Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

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

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: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2bdf67eb

fs/fat/inode.c

+19 −2
Original line number Diff line number Diff line
@@ -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);