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[PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed
From: |
Andrey Shinkevich |
Subject: |
[PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed |
Date: |
Mon, 12 Oct 2020 20:43:21 +0300 |
If the flag BDRV_REQ_PREFETCH was set, pass it further to the
COR-driver to skip unneeded reading. It can be taken into account for
the COR-algorithms optimization. That check is being made during the
block stream job by the moment.
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
---
block/copy-on-read.c | 13 +++++++++----
block/io.c | 3 ++-
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index b136895..278a11a 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -148,10 +148,15 @@ static int coroutine_fn
cor_co_preadv_part(BlockDriverState *bs,
}
}
- ret = bdrv_co_preadv_part(bs->file, offset, n, qiov, qiov_offset,
- local_flags);
- if (ret < 0) {
- return ret;
+ if (!!(flags & BDRV_REQ_PREFETCH) &
+ !(local_flags & BDRV_REQ_COPY_ON_READ)) {
+ /* Skip non-guest reads if no copy needed */
+ } else {
+ ret = bdrv_co_preadv_part(bs->file, offset, n, qiov, qiov_offset,
+ local_flags);
+ if (ret < 0) {
+ return ret;
+ }
}
offset += n;
diff --git a/block/io.c b/block/io.c
index 11df188..bff1808 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1512,7 +1512,8 @@ static int coroutine_fn bdrv_aligned_preadv(BdrvChild
*child,
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 & bs->supported_read_flags);
goto out;
}
--
1.8.3.1
- Re: [PATCH v11 05/13] copy-on-read: limit COR operations to base in COR driver, (continued)
[PATCH v11 06/13] block: modify the comment for BDRV_REQ_PREFETCH flag, Andrey Shinkevich, 2020/10/12
[PATCH v11 07/13] block: include supported_read_flags into BDS structure, Andrey Shinkevich, 2020/10/12
[PATCH v11 08/13] copy-on-read: add support for BDRV_REQ_PREFETCH to COR-filter, Andrey Shinkevich, 2020/10/12
[PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed,
Andrey Shinkevich <=
Re: [PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed, Andrey Shinkevich, 2020/10/21
Re: [PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed, Andrey Shinkevich, 2020/10/22
Re: [PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed, Vladimir Sementsov-Ogievskiy, 2020/10/22
Re: [PATCH v11 09/13] copy-on-read: skip non-guest reads if no copy needed, Andrey Shinkevich, 2020/10/14
[PATCH v11 10/13] stream: skip filters when writing backing file name to QCOW2 header, Andrey Shinkevich, 2020/10/12