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Illumos 4631 - zvol_get_stats triggering too many reads

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4631 zvol_get_stats triggering too many reads

Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/4631
  https://github.com/illumos/illumos-gate/commit/bbfa8ea

Ported-by: Boris Protopopov <bprotopopov@hotmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2612
Closes #2480
This commit is contained in:
Matthew Ahrens
2014-07-15 03:43:18 -04:00
committed by Brian Behlendorf
parent 2fe5011008
commit bd089c5477
3 changed files with 65 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/dbuf.c
+25 -13
View File
@@ -211,8 +211,7 @@ dbuf_hash_insert(dmu_buf_impl_t *db)
}
/*
* Remove an entry from the hash table. This operation will
* fail if there are any existing holds on the db.
* Remove an entry from the hash table. It must be in the EVICTING state.
*/
static void
dbuf_hash_remove(dmu_buf_impl_t *db)
@@ -226,7 +225,7 @@ dbuf_hash_remove(dmu_buf_impl_t *db)
idx = hv & h->hash_table_mask;
/*
* We musn't hold db_mtx to maintin lock ordering:
* We musn't hold db_mtx to maintain lock ordering:
* DBUF_HASH_MUTEX > db_mtx.
*/
ASSERT(refcount_is_zero(&db->db_holds));
@@ -487,7 +486,6 @@ static void
dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
{
ASSERT(MUTEX_HELD(&db->db_mtx));
ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf));
db->db_buf = buf;
if (buf != NULL) {
ASSERT(buf->b_data != NULL);
@@ -1595,12 +1593,15 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
* when we are not holding the dn_dbufs_mtx, we can't clear the
* entry in the dn_dbufs list. We have to wait until dbuf_destroy()
* in this case. For callers from the DMU we will usually see:
* dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()
* dbuf_clear()->arc_clear_callback()->dbuf_do_evict()->dbuf_destroy()
* For the arc callback, we will usually see:
* dbuf_do_evict()->dbuf_clear();dbuf_destroy()
* Sometimes, though, we will get a mix of these two:
* DMU: dbuf_clear()->arc_buf_evict()
* DMU: dbuf_clear()->arc_clear_callback()
* ARC: dbuf_do_evict()->dbuf_destroy()
*
* This routine will dissociate the dbuf from the arc, by calling
* arc_clear_callback(), but will not evict the data from the ARC.
*/
void
dbuf_clear(dmu_buf_impl_t *db)
@@ -1608,7 +1609,7 @@ dbuf_clear(dmu_buf_impl_t *db)
dnode_t *dn;
dmu_buf_impl_t *parent = db->db_parent;
dmu_buf_impl_t *dndb;
int dbuf_gone = FALSE;
boolean_t dbuf_gone = B_FALSE;
ASSERT(MUTEX_HELD(&db->db_mtx));
ASSERT(refcount_is_zero(&db->db_holds));
@@ -1654,7 +1655,7 @@ dbuf_clear(dmu_buf_impl_t *db)
}
if (db->db_buf)
dbuf_gone = arc_buf_evict(db->db_buf);
dbuf_gone = arc_clear_callback(db->db_buf);
if (!dbuf_gone)
mutex_exit(&db->db_mtx);
@@ -1831,8 +1832,7 @@ dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
static int
dbuf_do_evict(void *private)
{
arc_buf_t *buf = private;
dmu_buf_impl_t *db = buf->b_private;
dmu_buf_impl_t *db = private;
if (!MUTEX_HELD(&db->db_mtx))
mutex_enter(&db->db_mtx);
@@ -2239,11 +2239,23 @@ dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
* block on-disk. If so, then we simply evict
* ourselves.
*/
if (!DBUF_IS_CACHEABLE(db) ||
arc_buf_eviction_needed(db->db_buf))
if (!DBUF_IS_CACHEABLE(db)) {
if (db->db_blkptr != NULL &&
!BP_IS_HOLE(db->db_blkptr) &&
!BP_IS_EMBEDDED(db->db_blkptr)) {
spa_t *spa =
dmu_objset_spa(db->db_objset);
blkptr_t bp = *db->db_blkptr;
dbuf_clear(db);
arc_freed(spa, &bp);
} else {
dbuf_clear(db);
}
} else if (arc_buf_eviction_needed(db->db_buf)) {
dbuf_clear(db);
else
} else {
mutex_exit(&db->db_mtx);
}
}
} else {
mutex_exit(&db->db_mtx);