Author: delphij
Date: Fri Aug 22 23:13:53 2014
New Revision: 270383
URL: http://svnweb.freebsd.org/changeset/base/270383
Log:
Instead of using timestamp in the AVL, use the memory address when
comparing.
Illumos issue:
5095 panic when adding a duplicate dbuf to dn_dbufs
MFC after: 3 days
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dbuf.h
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dnode.h
Directory Properties:
head/sys/cddl/contrib/opensolaris/ (props changed)
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c Fri Aug 22
22:13:36 2014 (r270382)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c Fri Aug 22
23:13:53 2014 (r270383)
@@ -70,12 +70,6 @@ dbuf_cons(void *vdb, void *unused, int k
cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
refcount_create(&db->db_holds);
-#if defined(illumos) || !defined(_KERNEL)
- db->db_creation = gethrtime();
-#else
- db->db_creation = cpu_ticks() ^ ((uint64_t)CPU_SEQID << 48);
-#endif
-
return (0);
}
@@ -823,7 +817,7 @@ dbuf_free_range(dnode_t *dn, uint64_t st
db_search.db_level = 0;
db_search.db_blkid = start_blkid;
- db_search.db_creation = 0;
+ db_search.db_state = DB_SEARCH;
mutex_enter(&dn->dn_dbufs_mtx);
if (start_blkid >= dn->dn_unlisted_l0_blkid) {
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c Fri Aug 22
22:13:36 2014 (r270382)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c Fri Aug 22
23:13:53 2014 (r270383)
@@ -69,33 +69,35 @@ dbuf_compare(const void *x1, const void
if (d1->db_level < d2->db_level) {
return (-1);
- } else if (d1->db_level > d2->db_level) {
+ }
+ if (d1->db_level > d2->db_level) {
return (1);
}
if (d1->db_blkid < d2->db_blkid) {
return (-1);
- } else if (d1->db_blkid > d2->db_blkid) {
+ }
+ if (d1->db_blkid > d2->db_blkid) {
return (1);
}
- /*
- * If a dbuf is being evicted while dn_dbufs_mutex is not held, we set
- * the db_state to DB_EVICTING but do not remove it from dn_dbufs. If
- * another thread creates a dbuf of the same blkid before the dbuf is
- * removed from dn_dbufs, we can reach a state where there are two
- * dbufs of the same blkid and level in db_dbufs. To maintain the avl
- * invariant that there cannot be duplicate items, we distinguish
- * between these two dbufs based on the time they were created.
- */
- if (d1->db_creation < d2->db_creation) {
+ if (d1->db_state < d2->db_state) {
return (-1);
- } else if (d1->db_creation > d2->db_creation) {
+ }
+ if (d1->db_state > d2->db_state) {
return (1);
- } else {
- ASSERT3P(d1, ==, d2);
- return (0);
}
+
+ ASSERT3S(d1->db_state, !=, DB_SEARCH);
+ ASSERT3S(d2->db_state, !=, DB_SEARCH);
+
+ if ((uintptr_t)d1 < (uintptr_t)d2) {
+ return (-1);
+ }
+ if ((uintptr_t)d1 > (uintptr_t)d2) {
+ return (1);
+ }
+ return (0);
}
/* ARGSUSED */
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dbuf.h
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dbuf.h Fri Aug
22 22:13:36 2014 (r270382)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dbuf.h Fri Aug
22 23:13:53 2014 (r270383)
@@ -66,8 +66,13 @@ extern "C" {
* | |
* | |
* +--------> NOFILL -------+
+ *
+ * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
+ * to find all dbufs in a range of a dnode and must be less than any other
+ * dbuf_states_t (see comment on dn_dbufs in dnode.h).
*/
typedef enum dbuf_states {
+ DB_SEARCH = -1,
DB_UNCACHED,
DB_FILL,
DB_NOFILL,
@@ -213,9 +218,6 @@ typedef struct dmu_buf_impl {
/* pointer to most recent dirty record for this buffer */
dbuf_dirty_record_t *db_last_dirty;
- /* Creation time of dbuf (see comment in dbuf_compare). */
- hrtime_t db_creation;
-
/*
* Our link on the owner dnodes's dn_dbufs list.
* Protected by its dn_dbufs_mtx.
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dnode.h
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dnode.h Fri Aug
22 22:13:36 2014 (r270382)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dnode.h Fri Aug
22 23:13:53 2014 (r270383)
@@ -211,7 +211,18 @@ typedef struct dnode {
refcount_t dn_holds;
kmutex_t dn_dbufs_mtx;
- avl_tree_t dn_dbufs; /* descendent dbufs */
+ /*
+ * Descendent dbufs, ordered by dbuf_compare. Note that dn_dbufs
+ * can contain multiple dbufs of the same (level, blkid) when a
+ * dbuf is marked DB_EVICTING without being removed from
+ * dn_dbufs. To maintain the avl invariant that there cannot be
+ * duplicate entries, we order the dbufs by an arbitrary value -
+ * their address in memory. This means that dn_dbufs cannot be used to
+ * directly look up a dbuf. Instead, callers must use avl_walk, have
+ * a reference to the dbuf, or look up a non-existant node with
+ * db_state = DB_SEARCH (see dbuf_free_range for an example).
+ */
+ avl_tree_t dn_dbufs;
/* protected by dn_struct_rwlock */
struct dmu_buf_impl *dn_bonus; /* bonus buffer dbuf */
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