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block/io: Ignore FUA with cache.no-flush=on

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For block drivers that don't advertise FUA support, we already call
bdrv_co_flush(), which considers BDRV_O_NO_FLUSH. However, drivers that
do support FUA still see the FUA flag with BDRV_O_NO_FLUSH and get the
associated performance penalty that cache.no-flush=on was supposed to
avoid.

Clear FUA for write requests if BDRV_O_NO_FLUSH is set.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2025-03-07 23:16:31 +01:00
parent 984a32f17e
commit 2f3b6e61f6
1 changed files with 4 additions and 0 deletions
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4
block/io.c
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@ -1058,6 +1058,10 @@ bdrv_driver_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
return -ENOMEDIUM;
}
if (bs->open_flags & BDRV_O_NO_FLUSH) {
flags &= ~BDRV_REQ_FUA;
}
if ((flags & BDRV_REQ_FUA) &&
(~bs->supported_write_flags & BDRV_REQ_FUA)) {
flags &= ~BDRV_REQ_FUA;