Commit 9ca59f4c authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Linus Torvalds

fat: ->i_pos race fix

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

Important place is fat_write_inode() only, other places without lock
are just for printk().

This adds lock for "BITS_PER_LONG == 32" kernel.
Signed-off-by: 's avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2bdf67eb
......@@ -542,6 +542,20 @@ static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}
static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
struct inode *inode)
{
loff_t i_pos;
#if BITS_PER_LONG == 32
spin_lock(&sbi->inode_hash_lock);
#endif
i_pos = MSDOS_I(inode)->i_pos;
#if BITS_PER_LONG == 32
spin_unlock(&sbi->inode_hash_lock);
#endif
return i_pos;
}
static int fat_write_inode(struct inode *inode, int wait)
{
struct super_block *sb = inode->i_sb;
......@@ -551,9 +565,12 @@ static int fat_write_inode(struct inode *inode, int wait)
loff_t i_pos;
int err;
if (inode->i_ino == MSDOS_ROOT_INO)
return 0;
retry:
i_pos = MSDOS_I(inode)->i_pos;
if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
i_pos = fat_i_pos_read(sbi, inode);
if (!i_pos)
return 0;
bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
......
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