kern/141387: [zfs] [patch] zfs snapshot -r failed because
filesystem was busy
Martin Matuska
mm at FreeBSD.org
Fri Dec 11 22:40:02 UTC 2009
>Number: 141387
>Category: kern
>Synopsis: [zfs] [patch] zfs snapshot -r failed because filesystem was busy
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Dec 11 22:40:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator: Martin Matuska
>Release: FreeBSD 8-STABLE amd64
>Organization:
>Environment:
System: FreeBSD 8-STABLE FreeBSD 8-STABLE #2
>Description:
There is a bug in ZFS recursive snapshot that was already fixed in OpenSolaris snv_111
I was able to reproduce this bug in FreeBSD.
References:
Opensolaris Bug ID: 6462803
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6462803
This bug was fixed in OpenSolaris snv_111:
http://dlc.sun.com/osol/on/downloads/b111/on-changelog-b111.html
Issues Resolved:
BUG/RFE:6462803 zfs snapshot -r failed because filesystem was busy
Files Changed:
update:usr/src/cmd/zdb/zdb_il.c
update:usr/src/grub/grub-0.97/stage2/zfs-include/zil.h
update:usr/src/uts/common/fs/zfs/sys/zil.h
update:usr/src/uts/common/fs/zfs/zil.c
Revision: 8989:cfce31f4eebf
hg clone ssh://anon@hg.opensolaris.org/hg/onnv/onnv-gate
hg diff -c 8989 onnv-gate
>How-To-Repeat:
This may happen during ZFS recursive snapshot (managed to reproduce it):
root at www:~ > zfs snapshot -r pool at test
cannot create snapshot 'pool at test': dataset is busy
no snapshots were created
>Fix:
Index: cddl/contrib/opensolaris/cmd/zdb/zdb_il.c
===================================================================
--- cddl/contrib/opensolaris/cmd/zdb/zdb_il.c (revision 200415)
+++ cddl/contrib/opensolaris/cmd/zdb/zdb_il.c (working copy)
@@ -19,12 +19,10 @@
* CDDL HEADER END
*/
/*
- * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
+ * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
-#pragma ident "%Z%%M% %I% %E% SMI"
-
/*
* Print intent log header and statistics.
*/
@@ -345,8 +343,10 @@
if (zh->zh_log.blk_birth == 0 || verbose < 2)
return;
- (void) printf("\n ZIL header: claim_txg %llu, seq %llu\n",
- (u_longlong_t)zh->zh_claim_txg, (u_longlong_t)zh->zh_replay_seq);
+ (void) printf("\n ZIL header: claim_txg %llu, claim_seq %llu",
+ (u_longlong_t)zh->zh_claim_txg, (u_longlong_t)zh->zh_claim_seq);
+ (void) printf(" replay_seq %llu, flags 0x%llx\n",
+ (u_longlong_t)zh->zh_replay_seq, (u_longlong_t)zh->zh_flags);
if (verbose >= 4)
print_log_bp(&zh->zh_log, "\n\tfirst block: ");
Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c (revision 200415)
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zil.c (working copy)
@@ -502,6 +502,25 @@
tx, zh->zh_claim_txg);
}
+/*
+ * return true if the initial log block is not valid
+ */
+static boolean_t
+zil_empty(zilog_t *zilog)
+{
+ const zil_header_t *zh = zilog->zl_header;
+ arc_buf_t *abuf = NULL;
+
+ if (BP_IS_HOLE(&zh->zh_log))
+ return (B_TRUE);
+
+ if (zil_read_log_block(zilog, &zh->zh_log, &abuf) != 0)
+ return (B_TRUE);
+
+ VERIFY(arc_buf_remove_ref(abuf, &abuf) == 1);
+ return (B_FALSE);
+}
+
int
zil_claim(char *osname, void *txarg)
{
@@ -522,6 +541,21 @@
zh = zil_header_in_syncing_context(zilog);
/*
+ * Record here whether the zil has any records to replay.
+ * If the header block pointer is null or the block points
+ * to the stubby then we know there are no valid log records.
+ * We use the header to store this state as the the zilog gets
+ * freed later in dmu_objset_close().
+ * The flags (and the rest of the header fields) are cleared in
+ * zil_sync() as a result of a zil_destroy(), after replaying the log.
+ *
+ * Note, the intent log can be empty but still need the
+ * stubby to be claimed.
+ */
+ if (!zil_empty(zilog))
+ zh->zh_flags |= ZIL_REPLAY_NEEDED;
+
+ /*
* Claim all log blocks if we haven't already done so, and remember
* the highest claimed sequence number. This ensures that if we can
* read only part of the log now (e.g. due to a missing device),
@@ -1345,25 +1379,6 @@
}
/*
- * return true if the initial log block is not valid
- */
-static boolean_t
-zil_empty(zilog_t *zilog)
-{
- const zil_header_t *zh = zilog->zl_header;
- arc_buf_t *abuf = NULL;
-
- if (BP_IS_HOLE(&zh->zh_log))
- return (B_TRUE);
-
- if (zil_read_log_block(zilog, &zh->zh_log, &abuf) != 0)
- return (B_TRUE);
-
- VERIFY(arc_buf_remove_ref(abuf, &abuf) == 1);
- return (B_FALSE);
-}
-
-/*
* Open an intent log.
*/
zilog_t *
@@ -1418,7 +1433,7 @@
const zil_header_t *zh = zilog->zl_header;
mutex_enter(&zilog->zl_lock);
- if (zh->zh_claim_txg != 0) { /* unplayed log */
+ if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */
mutex_exit(&zilog->zl_lock);
return (EBUSY);
}
@@ -1645,7 +1660,7 @@
const zil_header_t *zh = zilog->zl_header;
zil_replay_arg_t zr;
- if (zil_empty(zilog)) {
+ if ((zh->zh_flags & ZIL_REPLAY_NEEDED) == 0) {
zil_destroy(zilog, B_TRUE);
return;
}
Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h (revision 200415)
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zil.h (working copy)
@@ -19,7 +19,7 @@
* CDDL HEADER END
*/
/*
- * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
+ * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
@@ -56,10 +56,16 @@
uint64_t zh_replay_seq; /* highest replayed sequence number */
blkptr_t zh_log; /* log chain */
uint64_t zh_claim_seq; /* highest claimed sequence number */
- uint64_t zh_pad[5];
+ uint64_t zh_flags; /* header flags */
+ uint64_t zh_pad[4];
} zil_header_t;
/*
+ * zh_flags bit settings
+ */
+#define ZIL_REPLAY_NEEDED 0x1 /* replay needed - internal only */
+
+/*
* Log block trailer - structure at the end of the header and each log block
*
* The zit_bt contains a zbt_cksum which for the intent log is
>Release-Note:
>Audit-Trail:
>Unformatted:
More information about the freebsd-bugs
mailing list