[Qemu-devel] [PATCH] block/sheepdog: add error handling to sd_snapshot_delete()

[Qemu-devel] [PATCH] block/sheepdog: add error handling to sd_snapshot_delete()

[Takashi Menjo]

Errors have been ignored in some code paths in sd_snapshot_delete().
This patch adds error handling.

Signed-off-by: Takashi Menjo <menjo.takashi@lab.ntt.co.jp>
---
 block/sheepdog.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/sheepdog.c b/block/sheepdog.c
index a3aeae4..6492405 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -2565,6 +2565,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
     SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
 
     if (!remove_objects(s)) {
+        error_report("failed to discard snapshot inode");
         return -1;
     }
 
@@ -2588,6 +2589,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
     ret = find_vdi_name(s, s->name, snap_id, snap_tag, &vid, true,
                         &local_err);
     if (ret) {
+        error_report_err(local_err);
         return ret;
     }
 
@@ -2601,6 +2603,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
                  buf, &wlen, &rlen);
     closesocket(fd);
     if (ret) {
+        error_setg_errno(errp, -ret, "failed to delete %s", s->name);
         return ret;
     }
 
-- 
2.7.4.windows.1

Re: [Qemu-devel] [PATCH] block/sheepdog: add error handling to sd_snapshot_delete()

[Jeff Cody]

On Fri, Mar 18, 2016 at 05:54:38PM +0900, Takashi Menjo wrote:
> Errors have been ignored in some code paths in sd_snapshot_delete().
> This patch adds error handling.
> 
> Signed-off-by: Takashi Menjo <menjo.takashi@lab.ntt.co.jp>

Thank you for the patch!

> ---
>  block/sheepdog.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/block/sheepdog.c b/block/sheepdog.c
> index a3aeae4..6492405 100644
> --- a/block/sheepdog.c
> +++ b/block/sheepdog.c
> @@ -2565,6 +2565,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
>      SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
>  
>      if (!remove_objects(s)) {
> +        error_report("failed to discard snapshot inode");

We want to set errp, so that the error is picked up correctly.  It is
assumed in QEMU that if there is an Error object passed, that it is
sufficient to check it for error (as opposed to checking the return
value).

You can use error_setg() here to do this, e.g.:

       error_setg(errp, "failed to discard snapshot inode");

>          return -1;
>      }
>  
> @@ -2588,6 +2589,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
>      ret = find_vdi_name(s, s->name, snap_id, snap_tag, &vid, true,
>                          &local_err);
>      if (ret) {
> +        error_report_err(local_err);

To propagate the local_err value to errp, use error_propagate:

    error_propagate(errp, local_err);

>          return ret;
>      }


There is another hunk that is missing an error_propagate in
sd_snapshot_delete:

2594     fd = connect_to_sdog(s, &local_err);
2595     if (fd < 0) {
2596         error_report_err(local_err);
2597         return -1;
2598     }
2599

>  
> @@ -2601,6 +2603,7 @@ static int sd_snapshot_delete(BlockDriverState *bs,
>                   buf, &wlen, &rlen);
>      closesocket(fd);
>      if (ret) {
> +        error_setg_errno(errp, -ret, "failed to delete %s", s->name);
>          return ret;
>      }

We also need to set errp in the switch statement on rsp->result:

2607     switch (rsp->result) {

[...]

2612     default:
2613         error_report("%s, %s", sd_strerror(rsp->result), s->name);
2614         return -1;
2615     }

Re: [Qemu-devel] [PATCH] block/sheepdog: add error handling to sd_snapshot_delete()

[MENJO, Takashi]

Thank you for your review, Jeff!
I'll submit a patch v2 soon.

In addition, I found that we also need to set errp below.
This will be fixed in v2, too.
| 2607    switch (rsp->result) {
| 2608    case SD_RES_NO_VDI:
| 2609        error_report("%s was already deleted", s->name);


Takashi

> -----Original Message-----
> From: Jeff Cody [mailto:jcody@redhat.com]
> Sent: Saturday, March 19, 2016 1:17 AM
> To: Takashi Menjo <menjo.takashi@lab.ntt.co.jp>
> Cc: qemu-devel@nongnu.org; Hitoshi Mitake <mitake.hitoshi@lab.ntt.co.jp>;
> Vasiliy Tolstov <v.tolstov@selfip.ru>; sheepdog@lists.wpkg.org
> Subject: Re: [PATCH] block/sheepdog: add error handling to
> sd_snapshot_delete()
> 
> On Fri, Mar 18, 2016 at 05:54:38PM +0900, Takashi Menjo wrote:
> > Errors have been ignored in some code paths in sd_snapshot_delete().
> > This patch adds error handling.
> >
> > Signed-off-by: Takashi Menjo <menjo.takashi@lab.ntt.co.jp>
> 
> Thank you for the patch!
> 
> > ---
> >  block/sheepdog.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index a3aeae4..6492405 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -2565,6 +2565,7 @@ static int sd_snapshot_delete(BlockDriverState
*bs,
> >      SheepdogVdiRsp *rsp = (SheepdogVdiRsp *)&hdr;
> >
> >      if (!remove_objects(s)) {
> > +        error_report("failed to discard snapshot inode");
> 
> We want to set errp, so that the error is picked up correctly.  It is
> assumed in QEMU that if there is an Error object passed, that it is
> sufficient to check it for error (as opposed to checking the return
> value).
> 
> You can use error_setg() here to do this, e.g.:
> 
>        error_setg(errp, "failed to discard snapshot inode");
> 
> >          return -1;
> >      }
> >
> > @@ -2588,6 +2589,7 @@ static int sd_snapshot_delete(BlockDriverState
*bs,
> >      ret = find_vdi_name(s, s->name, snap_id, snap_tag, &vid, true,
> >                          &local_err);
> >      if (ret) {
> > +        error_report_err(local_err);
> 
> To propagate the local_err value to errp, use error_propagate:
> 
>     error_propagate(errp, local_err);
> 
> >          return ret;
> >      }
> 
> 
> There is another hunk that is missing an error_propagate in
> sd_snapshot_delete:
> 
> 2594     fd = connect_to_sdog(s, &local_err);
> 2595     if (fd < 0) {
> 2596         error_report_err(local_err);
> 2597         return -1;
> 2598     }
> 2599
> 
> >
> > @@ -2601,6 +2603,7 @@ static int sd_snapshot_delete(BlockDriverState
*bs,
> >                   buf, &wlen, &rlen);
> >      closesocket(fd);
> >      if (ret) {
> > +        error_setg_errno(errp, -ret, "failed to delete %s", s->name);
> >          return ret;
> >      }
> 
> We also need to set errp in the switch statement on rsp->result:
> 
> 2607     switch (rsp->result) {
> 
> [...]
> 
> 2612     default:
> 2613         error_report("%s, %s", sd_strerror(rsp->result), s->name);
> 2614         return -1;
> 2615     }
> 
> 
>