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List: qemu-block
Subject: [Qemu-block] [PULL 09/13] block: Fix documentation for BDRV_REQ_MAY_UNMAP
From: Kevin Wolf <kwolf () redhat ! com>
Date: 2018-07-30 15:09:54
Message-ID: 20180730150958.14607-10-kwolf () redhat ! com
[Download RAW message or body]
BDRV_REQ_MAY_UNMAP in a write_zeroes request does not only allow the
driver to unmap the blocks, but it actively requests that the blocks be
unmapped afterwards if at all possible.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/block/block.h | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/include/block/block.h b/include/block/block.h
index f85e3a6ed3..4e0871aaf9 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -43,11 +43,12 @@ typedef struct BlockFragInfo {
typedef enum {
BDRV_REQ_COPY_ON_READ = 0x1,
BDRV_REQ_ZERO_WRITE = 0x2,
- /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver
- * is allowed to optimize a write zeroes request by unmapping (discarding)
- * blocks if it is guaranteed that the result will read back as
- * zeroes. The flag is only passed to the driver if the block device is
- * opened with BDRV_O_UNMAP.
+
+ /*
+ * The BDRV_REQ_MAY_UNMAP flag is used in write_zeroes requests to indicate
+ * that the block driver should unmap (discard) blocks if it is guaranteed
+ * that the result will read back as zeroes. The flag is only passed to the
+ * driver if the block device is opened with BDRV_O_UNMAP.
*/
BDRV_REQ_MAY_UNMAP = 0x4,
--
2.13.6
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