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Fix a race condition in dsl_dataset_sync() when activating features 

The zio returned from arc_write() in dmu_objset_sync() uses
zio_nowait(). However we may reach the end of dsl_dataset_sync()
which checks if we need to activate features in the filesystem
without knowing if that zio has even run through the ZIO pipeline yet.
In that case we will flag features to be activated in
dsl_dataset_block_born() but dsl_dataset_sync() has already
completed its run and those features will not actually be activated.
Mitigate this by moving the feature activation code in
dsl_dataset_sync_done(). Also add new ASSERTs in
dsl_scan_visitbp() checking if a block contradicts any filesystem
flags.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #13816
This commit is contained in:
George Amanakis 2023-02-14 01:37:46 +01:00 committed by Brian Behlendorf
parent 8473829d1f
commit 57159a519b
4 changed files with 34 additions and 11 deletions
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1
include/sys/dsl_dataset.h
View File

@ -363,6 +363,7 @@ int dsl_dataset_rename_snapshot(const char *fsname,
const char *oldsnapname, const char *newsnapname, boolean_t recursive);
int dsl_dataset_snapshot_tmp(const char *fsname, const char *snapname,
minor_t cleanup_minor, const char *htag);
boolean_t zfeature_active(spa_feature_t f, void *arg);
blkptr_t *dsl_dataset_get_blkptr(dsl_dataset_t *ds);

1
module/zfs/dmu_send.c
View File

@ -493,6 +493,7 @@ dmu_dump_write(dmu_send_cookie_t *dscp, dmu_object_type_t type, uint64_t object,
(bp != NULL ? BP_GET_COMPRESS(bp) != ZIO_COMPRESS_OFF &&
io_compressed : lsize != psize);
if (raw || compressed) {
ASSERT(bp != NULL);
ASSERT(raw || dscp->dsc_featureflags &
DMU_BACKUP_FEATURE_COMPRESSED);
ASSERT(!BP_IS_EMBEDDED(bp));

23
module/zfs/dsl_dataset.c
View File

@ -1026,7 +1026,7 @@ dsl_dataset_has_owner(dsl_dataset_t *ds)
return (rv);
}
static boolean_t
boolean_t
zfeature_active(spa_feature_t f, void *arg)
{
switch (spa_feature_table[f].fi_type) {
@ -2108,16 +2108,6 @@ dsl_dataset_sync(dsl_dataset_t *ds, zio_t *zio, dmu_tx_t *tx)
}
dmu_objset_sync(ds->ds_objset, zio, tx);
for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
if (zfeature_active(f, ds->ds_feature_activation[f])) {
if (zfeature_active(f, ds->ds_feature[f]))
continue;
dsl_dataset_activate_feature(ds->ds_object, f,
ds->ds_feature_activation[f], tx);
ds->ds_feature[f] = ds->ds_feature_activation[f];
}
}
}
/*
@ -2292,6 +2282,17 @@ dsl_dataset_sync_done(dsl_dataset_t *ds, dmu_tx_t *tx)
ASSERT(!dmu_objset_is_dirty(os, dmu_tx_get_txg(tx)));
dmu_buf_rele(ds->ds_dbuf, ds);
for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
if (zfeature_active(f,
ds->ds_feature_activation[f])) {
if (zfeature_active(f, ds->ds_feature[f]))
continue;
dsl_dataset_activate_feature(ds->ds_object, f,
ds->ds_feature_activation[f], tx);
ds->ds_feature[f] = ds->ds_feature_activation[f];
}
}
}
int

20
module/zfs/dsl_scan.c
View File

@ -2005,6 +2005,26 @@ dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb,
return;
}
/*
* Check if this block contradicts any filesystem flags.
*/
spa_feature_t f = SPA_FEATURE_LARGE_BLOCKS;
if (BP_GET_LSIZE(bp) > SPA_OLD_MAXBLOCKSIZE)
ASSERT(dsl_dataset_feature_is_active(ds, f));
f = zio_checksum_to_feature(BP_GET_CHECKSUM(bp));
if (f != SPA_FEATURE_NONE)
ASSERT(dsl_dataset_feature_is_active(ds, f));
f = zio_compress_to_feature(BP_GET_COMPRESS(bp));
if (f != SPA_FEATURE_NONE)
ASSERT(dsl_dataset_feature_is_active(ds, f));
if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg) {
scn->scn_lt_min_this_txg++;
return;
}
if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg) {
scn->scn_lt_min_this_txg++;
return;