| Message ID | 1334308672-18507-1-git-send-email-namei.unix@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 04/13/2012 05:17 PM, Liu Yuan wrote: > From: Liu Yuan <tailai.ly@taobao.com> > > The 'qemu-img convert -h' advertise that the default cache mode is > 'writeback', while in fact it is 'unsafe'. > > This patch 1) fix the help manual and 2) let bdrv_close() call bdrv_flush() > > 2) is needed because some backend storage doesn't have a self-flush > mechanism(for e.g., sheepdog), so we need to call bdrv_flush() to make > sure the image is really writen to the storage instead of hanging around > writeback cache forever. > Hi Kevin, Just a ping. Seems that this patch is not merged into your block tree yet. Thanks, Yuan
Am 13.04.2012 11:17, schrieb Liu Yuan: > From: Liu Yuan <tailai.ly@taobao.com> > > The 'qemu-img convert -h' advertise that the default cache mode is > 'writeback', while in fact it is 'unsafe'. > > This patch 1) fix the help manual and 2) let bdrv_close() call bdrv_flush() > > 2) is needed because some backend storage doesn't have a self-flush > mechanism(for e.g., sheepdog), so we need to call bdrv_flush() to make > sure the image is really writen to the storage instead of hanging around > writeback cache forever. > > Signed-off-by: Liu Yuan <tailai.ly@taobao.com> > --- > block.c | 1 + > qemu-img.c | 4 ++-- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index c0c90f0..1ee2bf0 100644 > --- a/block.c > +++ b/block.c > @@ -812,6 +812,7 @@ unlink_and_fail: > > void bdrv_close(BlockDriverState *bs) > { > + bdrv_flush(bs); > if (bs->drv) { > if (bs->job) { > block_job_cancel_sync(bs->job); > diff --git a/qemu-img.c b/qemu-img.c > index 6a61ca8..6e54db3 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -66,8 +66,8 @@ static void help(void) > " 'filename' is a disk image filename\n" > " 'fmt' is the disk image format. It is guessed automatically in most cases\n" > " 'cache' is the cache mode used to write the output disk image, the valid\n" > - " options are: 'none', 'writeback' (default), 'writethrough', 'directsync'\n" > - " and 'unsafe'\n" > + " options are: 'none', 'writeback', 'writethrough', 'directsync'\n" > + " and 'unsafe' (default)\n" > " 'size' is the disk image size in bytes. Optional suffixes\n" > " 'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)\n" > " and T (terabyte, 1024G) are supported. 'b' is ignored.\n" You can't say it like this, this would apply to all qemu subcommands. qemu-img only uses unsafe when it doesn't harm the integrity of the image, which is only the case for qemu-img convert. I think we need to say something like: options are: 'none', 'writeback' (default, except for convert), 'writethrough', 'directsync' and 'unsafe' (default for convert) Kevin
diff --git a/block.c b/block.c index c0c90f0..1ee2bf0 100644 --- a/block.c +++ b/block.c @@ -812,6 +812,7 @@ unlink_and_fail: void bdrv_close(BlockDriverState *bs) { + bdrv_flush(bs); if (bs->drv) { if (bs->job) { block_job_cancel_sync(bs->job); diff --git a/qemu-img.c b/qemu-img.c index 6a61ca8..6e54db3 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -66,8 +66,8 @@ static void help(void) " 'filename' is a disk image filename\n" " 'fmt' is the disk image format. It is guessed automatically in most cases\n" " 'cache' is the cache mode used to write the output disk image, the valid\n" - " options are: 'none', 'writeback' (default), 'writethrough', 'directsync'\n" - " and 'unsafe'\n" + " options are: 'none', 'writeback', 'writethrough', 'directsync'\n" + " and 'unsafe' (default)\n" " 'size' is the disk image size in bytes. Optional suffixes\n" " 'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)\n" " and T (terabyte, 1024G) are supported. 'b' is ignored.\n"