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MFV r328225: 8603 rename zilog's "zl_writer_lock" to "zl_issuer_lock"

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illumos/illumos-gate@cf07d3da99

https://www.illumos.org/issues/8603:
  To help make the ZIL's code more understandable, it was suggested that
  the zilog_t's "zl_writer_lock" field should be renamed to "zl_issuer_lock".

Reviewed by: C Fraire <cfraire@me.com>
Approved by: Dan McDonald <danmcd@joyent.com>
Author: Prakash Surya <prakash.surya@delphix.com>
This commit is contained in:
Alexander Motin 2018-01-21 23:11:20 +00:00
commit d252c97fc0
2 changed files with 27 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil_impl.h
View File

@ -57,9 +57,9 @@ typedef enum {
* Log write block (lwb)
*
* Prior to an lwb being issued to disk via zil_lwb_write_issue(), it
* will be protected by the zilog's "zl_writer_lock". Basically, prior
* will be protected by the zilog's "zl_issuer_lock". Basically, prior
* to it being issued, it will only be accessed by the thread that's
* holding the "zl_writer_lock". After the lwb is issued, the zilog's
* holding the "zl_issuer_lock". After the lwb is issued, the zilog's
* "zl_lock" is used to protect the lwb against concurrent access.
*/
typedef struct lwb {
@ -91,10 +91,10 @@ typedef struct lwb {
*
* The "zcw_lock" field is used to protect the commit waiter against
* concurrent access. This lock is often acquired while already holding
* the zilog's "zl_writer_lock" or "zl_lock"; see the functions
* the zilog's "zl_issuer_lock" or "zl_lock"; see the functions
* zil_process_commit_list() and zil_lwb_flush_vdevs_done() as examples
* of this. Thus, one must be careful not to acquire the
* "zl_writer_lock" or "zl_lock" when already holding the "zcw_lock";
* "zl_issuer_lock" or "zl_lock" when already holding the "zcw_lock";
* e.g. see the zil_commit_waiter_timeout() function.
*/
typedef struct zil_commit_waiter {
@ -161,7 +161,7 @@ struct zilog {
uint8_t zl_keep_first; /* keep first log block in destroy */
uint8_t zl_replay; /* replaying records while set */
uint8_t zl_stop_sync; /* for debugging */
kmutex_t zl_writer_lock; /* single writer, per ZIL, at a time */
kmutex_t zl_issuer_lock; /* single writer, per ZIL, at a time */
uint8_t zl_logbias; /* latency or throughput */
uint8_t zl_sync; /* synchronous or asynchronous */
int zl_parse_error; /* last zil_parse() error */

