block: introduce BDRV_REQ_NO_WAIT flag

Add flag to make serialising request no wait: if there are conflicting
requests, just return error immediately. It's will be used in upcoming
preallocate filter.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20201021145859.11201-7-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2020-10-21 17:58:44 +03:00 committed by Max Reitz
parent 8ac5aab255
commit d1a764d126
2 changed files with 18 additions and 2 deletions

View file

@ -77,8 +77,15 @@ typedef enum {
* written to qiov parameter which may be NULL.
*/
BDRV_REQ_PREFETCH = 0x200,
/*
* If we need to wait for other requests, just fail immediately. Used
* only together with BDRV_REQ_SERIALISING.
*/
BDRV_REQ_NO_WAIT = 0x400,
/* Mask of valid flags */
BDRV_REQ_MASK = 0x3ff,
BDRV_REQ_MASK = 0x7ff,
} BdrvRequestFlags;
typedef struct BlockSizes {