Eric Lee / smarc-ti-linux-kernel

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Commit 7307de80510a70e5e5aa98de1e80ccbb7d90a3a8

Authored by Mark Fasheh
1 parent 607d44aa3f

ocfs2: shared writeable mmap 

Implement cluster consistent shared writeable mappings using the
->page_mkwrite() callback.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

Showing 4 changed files with 200 additions and 39 deletions Side-by-side Diff

... ... @@ -1034,7 +1034,8 @@
1034 1034 */
1035 1035 static int ocfs2_grab_pages_for_write(struct address_space *mapping,
1036 1036 struct ocfs2_write_ctxt *wc,
1037   - u32 cpos, loff_t user_pos, int new)
  1037 + u32 cpos, loff_t user_pos, int new,
  1038 + struct page *mmap_page)
1038 1039 {
1039 1040 int ret = 0, i;
1040 1041 unsigned long start, target_index, index;
... ... @@ -1058,11 +1059,36 @@
1058 1059 for(i = 0; i < wc->w_num_pages; i++) {
1059 1060 index = start + i;
1060 1061  
1061   - wc->w_pages[i] = find_or_create_page(mapping, index, GFP_NOFS);
1062   - if (!wc->w_pages[i]) {
1063   - ret = -ENOMEM;
1064   - mlog_errno(ret);
1065   - goto out;
  1062 + if (index == target_index && mmap_page) {
  1063 + /*
  1064 + * ocfs2_pagemkwrite() is a little different
  1065 + * and wants us to directly use the page
  1066 + * passed in.
  1067 + */
  1068 + lock_page(mmap_page);
  1069 +
  1070 + if (mmap_page->mapping != mapping) {
  1071 + unlock_page(mmap_page);
  1072 + /*
  1073 + * Sanity check - the locking in
  1074 + * ocfs2_pagemkwrite() should ensure
  1075 + * that this code doesn't trigger.
  1076 + */
  1077 + ret = -EINVAL;
  1078 + mlog_errno(ret);
  1079 + goto out;
  1080 + }
  1081 +
  1082 + page_cache_get(mmap_page);
  1083 + wc->w_pages[i] = mmap_page;
  1084 + } else {
  1085 + wc->w_pages[i] = find_or_create_page(mapping, index,
  1086 + GFP_NOFS);
  1087 + if (!wc->w_pages[i]) {
  1088 + ret = -ENOMEM;
  1089 + mlog_errno(ret);
  1090 + goto out;
  1091 + }
1066 1092 }
1067 1093  
1068 1094 if (index == target_index)
... ... @@ -1213,10 +1239,10 @@
1213 1239 }
1214 1240 }
1215 1241  
1216   -static int ocfs2_write_begin_nolock(struct address_space *mapping,
1217   - loff_t pos, unsigned len, unsigned flags,
1218   - struct page **pagep, void **fsdata,
1219   - struct buffer_head *di_bh)
  1242 +int ocfs2_write_begin_nolock(struct address_space *mapping,
  1243 + loff_t pos, unsigned len, unsigned flags,
  1244 + struct page **pagep, void **fsdata,
  1245 + struct buffer_head *di_bh, struct page *mmap_page)
1220 1246 {
1221 1247 int ret, i, credits = OCFS2_INODE_UPDATE_CREDITS;
1222 1248 unsigned int num_clusters = 0, clusters_to_alloc = 0;
... ... @@ -1318,7 +1344,7 @@
1318 1344 * extent.
1319 1345 */
1320 1346 ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
1321   - clusters_to_alloc);
  1347 + clusters_to_alloc, mmap_page);
1322 1348 if (ret) {
1323 1349 mlog_errno(ret);
1324 1350 goto out_commit;
... ... @@ -1386,7 +1412,7 @@
1386 1412 }
1387 1413  
1388 1414 ret = ocfs2_write_begin_nolock(mapping, pos, len, flags, pagep,
1389   - fsdata, di_bh);
  1415 + fsdata, di_bh, NULL);
1390 1416 if (ret) {
1391 1417 mlog_errno(ret);
1392 1418 goto out_fail_data;
... ... @@ -1407,9 +1433,9 @@
1407 1433 return ret;
1408 1434 }
1409 1435  
1410   -static int ocfs2_write_end_nolock(struct address_space *mapping,
1411   - loff_t pos, unsigned len, unsigned copied,
1412   - struct page *page, void *fsdata)
  1436 +int ocfs2_write_end_nolock(struct address_space *mapping,
  1437 + loff_t pos, unsigned len, unsigned copied,
  1438 + struct page *page, void *fsdata)
1413 1439 {
1414 1440 int i;
1415 1441 unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
... ... @@ -50,6 +50,15 @@
50 50 loff_t pos, unsigned len, unsigned copied,
51 51 struct page *page, void *fsdata);
52 52  
