summaryrefslogtreecommitdiff
path: root/drivers/md/dm-zoned-target.c
diff options
context:
space:
mode:
authorDmitry Fomichev <dmitry.fomichev@wdc.com>2019-11-07 01:34:35 +0300
committerMike Snitzer <snitzer@redhat.com>2019-11-07 18:08:36 +0300
commite7fad909b68aa37470d9f2d2731b5bec355ee5d6 (patch)
tree46aa9d420dd63b0767cab11267db4a56b99435c0 /drivers/md/dm-zoned-target.c
parent72d7df4c8079306e7fbd6243bf951461ed647a47 (diff)
downloadlinux-e7fad909b68aa37470d9f2d2731b5bec355ee5d6.tar.xz
dm zoned: reduce overhead of backing device checks
Commit 75d66ffb48efb3 added backing device health checks and as a part of these checks, check_events() block ops template call is invoked in dm-zoned mapping path as well as in reclaim and flush path. Calling check_events() with ATA or SCSI backing devices introduces a blocking scsi_test_unit_ready() call being made in sd_check_events(). Even though the overhead of calling scsi_test_unit_ready() is small for ATA zoned devices, it is much larger for SCSI and it affects performance in a very negative way. Fix this performance regression by executing check_events() only in case of any I/O errors. The function dmz_bdev_is_dying() is modified to call only blk_queue_dying(), while calls to check_events() are made in a new helper function, dmz_check_bdev(). Reported-by: zhangxiaoxu <zhangxiaoxu5@huawei.com> Fixes: 75d66ffb48efb3 ("dm zoned: properly handle backing device failure") Cc: stable@vger.kernel.org Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-zoned-target.c')
-rw-r--r--drivers/md/dm-zoned-target.c54
1 files changed, 38 insertions, 16 deletions
diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
index d3bcc4197f5d..4574e0dedbd6 100644
--- a/drivers/md/dm-zoned-target.c
+++ b/drivers/md/dm-zoned-target.c
@@ -80,6 +80,8 @@ static inline void dmz_bio_endio(struct bio *bio, blk_status_t status)
if (status != BLK_STS_OK && bio->bi_status == BLK_STS_OK)
bio->bi_status = status;
+ if (bio->bi_status != BLK_STS_OK)
+ bioctx->target->dev->flags |= DMZ_CHECK_BDEV;
if (refcount_dec_and_test(&bioctx->ref)) {
struct dm_zone *zone = bioctx->zone;
@@ -565,32 +567,52 @@ out:
}
/*
- * Check the backing device availability. If it's on the way out,
+ * Check if the backing device is being removed. If it's on the way out,
* start failing I/O. Reclaim and metadata components also call this
* function to cleanly abort operation in the event of such failure.
*/
bool dmz_bdev_is_dying(struct dmz_dev *dmz_dev)
{
- struct gendisk *disk;
+ if (dmz_dev->flags & DMZ_BDEV_DYING)
+ return true;
- if (!(dmz_dev->flags & DMZ_BDEV_DYING)) {
- disk = dmz_dev->bdev->bd_disk;
- if (blk_queue_dying(bdev_get_queue(dmz_dev->bdev))) {
- dmz_dev_warn(dmz_dev, "Backing device queue dying");
- dmz_dev->flags |= DMZ_BDEV_DYING;
- } else if (disk->fops->check_events) {
- if (disk->fops->check_events(disk, 0) &
- DISK_EVENT_MEDIA_CHANGE) {
- dmz_dev_warn(dmz_dev, "Backing device offline");
- dmz_dev->flags |= DMZ_BDEV_DYING;
- }
- }
+ if (dmz_dev->flags & DMZ_CHECK_BDEV)
+ return !dmz_check_bdev(dmz_dev);
+
+ if (blk_queue_dying(bdev_get_queue(dmz_dev->bdev))) {
+ dmz_dev_warn(dmz_dev, "Backing device queue dying");
+ dmz_dev->flags |= DMZ_BDEV_DYING;
}
return dmz_dev->flags & DMZ_BDEV_DYING;
}
/*
+ * Check the backing device availability. This detects such events as
+ * backing device going offline due to errors, media removals, etc.
+ * This check is less efficient than dmz_bdev_is_dying() and should
+ * only be performed as a part of error handling.
+ */
+bool dmz_check_bdev(struct dmz_dev *dmz_dev)
+{
+ struct gendisk *disk;
+
+ dmz_dev->flags &= ~DMZ_CHECK_BDEV;
+
+ if (dmz_bdev_is_dying(dmz_dev))
+ return false;
+
+ disk = dmz_dev->bdev->bd_disk;
+ if (disk->fops->check_events &&
+ disk->fops->check_events(disk, 0) & DISK_EVENT_MEDIA_CHANGE) {
+ dmz_dev_warn(dmz_dev, "Backing device offline");
+ dmz_dev->flags |= DMZ_BDEV_DYING;
+ }
+
+ return !(dmz_dev->flags & DMZ_BDEV_DYING);
+}
+
+/*
* Process a new BIO.
*/
static int dmz_map(struct dm_target *ti, struct bio *bio)
@@ -902,8 +924,8 @@ static int dmz_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
{
struct dmz_target *dmz = ti->private;
- if (dmz_bdev_is_dying(dmz->dev))
- return -ENODEV;
+ if (!dmz_check_bdev(dmz->dev))
+ return -EIO;
*bdev = dmz->dev->bdev;