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authorPaolo Bonzini <pbonzini@redhat.com>2012-06-06 00:04:49 +0200
committerKevin Wolf <kwolf@redhat.com>2012-06-15 14:03:43 +0200
commitf05fa4ad0327579e143b20062e9d45b3ca935e24 (patch)
treece14709853445287b07eb85c1be93ab790cb0c66 /block.c
parent0fd05e8dd1ee7ae143fba3d6bcc6abe3fbeaeb34 (diff)
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block: flush in writethrough mode after writes
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 <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/block.c b/block.c
index 85ef6af..7538112 100644
--- a/block.c
+++ b/block.c
@@ -1758,8 +1758,8 @@ 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);
}
@@ -1808,6 +1808,9 @@ 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);
}
@@ -1977,6 +1980,10 @@ 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);
}