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Revert "Fix data race between zil_commit() and zil_suspend()" 

This reverts commit 4c856fb333 to
resolve a newly introduced deadlock which in practice in more
disruptive that the issue this commit intended to address.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #14775
Closes #14790
This commit is contained in:
Brian Behlendorf 2023-04-25 16:40:55 -07:00 committed by GitHub
parent 6d59d5df98
commit 0e8a42bbee
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 0 additions and 28 deletions
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1
include/sys/zil_impl.h
View File

@ -183,7 +183,6 @@ struct zilog {
uint64_t zl_destroy_txg; /* txg of last zil_destroy() */ uint64_t zl_destroy_txg; /* txg of last zil_destroy() */
uint64_t zl_replayed_seq[TXG_SIZE]; /* last replayed rec seq */ uint64_t zl_replayed_seq[TXG_SIZE]; /* last replayed rec seq */
uint64_t zl_replaying_seq; /* current replay seq number */ uint64_t zl_replaying_seq; /* current replay seq number */
krwlock_t zl_suspend_lock; /* protects suspend count */
uint32_t zl_suspend; /* log suspend count */ uint32_t zl_suspend; /* log suspend count */
kcondvar_t zl_cv_suspend; /* log suspend completion */ kcondvar_t zl_cv_suspend; /* log suspend completion */
uint8_t zl_suspending; /* log is currently suspending */ uint8_t zl_suspending; /* log is currently suspending */

27
module/zfs/zil.c
View File

@ -3317,21 +3317,6 @@ zil_commit(zilog_t *zilog, uint64_t foid)
return; return;
} }
/*
* The ->zl_suspend_lock rwlock ensures that all in-flight
* zil_commit() operations finish before suspension begins and that
* no more begin. Without it, it is possible for the scheduler to
* preempt us right after the zilog->zl_suspend suspend check, run
* another thread that runs zil_suspend() and after the other thread
* has finished its call to zil_commit_impl(), resume this thread while
* zil is suspended. This can trigger an assertion failure in
* VERIFY(list_is_empty(&lwb->lwb_itxs)). If it is held, it means that
* `zil_suspend()` is executing in another thread, so we go to
* txg_wait_synced().
*/
if (!rw_tryenter(&zilog->zl_suspend_lock, RW_READER))
goto wait;
/* /*
* If the ZIL is suspended, we don't want to dirty it by calling * If the ZIL is suspended, we don't want to dirty it by calling
* zil_commit_itx_assign() below, nor can we write out * zil_commit_itx_assign() below, nor can we write out
@ -3340,14 +3325,11 @@ zil_commit(zilog_t *zilog, uint64_t foid)
* semantics, and avoid calling those functions altogether. * semantics, and avoid calling those functions altogether.
*/ */
if (zilog->zl_suspend > 0) { if (zilog->zl_suspend > 0) {
rw_exit(&zilog->zl_suspend_lock);
wait:
txg_wait_synced(zilog->zl_dmu_pool, 0); txg_wait_synced(zilog->zl_dmu_pool, 0);
return; return;
} }
zil_commit_impl(zilog, foid); zil_commit_impl(zilog, foid);
rw_exit(&zilog->zl_suspend_lock);
} }
void void
@ -3612,8 +3594,6 @@ zil_alloc(objset_t *os, zil_header_t *zh_phys)
cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL); cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL);
cv_init(&zilog->zl_lwb_io_cv, NULL, CV_DEFAULT, NULL); cv_init(&zilog->zl_lwb_io_cv, NULL, CV_DEFAULT, NULL);
rw_init(&zilog->zl_suspend_lock, NULL, RW_DEFAULT, NULL);
return (zilog); return (zilog);
} }
@ -3653,8 +3633,6 @@ zil_free(zilog_t *zilog)
cv_destroy(&zilog->zl_cv_suspend); cv_destroy(&zilog->zl_cv_suspend);
cv_destroy(&zilog->zl_lwb_io_cv); cv_destroy(&zilog->zl_lwb_io_cv);
rw_destroy(&zilog->zl_suspend_lock);
kmem_free(zilog, sizeof (zilog_t)); kmem_free(zilog, sizeof (zilog_t));
} }
@ -3782,14 +3760,11 @@ zil_suspend(const char *osname, void **cookiep)
return (error); return (error);
zilog = dmu_objset_zil(os); zilog = dmu_objset_zil(os);
rw_enter(&zilog->zl_suspend_lock, RW_WRITER);
mutex_enter(&zilog->zl_lock); mutex_enter(&zilog->zl_lock);
zh = zilog->zl_header; zh = zilog->zl_header;
if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */ if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */
mutex_exit(&zilog->zl_lock); mutex_exit(&zilog->zl_lock);
rw_exit(&zilog->zl_suspend_lock);
dmu_objset_rele(os, suspend_tag); dmu_objset_rele(os, suspend_tag);
return (SET_ERROR(EBUSY)); return (SET_ERROR(EBUSY));
} }
@ -3803,7 +3778,6 @@ zil_suspend(const char *osname, void **cookiep)
if (cookiep == NULL && !zilog->zl_suspending && if (cookiep == NULL && !zilog->zl_suspending &&
(zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) { (zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) {
mutex_exit(&zilog->zl_lock); mutex_exit(&zilog->zl_lock);
rw_exit(&zilog->zl_suspend_lock);
dmu_objset_rele(os, suspend_tag); dmu_objset_rele(os, suspend_tag);
return (0); return (0);
} }
@ -3812,7 +3786,6 @@ zil_suspend(const char *osname, void **cookiep)
dsl_pool_rele(dmu_objset_pool(os), suspend_tag); dsl_pool_rele(dmu_objset_pool(os), suspend_tag);
zilog->zl_suspend++; zilog->zl_suspend++;
rw_exit(&zilog->zl_suspend_lock);
if (zilog->zl_suspend > 1) { if (zilog->zl_suspend > 1) {
/* /*