dm: add support for REQ_NOWAIT and enable it for linear target

Add DM target feature flag DM_TARGET_NOWAIT which advertises that
target works with REQ_NOWAIT bios.

Add dm_table_supports_nowait() and update dm_table_set_restrictions()
to set/clear QUEUE_FLAG_NOWAIT accordingly.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index e1db434463272346dd15ea01d2dd74daaba0e73b..00774b5d7668adc4dec198e8b16b5d03f90aa9ac 100644 (file)
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -228,10 +228,11 @@ static struct target_type linear_target = {
        .name   = "linear",
        .version = {1, 4, 0},
 #ifdef CONFIG_BLK_DEV_ZONED
-       .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
+       .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT |
+                   DM_TARGET_ZONED_HM,
        .report_zones = linear_report_zones,
 #else
-       .features = DM_TARGET_PASSES_INTEGRITY,
+       .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT,
 #endif
        .module = THIS_MODULE,
        .ctr    = linear_ctr,

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 12d909044c1057d78da4678852e8575b6d4ff6a2..07c319e9858136186444dec71faadd68f688958b 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1748,6 +1748,33 @@ static bool dm_table_supports_write_zeroes(struct dm_table *t)
        return true;
 }
 
+static int device_not_nowait_capable(struct dm_target *ti, struct dm_dev *dev,
+                                    sector_t start, sector_t len, void *data)
+{
+       struct request_queue *q = bdev_get_queue(dev->bdev);
+
+       return q && !blk_queue_nowait(q);
+}
+
+static bool dm_table_supports_nowait(struct dm_table *t)
+{
+       struct dm_target *ti;
+       unsigned i = 0;
+
+       while (i < dm_table_get_num_targets(t)) {
+               ti = dm_table_get_target(t, i++);
+
+               if (!dm_target_supports_nowait(ti->type))
+                       return false;
+
+               if (!ti->type->iterate_devices ||
+                   ti->type->iterate_devices(ti, device_not_nowait_capable, NULL))
+                       return false;
+       }
+
+       return true;
+}
+
 static int device_not_discard_capable(struct dm_target *ti, struct dm_dev *dev,
                                      sector_t start, sector_t len, void *data)
 {
@@ -1850,6 +1877,11 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         */
        q->limits = *limits;
 
+       if (dm_table_supports_nowait(t))
+               blk_queue_flag_set(QUEUE_FLAG_NOWAIT, q);
+       else
+               blk_queue_flag_clear(QUEUE_FLAG_NOWAIT, q);
+
        if (!dm_table_supports_discards(t)) {
                blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
                /* Must also clear discard limits... */

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3dedd9cc4fb65287d4c46e020d2970a2230b049d..59b0687f9235a53470b0e6df4f4cc7175fb7404b 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1802,7 +1802,9 @@ static blk_qc_t dm_submit_bio(struct bio *bio)
        if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
                dm_put_live_table(md, srcu_idx);
 
-               if (!(bio->bi_opf & REQ_RAHEAD))
+               if (bio->bi_opf & REQ_NOWAIT)
+                       bio_wouldblock_error(bio);
+               else if (!(bio->bi_opf & REQ_RAHEAD))
                        queue_io(md, bio);
                else
                        bio_io_error(bio);

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 93096e524e43945554209226cb1a389a7991fe18..d6f8d4ba8d48a1b66e0a2470b7ceb7ea09ab1ee2 100644 (file)
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -252,6 +252,12 @@ struct target_type {
 #define DM_TARGET_ZONED_HM             0x00000040
 #define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)
 
+/*
+ * A target handles REQ_NOWAIT
+ */
+#define DM_TARGET_NOWAIT               0x00000080
+#define dm_target_supports_nowait(type) ((type)->features & DM_TARGET_NOWAIT)
+
 struct dm_target {
        struct dm_table *table;
        struct target_type *type;