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block: include supported_read_flags into BDS structure

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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
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10
block/io.c
View File

@ -1453,6 +1453,9 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
if (flags & BDRV_REQ_COPY_ON_READ) {
int64_t pnum;
/* The flag BDRV_REQ_COPY_ON_READ has reached its addressee */
flags &= ~BDRV_REQ_COPY_ON_READ;
ret = bdrv_is_allocated(bs, offset, bytes, &pnum);
if (ret < 0) {
goto out;
@ -1474,9 +1477,11 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
goto out;
}
assert(!(flags & ~bs->supported_read_flags));
max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align);
if (bytes <= max_bytes && bytes <= max_transfer) {
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, qiov_offset, 0);
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, qiov_offset, flags);
goto out;
}
@ -1489,7 +1494,8 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild *child,
ret = bdrv_driver_preadv(bs, offset + bytes - bytes_remaining,
num, qiov,
qiov_offset + bytes - bytes_remaining, 0);
qiov_offset + bytes - bytes_remaining,
flags);
max_bytes -= num;
} else {
num = bytes_remaining;

4
include/block/block_int.h
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