propagate-errors-up-to-ext4_find_entry-s-callers

   1 ext4: propagate errors up to ext4_find_entry()'s callers
   2
   3 If we run into some kind of error, such as ENOMEM, while calling
   4 ext4_getblk() or ext4_dx_find_entry(), we need to make sure this error
   5 gets propagated up to ext4_find_entry() and then to its callers.  This
   6 way, transient errors such as ENOMEM can get propagated to the VFS.
   7 This is important so that the system calls return the appropriate
   8 error, and also so that in the case of ext4_lookup(), we return an
   9 error instead of a NULL inode, since that will result in a negative
  10 dentry cache entry that will stick around long past the OOM condition
  11 which caused a transient ENOMEM error.
  12
  13 Google-Bug-Id: #17142205
  14
  15 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  16 Cc: stable@vger.kernel.org
  17 ---
  18  fs/ext4/namei.c | 35 +++++++++++++++++++++++++++++++++--
  19  1 file changed, 33 insertions(+), 2 deletions(-)
  20
  21 diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
  22 index b147a67..ae7088b 100644
  23 --- a/fs/ext4/namei.c
  24 +++ b/fs/ext4/namei.c
  25 @@ -1227,7 +1227,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
  26                                    buffer */
  27         int num = 0;
  28         ext4_lblk_t  nblocks;
  29 -       int i, err;
  30 +       int i, err = 0;
  31         int namelen;
  32
  33         *res_dir = NULL;
  34 @@ -1264,7 +1264,11 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
  35                  * return.  Otherwise, fall back to doing a search the
  36                  * old fashioned way.
  37                  */
  38 -               if (bh || (err != ERR_BAD_DX_DIR))
  39 +               if (err == -ENOENT)
  40 +                       return NULL;
  41 +               if (err && err != ERR_BAD_DX_DIR)
  42 +                       return ERR_PTR(err);
  43 +               if (bh)
  44                         return bh;
  45                 dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, "
  46                                "falling back\n"));
  47 @@ -1295,6 +1299,11 @@ restart:
  48                                 }
  49                                 num++;
  50                                 bh = ext4_getblk(NULL, dir, b++, 0, &err);
  51 +                               if (unlikely(err)) {
  52 +                                       if (ra_max == 0)
  53 +                                               return ERR_PTR(err);
  54 +                                       break;
  55 +                               }
  56                                 bh_use[ra_max] = bh;
  57                                 if (bh)
  58                                         ll_rw_block(READ | REQ_META | REQ_PRIO,
  59 @@ -1417,6 +1426,8 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
  60                 return ERR_PTR(-ENAMETOOLONG);
  61
  62         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  63 +       if (IS_ERR(bh))
  64 +               return (struct dentry *) bh;
  65         inode = NULL;
  66         if (bh) {
  67                 __u32 ino = le32_to_cpu(de->inode);
  68 @@ -1450,6 +1461,8 @@ struct dentry *ext4_get_parent(struct dentry *child)
  69         struct buffer_head *bh;
  70
  71         bh = ext4_find_entry(child->d_inode, &dotdot, &de, NULL);
  72 +       if (IS_ERR(bh))
  73 +               return (struct dentry *) bh;
  74         if (!bh)
  75                 return ERR_PTR(-ENOENT);
  76         ino = le32_to_cpu(de->inode);
  77 @@ -2727,6 +2740,8 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
  78
  79         retval = -ENOENT;
  80         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  81 +       if (IS_ERR(bh))
  82 +               return PTR_ERR(bh);
  83         if (!bh)
  84                 goto end_rmdir;
  85
  86 @@ -2794,6 +2809,8 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
  87
  88         retval = -ENOENT;
  89         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  90 +       if (IS_ERR(bh))
  91 +               return PTR_ERR(bh);
  92         if (!bh)
  93                 goto end_unlink;
  94
  95 @@ -3121,6 +3138,8 @@ static int ext4_find_delete_entry(handle_t *handle, struct inode *dir,
  96         struct ext4_dir_entry_2 *de;
  97
  98         bh = ext4_find_entry(dir, d_name, &de, NULL);
  99 +       if (IS_ERR(bh))
 100 +               return PTR_ERR(bh);
 101         if (bh) {
 102                 retval = ext4_delete_entry(handle, dir, de, bh);
 103                 brelse(bh);
 104 @@ -3202,6 +3221,8 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 105                 dquot_initialize(new.inode);
 106
 107         old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
 108 +       if (IS_ERR(old.bh))
 109 +               return PTR_ERR(old.bh);
 110         /*
 111          *  Check for inode number is _not_ due to possible IO errors.
 112          *  We might rmdir the source, keep it as pwd of some process
 113 @@ -3214,6 +3235,10 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 114
 115         new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
 116                                  &new.de, &new.inlined);
 117 +       if (IS_ERR(new.bh)) {
 118 +               retval = PTR_ERR(new.bh);
 119 +               goto end_rename;
 120 +       }
 121         if (new.bh) {
 122                 if (!new.inode) {
 123                         brelse(new.bh);
 124 @@ -3330,6 +3355,8 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
 125
 126         old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,
 127                                  &old.de, &old.inlined);
 128 +       if (IS_ERR(old.bh))
 129 +               return PTR_ERR(old.bh);
 130         /*
 131          *  Check for inode number is _not_ due to possible IO errors.
 132          *  We might rmdir the source, keep it as pwd of some process
 133 @@ -3342,6 +3369,10 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
 134
 135         new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
 136                                  &new.de, &new.inlined);
 137 +       if (IS_ERR(new.bh)) {
 138 +               retval = PTR_ERR(new.bh);
 139 +               goto end_rename;
 140 +       }
 141
 142         /* RENAME_EXCHANGE case: old *and* new must both exist */
 143         if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino)
 144 --
 145 2.1.0
 146