ext2_fix_max_size.patch

   1 ext2: Fix the max file size for ext2 file system.
   2
   3 From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4
   5 The max file size for ext2 file system is now calculated
   6 with hardcoded 4K block size. The patch fixes it to be
   7 calculated with the right block size.
   8
   9 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  10 ---
  11
  12  fs/ext2/super.c |   32 ++++++++++++++++++++++++++++----
  13  1 files changed, 28 insertions(+), 4 deletions(-)
  14
  15
  16 diff --git a/fs/ext2/super.c b/fs/ext2/super.c
  17 index 154e25f..6abaf75 100644
  18 --- a/fs/ext2/super.c
  19 +++ b/fs/ext2/super.c
  20 @@ -680,11 +680,31 @@ static int ext2_check_descriptors (struct super_block * sb)
  21  static loff_t ext2_max_size(int bits)
  22  {
  23         loff_t res = EXT2_NDIR_BLOCKS;
  24 -       /* This constant is calculated to be the largest file size for a
  25 -        * dense, 4k-blocksize file such that the total number of
  26 +       int meta_blocks;
  27 +       loff_t upper_limit;
  28 +
  29 +       /* This is calculated to be the largest file size for a
  30 +        * dense, file such that the total number of
  31          * sectors in the file, including data and all indirect blocks,
  32 -        * does not exceed 2^32. */
  33 -       const loff_t upper_limit = 0x1ff7fffd000LL;
  34 +        * does not exceed 2^32 -1
  35 +        * __u32 i_blocks representing the total number of
  36 +        * 512 bytes blocks of the file
  37 +        */
  38 +       upper_limit = (1LL << 32) - 1;
  39 +
  40 +       /* total blocks in file system block size */
  41 +       upper_limit >>= (bits - 9);
  42 +
  43 +
  44 +       /* indirect blocks */
  45 +       meta_blocks = 1;
  46 +       /* double indirect blocks */
  47 +       meta_blocks += 1 + (1LL << (bits-2));
  48 +       /* tripple indirect blocks */
  49 +       meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2)));
  50 +
  51 +       upper_limit -= meta_blocks;
  52 +       upper_limit <<= bits;
  53
  54         res += 1LL << (bits-2);
  55         res += 1LL << (2*(bits-2));
  56 @@ -692,6 +712,10 @@ static loff_t ext2_max_size(int bits)
  57         res <<= bits;
  58         if (res > upper_limit)
  59                 res = upper_limit;
  60 +
  61 +       if (res > MAX_LFS_FILESIZE)
  62 +               res = MAX_LFS_FILESIZE;
  63 +
  64         return res;
  65  }
  66