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

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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>
This commit is contained in:
Fabian Frederick 2015-02-17 13:45:31 -08:00 committed by Linus Torvalds
parent 61da3ae241
commit ed3ad79f87
1 changed files with 0 additions and 4 deletions
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4
fs/ufs/super.c
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@ -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)