  53 +int ocfs2_write_end_nolock(struct address_space *mapping,
  54 + loff_t pos, unsigned len, unsigned copied,
  55 + struct page *page, void *fsdata);
  56 +
  57 +int ocfs2_write_begin_nolock(struct address_space *mapping,
  58 + loff_t pos, unsigned len, unsigned flags,
  59 + struct page **pagep, void **fsdata,
  60 + struct buffer_head *di_bh, struct page *mmap_page);
  61 +
53 62 /* all ocfs2_dio_end_io()'s fault */
54 63 #define ocfs2_iocb_is_rw_locked(iocb) \
55 64 test_bit(0, (unsigned long *)&iocb->private)
... ... @@ -1001,6 +1001,13 @@
1001 1001 goto bail_unlock;
1002 1002 }
1003 1003  
  1004 + /*
  1005 + * This will intentionally not wind up calling vmtruncate(),
  1006 + * since all the work for a size change has been done above.
  1007 + * Otherwise, we could get into problems with truncate as
  1008 + * ip_alloc_sem is used there to protect against i_size
  1009 + * changes.
  1010 + */
1004 1011 status = inode_setattr(inode, attr);
1005 1012 if (status < 0) {
1006 1013 mlog_errno(status);
... ... @@ -37,11 +37,29 @@
37 37  
38 38 #include "ocfs2.h"
39 39  
  40 +#include "aops.h"
40 41 #include "dlmglue.h"
41 42 #include "file.h"
42 43 #include "inode.h"
43 44 #include "mmap.h"
44 45  
  46 +static inline int ocfs2_vm_op_block_sigs(sigset_t *blocked, sigset_t *oldset)
  47 +{
  48 + /* The best way to deal with signals in the vm path is
  49 + * to block them upfront, rather than allowing the
  50 + * locking paths to return -ERESTARTSYS. */
  51 + sigfillset(blocked);
  52 +
  53 + /* We should technically never get a bad return value
  54 + * from sigprocmask */
  55 + return sigprocmask(SIG_BLOCK, blocked, oldset);
  56 +}
  57 +
  58 +static inline int ocfs2_vm_op_unblock_sigs(sigset_t *oldset)
  59 +{
  60 + return sigprocmask(SIG_SETMASK, oldset, NULL);
  61 +}
  62 +
45 63 static struct page *ocfs2_nopage(struct vm_area_struct * area,
46 64 unsigned long address,
47 65 int *type)
... ... @@ -53,14 +71,7 @@
53 71 mlog_entry("(area=%p, address=%lu, type=%p)\n", area, address,
54 72 type);
55 73  
56   - /* The best way to deal with signals in this path is
57   - * to block them upfront, rather than allowing the
58   - * locking paths to return -ERESTARTSYS. */
59   - sigfillset(&blocked);
60   -
61   - /* We should technically never get a bad ret return
62   - * from sigprocmask */
63   - ret = sigprocmask(SIG_BLOCK, &blocked, &oldset);
  74 + ret = ocfs2_vm_op_block_sigs(&blocked, &oldset);
64 75 if (ret < 0) {
65 76 mlog_errno(ret);
66 77 goto out;
... ... @@ -68,7 +79,7 @@
68 79  
69 80 page = filemap_nopage(area, address, type);
70 81  
71   - ret = sigprocmask(SIG_SETMASK, &oldset, NULL);
  82 + ret = ocfs2_vm_op_unblock_sigs(&oldset);
72 83 if (ret < 0)
73 84 mlog_errno(ret);
74 85 out:
75 86  
76 87  
77 88  
78 89  
79 90  
80 91  
... ... @@ -76,27 +87,135 @@
76 87 return page;
77 88 }
78 89  
79   -static struct vm_operations_struct ocfs2_file_vm_ops = {
80   - .nopage = ocfs2_nopage,
81   -};
  90 +static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
  91 + struct page *page)
  92 +{
  93 + int ret;
  94 + struct address_space *mapping = inode->i_mapping;
  95 + loff_t pos = page->index << PAGE_CACHE_SHIFT;
  96 + unsigned int len = PAGE_CACHE_SIZE;
  97 + pgoff_t last_index;
  98 + struct page *locked_page = NULL;
  99 + void *fsdata;
  100 + loff_t size = i_size_read(inode);
82 101  
83   -int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
  102 + /*
  103 + * Another node might have truncated while we were waiting on
  104 + * cluster locks.
  105 + */
  106 + last_index = size >> PAGE_CACHE_SHIFT;
  107 + if (page->index > last_index) {
  108 + ret = -EINVAL;
  109 + goto out;
  110 + }
  111 +
  112 + /*
  113 + * The i_size check above doesn't catch the case where nodes
  114 + * truncated and then re-extended the file. We'll re-check the
