From: Dmitry Fomichev dmitry.fomichev@wdc.com
commit e7fad909b68aa37470d9f2d2731b5bec355ee5d6 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/dm-zoned-metadata.c | 29 ++++++++++++++-------- drivers/md/dm-zoned-reclaim.c | 8 +----- drivers/md/dm-zoned-target.c | 54 ++++++++++++++++++++++++++++------------- drivers/md/dm-zoned.h | 2 + 4 files changed, 61 insertions(+), 32 deletions(-)
--- a/drivers/md/dm-zoned-metadata.c +++ b/drivers/md/dm-zoned-metadata.c @@ -552,6 +552,7 @@ static struct dmz_mblock *dmz_get_mblock TASK_UNINTERRUPTIBLE); if (test_bit(DMZ_META_ERROR, &mblk->state)) { dmz_release_mblock(zmd, mblk); + dmz_check_bdev(zmd->dev); return ERR_PTR(-EIO); }
@@ -623,6 +624,8 @@ static int dmz_rdwr_block(struct dmz_met ret = submit_bio_wait(bio); bio_put(bio);
+ if (ret) + dmz_check_bdev(zmd->dev); return ret; }
@@ -689,6 +692,7 @@ static int dmz_write_dirty_mblocks(struc TASK_UNINTERRUPTIBLE); if (test_bit(DMZ_META_ERROR, &mblk->state)) { clear_bit(DMZ_META_ERROR, &mblk->state); + dmz_check_bdev(zmd->dev); ret = -EIO; } nr_mblks_submitted--; @@ -766,7 +770,7 @@ int dmz_flush_metadata(struct dmz_metada /* If there are no dirty metadata blocks, just flush the device cache */ if (list_empty(&write_list)) { ret = blkdev_issue_flush(zmd->dev->bdev, GFP_NOIO, NULL); - goto out; + goto err; }
/* @@ -776,7 +780,7 @@ int dmz_flush_metadata(struct dmz_metada */ ret = dmz_log_dirty_mblocks(zmd, &write_list); if (ret) - goto out; + goto err;
/* * The log is on disk. It is now safe to update in place @@ -784,11 +788,11 @@ int dmz_flush_metadata(struct dmz_metada */ ret = dmz_write_dirty_mblocks(zmd, &write_list, zmd->mblk_primary); if (ret) - goto out; + goto err;
ret = dmz_write_sb(zmd, zmd->mblk_primary); if (ret) - goto out; + goto err;
while (!list_empty(&write_list)) { mblk = list_first_entry(&write_list, struct dmz_mblock, link); @@ -803,16 +807,20 @@ int dmz_flush_metadata(struct dmz_metada
zmd->sb_gen++; out: - if (ret && !list_empty(&write_list)) { - spin_lock(&zmd->mblk_lock); - list_splice(&write_list, &zmd->mblk_dirty_list); - spin_unlock(&zmd->mblk_lock); - } - dmz_unlock_flush(zmd); up_write(&zmd->mblk_sem);
return ret; + +err: + if (!list_empty(&write_list)) { + spin_lock(&zmd->mblk_lock); + list_splice(&write_list, &zmd->mblk_dirty_list); + spin_unlock(&zmd->mblk_lock); + } + if (!dmz_check_bdev(zmd->dev)) + ret = -EIO; + goto out; }
/* @@ -1235,6 +1243,7 @@ static int dmz_update_zone(struct dmz_me if (ret) { dmz_dev_err(zmd->dev, "Get zone %u report failed", dmz_id(zmd, zone)); + dmz_check_bdev(zmd->dev); return ret; }
--- a/drivers/md/dm-zoned-reclaim.c +++ b/drivers/md/dm-zoned-reclaim.c @@ -81,6 +81,7 @@ static int dmz_reclaim_align_wp(struct d "Align zone %u wp %llu to %llu (wp+%u) blocks failed %d", dmz_id(zmd, zone), (unsigned long long)wp_block, (unsigned long long)block, nr_blocks, ret); + dmz_check_bdev(zrc->dev); return ret; }
@@ -488,12 +489,7 @@ static void dmz_reclaim_work(struct work ret = dmz_do_reclaim(zrc); if (ret) { dmz_dev_debug(zrc->dev, "Reclaim error %d\n", ret); - if (ret == -EIO) - /* - * LLD might be performing some error handling sequence - * at the underlying device. To not interfere, do not - * attempt to schedule the next reclaim run immediately. - */ + if (!dmz_check_bdev(zrc->dev)) return; }
--- a/drivers/md/dm-zoned-target.c +++ b/drivers/md/dm-zoned-target.c @@ -79,6 +79,8 @@ static inline void dmz_bio_endio(struct
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 (atomic_dec_and_test(&bioctx->ref)) { struct dm_zone *zone = bioctx->zone; @@ -564,32 +566,52 @@ 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_t { 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;
--- a/drivers/md/dm-zoned.h +++ b/drivers/md/dm-zoned.h @@ -71,6 +71,7 @@ struct dmz_dev {
/* Device flags. */ #define DMZ_BDEV_DYING (1 << 0) +#define DMZ_CHECK_BDEV (2 << 0)
/* * Zone descriptor. @@ -254,5 +255,6 @@ void dmz_schedule_reclaim(struct dmz_rec * Functions defined in dm-zoned-target.c */ bool dmz_bdev_is_dying(struct dmz_dev *dmz_dev); +bool dmz_check_bdev(struct dmz_dev *dmz_dev);
#endif /* DM_ZONED_H */