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-rw-r--r--module/zfs/zvol.c95
1 files changed, 78 insertions, 17 deletions
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 613b47ef9..4168be440 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -33,6 +33,8 @@
*
* Volumes are persistent through reboot and module load. No user command
* needs to be run before opening and using a device.
+ *
+ * Copyright (c) 2016 Actifio, Inc. All rights reserved.
*/
#include <sys/dbuf.h>
@@ -599,6 +601,8 @@ zvol_write(struct bio *bio)
dmu_tx_t *tx;
rl_t *rl;
+ ASSERT(zv && zv->zv_open_count > 0);
+
if (bio->bi_rw & VDEV_REQ_FLUSH)
zil_commit(zv->zv_zilog, ZVOL_OBJ);
@@ -647,6 +651,8 @@ zvol_discard(struct bio *bio)
int error;
rl_t *rl;
+ ASSERT(zv && zv->zv_open_count > 0);
+
if (end > zv->zv_volsize)
return (SET_ERROR(EIO));
@@ -691,10 +697,11 @@ zvol_read(struct bio *bio)
int error;
rl_t *rl;
+ ASSERT(zv && zv->zv_open_count > 0);
+
if (len == 0)
return (0);
-
rl = zfs_range_lock(&zv->zv_znode, offset, len, RL_READER);
error = dmu_read_bio(zv->zv_objset, ZVOL_OBJ, bio);
@@ -967,7 +974,7 @@ zvol_last_close(zvol_state_t *zv)
static int
zvol_open(struct block_device *bdev, fmode_t flag)
{
- zvol_state_t *zv = bdev->bd_disk->private_data;
+ zvol_state_t *zv;
int error = 0, drop_mutex = 0;
/*
@@ -981,7 +988,17 @@ zvol_open(struct block_device *bdev, fmode_t flag)
drop_mutex = 1;
}
- ASSERT3P(zv, !=, NULL);
+ /*
+ * Obtain a copy of private_data under the lock to make sure
+ * that either the result of zvol_freeg() setting
+ * bdev->bd_disk->private_data to NULL is observed, or zvol_free()
+ * is not called on this zv because of the positive zv_open_count.
+ */
+ zv = bdev->bd_disk->private_data;
+ if (zv == NULL) {
+ error = -ENXIO;
+ goto out_mutex;
+ }
if (zv->zv_open_count == 0) {
error = zvol_first_open(zv);
@@ -996,6 +1013,8 @@ zvol_open(struct block_device *bdev, fmode_t flag)
zv->zv_open_count++;
+ check_disk_change(bdev);
+
out_open_count:
if (zv->zv_open_count == 0)
zvol_last_close(zv);
@@ -1004,8 +1023,6 @@ out_mutex:
if (drop_mutex)
mutex_exit(&zvol_state_lock);
- check_disk_change(bdev);
-
return (SET_ERROR(error));
}
@@ -1019,16 +1036,16 @@ zvol_release(struct gendisk *disk, fmode_t mode)
zvol_state_t *zv = disk->private_data;
int drop_mutex = 0;
+ ASSERT(zv && zv->zv_open_count > 0);
+
if (!mutex_owned(&zvol_state_lock)) {
mutex_enter(&zvol_state_lock);
drop_mutex = 1;
}
- if (zv->zv_open_count > 0) {
- zv->zv_open_count--;
- if (zv->zv_open_count == 0)
- zvol_last_close(zv);
- }
+ zv->zv_open_count--;
+ if (zv->zv_open_count == 0)
+ zvol_last_close(zv);
if (drop_mutex)
mutex_exit(&zvol_state_lock);
@@ -1045,8 +1062,7 @@ zvol_ioctl(struct block_device *bdev, fmode_t mode,
zvol_state_t *zv = bdev->bd_disk->private_data;
int error = 0;
- if (zv == NULL)
- return (SET_ERROR(-ENXIO));
+ ASSERT(zv && zv->zv_open_count > 0);
switch (cmd) {
case BLKFLSBUF:
@@ -1080,6 +1096,8 @@ static int zvol_media_changed(struct gendisk *disk)
{
zvol_state_t *zv = disk->private_data;
+ ASSERT(zv && zv->zv_open_count > 0);
+
return (zv->zv_changed);
}
@@ -1087,6 +1105,8 @@ static int zvol_revalidate_disk(struct gendisk *disk)
