| Message ID | 1370634755-18132-4-git-send-email-lcapitulino@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > --- > block.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 79ad33d..c78f152 100644 > --- a/block.c > +++ b/block.c > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > if (local_err != NULL) { > error_propagate(errp, local_err); > } else { > - error_set(errp, QERR_OPEN_FILE_FAILED, > - reopen_state->bs->filename); > + error_setg_file_open(errp, errno, reopen_state->bs->filename); s/errno/-ret/
On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > --- > block.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 79ad33d..c78f152 100644 > --- a/block.c > +++ b/block.c > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > if (local_err != NULL) { > error_propagate(errp, local_err); > } else { > - error_set(errp, QERR_OPEN_FILE_FAILED, > - reopen_state->bs->filename); > + error_setg_file_open(errp, errno, reopen_state->bs->filename); Looking closer, my suggestion was wrong too. I think QERR_OPEN_FILE_FAILED is simply the wrong error here. We don't know that the error occurred when trying to open a file. errno does not necessarily contain the error value! Stefan
On Mon, 10 Jun 2013 10:43:47 +0200 Stefan Hajnoczi <stefanha@gmail.com> wrote: > On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > --- > > block.c | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/block.c b/block.c > > index 79ad33d..c78f152 100644 > > --- a/block.c > > +++ b/block.c > > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > > if (local_err != NULL) { > > error_propagate(errp, local_err); > > } else { > > - error_set(errp, QERR_OPEN_FILE_FAILED, > > - reopen_state->bs->filename); > > + error_setg_file_open(errp, errno, reopen_state->bs->filename); > > Looking closer, my suggestion was wrong too. > > I think QERR_OPEN_FILE_FAILED is simply the wrong error here. We don't > know that the error occurred when trying to open a file. Right. > errno does not necessarily contain the error value! There are two ways to fix it (and they're not mutually exclusive): 1. We could review all bdrv_reopen_prepare() methods and make sure they set errno on failure 2. We set errno=0 before calling the bdrv_reopen_prepare() method and if there's an error and if errno != 0 we use it, otherwise we set a generic "failed to prepare to reopen image" error Option 1 goes a bit beyond the time I'd like to spent on this series. Option 2 is quite reasonable. What do you think?
Am 10.06.2013 um 15:21 hat Luiz Capitulino geschrieben: > On Mon, 10 Jun 2013 10:43:47 +0200 > Stefan Hajnoczi <stefanha@gmail.com> wrote: > > > On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > > --- > > > block.c | 3 +-- > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > diff --git a/block.c b/block.c > > > index 79ad33d..c78f152 100644 > > > --- a/block.c > > > +++ b/block.c > > > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > > > if (local_err != NULL) { > > > error_propagate(errp, local_err); > > > } else { > > > - error_set(errp, QERR_OPEN_FILE_FAILED, > > > - reopen_state->bs->filename); > > > + error_setg_file_open(errp, errno, reopen_state->bs->filename); > > > > Looking closer, my suggestion was wrong too. > > > > I think QERR_OPEN_FILE_FAILED is simply the wrong error here. We don't > > know that the error occurred when trying to open a file. > > Right. > > > errno does not necessarily contain the error value! > > There are two ways to fix it (and they're not mutually exclusive): > > 1. We could review all bdrv_reopen_prepare() methods and make sure they > set errno on failure > > 2. We set errno=0 before calling the bdrv_reopen_prepare() method and if > there's an error and if errno != 0 we use it, otherwise we set a generic > "failed to prepare to reopen image" error > > Option 1 goes a bit beyond the time I'd like to spent on this series. > Option 2 is quite reasonable. > > What do you think? errno is definitely not reliable here and won't be. You must use -ret if you want a meaningful error message. I think Stefan's point was more that "Could not open" might not be the right message for a reopen, so we'd have to use error_setg_errno() directly with a different message here, like "Could not prepare reopen for '%s'". The _real_ solution, of course, is to make bdrv_prepare_reopen() a void function and always set errp when something goes wrong. Kevin
