Fix-EXT_MAX_BLOCK.patch

   1 ext4: fix invalid block number magic for >16 TB fs
   2
   3 From: Girish Shilamkar <Girish.Shilamkar@Sun.COM>
   4
   5 The magic constant EXT_MAX_BLOCK = 0xffffffff in extents code is used
   6 in some places to return "invalid block number", and to set the extent
   7 length = "whole file" in other places.
   8
   9 So with >= 16 TB fs we would prefer to use it differently. We can have
  10 EXT_UNSET_BLOCK = 1 to indicate "invalid block number" as it will never
  11 be valid block for allocation.  And for the "whole file" use case we can
  12 continue using current EXT_MAX_BLOCK.
  13
  14 Signed-off-by:  Girish Shilamkar <Girish.Shilamkar@Sun.COM>
  15 Signed-off-by:  Mingming Cao <cmm@us.ibm.com>
  16 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  17 ---
  18  fs/ext4/ext4_extents.h |    1 +
  19  fs/ext4/extents.c      |   20 ++++++++++----------
  20  2 files changed, 11 insertions(+), 10 deletions(-)
  21
  22 Index: linux-2.6.26-rc9/fs/ext4/ext4_extents.h
  23 ===================================================================
  24 --- linux-2.6.26-rc9.orig/fs/ext4/ext4_extents.h        2008-07-08 16:52:23.000000000 -0700
  25 +++ linux-2.6.26-rc9/fs/ext4/ext4_extents.h     2008-07-08 16:59:41.000000000 -0700
  26 @@ -126,6 +126,7 @@ struct ext4_ext_path {
  27
  28
  29  #define EXT_MAX_BLOCK  0xffffffff
  30 +#define EXT_UNSET_BLOCK 1
  31
  32  /*
  33   * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
  34 Index: linux-2.6.26-rc9/fs/ext4/extents.c
  35 ===================================================================
  36 --- linux-2.6.26-rc9.orig/fs/ext4/extents.c     2008-07-08 16:52:32.000000000 -0700
  37 +++ linux-2.6.26-rc9/fs/ext4/extents.c  2008-07-08 16:59:41.000000000 -0700
  38 @@ -1204,7 +1204,7 @@ ext4_ext_search_right(struct inode *inod
  39
  40  /*
  41   * ext4_ext_next_allocated_block:
  42 - * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
  43 + * returns allocated block in subsequent extent or EXT_UNSET_BLOCK.
  44   * NOTE: it considers block number from index entry as
  45   * allocated block. Thus, index entries have to be consistent
  46   * with leaves.
  47 @@ -1218,7 +1218,7 @@ ext4_ext_next_allocated_block(struct ext
  48         depth = path->p_depth;
  49
  50         if (depth == 0 && path->p_ext == NULL)
  51 -               return EXT_MAX_BLOCK;
  52 +               return EXT_UNSET_BLOCK;
  53
  54         while (depth >= 0) {
  55                 if (depth == path->p_depth) {
  56 @@ -1235,12 +1235,12 @@ ext4_ext_next_allocated_block(struct ext
  57                 depth--;
  58         }
  59
  60 -       return EXT_MAX_BLOCK;
  61 +       return EXT_UNSET_BLOCK;
  62  }
  63
  64  /*
  65   * ext4_ext_next_leaf_block:
  66 - * returns first allocated block from next leaf or EXT_MAX_BLOCK
  67 + * returns first allocated block from next leaf or EXT_UNSET_BLOCK
  68   */
  69  static ext4_lblk_t ext4_ext_next_leaf_block(struct inode *inode,
  70                                         struct ext4_ext_path *path)
  71 @@ -1252,7 +1252,7 @@ static ext4_lblk_t ext4_ext_next_leaf_bl
  72
  73         /* zero-tree has no leaf blocks at all */
  74         if (depth == 0)
  75 -               return EXT_MAX_BLOCK;
  76 +               return EXT_UNSET_BLOCK;
  77
  78         /* go to index block */
  79         depth--;
  80 @@ -1265,7 +1265,7 @@ static ext4_lblk_t ext4_ext_next_leaf_bl
  81                 depth--;
  82         }
  83
  84 -       return EXT_MAX_BLOCK;
  85 +       return EXT_UNSET_BLOCK;
  86  }
  87
  88  /*
  89 @@ -1445,7 +1445,7 @@ unsigned int ext4_ext_check_overlap(stru
  90          */
  91         if (b2 < b1) {
  92                 b2 = ext4_ext_next_allocated_block(path);
  93 -               if (b2 == EXT_MAX_BLOCK)
  94 +               if (b2 == EXT_UNSET_BLOCK)
  95                         goto out;
  96         }
  97
  98 @@ -1524,7 +1524,7 @@ repeat:
  99         fex = EXT_LAST_EXTENT(eh);
 100         next = ext4_ext_next_leaf_block(inode, path);
 101         if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)
 102 -           && next != EXT_MAX_BLOCK) {
 103 +           && next != EXT_UNSET_BLOCK) {
 104                 ext_debug("next leaf block - %d\n", next);
 105                 BUG_ON(npath != NULL);
 106                 npath = ext4_ext_find_extent(inode, next, NULL);
 107 @@ -1883,8 +1883,8 @@ ext4_ext_rm_leaf(handle_t *handle, struc
 108                 path[depth].p_ext = ex;
 109
 110                 a = ex_ee_block > start ? ex_ee_block : start;
 111 -               b = ex_ee_block + ex_ee_len - 1 < EXT_MAX_BLOCK ?
 112 -                       ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;
 113 +               b = (unsigned long long)ex_ee_block + ex_ee_len - 1 <
 114 +                   EXT_MAX_BLOCK ? ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCK;
 115
 116                 ext_debug("  border %u:%u\n", a, b);
 117