block: refacto blkdev_issue_zeroout

Split out two well-defined helpers for hardware supported Write Zeroes
and manually writing zeroes using the Write command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240701165219.1571322-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 02f69c683a9839109d0337ee194ec3d673296376..9dbab472c63f12d223fd5cb48c85335c697a2507 100644 (file)
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -135,6 +135,32 @@ static void __blkdev_issue_write_zeroes(struct block_device *bdev,
        *biop = bio;
 }
 
+static int blkdev_issue_write_zeroes(struct block_device *bdev, sector_t sector,
+               sector_t nr_sects, gfp_t gfp, unsigned flags)
+{
+       struct bio *bio = NULL;
+       struct blk_plug plug;
+       int ret = 0;
+
+       blk_start_plug(&plug);
+       __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp, &bio, flags);
+       if (bio) {
+               ret = submit_bio_wait(bio);
+               bio_put(bio);
+       }
+       blk_finish_plug(&plug);
+
+       /*
+        * For some devices there is no non-destructive way to verify whether
+        * WRITE ZEROES is actually supported.  These will clear the capability
+        * on an I/O error, in which case we'll turn any error into
+        * "not supported" here.
+        */
+       if (ret && !bdev_write_zeroes_sectors(bdev))
+               return -EOPNOTSUPP;
+       return ret;
+}
+
 /*
  * Convert a number of 512B sectors to a number of pages.
  * The result is limited to a number of pages that can fit into a BIO.
@@ -175,6 +201,27 @@ static void __blkdev_issue_zero_pages(struct block_device *bdev,
        *biop = bio;
 }
 
+static int blkdev_issue_zero_pages(struct block_device *bdev, sector_t sector,
+               sector_t nr_sects, gfp_t gfp, unsigned flags)
+{
+       struct bio *bio = NULL;
+       struct blk_plug plug;
+       int ret = 0;
+
+       if (flags & BLKDEV_ZERO_NOFALLBACK)
+               return -EOPNOTSUPP;
+
+       blk_start_plug(&plug);
+       __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp, &bio);
+       if (bio) {
+               ret = submit_bio_wait(bio);
+               bio_put(bio);
+       }
+       blk_finish_plug(&plug);
+
+       return ret;
+}
+
 /**
  * __blkdev_issue_zeroout - generate number of zero filed write bios
  * @bdev:      blockdev to issue
@@ -230,52 +277,21 @@ EXPORT_SYMBOL(__blkdev_issue_zeroout);
 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
                sector_t nr_sects, gfp_t gfp_mask, unsigned flags)
 {
-       int ret = 0;
-       sector_t bs_mask;
-       struct bio *bio;
-       struct blk_plug plug;
-       bool try_write_zeroes = !!bdev_write_zeroes_sectors(bdev);
+       int ret;
 
-       bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
-       if ((sector | nr_sects) & bs_mask)
+       if ((sector | nr_sects) & ((bdev_logical_block_size(bdev) >> 9) - 1))
                return -EINVAL;
        if (bdev_read_only(bdev))
                return -EPERM;
-       if ((flags & BLKDEV_ZERO_NOFALLBACK) && !try_write_zeroes)
-               return -EOPNOTSUPP;
 
-retry:
-       bio = NULL;
-       blk_start_plug(&plug);
-       if (try_write_zeroes) {
-               __blkdev_issue_write_zeroes(bdev, sector, nr_sects, gfp_mask,
-                               &bio, flags);
-       } else {
-               __blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask,
-                               &bio);
-       }
-       if (bio) {
-               ret = submit_bio_wait(bio);
-               bio_put(bio);
-       }
-       blk_finish_plug(&plug);
-       if (ret && try_write_zeroes) {
-               if (!(flags & BLKDEV_ZERO_NOFALLBACK)) {
-                       try_write_zeroes = false;
-                       goto retry;
-               }
-               if (!bdev_write_zeroes_sectors(bdev)) {
-                       /*
-                        * Zeroing offload support was indicated, but the
-                        * device reported ILLEGAL REQUEST (for some devices
-                        * there is no non-destructive way to verify whether
-                        * WRITE ZEROES is actually supported).
-                        */
-                       ret = -EOPNOTSUPP;
-               }
+       if (bdev_write_zeroes_sectors(bdev)) {
+               ret = blkdev_issue_write_zeroes(bdev, sector, nr_sects,
+                               gfp_mask, flags);
+               if (!ret)
+                       return ret;
        }
 
-       return ret;
+       return blkdev_issue_zero_pages(bdev, sector, nr_sects, gfp_mask, flags);
 }
 EXPORT_SYMBOL(blkdev_issue_zeroout);