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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>
This commit is contained in:
Paolo Bonzini 2012-06-06 00:04:49 +02:00 committed by Kevin Wolf
parent 0fd05e8dd1
commit f05fa4ad03
1 changed files with 9 additions and 2 deletions
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11
block.c
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@ -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);
}