. We have exclusive
   * access to the inode.
   */
  void

  ext4_xattr_delete_inode(handle_t *handle, struct inode *inode)

  {
  	struct buffer_head *bh = NULL;

  	if (!EXT4_I(inode)->i_file_acl)

  		goto cleanup;

  	bh = sb_bread(inode->i_sb, EXT4_I(inode)->i_file_acl);

  	if (!bh) {

  		EXT4_ERROR_INODE(inode, "block %llu read error",
  				 EXT4_I(inode)->i_file_acl);

  		goto cleanup;
  	}

  	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||

  	    BHDR(bh)->h_blocks != cpu_to_le32(1)) {

  		EXT4_ERROR_INODE(inode, "bad block %llu",
  				 EXT4_I(inode)->i_file_acl);

  		goto cleanup;
  	}

  	ext4_xattr_release_block(handle, inode, bh);
  	EXT4_I(inode)->i_file_acl = 0;

  
  cleanup:
  	brelse(bh);
  }
  
  /*

   * ext4_xattr_put_super()

   *
   * This is called when a file system is unmounted.
   */
  void

  ext4_xattr_put_super(struct super_block *sb)

  {
  	mb_cache_shrink(sb->s_bdev);
  }
  
  /*

   * ext4_xattr_cache_insert()

   *
   * Create a new entry in the extended attribute cache, and insert
   * it unless such an entry is already in the cache.
   *
   * Returns 0, or a negative error number on failure.
   */
  static void

  ext4_xattr_cache_insert(struct buffer_head *bh)

  {
  	__u32 hash = le32_to_cpu(BHDR(bh)->h_hash);
  	struct mb_cache_entry *ce;
  	int error;

  	ce = mb_cache_entry_alloc(ext4_xattr_cache, GFP_NOFS);

  	if (!ce) {
  		ea_bdebug(bh, "out of memory");
  		return;
  	}

  	error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, hash);

  	if (error) {
  		mb_cache_entry_free(ce);
  		if (error == -EBUSY) {
  			ea_bdebug(bh, "already in cache");
  			error = 0;
  		}
  	} else {
  		ea_bdebug(bh, "inserting [%x]", (int)hash);
  		mb_cache_entry_release(ce);
  	}
  }
  
  /*

   * ext4_xattr_cmp()

   *
   * Compare two extended attribute blocks for equality.
   *
   * Returns 0 if the blocks are equal, 1 if they differ, and
   * a negative error number on errors.
   */
  static int

  ext4_xattr_cmp(struct ext4_xattr_header *header1,
  	       struct ext4_xattr_header *header2)

  {

  	struct ext4_xattr_entry *entry1, *entry2;

  
  	entry1 = ENTRY(header1+1);
  	entry2 = ENTRY(header2+1);
  	while (!IS_LAST_ENTRY(entry1)) {
  		if (IS_LAST_ENTRY(entry2))
  			return 1;
  		if (entry1->e_hash != entry2->e_hash ||
  		    entry1->e_name_index != entry2->e_name_index ||
  		    entry1->e_name_len != entry2->e_name_len ||
  		    entry1->e_value_size != entry2->e_value_size ||
  		    memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len))
  			return 1;
  		if (entry1->e_value_block != 0 || entry2->e_value_block != 0)
  			return -EIO;
  		if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs),
  			   (char *)header2 + le16_to_cpu(entry2->e_value_offs),
  			   le32_to_cpu(entry1->e_value_size)))
  			return 1;

  		entry1 = EXT4_XATTR_NEXT(entry1);
  		entry2 = EXT4_XATTR_NEXT(entry2);

  	}
  	if (!IS_LAST_ENTRY(entry2))
  		return 1;
  	return 0;
  }
  
  /*

   * ext4_xattr_cache_find()

   *
   * Find an identical extended attribute block.
   *
   * Returns a pointer to the block found, or NULL if such a block was
   * not found or an error occurred.
   */
  static struct buffer_head *

  ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,

  		      struct mb_cache_entry **pce)
  {
  	__u32 hash = le32_to_cpu(header->h_hash);
  	struct mb_cache_entry *ce;
  
  	if (!header->h_hash)
  		return NULL;  /* never share */
  	ea_idebug(inode, "looking for cached blocks [%x]", (int)hash);
  again:

  	ce = mb_cache_entry_find_first(ext4_xattr_cache, inode->i_sb->s_bdev,
  				       hash);

  	while (ce) {
  		struct buffer_head *bh;
  
  		if (IS_ERR(ce)) {
  			if (PTR_ERR(ce) == -EAGAIN)
  				goto again;
  			break;
  		}
  		bh = sb_bread(inode->i_sb, ce->e_block);
  		if (!bh) {

  			EXT4_ERROR_INODE(inode, "block %lu read error",
  					 (unsigned long) ce->e_block);

  		} else if (le32_to_cpu(BHDR(bh)->h_refcount) >=

  				EXT4_XATTR_REFCOUNT_MAX) {

  			ea_idebug(inode, "block %lu refcount %d>=%d",
  				  (unsigned long) ce->e_block,
  				  le32_to_cpu(BHDR(bh)->h_refcount),

  					  EXT4_XATTR_REFCOUNT_MAX);
  		} else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {

  			*pce = ce;
  			return bh;
  		}
  		brelse(bh);

  		ce = mb_cache_entry_find_next(ce, inode->i_sb->s_bdev, hash);

  	}
  	return NULL;
  }
  
  #define NAME_HASH_SHIFT 5
  #define VALUE_HASH_SHIFT 16
  
  /*

   * ext4_xattr_hash_entry()

   *
   * Compute the hash of an extended attribute.
   */

  static inline void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
  					 struct ext4_xattr_entry *entry)

  {
  	__u32 hash = 0;
  	char *name = entry->e_name;
  	int n;

  	for (n = 0; n < entry->e_name_len; n++) {

  		hash = (hash << NAME_HASH_SHIFT) ^
  		       (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
  		       *name++;
  	}
  
  	if (entry->e_value_block == 0 && entry->e_value_size != 0) {
  		__le32 *value = (__le32 *)((char *)header +
  			le16_to_cpu(entry->e_value_offs));
  		for (n = (le32_to_cpu(entry->e_value_size) +

  		     EXT4_XATTR_ROUND) >> EXT4_XATTR_PAD_BITS; n; n--) {

  			hash = (hash << VALUE_HASH_SHIFT) ^
  			       (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
  			       le32_to_cpu(*value++);
  		}
  	}
  	entry->e_hash = cpu_to_le32(hash);
  }
  
  #undef NAME_HASH_SHIFT
  #undef VALUE_HASH_SHIFT
  
  #define BLOCK_HASH_SHIFT 16
  
  /*

   * ext4_xattr_rehash()

   *
   * Re-compute the extended attribute hash value after an entry has changed.
   */

  static void ext4_xattr_rehash(struct ext4_xattr_header *header,
  			      struct ext4_xattr_entry *entry)

  {

  	struct ext4_xattr_entry *here;

  	__u32 hash = 0;

  	ext4_xattr_hash_entry(header, entry);

  	here = ENTRY(header+1);
  	while (!IS_LAST_ENTRY(here)) {
  		if (!here->e_hash) {
  			/* Block is not shared if an entry's hash value == 0 */
  			hash = 0;
  			break;
  		}
  		hash = (hash << BLOCK_HASH_SHIFT) ^
  		       (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^
  		       le32_to_cpu(here->e_hash);

  		here = EXT4_XATTR_NEXT(here);

  	}
  	header->h_hash = cpu_to_le32(hash);
  }
  
  #undef BLOCK_HASH_SHIFT
  
  int __init

  ext4_init_xattr(void)

  {

  	ext4_xattr_cache = mb_cache_create("ext4_xattr", 6);

  	if (!ext4_xattr_cache)

  		return -ENOMEM;
  	return 0;
  }
  
  void

  ext4_exit_xattr(void)

  {

  	if (ext4_xattr_cache)
  		mb_cache_destroy(ext4_xattr_cache);
  	ext4_xattr_cache = NULL;

  }