fat: mmu_private race fix

mmu_private is 64bits value, hence it's not atomic to update.

So, the access rule for mmu_private is we must hold ->i_mutex.  But,
fat_get_block() path doesn't follow the rule on non-allocation path.

This fixes by using i_size instead if non-allocation path.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index be88208b83a6..9e37ad93c730 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -64,7 +64,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
         sector_t phys;
         int err, offset;
 
-        err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
+        err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
         if (err)
                 return err;
         if (phys) {
@@ -94,7 +94,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
         *max_blocks = min(mapped_blocks, *max_blocks);
         MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 
-        err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
+        err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
         if (err)
                 return err;