Use spa as key besides objsetid for snapentry

objsetid is not unique across pool, so using it solely as key would cause
panic when automounting two snapshot on different pools with the same
objsetid. We fix this by adding spa pointer as additional key.

Signed-off-by: Chunwei Chen <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Signed-off-by: Richard Yao <[email protected]>
Issue #3948
Issue #3786
Issue #3887

1 files changed, 22 insertions, 10 deletions

diff --git a/module/zfs/zfs_ctldir.c b/module/zfs/zfs_ctldir.c
index 745a467b7..b03c4e5d0 100644
--- a/module/zfs/zfs_ctldir.c
+++ b/module/zfs/zfs_ctldir.c
@@ -81,6 +81,7 @@
 #include <sys/zfs_vnops.h>
 #include <sys/stat.h>
 #include <sys/dmu.h>
+#include <sys/dmu_objset.h>
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_deleg.h>
 #include <sys/mount.h>
@@ -117,6 +118,7 @@ static taskq_t *zfs_expire_taskq;
 typedef struct {
 	char		*se_name;	/* full snapshot name */
 	char		*se_path;	/* full mount path */
+	spa_t		*se_spa;	/* pool spa */
 	uint64_t	se_objsetid;	/* snapshot objset id */
 	struct dentry   *se_root_dentry; /* snapshot root dentry */
 	taskqid_t	se_taskqid;	/* scheduled unmount taskqid */
@@ -132,8 +134,8 @@ static void zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay);
  * the snapshot name and provided mount point.  No reference is taken.
  */
 static zfs_snapentry_t *
-zfsctl_snapshot_alloc(char *full_name, char *full_path, uint64_t objsetid,
-    struct dentry *root_dentry)
+zfsctl_snapshot_alloc(char *full_name, char *full_path, spa_t *spa,
+    uint64_t objsetid, struct dentry *root_dentry)
 {
 	zfs_snapentry_t *se;
 
@@ -141,6 +143,7 @@ zfsctl_snapshot_alloc(char *full_name, char *full_path, uint64_t objsetid,
 
 	se->se_name = strdup(full_name);
 	se->se_path = strdup(full_path);
+	se->se_spa = spa;
 	se->se_objsetid = objsetid;
 	se->se_root_dentry = root_dentry;
 	se->se_taskqid = -1;
@@ -242,6 +245,9 @@ snapentry_compare_by_objsetid(const void *a, const void *b)
 	const zfs_snapentry_t *se_a = a;
 	const zfs_snapentry_t *se_b = b;
 
+	if (se_a->se_spa != se_b->se_spa)
+		return ((ulong_t)se_a->se_spa < (ulong_t)se_b->se_spa ? -1 : 1);
+
 	if (se_a->se_objsetid < se_b->se_objsetid)
 		return (-1);
 	else if (se_a->se_objsetid > se_b->se_objsetid)
@@ -278,12 +284,13 @@ zfsctl_snapshot_find_by_name(char *snapname)
  * as zfsctl_snapshot_find_by_name().
  */
 static zfs_snapentry_t *
-zfsctl_snapshot_find_by_objsetid(uint64_t objsetid)
+zfsctl_snapshot_find_by_objsetid(spa_t *spa, uint64_t objsetid)
 {
 	zfs_snapentry_t *se, search;
 
 	ASSERT(MUTEX_HELD(&zfs_snapshot_lock));
 
+	search.se_spa = spa;
 	search.se_objsetid = objsetid;
 	se = avl_find(&zfs_snapshots_by_objsetid, &search, NULL);
 	if (se)
@@ -323,6 +330,7 @@ static void
 snapentry_expire(void *data)
 {
 	zfs_snapentry_t *se = (zfs_snapentry_t *)data;
+	spa_t *spa = se->se_spa;
 	uint64_t objsetid = se->se_objsetid;
 
 	se->se_taskqid = -1;
@@ -334,7 +342,7 @@ snapentry_expire(void *data)
 	 * This can occur when the snapshot is busy.
 	 */
 	mutex_enter(&zfs_snapshot_lock);
-	if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) {
+	if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) {
 		zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot);
 		zfsctl_snapshot_rele(se);
 	}
@@ -377,13 +385,13 @@ zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay)
  * and held until the outstanding task is handled or cancelled.
  */
 int
-zfsctl_snapshot_unmount_delay(uint64_t objsetid, int delay)
+zfsctl_snapshot_unmount_delay(spa_t *spa, uint64_t objsetid, int delay)
 {
 	zfs_snapentry_t *se;
 	int error = ENOENT;
 
 	mutex_enter(&zfs_snapshot_lock);
-	if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) {
+	if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) {
 		zfsctl_snapshot_unmount_cancel(se);
 		zfsctl_snapshot_unmount_delay_impl(se, delay);
 		zfsctl_snapshot_rele(se);
@@ -560,10 +568,12 @@ zfsctl_destroy(zfs_sb_t *zsb)
 {
 	if (zsb->z_issnap) {
 		zfs_snapentry_t *se;
+		spa_t *spa = zsb->z_os->os_spa;
 		uint64_t objsetid = dmu_objset_id(zsb->z_os);
 
 		mutex_enter(&zfs_snapshot_lock);
-		if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) {
+		if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid))
+		    != NULL) {
 			zfsctl_snapshot_unmount_cancel(se);
 			zfsctl_snapshot_remove(se);
 			zfsctl_snapshot_rele(se);
@@ -1129,7 +1139,8 @@ zfsctl_snapshot_mount(struct path *path, int flags)
 
 		mutex_enter(&zfs_snapshot_lock);
 		se = zfsctl_snapshot_alloc(full_name, full_path,
-		    dmu_objset_id(snap_zsb->z_os), dentry);
+		    snap_zsb->z_os->os_spa, dmu_objset_id(snap_zsb->z_os),
+		    dentry);
 		zfsctl_snapshot_add(se);
 		zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot);
 		mutex_exit(&zfs_snapshot_lock);
@@ -1152,6 +1163,7 @@ zfsctl_lookup_objset(struct super_block *sb, uint64_t objsetid, zfs_sb_t **zsbp)
 {
 	zfs_snapentry_t *se;
 	int error;
+	spa_t *spa = ((zfs_sb_t *)(sb->s_fs_info))->z_os->os_spa;
 
 	/*
 	 * Verify that the snapshot is mounted then lookup the mounted root
@@ -1161,7 +1173,7 @@ zfsctl_lookup_objset(struct super_block *sb, uint64_t objsetid, zfs_sb_t **zsbp)
 	 * because we hold the zfs_snapshot_lock to prevent the race.
 	 */
 	mutex_enter(&zfs_snapshot_lock);
-	if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) {
+	if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) {
 		zfs_sb_t *zsb;
 
 		zsb = ITOZSB(se->se_root_dentry->d_inode);
@@ -1170,7 +1182,7 @@ zfsctl_lookup_objset(struct super_block *sb, uint64_t objsetid, zfs_sb_t **zsbp)
 		if (time_after(jiffies, zsb->z_snap_defer_time +
 		    MAX(zfs_expire_snapshot * HZ / 2, HZ))) {
 			zsb->z_snap_defer_time = jiffies;
-			zfsctl_snapshot_unmount_delay(objsetid,
+			zfsctl_snapshot_unmount_delay(spa, objsetid,
 			    zfs_expire_snapshot);
 		}