ext4: store maxbytes for bitmapped files and return EFBIG as appropriate

Calculate & store the max offset for bitmapped files, and
catch too-large seeks, truncates, and writes in ext4, shortening
or rejecting as appropriate.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c79e46b7f159..0931831537a2 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1922,6 +1922,7 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
                 }
         }
 
+        sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits);
         sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits);
 
         if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {