block: include supported_read_flags into BDS structure

Add the new member supported_read_flags to the BlockDriverState
structure. It will control the flags set for copy-on-read operations.
Make the block generic layer evaluate supported read flags before they
go to a block driver.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
 [vsementsov: use assert instead of abort]
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20201216061703.70908-8-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Andrey Shinkevich 2020-12-16 09:16:57 +03:00 committed by Max Reitz
parent b6e0985a4c
commit 897dd0ec4f
2 changed files with 12 additions and 2 deletions

View file

@ -881,6 +881,10 @@ struct BlockDriverState {
/* I/O Limits */
BlockLimits bl;
/*
* Flags honored during pread
*/
unsigned int supported_read_flags;
/* Flags honored during pwrite (so far: BDRV_REQ_FUA,
* BDRV_REQ_WRITE_UNCHANGED).
* If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those