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/ext4.h  |  2 +-
  19  fs/ext4/namei.c | 35 +++++++++++++++++++++++++++++++++--
  20  2 files changed, 34 insertions(+), 3 deletions(-)
  21
  22 diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
  23 index 5b19760..4d95c33 100644
  24 --- a/fs/ext4/ext4.h
  25 +++ b/fs/ext4/ext4.h
  26 @@ -1825,7 +1825,7 @@ ext4_group_first_block_no(struct super_block *sb, ext4_group_t group_no)
  27  /*
  28   * Special error return code only used by dx_probe() and its callers.
  29   */
  30 -#define ERR_BAD_DX_DIR -75000
  31 +#define ERR_BAD_DX_DIR (-(MAX_ERRNO - 1))
  32
  33  /*
  34   * Timeout and state flag for lazy initialization inode thread.
  35 diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
  36 index b147a67..ae7088b 100644
  37 --- a/fs/ext4/namei.c
  38 +++ b/fs/ext4/namei.c
  39 @@ -1227,7 +1227,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
  40                                    buffer */
  41         int num = 0;
  42         ext4_lblk_t  nblocks;
  43 -       int i, err;
  44 +       int i, err = 0;
  45         int namelen;
  46
  47         *res_dir = NULL;
  48 @@ -1264,7 +1264,11 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
  49                  * return.  Otherwise, fall back to doing a search the
  50                  * old fashioned way.
  51                  */
  52 -               if (bh || (err != ERR_BAD_DX_DIR))
  53 +               if (err == -ENOENT)
  54 +                       return NULL;
  55 +               if (err && err != ERR_BAD_DX_DIR)
  56 +                       return ERR_PTR(err);
  57 +               if (bh)
  58                         return bh;
  59                 dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, "
  60                                "falling back\n"));
  61 @@ -1295,6 +1299,11 @@ restart:
  62                                 }
  63                                 num++;
  64                                 bh = ext4_getblk(NULL, dir, b++, 0, &err);
  65 +                               if (unlikely(err)) {
  66 +                                       if (ra_max == 0)
  67 +                                               return ERR_PTR(err);
  68 +                                       break;
  69 +                               }
  70                                 bh_use[ra_max] = bh;
  71                                 if (bh)
  72                                         ll_rw_block(READ | REQ_META | REQ_PRIO,
  73 @@ -1417,6 +1426,8 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
  74                 return ERR_PTR(-ENAMETOOLONG);
  75
  76         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  77 +       if (IS_ERR(bh))
  78 +               return (struct dentry *) bh;
  79         inode = NULL;
  80         if (bh) {
  81                 __u32 ino = le32_to_cpu(de->inode);
  82 @@ -1450,6 +1461,8 @@ struct dentry *ext4_get_parent(struct dentry *child)
  83         struct buffer_head *bh;
  84
  85         bh = ext4_find_entry(child->d_inode, &dotdot, &de, NULL);
  86 +       if (IS_ERR(bh))
  87 +               return (struct dentry *) bh;
  88         if (!bh)
  89                 return ERR_PTR(-ENOENT);
  90         ino = le32_to_cpu(de->inode);
  91 @@ -2727,6 +2740,8 @@ static int ext4_rmdir(struct inode *dir, struct dentry *dentry)
  92
  93         retval = -ENOENT;
  94         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
  95 +       if (IS_ERR(bh))
  96 +               return PTR_ERR(bh);
  97         if (!bh)
  98                 goto end_rmdir;
  99
 100 @@ -2794,6 +2809,8 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 101
 102         retval = -ENOENT;
 103         bh = ext4_find_entry(dir, &dentry->d_name, &de, NULL);
 104 +       if (IS_ERR(bh))
 105 +               return PTR_ERR(bh);
 106         if (!bh)
 107                 goto end_unlink;
 108
 109 @@ -3121,6 +3138,8 @@ static int ext4_find_delete_entry(handle_t *handle, struct inode *dir,
 110         struct ext4_dir_entry_2 *de;
 111
 112         bh = ext4_find_entry(dir, d_name, &de, NULL);
 113 +       if (IS_ERR(bh))
 114 +               return PTR_ERR(bh);
 115         if (bh) {
 116                 retval = ext4_delete_entry(handle, dir, de, bh);
 117                 brelse(bh);
 118 @@ -3202,6 +3221,8 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 119                 dquot_initialize(new.inode);
 120
 121         old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
 122 +       if (IS_ERR(old.bh))
 123 +               return PTR_ERR(old.bh);
 124         /*
 125          *  Check for inode number is _not_ due to possible IO errors.
 126          *  We might rmdir the source, keep it as pwd of some process
 127 @@ -3214,6 +3235,10 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry,
 128
 129         new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
 130                                  &new.de, &new.inlined);
 131 +       if (IS_ERR(new.bh)) {
 132 +               retval = PTR_ERR(new.bh);
 133 +               goto end_rename;
 134 +       }
 135         if (new.bh) {
 136                 if (!new.inode) {
 137                         brelse(new.bh);
 138 @@ -3330,6 +3355,8 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
 139
 140         old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,
 141                                  &old.de, &old.inlined);
 142 +       if (IS_ERR(old.bh))
 143 +               return PTR_ERR(old.bh);
 144         /*
 145          *  Check for inode number is _not_ due to possible IO errors.
 146          *  We might rmdir the source, keep it as pwd of some process
 147 @@ -3342,6 +3369,10 @@ static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,
 148
 149         new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
 150                                  &new.de, &new.inlined);
 151 +       if (IS_ERR(new.bh)) {
 152 +               retval = PTR_ERR(new.bh);
 153 +               goto end_rename;
 154 +       }
 155
 156         /* RENAME_EXCHANGE case: old *and* new must both exist */
 157         if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino)