Fix deadlocks resulting from the post-kmem rework merge

Put the following functions under PF_FSTRANS to prevent deadlocks due to re-entering the filesystem during reclaim: dbuf_hold() dmu_prefetch() sa_buf_hold() Testing this one now: dmu_zfetch_fetch() - z_hold_mtx[] via zget and zf_rwlock via dmu_zfetch
openzfs · Mar 24, 2015 · fc43636 · fc43636
1 parent 4c7b7ee
commit fc43636
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Showing 4 changed files with 22 additions and 2 deletions.
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
@@ -2088,7 +2088,12 @@ dmu_buf_impl_t *
 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
 {
 	dmu_buf_impl_t *db;
-	int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
+	int err;
+	fstrans_cookie_t cookie;
+
+	cookie = spl_fstrans_mark();
+	err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
+	spl_fstrans_unmark(cookie);
 	return (err ? NULL : db);
 }
 

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
@@ -541,14 +541,17 @@ dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 		return;
 
 	if (len == 0) {  /* they're interested in the bonus buffer */
+		fstrans_cookie_t cookie;
 		dn = DMU_META_DNODE(os);
 
 		if (object == 0 || object >= DN_MAX_OBJECT)
 			return;
 
 		rw_enter(&dn->dn_struct_rwlock, RW_READER);
 		blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
+		cookie = spl_fstrans_mark();
 		dbuf_prefetch(dn, blkid, ZIO_PRIORITY_SYNC_READ);
+		spl_fstrans_unmark(cookie);
 		rw_exit(&dn->dn_struct_rwlock);
 		return;
 	}
@@ -573,10 +576,13 @@ dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 
 	if (nblks != 0) {
 		int i;
+		fstrans_cookie_t cookie;
 
 		blkid = dbuf_whichblock(dn, offset);
+		cookie = spl_fstrans_mark();
 		for (i = 0; i < nblks; i++)
 			dbuf_prefetch(dn, blkid + i, ZIO_PRIORITY_SYNC_READ);
+		spl_fstrans_unmark(cookie);
 	}
 
 	rw_exit(&dn->dn_struct_rwlock);

diff --git a/module/zfs/dmu_zfetch.c b/module/zfs/dmu_zfetch.c
@@ -289,12 +289,15 @@ dmu_zfetch_fetch(dnode_t *dn, uint64_t blkid, uint64_t nblks)
 {
 	uint64_t	fetchsz;
 	uint64_t	i;
+	fstrans_cookie_t cookie;
 
 	fetchsz = dmu_zfetch_fetchsz(dn, blkid, nblks);
 
+	cookie = spl_fstrans_mark();
 	for (i = 0; i < fetchsz; i++) {
 		dbuf_prefetch(dn, blkid + i, ZIO_PRIORITY_ASYNC_READ);
 	}
+	spl_fstrans_unmark(cookie);
 
 	return (fetchsz);
 }

diff --git a/module/zfs/sa.c b/module/zfs/sa.c
@@ -1436,7 +1436,13 @@ sa_handle_get(objset_t *objset, uint64_t objid, void *userp,
 int
 sa_buf_hold(objset_t *objset, uint64_t obj_num, void *tag, dmu_buf_t **db)
 {
-	return (dmu_bonus_hold(objset, obj_num, tag, db));
+	fstrans_cookie_t cookie;
+	int rval;
+
+	cookie = spl_fstrans_mark();
+	rval = (dmu_bonus_hold(objset, obj_num, tag, db));
+	spl_fstrans_unmark(cookie);
+	return (rval);
 }
 
 void