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Date: Thu, 30 Apr 2015 16:45:40 +0200
From: Thomas Huth <thuth@redhat.com>
Message-ID: <20150430164540.2f4bcc6f@thh440s>
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Subject: Re: [Qemu-devel] [PATCH v3 1/2] qga/commands-posix: Fix bug in
 guest-fstrim
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To: Justin Ossevoort <justin@quarantainenet.nl>
Cc: qemu-stable@nongnu.org, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com

On Thu, 30 Apr 2015 16:29:57 +0200
Justin Ossevoort <justin@quarantainenet.nl> wrote:

> The FITRIM ioctl updates the fstrim_range structure it receives. This
> way the caller can determine how many bytes were trimmed. The
> guest-fstrim logic reuses the same fstrim_range for each filesystem,
> effectively limiting each filesystem to trim at most as much as the
> previous was able to trim.
> 
> If a previous filesystem would have trimmed 0 bytes, than the next
> filesystem would report an error 'Invalid argument' because a FITRIM
> request with length 0 is not valid.
> 
> This change resets the fstrim_range structure for each filesystem.
> 
> Signed-off-by: Justin Ossevoort <justin@quarantainenet.nl>
> ---
>  qga/commands-posix.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index ba8de62..4449628 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -1332,11 +1332,7 @@ void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
>      struct FsMount *mount;
>      int fd;
>      Error *local_err = NULL;
> -    struct fstrim_range r = {
> -        .start = 0,
> -        .len = -1,
> -        .minlen = has_minimum ? minimum : 0,
> -    };
> +    struct fstrim_range r;
>  
>      slog("guest-fstrim called");
>  
> @@ -1360,6 +1356,9 @@ void qmp_guest_fstrim(bool has_minimum, int64_t minimum, Error **errp)
>           * error means an unexpected error, so return it in those cases.  In
>           * some other cases ENOTTY will be reported (e.g. CD-ROMs).
>           */
> +        r.start = 0;
> +        r.len = -1;
> +        r.minlen = has_minimum ? minimum : 0;
>          ret = ioctl(fd, FITRIM, &r);
>          if (ret == -1) {
>              if (errno != ENOTTY && errno != EOPNOTSUPP) {

Reviewed-by: Thomas Huth <thuth@redhat.com>

(I've also put qemu-stable on cc: since I think that is a bug that
should be fixed in the stable branches, too).