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7580 ztest failure in dbuf_read_impl

illumos/illumos-gate@1a01181fdc
1a01181fdc

https://www.illumos.org/issues/7580
  We need to prevent any reader whenever we're about the zero out all the
  blkptrs. To do this we need to grab the dn_struct_rwlock as writer in
  dbuf_write_children_ready and free_children just prior to calling bzero.

Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Steve Gonczi <steve.gonczi@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: George Wilson <george.wilson@delphix.com>
This commit is contained in:
jpaetzel 2017-04-27 16:38:28 +00:00
parent 2750ce9b17
commit 6911f4a88c
2 changed files with 21 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c
View File

@ -3317,13 +3317,13 @@ dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
dmu_buf_impl_t *db = vdb;
dnode_t *dn;
blkptr_t *bp;
uint64_t i;
int epbs;
unsigned int epbs, i;
ASSERT3U(db->db_level, >, 0);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
ASSERT3U(epbs, <, 31);
/* Determine if all our children are holes */
for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++) {
@ -3336,8 +3336,14 @@ dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
* we may get compressed away.
*/
if (i == 1 << epbs) {
/* didn't find any non-holes */
/*
* We only found holes. Grab the rwlock to prevent
* anybody from reading the blocks we're about to
* zero out.
*/
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
bzero(db->db.db_data, db->db.db_size);
rw_exit(&dn->dn_struct_rwlock);
}
DB_DNODE_EXIT(db);
}

17
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode_sync.c
View File

@ -236,8 +236,8 @@ free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
dnode_t *dn;
blkptr_t *bp;
dmu_buf_impl_t *subdb;
uint64_t start, end, dbstart, dbend, i;
int epbs, shift;
uint64_t start, end, dbstart, dbend;
unsigned int epbs, shift, i;
/*
* There is a small possibility that this block will not be cached:
@ -254,6 +254,7 @@ free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
ASSERT3U(epbs, <, 31);
shift = (db->db_level - 1) * epbs;
dbstart = db->db_blkid << epbs;
start = blkid >> shift;
@ -273,12 +274,12 @@ free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
FREE_VERIFY(db, start, end, tx);
free_blocks(dn, bp, end-start+1, tx);
} else {
for (i = start; i <= end; i++, bp++) {
for (uint64_t id = start; id <= end; id++, bp++) {
if (BP_IS_HOLE(bp))
continue;
rw_enter(&dn->dn_struct_rwlock, RW_READER);
VERIFY0(dbuf_hold_impl(dn, db->db_level - 1,
i, TRUE, FALSE, FTAG, &subdb));
id, TRUE, FALSE, FTAG, &subdb));
rw_exit(&dn->dn_struct_rwlock);
ASSERT3P(bp, ==, subdb->db_blkptr);
@ -293,8 +294,14 @@ free_children(dmu_buf_impl_t *db, uint64_t blkid, uint64_t nblks,
break;
}
if (i == 1 << epbs) {
/* didn't find any non-holes */
/*
* We only found holes. Grab the rwlock to prevent
* anybody from reading the blocks we're about to
* zero out.
*/
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
bzero(db->db.db_data, db->db.db_size);
rw_exit(&dn->dn_struct_rwlock);
free_blocks(dn, db->db_blkptr, 1, tx);
} else {
/*