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[Qemu-devel] [RFC PATCH 1/7] block: flush in writethrough mode after wri
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [RFC PATCH 1/7] block: flush in writethrough mode after writes |
Date: |
Fri, 18 May 2012 16:18:26 +0200 |
We want to make the formats handle their own flushes
autonomously, while keeping for guests the ability to use a writethrough
cache. Since formats will write metadata via bs->file, bdrv_co_do_writev
is the only place where we need to add a flush.
Signed-off-by: Paolo Bonzini <address@hidden>
---
block.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index af2ab4f..7add33c 100644
--- a/block.c
+++ b/block.c
@@ -1747,8 +1747,8 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
return ret;
}
- /* No flush needed for cache modes that use O_DSYNC */
- if ((bs->open_flags & BDRV_O_CACHE_WB) != 0) {
+ /* No flush needed for cache modes that already do it */
+ if (bs->enable_write_cache) {
bdrv_flush(bs);
}
@@ -1797,6 +1797,9 @@ static int coroutine_fn
bdrv_co_do_copy_on_readv(BlockDriverState *bs,
ret = bdrv_co_do_write_zeroes(bs, cluster_sector_num,
cluster_nb_sectors);
} else {
+ /* This does not change the data on the disk, it is not necessary
+ * to flush even in cache=writethrough mode.
+ */
ret = drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors,
&bounce_qiov);
}
@@ -1966,6 +1969,10 @@ static int coroutine_fn
bdrv_co_do_writev(BlockDriverState *bs,
ret = drv->bdrv_co_writev(bs, sector_num, nb_sectors, qiov);
}
+ if (ret == 0 && !bs->enable_write_cache) {
+ ret = bdrv_co_flush(bs);
+ }
+
if (bs->dirty_bitmap) {
set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
}
--
1.7.10.1
- [Qemu-devel] [RFC PATCH 0/7] Manual writethrough cache and cache mode toggle, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 2/7] savevm: flush after saving vm state, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 1/7] block: flush in writethrough mode after writes,
Paolo Bonzini <=
- [Qemu-devel] [RFC PATCH 3/7] block: do not pass BDRV_O_CACHE_WB to the protocol, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 5/7] block: add bdrv_set_enable_write_cache, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 4/7] block: copy enable_write_cache in bdrv_append, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 6/7] ide: support enable/disable write cache, Paolo Bonzini, 2012/05/18
- [Qemu-devel] [RFC PATCH 7/7] block: do not handle writethrough in qcow2 caches, Paolo Bonzini, 2012/05/18