| Message ID | CAKYApDDeMtGm8jUCJVNXzj6owZPPKKcQboCMdMS_kTzOzWXOQg@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
@subject: It's a bit long, and it's missing a prefix telling what this patch is about. I would have probably used "block/vdi: Use bdrv_flush after metadata updates" or something like that. On 01.05.2015 17:03, phoeagon wrote: > Looks like VDI is the only writable image format that does not use > write-with-barrier(sync) when updating the metadata. A sequence of > commits b0ad5a455d~078a458e077d6b0db2 fixes this for > QCOW/COW/QCOW2/VPC/VMDK, but the VDI does not issue a barrier by sync > after updating the metadata. > > This commit adds a `bdrv_flush` after updating block map. > > > Signed-off-by: Zhe Qiu <address@hidden> Hm, this doesn't look quite right. :-) > --------------- These should be only "---", I guess, so the block below is omitted from the commit message. > From 2ea36d9a0e676b534483dc54c191f421f9889dc6 Mon Sep 17 00:00:00 2001 > From: phoeagon <address@hidden> > Date: Fri, 1 May 2015 19:00:22 +0800 > Subject: [PATCH] use bdrv_flush to provide barrier semantic in block/vdi.c > > In reference to > b0ad5a455d7e5352d4c86ba945112011dbeadfb8~078a458e077d6b0db262c4b05fee51d01de2d1d2, > metadata writes to qcow2/cow/qcow/vpc/vmdk are all synced prior to > succeeding writes. > --- > block/vdi.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/vdi.c b/block/vdi.c > index 7642ef3..5d09b36 100644 > --- a/block/vdi.c > +++ b/block/vdi.c > @@ -713,6 +713,7 @@ static int vdi_co_write(BlockDriverState *bs, > logout("will write %u block map sectors starting from entry > %u\n", > n_sectors, bmap_first); > ret = bdrv_write(bs->file, offset, base, n_sectors); > + ret = bdrv_flush(bs->file); This overwrites the return value from bdrv_write(), which I don't think is right. We could either ignore bdrv_flush()'s return value, or make it something like "if (ret < 0) { bdrv_flush(bs->file); } else { ret = bdrv_flush(bs->file); }" or "ret_flush = bdrv_flush(bs->file); if (!(ret < 0)) { ret = ret_flush; }". Or skip the flush in case bdrv_write() failed ("if (ret < 0) { return ret; } ret = bdrv_flush(bs->file);"), like bdrv_pwrite_sync() does. The idea of the change (adding the flush) looks good, though. Max > } > return ret; > -- > 2.3.7 >
diff --git a/block/vdi.c b/block/vdi.c index 7642ef3..5d09b36 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -713,6 +713,7 @@ static int vdi_co_write(BlockDriverState *bs, logout("will write %u block map sectors starting from entry %u\n", n_sectors, bmap_first); ret = bdrv_write(bs->file, offset, base, n_sectors); + ret = bdrv_flush(bs->file); } return ret;