[PATCH 08/10] block: refacto blkdev_issue_zeroout

Christoph Hellwig
2024-07-01T16:52:56Z

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>
---
block/blk-lib.c | 94 +++++++++++++++++++++++++++++--------------------
1 file changed, 55 insertions(+), 39 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 10325e91560c40..9585178a51a60c 100644
--- 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);

--
2.43.0