In preparation for fixing device mapper zone write handling, introduce
the inline helper function bio_needs_zone_write_plugging() to test if a
BIO requires handling through zone write plugging using the function
blk_zone_plug_bio(). This function returns true for any write
(op_is_write(bio) == true) operation directed at a zoned block device
using zone write plugging, that is, a block device with a disk that has
a zone write plug hash table.
This helper allows simplifying the check on entry to blk_zone_plug_bio()
and used in to protect calls to it for blk-mq devices and DM devices.
Fixes: f211268ed1f9 ("dm: Use the block layer zone append emulation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
---
block/blk-mq.c | 6 +++--
block/blk-zoned.c | 20 +--------------
drivers/md/dm.c | 4 ++-
include/linux/blkdev.h | 55 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 63 insertions(+), 22 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4806b867e37d..0c61492724d2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3169,8 +3169,10 @@ void blk_mq_submit_bio(struct bio *bio)
if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
goto queue_exit;
- if (blk_queue_is_zoned(q) && blk_zone_plug_bio(bio, nr_segs))
- goto queue_exit;
+ if (bio_needs_zone_write_plugging(bio)) {
+ if (blk_zone_plug_bio(bio, nr_segs))
+ goto queue_exit;
+ }
new_request:
if (rq) {
diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 55e64ca869d7..16b08bf8f82a 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -1145,25 +1145,7 @@ bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs)
{
struct block_device *bdev = bio->bi_bdev;
- if (!bdev->bd_disk->zone_wplugs_hash)
- return false;
-
- /*
- * If the BIO already has the plugging flag set, then it was already
- * handled through this path and this is a submission from the zone
- * plug bio submit work.
- */
- if (bio_flagged(bio, BIO_ZONE_WRITE_PLUGGING))
- return false;
-
- /*
- * We do not need to do anything special for empty flush BIOs, e.g
- * BIOs such as issued by blkdev_issue_flush(). The is because it is
- * the responsibility of the user to first wait for the completion of
- * write operations for flush to have any effect on the persistence of
- * the written data.
- */
- if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
+ if (WARN_ON_ONCE(!bdev->bd_disk->zone_wplugs_hash))
return false;
/*
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 55579adbeb3f..e477765cdd27 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1781,7 +1781,9 @@ static inline bool dm_zone_bio_needs_split(struct mapped_device *md,
}
static inline bool dm_zone_plug_bio(struct mapped_device *md, struct bio *bio)
{
- return dm_emulate_zone_append(md) && blk_zone_plug_bio(bio, 0);
+ if (!bio_needs_zone_write_plugging(bio))
+ return false;
+ return blk_zone_plug_bio(bio, 0);
}
static blk_status_t __send_zone_reset_all_emulated(struct clone_info *ci,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c2b3ddea8b6d..a7d09ef4f448 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -848,6 +848,55 @@ static inline unsigned int disk_nr_zones(struct gendisk *disk)
{
return disk->nr_zones;
}
+
+/**
+ * bio_needs_zone_write_plugging - Check if a BIO needs to be handled with zone
+ * write plugging
+ * @bio: The BIO being submitted
+ *
+ * Return true whenever @bio execution needs to be handled through zone
+ * write plugging (using blk_zone_plug_bio()). Return false otherwise.
+ */
+static inline bool bio_needs_zone_write_plugging(struct bio *bio)
+{
+ enum req_op op = bio_op(bio);
+
+ /*
+ * Only zoned block devices have a zone write plug hash table. But not
+ * all of them have one (e.g. DM devices may not need one).
+ */
+ if (!bio->bi_bdev->bd_disk->zone_wplugs_hash)
+ return false;
+
+ /* Only write operations need zone write plugging. */
+ if (!op_is_write(op))
+ return false;
+
+ /* Ignore empty flush */
+ if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
+ return false;
+
+ /* Ignore BIOs that already have been handled by zone write plugging. */
+ if (bio_flagged(bio, BIO_ZONE_WRITE_PLUGGING))
+ return false;
+
+ /*
+ * All zone write operations must be handled through zone write plugging
+ * using blk_zone_plug_bio().
+ */
+ switch (op) {
+ case REQ_OP_ZONE_APPEND:
+ case REQ_OP_WRITE:
+ case REQ_OP_WRITE_ZEROES:
+ case REQ_OP_ZONE_FINISH:
+ case REQ_OP_ZONE_RESET:
+ case REQ_OP_ZONE_RESET_ALL:
+ return true;
+ default:
+ return false;
+ }
+}
+
bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs);
/**
@@ -877,6 +926,12 @@ static inline unsigned int disk_nr_zones(struct gendisk *disk)
{
return 0;
}
+
+static inline bool bio_needs_zone_write_plugging(struct bio *bio)
+{
+ return false;
+}
+
static inline bool blk_zone_plug_bio(struct bio *bio, unsigned int nr_segs)
{
return false;
--
2.49.0
