block: Simplify report zones execution

All kernel users of blkdev_report_zones() as well as applications use
through ioctl(BLKZONEREPORT) expect to potentially get less zone
descriptors than requested. As such, the use of the internal report
zones command execution loop implemented by blk_report_zones() is
not necessary and can even be harmful to performance by causing the
execution of inefficient small zones report command to service the
reminder of a requested zone array.

This patch removes blk_report_zones(), simplifying the code. Also
remove a now incorrect comment in dm_blk_report_zones().

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Javier Gonzalez <javier@javigon.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 523a28d..ea4e086 100644 (file)
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -119,31 +119,6 @@ static bool blkdev_report_zone(struct block_device *bdev, struct blk_zone *rep)
        return true;
 }
 
-static int blk_report_zones(struct gendisk *disk, sector_t sector,
-                           struct blk_zone *zones, unsigned int *nr_zones)
-{
-       struct request_queue *q = disk->queue;
-       unsigned int z = 0, n, nrz = *nr_zones;
-       sector_t capacity = get_capacity(disk);
-       int ret;
-
-       while (z < nrz && sector < capacity) {
-               n = nrz - z;
-               ret = disk->fops->report_zones(disk, sector, &zones[z], &n);
-               if (ret)
-                       return ret;
-               if (!n)
-                       break;
-               sector += blk_queue_zone_sectors(q) * n;
-               z += n;
-       }
-
-       WARN_ON(z > *nr_zones);
-       *nr_zones = z;
-
-       return 0;
-}
-
 /**
  * blkdev_report_zones - Get zones information
  * @bdev:      Target block device
@@ -164,6 +139,7 @@ int blkdev_report_zones(struct block_device *bdev, sector_t sector,
                        struct blk_zone *zones, unsigned int *nr_zones)
 {
        struct request_queue *q = bdev_get_queue(bdev);
+       struct gendisk *disk = bdev->bd_disk;
        unsigned int i, nrz;
        int ret;
 
@@ -175,7 +151,7 @@ int blkdev_report_zones(struct block_device *bdev, sector_t sector,
         * report_zones method. If it does not have one defined, the device
         * driver has a bug. So warn about that.
         */
-       if (WARN_ON_ONCE(!bdev->bd_disk->fops->report_zones))
+       if (WARN_ON_ONCE(!disk->fops->report_zones))
                return -EOPNOTSUPP;
 
        if (!*nr_zones || sector >= bdev->bd_part->nr_sects) {
@@ -185,8 +161,8 @@ int blkdev_report_zones(struct block_device *bdev, sector_t sector,
 
        nrz = min(*nr_zones,
                  __blkdev_nr_zones(q, bdev->bd_part->nr_sects - sector));
-       ret = blk_report_zones(bdev->bd_disk, get_start_sect(bdev) + sector,
-                              zones, &nrz);
+       ret = disk->fops->report_zones(disk, get_start_sect(bdev) + sector,
+                                      zones, &nrz);
        if (ret)
                return ret;
 
@@ -561,7 +537,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
 
        while (z < nr_zones) {
                nrz = min(nr_zones - z, rep_nr_zones);
-               ret = blk_report_zones(disk, sector, zones, &nrz);
+               ret = disk->fops->report_zones(disk, sector, zones, &nrz);
                if (ret)
                        goto out;
                if (!nrz)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index bc143c1..89189c2 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -473,12 +473,6 @@ static int dm_blk_report_zones(struct gendisk *disk, sector_t sector,
                goto out;
        }
 
-       /*
-        * blkdev_report_zones() will loop and call this again to cover all the
-        * zones of the target, eventually moving on to the next target.
-        * So there is no need to loop here trying to fill the entire array
-        * of zones.
-        */
        ret = tgt->type->report_zones(tgt, sector, zones, nr_zones);
 
 out: