diff options
| author | Max Reitz <mreitz@redhat.com> | 2018-04-21 15:29:23 +0200 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2018-05-15 16:15:21 +0200 |
| commit | c6035964f8316b504060618d05b5dd434f18595b (patch) | |
| tree | d6b2279cf0ce77c58d2d41cb1014d265c1380c3d | |
| parent | 24b7c538fea86b598e2a335f4805a0ab50a30e98 (diff) | |
block: Add BDRV_REQ_WRITE_UNCHANGED flag
This flag signifies that a write request will not change the visible
disk content. With this flag set, it is sufficient to have the
BLK_PERM_WRITE_UNCHANGED permission instead of BLK_PERM_WRITE.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-4-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
| -rw-r--r-- | block/io.c | 6 | ||||
| -rw-r--r-- | include/block/block.h | 6 |
2 files changed, 10 insertions, 2 deletions
diff --git a/block/io.c b/block/io.c index 4fad5ac2fe..9e8449e795 100644 --- a/block/io.c +++ b/block/io.c @@ -1504,7 +1504,11 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child, assert(!waited || !req->serialising); assert(req->overlap_offset <= offset); assert(offset + bytes <= req->overlap_offset + req->overlap_bytes); - assert(child->perm & BLK_PERM_WRITE); + if (flags & BDRV_REQ_WRITE_UNCHANGED) { + assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); + } else { + assert(child->perm & BLK_PERM_WRITE); + } assert(end_sector <= bs->total_sectors || child->perm & BLK_PERM_RESIZE); ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req); diff --git a/include/block/block.h b/include/block/block.h index 397b5e8d44..3894edda9d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -54,8 +54,12 @@ typedef enum { BDRV_REQ_FUA = 0x10, BDRV_REQ_WRITE_COMPRESSED = 0x20, + /* Signifies that this write request will not change the visible disk + * content. */ + BDRV_REQ_WRITE_UNCHANGED = 0x40, + /* Mask of valid flags */ - BDRV_REQ_MASK = 0x3f, + BDRV_REQ_MASK = 0x7f, } BdrvRequestFlags; typedef struct BlockSizes { |