44
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c
View File

@ -1104,7 +1104,7 @@ zil_lwb_write_open(zilog_t *zilog, lwb_t *lwb)
zbookmark_phys_t zb;
zio_priority_t prio;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
ASSERT3P(lwb, !=, NULL);
EQUIV(lwb->lwb_root_zio == NULL, lwb->lwb_state == LWB_STATE_CLOSED);
EQUIV(lwb->lwb_root_zio != NULL, lwb->lwb_state == LWB_STATE_OPENED);
@ -1201,7 +1201,7 @@ zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb)
int i, error;
boolean_t slog;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
ASSERT3P(lwb->lwb_root_zio, !=, NULL);
ASSERT3P(lwb->lwb_write_zio, !=, NULL);
ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED);
@ -1335,7 +1335,7 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb)
char *lr_buf;
uint64_t dlen, dnow, lwb_sp, reclen, txg;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
ASSERT3P(lwb, !=, NULL);
ASSERT3P(lwb->lwb_buf, !=, NULL);
@ -1751,7 +1751,7 @@ zil_get_commit_list(zilog_t *zilog)
uint64_t otxg, txg;
list_t *commit_list = &zilog->zl_itx_commit_list;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */
otxg = ZILTEST_TXG;
@ -1858,7 +1858,7 @@ zil_prune_commit_list(zilog_t *zilog)
{
itx_t *itx;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
while (itx = list_head(&zilog->zl_itx_commit_list)) {
lr_t *lrc = &itx->itx_lr;
@ -1908,12 +1908,12 @@ zil_commit_writer_stall(zilog_t *zilog)
* crash (because the previous lwb on-disk would not point to
* it).
*
* We must hold the zilog's zl_writer_lock while we do this, to
* We must hold the zilog's zl_issuer_lock while we do this, to
* ensure no new threads enter zil_process_commit_list() until
* all lwb's in the zl_lwb_list have been synced and freed
* (which is achieved via the txg_wait_synced() call).
*/
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
txg_wait_synced(zilog->zl_dmu_pool, 0);
ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL);
}
@ -1932,7 +1932,7 @@ zil_process_commit_list(zilog_t *zilog)
lwb_t *lwb;
itx_t *itx;
ASSERT(MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock));
/*
* Return if there's nothing to commit before we dirty the fs by
@ -2102,17 +2102,17 @@ zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw)
ASSERT(spa_writeable(zilog->zl_spa));
ASSERT0(zilog->zl_suspend);
mutex_enter(&zilog->zl_writer_lock);
mutex_enter(&zilog->zl_issuer_lock);
if (zcw->zcw_lwb != NULL || zcw->zcw_done) {
/*
* It's possible that, while we were waiting to acquire
* the "zl_writer_lock", another thread committed this
* the "zl_issuer_lock", another thread committed this
* waiter to an lwb. If that occurs, we bail out early,
* without processing any of the zilog's queue of itxs.
*
* On certain workloads and system configurations, the
* "zl_writer_lock" can become highly contended. In an
* "zl_issuer_lock" can become highly contended. In an
* attempt to reduce this contention, we immediately drop
* the lock if the waiter has already been processed.
*
@ -2129,13 +2129,13 @@ zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw)
zil_process_commit_list(zilog);
out:
mutex_exit(&zilog->zl_writer_lock);
mutex_exit(&zilog->zl_issuer_lock);
}
static void
zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
{
ASSERT(!MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock));
ASSERT(MUTEX_HELD(&zcw->zcw_lock));
ASSERT3B(zcw->zcw_done, ==, B_FALSE);
@ -2147,7 +2147,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
* If the lwb has already been issued by another thread, we can
* immediately return since there's no work to be done (the
* point of this function is to issue the lwb). Additionally, we
* do this prior to acquiring the zl_writer_lock, to avoid
* do this prior to acquiring the zl_issuer_lock, to avoid
* acquiring it when it's not necessary to do so.
*/
if (lwb->lwb_state == LWB_STATE_ISSUED ||
@ -2156,13 +2156,13 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
/*
* In order to call zil_lwb_write_issue() we must hold the
* zilog's "zl_writer_lock". We can't simply acquire that lock,
* zilog's "zl_issuer_lock". We can't simply acquire that lock,
* since we're already holding the commit waiter's "zcw_lock",
* and those two locks are aquired in the opposite order
* elsewhere.
*/
mutex_exit(&zcw->zcw_lock);
mutex_enter(&zilog->zl_writer_lock);
mutex_enter(&zilog->zl_issuer_lock);
mutex_enter(&zcw->zcw_lock);
/*
@ -2180,7 +2180,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
/*
* We've already checked this above, but since we hadn't
* acquired the zilog's zl_writer_lock, we have to perform this
* acquired the zilog's zl_issuer_lock, we have to perform this
* check a second time while holding the lock. We can't call
* zil_lwb_write_issue() if the lwb had already been issued.
*/
@ -2243,7 +2243,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
}
out:
mutex_exit(&zilog->zl_writer_lock);
mutex_exit(&zilog->zl_issuer_lock);
ASSERT(MUTEX_HELD(&zcw->zcw_lock));
}
@ -2270,7 +2270,7 @@ static void
zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw)
{
ASSERT(!MUTEX_HELD(&zilog->zl_lock));
ASSERT(!MUTEX_HELD(&zilog->zl_writer_lock));
ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock));
ASSERT(spa_writeable(zilog->zl_spa));
ASSERT0(zilog->zl_suspend);
@ -2531,7 +2531,7 @@ zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw)
* on two fundamental concepts:
*
* 1. The creation and issuance of lwb zio's is protected by
* the zilog's "zl_writer_lock", which ensures only a single
* the zilog's "zl_issuer_lock", which ensures only a single
* thread is creating and/or issuing lwb's at a time
* 2. The "previous" lwb is a child of the "current" lwb
* (leveraging the zio parent-child depenency graph)
@ -2780,7 +2780,7 @@ zil_alloc(objset_t *os, zil_header_t *zh_phys)
zilog->zl_last_lwb_latency = 0;
mutex_init(&zilog->zl_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&zilog->zl_writer_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&zilog->zl_issuer_lock, NULL, MUTEX_DEFAULT, NULL);
for (int i = 0; i < TXG_SIZE; i++) {
mutex_init(&zilog->zl_itxg[i].itxg_lock, NULL,
@ -2825,7 +2825,7 @@ zil_free(zilog_t *zilog)
mutex_destroy(&zilog->zl_itxg[i].itxg_lock);
}
mutex_destroy(&zilog->zl_writer_lock);
mutex_destroy(&zilog->zl_issuer_lock);
mutex_destroy(&zilog->zl_lock);
cv_destroy(&zilog->zl_cv_suspend);