Currently blkdev_issue_zeroout cascades down from discards (if the driver
gurantees that discards zero data), to WRITE SAME and then to a loop
writing zeroes. Unfortunately we ignore tun-time EOPNOTSUPP errors in the
block layer blkdev_issue_discard helper to work around DM volumes that
may have mixed discard support underneath.
This path intoroduces a new BLKDEV_DISCARD_ZERO flag to
blkdev_issue_discard that indicates we are called for zeroing operation.
This allows both to ignore the EOPNOTSUPP hack and actually consolidating
the discard_zeroes_data check into the function.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-lib.c | 17 +++++++++++------
include/linux/blkdev.h | 4 +++-
2 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 78626c2..45b35b1 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -36,12 +36,17 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
return -ENXIO;
if (flags & BLKDEV_DISCARD_SECURE) {
+ if (flags & BLKDEV_DISCARD_ZERO)
+ return -EOPNOTSUPP;
if (!blk_queue_secure_erase(q))
return -EOPNOTSUPP;
op = REQ_OP_SECURE_ERASE;
} else {
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
+ if ((flags & BLKDEV_DISCARD_ZERO) &&
+ !q->limits.discard_zeroes_data)
+ return -EOPNOTSUPP;
op = REQ_OP_DISCARD;
}
@@ -116,7 +121,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
&bio);
if (!ret && bio) {
ret = submit_bio_wait(bio);
- if (ret == -EOPNOTSUPP)
+ if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
ret = 0;
}
blk_finish_plug(&plug);
@@ -241,11 +246,11 @@ static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, bool discard)
{
- struct request_queue *q = bdev_get_queue(bdev);
-
- if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
- blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
- return 0;
+ if (discard) {
+ if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
+ BLKDEV_DISCARD_ZERO))
+ return 0;
+ }
if (bdev_write_same(bdev) &&
blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9d1e0a4..b65ca66 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1136,7 +1136,9 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
return bqt->tag_index[tag];
}
-#define BLKDEV_DISCARD_SECURE 0x01 /* secure discard */
+
+#define BLKDEV_DISCARD_SECURE (1 << 0) /* issue a secure erase */
+#define BLKDEV_DISCARD_ZERO (1 << 1) /* must reliably zero data */
extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-block" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
