diff options
Diffstat (limited to 'module/zfs/rrwlock.c')
| -rw-r--r-- | module/zfs/rrwlock.c | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/module/zfs/rrwlock.c b/module/zfs/rrwlock.c index 7f9290bd4..8e80166c7 100644 --- a/module/zfs/rrwlock.c +++ b/module/zfs/rrwlock.c @@ -75,8 +75,9 @@ uint_t rrw_tsd_key; typedef struct rrw_node { - struct rrw_node *rn_next; - rrwlock_t *rn_rrl; + struct rrw_node *rn_next; + rrwlock_t *rn_rrl; + void *rn_tag; } rrw_node_t; static rrw_node_t * @@ -98,13 +99,14 @@ rrn_find(rrwlock_t *rrl) * Add a node to the head of the singly linked list. */ static void -rrn_add(rrwlock_t *rrl) +rrn_add(rrwlock_t *rrl, void *tag) { rrw_node_t *rn; rn = kmem_alloc(sizeof (*rn), KM_SLEEP); rn->rn_rrl = rrl; rn->rn_next = tsd_get(rrw_tsd_key); + rn->rn_tag = tag; VERIFY(tsd_set(rrw_tsd_key, rn) == 0); } @@ -113,7 +115,7 @@ rrn_add(rrwlock_t *rrl) * thread's list and return TRUE; otherwise return FALSE. */ static boolean_t -rrn_find_and_remove(rrwlock_t *rrl) +rrn_find_and_remove(rrwlock_t *rrl, void *tag) { rrw_node_t *rn; rrw_node_t *prev = NULL; @@ -122,7 +124,7 @@ rrn_find_and_remove(rrwlock_t *rrl) return (B_FALSE); for (rn = tsd_get(rrw_tsd_key); rn != NULL; rn = rn->rn_next) { - if (rn->rn_rrl == rrl) { + if (rn->rn_rrl == rrl && rn->rn_tag == tag) { if (prev) prev->rn_next = rn->rn_next; else @@ -136,7 +138,7 @@ rrn_find_and_remove(rrwlock_t *rrl) } void -rrw_init(rrwlock_t *rrl) +rrw_init(rrwlock_t *rrl, boolean_t track_all) { mutex_init(&rrl->rr_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&rrl->rr_cv, NULL, CV_DEFAULT, NULL); @@ -144,6 +146,7 @@ rrw_init(rrwlock_t *rrl) refcount_create(&rrl->rr_anon_rcount); refcount_create(&rrl->rr_linked_rcount); rrl->rr_writer_wanted = B_FALSE; + rrl->rr_track_all = track_all; } void @@ -156,12 +159,13 @@ rrw_destroy(rrwlock_t *rrl) refcount_destroy(&rrl->rr_linked_rcount); } -static void +void rrw_enter_read(rrwlock_t *rrl, void *tag) { mutex_enter(&rrl->rr_lock); #if !defined(DEBUG) && defined(_KERNEL) - if (!rrl->rr_writer && !rrl->rr_writer_wanted) { + if (rrl->rr_writer == NULL && !rrl->rr_writer_wanted && + !rrl->rr_track_all) { rrl->rr_anon_rcount.rc_count++; mutex_exit(&rrl->rr_lock); return; @@ -171,14 +175,14 @@ rrw_enter_read(rrwlock_t *rrl, void *tag) ASSERT(rrl->rr_writer != curthread); ASSERT(refcount_count(&rrl->rr_anon_rcount) >= 0); - while (rrl->rr_writer || (rrl->rr_writer_wanted && + while (rrl->rr_writer != NULL || (rrl->rr_writer_wanted && refcount_is_zero(&rrl->rr_anon_rcount) && rrn_find(rrl) == NULL)) cv_wait(&rrl->rr_cv, &rrl->rr_lock); - if (rrl->rr_writer_wanted) { + if (rrl->rr_writer_wanted || rrl->rr_track_all) { /* may or may not be a re-entrant enter */ - rrn_add(rrl); + rrn_add(rrl, tag); (void) refcount_add(&rrl->rr_linked_rcount, tag); } else { (void) refcount_add(&rrl->rr_anon_rcount, tag); @@ -187,7 +191,7 @@ rrw_enter_read(rrwlock_t *rrl, void *tag) mutex_exit(&rrl->rr_lock); } -static void +void rrw_enter_write(rrwlock_t *rrl) { mutex_enter(&rrl->rr_lock); @@ -233,10 +237,12 @@ rrw_exit(rrwlock_t *rrl, void *tag) if (rrl->rr_writer == NULL) { int64_t count; - if (rrn_find_and_remove(rrl)) + if (rrn_find_and_remove(rrl, tag)) { count = refcount_remove(&rrl->rr_linked_rcount, tag); - else + } else { + ASSERT(!rrl->rr_track_all); count = refcount_remove(&rrl->rr_anon_rcount, tag); + } if (count == 0) cv_broadcast(&rrl->rr_cv); } else { @@ -249,6 +255,11 @@ rrw_exit(rrwlock_t *rrl, void *tag) mutex_exit(&rrl->rr_lock); } +/* + * If the lock was created with track_all, rrw_held(RW_READER) will return + * B_TRUE iff the current thread has the lock for reader. Otherwise it may + * return B_TRUE if any thread has the lock for reader. + */ boolean_t rrw_held(rrwlock_t *rrl, krw_t rw) { @@ -259,7 +270,7 @@ rrw_held(rrwlock_t *rrl, krw_t rw) held = (rrl->rr_writer == curthread); } else { held = (!refcount_is_zero(&rrl->rr_anon_rcount) || - !refcount_is_zero(&rrl->rr_linked_rcount)); + rrn_find(rrl) != NULL); } mutex_exit(&rrl->rr_lock); |