Commit ed3ad79f authored Feb 17, 2015 by Fabian Frederick Committed by Linus Torvalds Feb 17, 2015

fs/ufs/super.c: fix potential race condition



Let locking subsystem decide on mutex management.  As reported by Andrew
Morton this patch fixes a bug:

: lock_ufs() is assuming that on non-preempt uniprocessor, the calling
: code will run atomically up to the matching unlock_ufs().
:
: But that isn't true. The very first site I looked at (ufs_frag_map)
: does sb_bread() under lock_ufs().  And sb_bread() will call schedule(),
: very commonly.
:
: The ->mutex_owner stuff is a bit hacky but should work OK.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 61da3ae2

fs/ufs/super.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -95,22 +95,18 @@

		void lock_ufs(struct super_block *sb)
		{
		#if defined(CONFIG_SMP) \|\| defined (CONFIG_PREEMPT)
		struct ufs_sb_info *sbi = UFS_SB(sb);

		mutex_lock(&sbi->mutex);
		sbi->mutex_owner = current;
		#endif
		}

		void unlock_ufs(struct super_block *sb)
		{
		#if defined(CONFIG_SMP) \|\| defined (CONFIG_PREEMPT)
		struct ufs_sb_info *sbi = UFS_SB(sb);

		sbi->mutex_owner = NULL;
		mutex_unlock(&sbi->mutex);
		#endif
		}

		static struct inode ufs_nfs_get_inode(struct super_block sb, u64 ino, u32 generation)