Message ID | CAKYApDBpL9GiLf7A0E6sff1H6zUgEmE9-pF=mndZjJiBCUpfGQ@mail.gmail.com |
---|---|
State | New |
Headers | show |
On 05/06/2015 11:23 AM, phoeagon wrote: > Thanks for your input. > > So I changed it to: > 1. Only call bdrv_flush when bdrv_pwrite was successful > 2. Only if bdrv_flush was unsuccessful that the return value of > vdi_co_write is updated. > In this way we try to avoid messing up any potential return value checks > possible while still propagating bdrv_flush errors. > That return value was a catch and I admit I'm no pro with the return value > convention in QEMU. bdrv_pwrite doesn't return the same value as > bdrv_pwrite_sync I assume (they do return negative values when fail, but > different values when successful) > --- > The text above [1]... > > Signed-off-by: Zhe Qiu <address@hidden> This S-o-b is still broken. > >>From 19b2fabbe00765b418362d8c1891f266091621f3 Mon Sep 17 00:00:00 2001 When sending a revised patch, it's better to send it as a new top-level thread, and with 'v2' somewhere in the subject line (hint: git send-email -v2). Your placement of the Signed-off-by line before the From: attribution line is incorrect > From: phoeagon <address-hidden> > Date: Thu, 7 May 2015 01:09:38 +0800 > Subject: [PATCH] block/vdi: Use bdrv_flush after metadata updates > > In reference to > b0ad5a455d7e5352d4c86ba945112011dbeadfb8~078a458e077d6b0db262c4b05fee51d01de2d1d2, > metadata writes to qcow2/cow/qcow/vpc/vmdk are all synced prior to > succeeding writes. > > --- ...[1] is more useful here, after the commit message body. I highly suggest you read http://wiki.qemu.org/Contribute/SubmitAPatch; it is also a good idea to use 'git send-email' to send a patch to yourself, then 'git am' on that message to see if it survived the round trip through email, before sending to the list. > block/vdi.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/block/vdi.c b/block/vdi.c > index 5d09b36..54a5fa8 100644 > --- a/block/vdi.c > +++ b/block/vdi.c > @@ -713,7 +713,11 @@ 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); > + if (!(ret < 0)) { This looks odd. Better might be: 'if (ret >= 0) {' > + int flush_ret = bdrv_flush(bs->file); > + if (flush_ret < 0) > + ret = flush_ret; Missing {} (hint: scripts/checkpatch.pl is an important part of good patch submission) > + } > } > > return ret; >
CC-ing qemu-block and Stefan Weil (maintainer of vdi). On 06.05.2015 19:23, phoeagon wrote: > Thanks for your input. > > So I changed it to: > 1. Only call bdrv_flush when bdrv_pwrite was successful > 2. Only if bdrv_flush was unsuccessful that the return value of > vdi_co_write is updated. One of both is enough. Both are too much. :-) It is indeed correct, technically (because ret is 0 before the bdrv_write()), but it's too verbose. (See below) > In this way we try to avoid messing up any potential return value > checks possible while still propagating bdrv_flush errors. > That return value was a catch and I admit I'm no pro with the return > value convention in QEMU. bdrv_pwrite doesn't return the same value as > bdrv_pwrite_sync I assume (they do return negative values when fail, > but different values when successful) It doesn't really matter, I think. Returning any non-negative value from vdi_co_write() should be enough to signal success. > --- > > > Signed-off-by: Zhe Qiu <address@hidden> > > From 19b2fabbe00765b418362d8c1891f266091621f3 Mon Sep 17 00:00:00 2001 > From: phoeagon <address-hidden> > Date: Thu, 7 May 2015 01:09:38 +0800 > Subject: [PATCH] block/vdi: Use bdrv_flush after metadata updates > > In reference to > b0ad5a455d7e5352d4c86ba945112011dbeadfb8~078a458e077d6b0db262c4b05fee51d01de2d1d2, > metadata writes to qcow2/cow/qcow/vpc/vmdk are all synced prior to > succeeding writes. > > --- > block/vdi.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/block/vdi.c b/block/vdi.c > index 5d09b36..54a5fa8 100644 > --- a/block/vdi.c > +++ b/block/vdi.c > @@ -713,7 +713,11 @@ 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); > + if (!(ret < 0)) { > + int flush_ret = bdrv_flush(bs->file); > + if (flush_ret < 0) > + ret = flush_ret; > + } I think bdrv_write() always returns 0 on success. In any case, it's fine for vdi_co_write() to return 0 on success (which is what bdrv_flush() returns), so shorting these four lines to "ret = bdrv_flush(bs->file);" is enough. The patch is correct, though, so if you want to leave it as it is, all you need to do is bring it into proper form (http://wiki.qemu.org/Contribute/SubmitAPatch). The previous version was nearly right, except for the things I mentioned: The subject needs to start with the part of qemu the patch is targeting (in this case "block/vdi: " or simply "vdi: "), the Signed-off-by needs to contain your name (or any alias you desire) and your email address, and comments for the patch should be separated from the actual commit message by "---". Finally, for sending the next version, please change the "[PATCH]" in the subject to "[PATCH v3]" in order to indicate that it will be version 3 of this patch. Thanks! Max > } > return ret; > -- > 2.4.0
diff --git a/block/vdi.c b/block/vdi.c index 5d09b36..54a5fa8 100644 --- a/block/vdi.c +++ b/block/vdi.c @@ -713,7 +713,11 @@ 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); + if (!(ret < 0)) { + int flush_ret = bdrv_flush(bs->file); + if (flush_ret < 0) + ret = flush_ret; + } } return ret; --