  115 + * page mapping after taking the page lock inside of
  116 + * ocfs2_write_begin_nolock().
  117 + */
  118 + if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
  119 + ret = -EINVAL;
  120 + goto out;
  121 + }
  122 +
  123 + /*
  124 + * Call ocfs2_write_begin() and ocfs2_write_end() to take
  125 + * advantage of the allocation code there. We pass a write
  126 + * length of the whole page (chopped to i_size) to make sure
  127 + * the whole thing is allocated.
  128 + *
  129 + * Since we know the page is up to date, we don't have to
  130 + * worry about ocfs2_write_begin() skipping some buffer reads
  131 + * because the "write" would invalidate their data.
  132 + */
  133 + if (page->index == last_index)
  134 + len = size & ~PAGE_CACHE_MASK;
  135 +
  136 + ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
  137 + &fsdata, di_bh, page);
  138 + if (ret) {
  139 + if (ret != -ENOSPC)
  140 + mlog_errno(ret);
  141 + goto out;
  142 + }
  143 +
  144 + ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
  145 + fsdata);
  146 + if (ret < 0) {
  147 + mlog_errno(ret);
  148 + goto out;
  149 + }
  150 + BUG_ON(ret != len);
  151 + ret = 0;
  152 +out:
  153 + return ret;
  154 +}
  155 +
  156 +static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct page *page)
84 157 {
85   - int ret = 0, lock_level = 0;
86   - struct ocfs2_super *osb = OCFS2_SB(file->f_dentry->d_inode->i_sb);
  158 + struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
  159 + struct buffer_head *di_bh = NULL;
  160 + sigset_t blocked, oldset;
  161 + int ret, ret2;
87 162  
  163 + ret = ocfs2_vm_op_block_sigs(&blocked, &oldset);
  164 + if (ret < 0) {
  165 + mlog_errno(ret);
  166 + return ret;
  167 + }
  168 +
88 169 /*
89   - * Only support shared writeable mmap for local mounts which
90   - * don't know about holes.
  170 + * The cluster locks taken will block a truncate from another
  171 + * node. Taking the data lock will also ensure that we don't
  172 + * attempt page truncation as part of a downconvert.
91 173 */
92   - if ((!ocfs2_mount_local(osb) || ocfs2_sparse_alloc(osb)) &&
93   - ((vma->vm_flags & VM_SHARED) || (vma->vm_flags & VM_MAYSHARE)) &&
94   - ((vma->vm_flags & VM_WRITE) || (vma->vm_flags & VM_MAYWRITE))) {
95   - mlog(0, "disallow shared writable mmaps %lx\n", vma->vm_flags);
96   - /* This is -EINVAL because generic_file_readonly_mmap
97   - * returns it in a similar situation. */
98   - return -EINVAL;
  174 + ret = ocfs2_meta_lock(inode, &di_bh, 1);
  175 + if (ret < 0) {
  176 + mlog_errno(ret);
  177 + goto out;
99 178 }
  179 +
  180 + /*
  181 + * The alloc sem should be enough to serialize with
  182 + * ocfs2_truncate_file() changing i_size as well as any thread
  183 + * modifying the inode btree.
  184 + */
  185 + down_write(&OCFS2_I(inode)->ip_alloc_sem);
  186 +
  187 + ret = ocfs2_data_lock(inode, 1);
  188 + if (ret < 0) {
  189 + mlog_errno(ret);
  190 + goto out_meta_unlock;
  191 + }
  192 +
  193 + ret = __ocfs2_page_mkwrite(inode, di_bh, page);
  194 +
  195 + ocfs2_data_unlock(inode, 1);
  196 +
  197 +out_meta_unlock:
  198 + up_write(&OCFS2_I(inode)->ip_alloc_sem);
  199 +
  200 + brelse(di_bh);
  201 + ocfs2_meta_unlock(inode, 1);
  202 +
  203 +out:
  204 + ret2 = ocfs2_vm_op_unblock_sigs(&oldset);
  205 + if (ret2 < 0)
  206 + mlog_errno(ret2);
  207 +
  208 + return ret;
  209 +}
  210 +
  211 +static struct vm_operations_struct ocfs2_file_vm_ops = {
  212 + .nopage = ocfs2_nopage,
  213 + .page_mkwrite = ocfs2_page_mkwrite,
  214 +};
  215 +
  216 +int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
  217 +{
  218 + int ret = 0, lock_level = 0;
100 219  
101 220 ret = ocfs2_meta_lock_atime(file->f_dentry->d_inode,
102 221 file->f_vfsmnt, &lock_level);