{
zvol_state_t *zv = disk->private_data;
+ ASSERT(zv && zv->zv_open_count > 0);
+
zv->zv_changed = 0;
set_capacity(zv->zv_disk, zv->zv_volsize >> 9);
@@ -1103,7 +1123,11 @@ static int
zvol_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
zvol_state_t *zv = bdev->bd_disk->private_data;
- sector_t sectors = get_capacity(zv->zv_disk);
+ sector_t sectors;
+
+ ASSERT(zv && zv->zv_open_count > 0);
+
+ sectors = get_capacity(zv->zv_disk);
if (sectors > 2048) {
geo->heads = 16;
@@ -1260,9 +1284,14 @@ out_kmem:
static void
zvol_free(zvol_state_t *zv)
{
+ ASSERT(MUTEX_HELD(&zvol_state_lock));
+ ASSERT(zv->zv_open_count == 0);
+
avl_destroy(&zv->zv_znode.z_range_avl);
mutex_destroy(&zv->zv_znode.z_range_lock);
+ zv->zv_disk->private_data = NULL;
+
del_gendisk(zv->zv_disk);
blk_cleanup_queue(zv->zv_queue);
put_disk(zv->zv_disk);
@@ -1395,7 +1424,15 @@ out:
if (error == 0) {
zvol_insert(zv);
+ /*
+ * Drop the lock to prevent deadlock with sys_open() ->
+ * zvol_open(), which first takes bd_disk->bd_mutex and then
+ * takes zvol_state_lock, whereas this code path first takes
+ * zvol_state_lock, and then takes bd_disk->bd_mutex.
+ */
+ mutex_exit(&zvol_state_lock);
add_disk(zv->zv_disk);
+ mutex_enter(&zvol_state_lock);
}
return (SET_ERROR(error));
@@ -1492,10 +1529,15 @@ int
zvol_create_minors(const char *name)
{
int error = 0;
+ fstrans_cookie_t cookie;
+
+ if (zvol_inhibit_dev)
+ return (0);
- if (!zvol_inhibit_dev)
- error = dmu_objset_find((char *)name, zvol_create_minors_cb,
- NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
+ cookie = spl_fstrans_mark();
+ error = dmu_objset_find((char *)name, zvol_create_minors_cb,
+ NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
+ spl_fstrans_unmark(cookie);
return (SET_ERROR(error));
}
@@ -1519,7 +1561,13 @@ zvol_remove_minors(const char *name)
if (name == NULL || strcmp(zv->zv_name, name) == 0 ||
(strncmp(zv->zv_name, name, namelen) == 0 &&
- zv->zv_name[namelen] == '/')) {
+ (zv->zv_name[namelen] == '/' ||
+ zv->zv_name[namelen] == '@'))) {
+
+ /* If in use, leave alone */
+ if (zv->zv_open_count > 0)
+ continue;
+
zvol_remove(zv);
zvol_free(zv);
}
@@ -1550,6 +1598,10 @@ zvol_rename_minors(const char *oldname, const char *newname)
for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
zv_next = list_next(&zvol_state_list, zv);
+ /* If in use, leave alone */
+ if (zv->zv_open_count > 0)
+ continue;
+
if (strcmp(zv->zv_name, oldname) == 0) {
__zvol_rename_minor(zv, newname);
} else if (strncmp(zv->zv_name, oldname, oldnamelen) == 0 &&
@@ -1590,8 +1642,17 @@ snapdev_snapshot_changed_cb(const char *dsname, void *arg) {
int
zvol_set_snapdev(const char *dsname, uint64_t snapdev) {
+ fstrans_cookie_t cookie;
+
+ if (zvol_inhibit_dev)
+ /* caller should continue to modify snapdev property */
+ return (-1);
+
+ cookie = spl_fstrans_mark();
(void) dmu_objset_find((char *) dsname, snapdev_snapshot_changed_cb,
&snapdev, DS_FIND_SNAPSHOTS | DS_FIND_CHILDREN);
+ spl_fstrans_unmark(cookie);
+
/* caller should continue to modify snapdev property */
return (-1);
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-19 19:15:57 +0000