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Add MUTEX_FSTRANS mutex type

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There are regions in the ZFS code where it is desirable to be able
to be set PF_FSTRANS while a specific mutex is held.  The ZFS code
could be updated to set/clear this flag in all the correct places,
but this is undesirable for a few reasons.

1) It would require changes to a significant amount of the ZFS
   code.  This would complicate applying patches from upstream.

2) It would be easy to accidentally miss a critical region in
   the initial patch or to have an future change introduce a
   new one.

Both of these concerns can be addressed by adding a new mutex type
which is responsible for managing PF_FSTRANS, support for which was
added to the SPL in commit 9099312 - Merge branch 'kmem-rework'.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Issue #435
This commit is contained in:
Brian Behlendorf 2015-02-25 10:29:02 -08:00
parent 5f920fbee1
commit d0d5dd7144
2 changed files with 31 additions and 21 deletions
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50
include/sys/mutex.h
View File

@ -32,29 +32,19 @@
typedef enum {
MUTEX_DEFAULT = 0,
MUTEX_SPIN = 1,
MUTEX_ADAPTIVE = 2
MUTEX_ADAPTIVE = 2,
MUTEX_FSTRANS = 3,
} kmutex_type_t;
typedef struct {
struct mutex m_mutex;
kmutex_type_t m_type;
spinlock_t m_lock; /* used for serializing mutex_exit */
kthread_t *m_owner;
unsigned int m_saved_flags;
} kmutex_t;
#define MUTEX(mp) (&((mp)->m_mutex))
static inline void
spl_mutex_set_owner(kmutex_t *mp)
{
mp->m_owner = current;
}
static inline void
spl_mutex_clear_owner(kmutex_t *mp)
{
mp->m_owner = NULL;
}
#define mutex_owner(mp) (ACCESS_ONCE((mp)->m_owner))
#define mutex_owned(mp) (mutex_owner(mp) == current)
#define MUTEX_HELD(mp) mutex_owned(mp)
@ -70,11 +60,18 @@ spl_mutex_clear_owner(kmutex_t *mp)
#define mutex_init(mp, name, type, ibc) \
{ \
static struct lock_class_key __key; \
ASSERT(type == MUTEX_DEFAULT); \
\
ASSERT3P(mp, !=, NULL); \
ASSERT3P(ibc, ==, NULL); \
ASSERT((type == MUTEX_DEFAULT) || \
(type == MUTEX_ADAPTIVE) || \
(type == MUTEX_FSTRANS)); \
\
__mutex_init(MUTEX(mp), #mp, &__key); \
spin_lock_init(&(mp)->m_lock); \
spl_mutex_clear_owner(mp); \
(mp)->m_type = type; \
(mp)->m_owner = NULL; \
(mp)->m_saved_flags = 0; \
}
#undef mutex_destroy
@ -87,8 +84,13 @@ spl_mutex_clear_owner(kmutex_t *mp)
({ \
int _rc_; \
\
if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) \
spl_mutex_set_owner(mp); \
if ((_rc_ = mutex_trylock(MUTEX(mp))) == 1) { \
(mp)->m_owner = current; \
if ((mp)->m_type == MUTEX_FSTRANS) { \
(mp)->m_saved_flags = current->flags; \
current->flags |= PF_FSTRANS; \
} \
} \
\
_rc_; \
})
@ -97,7 +99,11 @@ spl_mutex_clear_owner(kmutex_t *mp)
{ \
ASSERT3P(mutex_owner(mp), !=, current); \
mutex_lock(MUTEX(mp)); \
spl_mutex_set_owner(mp); \
(mp)->m_owner = current; \
if ((mp)->m_type == MUTEX_FSTRANS) { \
(mp)->m_saved_flags = current->flags; \
current->flags |= PF_FSTRANS; \
} \
}
/*
@ -122,7 +128,11 @@ spl_mutex_clear_owner(kmutex_t *mp)
#define mutex_exit(mp) \
{ \
spin_lock(&(mp)->m_lock); \
spl_mutex_clear_owner(mp); \
if ((mp)->m_type == MUTEX_FSTRANS) { \
current->flags &= ~(PF_FSTRANS); \
current->flags |= (mp)->m_saved_flags; \
} \
(mp)->m_owner = NULL; \
mutex_unlock(MUTEX(mp)); \
spin_unlock(&(mp)->m_lock); \
}

2
module/splat/splat-atomic.c
View File

@ -145,7 +145,7 @@ splat_atomic_test1(struct file *file, void *arg)
ap.ap_magic = SPLAT_ATOMIC_TEST_MAGIC;
ap.ap_file = file;
mutex_init(&ap.ap_lock, SPLAT_ATOMIC_TEST1_NAME, NULL, NULL);
mutex_init(&ap.ap_lock, SPLAT_ATOMIC_TEST1_NAME, MUTEX_DEFAULT, NULL);
init_waitqueue_head(&ap.ap_waitq);
ap.ap_atomic = SPLAT_ATOMIC_INIT_VALUE;
ap.ap_atomic_exited = 0;