ext4_get_extent_length_fix.patch

   1 ext4: Use the ext4_ext_actual_len() helper function
   2
   3 From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4
   5 ext4 uses the high bit of the extent length to encode whether the extent
   6 is intialized or not. The helper function ext4_ext_get_actual_len should
   7 be used to get the actual length of the extent.
   8
   9 This addresses the kernel bug documented here:
  10      http://bugzilla.kernel.org/show_bug.cgi?id=9732
  11
  12 kernel BUG at fs/ext4/extents.c:1056!
  13 ....
  14 Call Trace:
  15 [<ffffffff88366073>] :ext4dev:ext4_ext_get_blocks+0x5ba/0x8c1
  16 [<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
  17 [<ffffffff812748f6>] _spin_unlock+0x17/0x20
  18 [<ffffffff883400a6>] :jbd2:start_this_handle+0x4e0/0x4fe
  19 [<ffffffff88366564>] :ext4dev:ext4_fallocate+0x175/0x39a
  20 [<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
  21 [<ffffffff81056480>] __lock_acquire+0x4e7/0xc4d
  22 [<ffffffff81053c91>] lock_release_holdtime+0x27/0x49
  23 [<ffffffff810a8de7>] sys_fallocate+0xe4/0x10d
  24 [<ffffffff8100c043>] tracesys+0xd5/0xda
  25
  26 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  27 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  28
  29 ---
  30
  31  fs/ext4/extents.c |   24 +++++++++++++-----------
  32  1 file changed, 13 insertions(+), 11 deletions(-)
  33
  34
  35 Index: linux-2.6.24-rc7/fs/ext4/extents.c
  36 ===================================================================
  37 --- linux-2.6.24-rc7.orig/fs/ext4/extents.c     2008-01-16 13:52:34.000000000 -0800
  38 +++ linux-2.6.24-rc7/fs/ext4/extents.c  2008-01-16 13:52:37.000000000 -0800
  39 @@ -1029,7 +1029,7 @@ ext4_ext_search_left(struct inode *inode
  40  {
  41         struct ext4_extent_idx *ix;
  42         struct ext4_extent *ex;
  43 -       int depth;
  44 +       int depth, ee_len;
  45
  46         BUG_ON(path == NULL);
  47         depth = path->p_depth;
  48 @@ -1043,6 +1043,7 @@ ext4_ext_search_left(struct inode *inode
  49          * first one in the file */
  50
  51         ex = path[depth].p_ext;
  52 +       ee_len = ext4_ext_get_actual_len(ex);
  53         if (*logical < le32_to_cpu(ex->ee_block)) {
  54                 BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);
  55                 while (--depth >= 0) {
  56 @@ -1052,10 +1053,10 @@ ext4_ext_search_left(struct inode *inode
  57                 return 0;
  58         }
  59
  60 -       BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));
  61 +       BUG_ON(*logical < (le32_to_cpu(ex->ee_block) + ee_len));
  62
  63 -       *logical = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1;
  64 -       *phys = ext_pblock(ex) + le16_to_cpu(ex->ee_len) - 1;
  65 +       *logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
  66 +       *phys = ext_pblock(ex) + ee_len - 1;
  67         return 0;
  68  }
  69
  70 @@ -1075,7 +1076,7 @@ ext4_ext_search_right(struct inode *inod
  71         struct ext4_extent_idx *ix;
  72         struct ext4_extent *ex;
  73         ext4_fsblk_t block;
  74 -       int depth;
  75 +       int depth, ee_len;
  76
  77         BUG_ON(path == NULL);
  78         depth = path->p_depth;
  79 @@ -1089,6 +1090,7 @@ ext4_ext_search_right(struct inode *inod
  80          * first one in the file */
  81
  82         ex = path[depth].p_ext;
  83 +       ee_len = ext4_ext_get_actual_len(ex);
  84         if (*logical < le32_to_cpu(ex->ee_block)) {
  85                 BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);
  86                 while (--depth >= 0) {
  87 @@ -1100,7 +1102,7 @@ ext4_ext_search_right(struct inode *inod
  88                 return 0;
  89         }
  90
  91 -       BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));
  92 +       BUG_ON(*logical < (le32_to_cpu(ex->ee_block) + ee_len));
  93
  94         if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
  95                 /* next allocated block in this leaf */
  96 @@ -1316,7 +1318,7 @@ ext4_can_extents_be_merged(struct inode
  97         if (ext1_ee_len + ext2_ee_len > max_len)
  98                 return 0;
  99  #ifdef AGGRESSIVE_TEST
 100 -       if (le16_to_cpu(ex1->ee_len) >= 4)
 101 +       if (ext1_ee_len >= 4)
 102                 return 0;
 103  #endif
 104
 105 @@ -2313,7 +2315,7 @@ int ext4_ext_get_blocks(handle_t *handle
 106                                    - le32_to_cpu(newex.ee_block)
 107                                    + ext_pblock(&newex);
 108                         /* number of remaining blocks in the extent */
 109 -                       allocated = le16_to_cpu(newex.ee_len) -
 110 +                       allocated = ext4_ext_get_actual_len(&newex) -
 111                                         (iblock - le32_to_cpu(newex.ee_block));
 112                         goto out;
 113                 } else {
 114 @@ -2429,7 +2431,7 @@ int ext4_ext_get_blocks(handle_t *handle
 115         newex.ee_len = cpu_to_le16(max_blocks);
 116         err = ext4_ext_check_overlap(inode, &newex, path);
 117         if (err)
 118 -               allocated = le16_to_cpu(newex.ee_len);
 119 +               allocated = ext4_ext_get_actual_len(&newex);
 120         else
 121                 allocated = max_blocks;
 122
 123 @@ -2461,7 +2463,7 @@ int ext4_ext_get_blocks(handle_t *handle
 124                  * but otherwise we'd need to call it every free() */
 125                 ext4_mb_discard_inode_preallocations(inode);
 126                 ext4_free_blocks(handle, inode, ext_pblock(&newex),
 127 -                                       le16_to_cpu(newex.ee_len), 0);
 128 +                                       ext4_ext_get_actual_len(&newex), 0);
 129                 goto out2;
 130         }
 131
 132 @@ -2470,7 +2472,7 @@ int ext4_ext_get_blocks(handle_t *handle
 133
 134         /* previous routine could use block we allocated */
 135         newblock = ext_pblock(&newex);
 136 -       allocated = le16_to_cpu(newex.ee_len);
 137 +       allocated = ext4_ext_get_actual_len(&newex);
 138  outnew:
 139         __set_bit(BH_New, &bh_result->b_state);
 140