fat: ->i_pos race fix (9ca59f4c) · Commits · 戴 / test

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:

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>

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);

Admin message