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fix dsl_scan_ds_clone_swapped logic

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It was incorrect with respect to swapping dataset IDs both in the
on-disk ZAP object and the in-memory queue.

In both cases, if only ds1 was already present, then it would be first
replaced with ds2 and then ds2 would be replaced back with ds1.  Also,
both cases did not properly handle a situation where both ds1 and ds2
are already queued.  A duplicate insertion would be attempted and its
failure would result in a panic.

This change has also been submitted to ZoL as zfsonlinux/zfs@dd262c9

PR:		239566
Reported by:	pascal.guitierrez@gmail.com
MFC after:	4 days
Sponsored by:	CyberSecure
This commit is contained in:
Andriy Gapon 2019-09-19 09:43:56 +00:00
parent 9a2ed10014
commit 6caa629e73
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=352506
1 changed files with 70 additions and 32 deletions
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102
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
View File

@ -2014,16 +2014,17 @@ ds_clone_swapped_bookmark(dsl_dataset_t *ds1, dsl_dataset_t *ds2,
}
/*
* Called when a parent dataset and its clone are swapped. If we were
* Called when an origin dataset and its clone are swapped. If we were
* currently traversing the dataset, we need to switch to traversing the
* newly promoted parent.
* newly promoted clone.
*/
void
dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
{
dsl_pool_t *dp = ds1->ds_dir->dd_pool;
dsl_scan_t *scn = dp->dp_scan;
uint64_t mintxg;
uint64_t mintxg1, mintxg2;
boolean_t ds1_queued, ds2_queued;
if (!dsl_scan_is_running(scn))
return;
@ -2031,44 +2032,81 @@ dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
ds_clone_swapped_bookmark(ds1, ds2, &scn->scn_phys.scn_bookmark);
ds_clone_swapped_bookmark(ds1, ds2, &scn->scn_phys_cached.scn_bookmark);
if (scan_ds_queue_contains(scn, ds1->ds_object, &mintxg)) {
scan_ds_queue_remove(scn, ds1->ds_object);
scan_ds_queue_insert(scn, ds2->ds_object, mintxg);
/*
* Handle the in-memory scan queue.
*/
ds1_queued = scan_ds_queue_contains(scn, ds1->ds_object, &mintxg1);
ds2_queued = scan_ds_queue_contains(scn, ds2->ds_object, &mintxg2);
/* Sanity checking. */
if (ds1_queued) {
ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
}
if (scan_ds_queue_contains(scn, ds2->ds_object, &mintxg)) {
scan_ds_queue_remove(scn, ds2->ds_object);
scan_ds_queue_insert(scn, ds1->ds_object, mintxg);
if (ds2_queued) {
ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
}
if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
ds1->ds_object, &mintxg) == 0) {
int err;
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
if (ds1_queued && ds2_queued) {
/*
* If both are queued, we don't need to do anything.
* The swapping code below would not handle this case correctly,
* since we can't insert ds2 if it is already there. That's
* because scan_ds_queue_insert() prohibits a duplicate insert
* and panics.
*/
} else if (ds1_queued) {
scan_ds_queue_remove(scn, ds1->ds_object);
scan_ds_queue_insert(scn, ds2->ds_object, mintxg1);
} else if (ds2_queued) {
scan_ds_queue_remove(scn, ds2->ds_object);
scan_ds_queue_insert(scn, ds1->ds_object, mintxg2);
}
/*
* Handle the on-disk scan queue.
* The on-disk state is an out-of-date version of the in-memory state,
* so the in-memory and on-disk values for ds1_queued and ds2_queued may
* be different. Therefore we need to apply the swap logic to the
* on-disk state independently of the in-memory state.
*/
ds1_queued = zap_lookup_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, &mintxg1) == 0;
ds2_queued = zap_lookup_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg2) == 0;
/* Sanity checking. */
if (ds1_queued) {
ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg1, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
}
if (ds2_queued) {
ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg2, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
}
if (ds1_queued && ds2_queued) {
/*
* If both are queued, we don't need to do anything.
* Alternatively, we could check for EEXIST from
* zap_add_int_key() and back out to the original state, but
* that would be more work than checking for this case upfront.
*/
} else if (ds1_queued) {
VERIFY3S(0, ==, zap_remove_int(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
err = zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
VERIFY(err == 0 || err == EEXIST);
if (err == EEXIST) {
/* Both were there to begin with */
VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj,
ds1->ds_object, mintxg, tx));
}
VERIFY3S(0, ==, zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg1, tx));
zfs_dbgmsg("clone_swap ds %llu; in queue; "
"replacing with %llu",
(u_longlong_t)ds1->ds_object,
(u_longlong_t)ds2->ds_object);
}
if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
ds2->ds_object, &mintxg) == 0) {
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
} else if (ds2_queued) {
VERIFY3S(0, ==, zap_remove_int(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
VERIFY3S(0, ==, zap_add_int_key(dp->dp_meta_objset,
scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg2, tx));
zfs_dbgmsg("clone_swap ds %llu; in queue; "
"replacing with %llu",
(u_longlong_t)ds2->ds_object,