On Mon, 10 Jun 2013 15:54:10 +0200 Kevin Wolf <kwolf@redhat.com> wrote: > Am 10.06.2013 um 15:21 hat Luiz Capitulino geschrieben: > > On Mon, 10 Jun 2013 10:43:47 +0200 > > Stefan Hajnoczi <stefanha@gmail.com> wrote: > > > > > On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > > > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > > > --- > > > > block.c | 3 +-- > > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > > > diff --git a/block.c b/block.c > > > > index 79ad33d..c78f152 100644 > > > > --- a/block.c > > > > +++ b/block.c > > > > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > > > > if (local_err != NULL) { > > > > error_propagate(errp, local_err); > > > > } else { > > > > - error_set(errp, QERR_OPEN_FILE_FAILED, > > > > - reopen_state->bs->filename); > > > > + error_setg_file_open(errp, errno, reopen_state->bs->filename); > > > > > > Looking closer, my suggestion was wrong too. > > > > > > I think QERR_OPEN_FILE_FAILED is simply the wrong error here. We don't > > > know that the error occurred when trying to open a file. > > > > Right. > > > > > errno does not necessarily contain the error value! > > > > There are two ways to fix it (and they're not mutually exclusive): > > > > 1. We could review all bdrv_reopen_prepare() methods and make sure they > > set errno on failure > > > > 2. We set errno=0 before calling the bdrv_reopen_prepare() method and if > > there's an error and if errno != 0 we use it, otherwise we set a generic > > "failed to prepare to reopen image" error > > > > Option 1 goes a bit beyond the time I'd like to spent on this series. > > Option 2 is quite reasonable. > > > > What do you think? > > errno is definitely not reliable here and won't be. You must use -ret if > you want a meaningful error message. > > I think Stefan's point was more that "Could not open" might not be the > right message for a reopen, so we'd have to use error_setg_errno() > directly with a different message here, like "Could not prepare reopen > for '%s'". Ok, but Stefan also said that -ret is not reliable. And after quickly checking the code I see he's right, as there are methods that return -1. I think the safest thing to do is to have a generic error message for for this now and in the future we should propagate errp or return -errno.
Am 10.06.2013 um 16:02 hat Luiz Capitulino geschrieben: > On Mon, 10 Jun 2013 15:54:10 +0200 > Kevin Wolf <kwolf@redhat.com> wrote: > > > Am 10.06.2013 um 15:21 hat Luiz Capitulino geschrieben: > > > On Mon, 10 Jun 2013 10:43:47 +0200 > > > Stefan Hajnoczi <stefanha@gmail.com> wrote: > > > > > > > On Fri, Jun 07, 2013 at 03:52:29PM -0400, Luiz Capitulino wrote: > > > > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > > > > --- > > > > > block.c | 3 +-- > > > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > > > > > diff --git a/block.c b/block.c > > > > > index 79ad33d..c78f152 100644 > > > > > --- a/block.c > > > > > +++ b/block.c > > > > > @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, > > > > > if (local_err != NULL) { > > > > > error_propagate(errp, local_err); > > > > > } else { > > > > > - error_set(errp, QERR_OPEN_FILE_FAILED, > > > > > - reopen_state->bs->filename); > > > > > + error_setg_file_open(errp, errno, reopen_state->bs->filename); > > > > > > > > Looking closer, my suggestion was wrong too. > > > > > > > > I think QERR_OPEN_FILE_FAILED is simply the wrong error here. We don't > > > > know that the error occurred when trying to open a file. > > > > > > Right. > > > > > > > errno does not necessarily contain the error value! > > > > > > There are two ways to fix it (and they're not mutually exclusive): > > > > > > 1. We could review all bdrv_reopen_prepare() methods and make sure they > > > set errno on failure > > > > > > 2. We set errno=0 before calling the bdrv_reopen_prepare() method and if > > > there's an error and if errno != 0 we use it, otherwise we set a generic > > > "failed to prepare to reopen image" error > > > > > > Option 1 goes a bit beyond the time I'd like to spent on this series. > > > Option 2 is quite reasonable. > > > > > > What do you think? > > > > errno is definitely not reliable here and won't be. You must use -ret if > > you want a meaningful error message. > > > > I think Stefan's point was more that "Could not open" might not be the > > right message for a reopen, so we'd have to use error_setg_errno() > > directly with a different message here, like "Could not prepare reopen > > for '%s'". > > Ok, but Stefan also said that -ret is not reliable. And after quickly > checking the code I see he's right, as there are methods that return -1. > > I think the safest thing to do is to have a generic error message for > for this now and in the future we should propagate errp or return -errno. Ah, yes. I agree, let's make it error_setg() without errno for now. Kevin
diff --git a/block.c b/block.c index 79ad33d..c78f152 100644 --- a/block.c +++ b/block.c @@ -1291,8 +1291,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, if (local_err != NULL) { error_propagate(errp, local_err); } else { - error_set(errp, QERR_OPEN_FILE_FAILED, - reopen_state->bs->filename); + error_setg_file_open(errp, errno, reopen_state->bs->filename); } goto error; }
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> --- block.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)