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Illumos #4047

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4047 panic from dbuf_free_range() from dmu_free_object() while
     doing zfs receive
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
  https://www.illumos.org/issues/4047
  illumos/illumos-gate@713d6c2088

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

Porting notes:

1. The exported symbol dmu_free_object() was renamed to
   dmu_free_long_object() in Illumos.
This commit is contained in:
Matthew Ahrens
2013-08-20 20:11:52 -08:00
committed by Brian Behlendorf
parent 46ba1e59d3
commit b663a23d36
8 changed files with 99 additions and 89 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/dbuf.c
+22 -11
View File
@@ -64,6 +64,12 @@ static void __dbuf_hold_impl_init(struct dbuf_hold_impl_data *dh,
void *tag, dmu_buf_impl_t **dbp, int depth);
static int __dbuf_hold_impl(struct dbuf_hold_impl_data *dh);
/*
* Number of times that zfs_free_range() took the slow path while doing
* a zfs receive. A nonzero value indicates a potential performance problem.
*/
uint64_t zfs_free_range_recv_miss;
static void dbuf_destroy(dmu_buf_impl_t *db);
static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
@@ -869,20 +875,22 @@ dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
}
dprintf_dnode(dn, "start=%llu end=%llu\n", start, end);
if (dmu_objset_is_receiving(dn->dn_objset)) {
/*
* When processing a free record from a zfs receive,
* there should have been no previous modifications to the
* data in this range. Therefore there should be no dbufs
* in the range. Searching dn_dbufs for these non-existent
* dbufs can be very expensive, so simply ignore this.
*/
VERIFY3P(dbuf_find(dn, 0, start), ==, NULL);
VERIFY3P(dbuf_find(dn, 0, end), ==, NULL);
mutex_enter(&dn->dn_dbufs_mtx);
if (start >= dn->dn_unlisted_l0_blkid * dn->dn_datablksz) {
/* There can't be any dbufs in this range; no need to search. */
mutex_exit(&dn->dn_dbufs_mtx);
return;
} else if (dmu_objset_is_receiving(dn->dn_objset)) {
/*
* If we are receiving, we expect there to be no dbufs in
* the range to be freed, because receive modifies each
* block at most once, and in offset order. If this is
* not the case, it can lead to performance problems,
* so note that we unexpectedly took the slow path.
*/
atomic_inc_64(&zfs_free_range_recv_miss);
}
mutex_enter(&dn->dn_dbufs_mtx);
for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
db_next = list_next(&dn->dn_dbufs, db);
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
@@ -1781,6 +1789,9 @@ dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
return (odb);
}
list_insert_head(&dn->dn_dbufs, db);
if (db->db_level == 0 && db->db_blkid >=
dn->dn_unlisted_l0_blkid)
dn->dn_unlisted_l0_blkid = db->db_blkid + 1;
db->db_state = DB_UNCACHED;
mutex_exit(&dn->dn_dbufs_mtx);
arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER);