From d0d5dd714424365a4da0d887cb641cb2f0ae8844 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Wed, 25 Feb 2015 10:29:02 -0800 Subject: [PATCH] Add MUTEX_FSTRANS mutex type 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 Signed-off-by: Tim Chase Issue #435 --- include/sys/mutex.h | 50 ++++++++++++++++++++++--------------- module/splat/splat-atomic.c | 2 +- 2 files changed, 31 insertions(+), 21 deletions(-) diff --git a/include/sys/mutex.h b/include/sys/mutex.h index 2e45093..5e2b250 100644 --- a/include/sys/mutex.h +++ b/include/sys/mutex.h @@ -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); \ } diff --git a/module/splat/splat-atomic.c b/module/splat/splat-atomic.c index a270dc4..e94f42f 100644 --- a/module/splat/splat-atomic.c +++ b/module/splat/splat-atomic.c @@ -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; -- 2.39.2