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Index: kern/kern_rangelock.c
===================================================================
--- kern/kern_rangelock.c
+++ kern/kern_rangelock.c
@@ -57,10 +57,15 @@
SYSINIT(vfs, SI_SUB_LOCK, SI_ORDER_ANY, rangelock_sys_init, NULL);
static struct rl_q_entry *
-rlqentry_alloc(void)
+rlqentry_alloc(int cansleep)
{
+ int zalloc_flag;
- return (uma_zalloc(rl_entry_zone, M_WAITOK));
+ if (cansleep == 1)
+ zalloc_flag = M_WAITOK;
+ else
+ zalloc_flag = M_NOWAIT;
+ return (uma_zalloc(rl_entry_zone, zalloc_flag));
}
void
@@ -196,11 +201,11 @@
/*
* Add the lock request to the queue of the pending requests for
- * rangelock. Sleep until the request can be granted.
+ * rangelock. Sleep until the request can be granted unless cansleep == 0.
*/
static void *
rangelock_enqueue(struct rangelock *lock, off_t start, off_t end, int mode,
- struct mtx *ilk)
+ struct mtx *ilk, int cansleep)
{
struct rl_q_entry *entry;
struct thread *td;
@@ -211,8 +216,11 @@
if (td->td_rlqe != NULL) {
entry = td->td_rlqe;
td->td_rlqe = NULL;
- } else
- entry = rlqentry_alloc();
+ } else {
+ entry = rlqentry_alloc(cansleep);
+ if (cansleep == 0 && entry == NULL)
+ return (NULL);
+ }
MPASS(entry != NULL);
entry->rl_q_flags = mode;
entry->rl_q_start = start;
@@ -226,11 +234,30 @@
*/
TAILQ_INSERT_TAIL(&lock->rl_waiters, entry, rl_q_link);
+ /*
+ * If rl_currdep == NULL, there is no entry waiting for a conflicting
+ * range to be resolved, so set rl_currdep to this entry. If there is
+ * no conflicting entry for this entry, rl_currdep will be set back to
+ * NULL by rangelock_calc_block().
+ */
if (lock->rl_currdep == NULL)
lock->rl_currdep = entry;
rangelock_calc_block(lock);
- while (!(entry->rl_q_flags & RL_LOCK_GRANTED))
+ while (!(entry->rl_q_flags & RL_LOCK_GRANTED)) {
+ if (cansleep == 0) {
+ /*
+ * If rl_currdep is this entry, rl_currdep needs to
+ * be set to the next entry in the rl_waiters list.
+ * However, since this entry is the last entry in the
+ * list, the next entry is NULL.
+ */
+ if (lock->rl_currdep == entry)
+ lock->rl_currdep = NULL;
+ rangelock_unlock_locked(lock, entry, ilk);
+ return (NULL);
+ }
msleep(entry, ilk, 0, "range", 0);
+ }
mtx_unlock(ilk);
return (entry);
}
@@ -239,12 +266,28 @@
rangelock_rlock(struct rangelock *lock, off_t start, off_t end, struct mtx *ilk)
{
- return (rangelock_enqueue(lock, start, end, RL_LOCK_READ, ilk));
+ return (rangelock_enqueue(lock, start, end, RL_LOCK_READ, ilk, 1));
}
void *
+rangelock_rlock_trylock(struct rangelock *lock, off_t start, off_t end,
+ struct mtx *ilk)
+{
+
+ return (rangelock_enqueue(lock, start, end, RL_LOCK_READ, ilk, 0));
+}
+
+void *
rangelock_wlock(struct rangelock *lock, off_t start, off_t end, struct mtx *ilk)
{
- return (rangelock_enqueue(lock, start, end, RL_LOCK_WRITE, ilk));
+ return (rangelock_enqueue(lock, start, end, RL_LOCK_WRITE, ilk, 1));
+}
+
+void *
+rangelock_wlock_trylock(struct rangelock *lock, off_t start, off_t end,
+ struct mtx *ilk)
+{
+
+ return (rangelock_enqueue(lock, start, end, RL_LOCK_WRITE, ilk, 0));
}
Index: sys/rangelock.h
===================================================================
--- sys/rangelock.h
+++ sys/rangelock.h
@@ -75,8 +75,12 @@
off_t start, off_t end, struct mtx *ilk);
void *rangelock_rlock(struct rangelock *lock, off_t start, off_t end,
struct mtx *ilk);
+void *rangelock_rlock_trylock(struct rangelock *lock, off_t start,
+ off_t end, struct mtx *ilk);
void *rangelock_wlock(struct rangelock *lock, off_t start, off_t end,
struct mtx *ilk);
+void *rangelock_wlock_trylock(struct rangelock *lock, off_t start,
+ off_t end, struct mtx *ilk);
void rlqentry_free(struct rl_q_entry *rlqe);
#endif /* _KERNEL */
Index: sys/vnode.h
===================================================================
--- sys/vnode.h
+++ sys/vnode.h
@@ -723,8 +723,12 @@
VI_MTX(vp))
#define vn_rangelock_rlock(vp, start, end) \
rangelock_rlock(&(vp)->v_rl, (start), (end), VI_MTX(vp))
+#define vn_rangelock_rlock_trylock(vp, start, end) \
+ rangelock_rlock_trylock(&(vp)->v_rl, (start), (end), VI_MTX(vp))
#define vn_rangelock_wlock(vp, start, end) \
rangelock_wlock(&(vp)->v_rl, (start), (end), VI_MTX(vp))
+#define vn_rangelock_wlock_trylock(vp, start, end) \
+ rangelock_wlock_trylock(&(vp)->v_rl, (start), (end), VI_MTX(vp))
int vfs_cache_lookup(struct vop_lookup_args *ap);
void vfs_timestamp(struct timespec *);

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