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Re: [Qemu-devel] [PATCH for-2.11 v2] file-posix: Clear out first sector
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH for-2.11 v2] file-posix: Clear out first sector in hdev_create |
Date: |
Fri, 8 Sep 2017 17:44:08 +0800 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
On Thu, 09/07 17:07, Kevin Wolf wrote:
> > diff --git a/block/file-posix.c b/block/file-posix.c
> > index f4de022ae0..a63bbf2b90 100644
> > --- a/block/file-posix.c
> > +++ b/block/file-posix.c
> > @@ -2703,6 +2703,16 @@ static int hdev_create(const char *filename,
> > QemuOpts *opts,
> > ret = -ENOSPC;
> > }
>
> So the error paths above only set ret, but don't actually return or jump
> to the end of the function.
>
> > + if (total_size) {
> > + uint8_t buf[BDRV_SECTOR_SIZE] = { 0 };
> > + int64_t zero_size = MIN(BDRV_SECTOR_SIZE, total_size);
> > + if (lseek(fd, 0, SEEK_SET) == -1) {
> > + ret = -errno;
> > + } else {
> > + ret = qemu_write_full(fd, buf, zero_size);
> > + ret = ret == zero_size ? 0 : -errno;
>
> Which means that an error above (like a too small block device or using
> a regular file) can be overwritten with a success value if clearing the
> first sector works. That's probably not quite right.
You're right, will fix.
Fam