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dbuf: Handle arcbuf assignment after block cloning 

In some cases dbuf_assign_arcbuf() may be called on a block that
was recently cloned.  If it happened in current TXG we must undo
the block cloning first, since the only one dirty record per TXG
can't and shouldn't mean both cloning and overwrite same time.

Reviewed-by: Kay Pedersen <mail@mkwg.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #15653
This commit is contained in:
Alexander Motin 2023-12-12 15:53:59 -05:00 committed by Brian Behlendorf
parent b13c91bb29
commit a701548eb4
1 changed files with 11 additions and 1 deletions
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12
module/zfs/dbuf.c
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@ -2930,7 +2930,8 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
while (db->db_state == DB_READ || db->db_state == DB_FILL) while (db->db_state == DB_READ || db->db_state == DB_FILL)
cv_wait(&db->db_changed, &db->db_mtx); cv_wait(&db->db_changed, &db->db_mtx);
ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED); ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED ||
db->db_state == DB_NOFILL);
if (db->db_state == DB_CACHED && if (db->db_state == DB_CACHED &&
zfs_refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) { zfs_refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
@ -2967,6 +2968,15 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
arc_buf_destroy(db->db_buf, db); arc_buf_destroy(db->db_buf, db);
} }
db->db_buf = NULL; db->db_buf = NULL;
} else if (db->db_state == DB_NOFILL) {
/*
* We will be completely replacing the cloned block. In case
* it was cloned in this transaction group, let's undirty the
* pending clone and mark the block as uncached. This will be
* as if the clone was never done.
*/
VERIFY(!dbuf_undirty(db, tx));
db->db_state = DB_UNCACHED;
} }
ASSERT(db->db_buf == NULL); ASSERT(db->db_buf == NULL);
dbuf_set_data(db, buf); dbuf_set_data(db, buf);