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Thu, 2 Jul 2020 09:30:22 +0000 (UTC) Date: Thu, 2 Jul 2020 10:30:19 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Subject: Re: [PATCH 2/3] util: support detailed error reporting for qemu_open Message-ID: <20200702093019.GE1888119@redhat.com> References: <20200701160509.1523847-1-berrange@redhat.com> <20200701160509.1523847-3-berrange@redhat.com> <87a70i7b4r.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87a70i7b4r.fsf@dusky.pond.sub.org> User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/02 04:18:28 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , Stefan Hajnoczi , P J P Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jul 02, 2020 at 07:13:08AM +0200, Markus Armbruster wrote: > Daniel P. Berrangé writes: > > > Create a "qemu_open_err" method which does the same as "qemu_open", > > but with a "Error **errp" for error reporting. There should be no > > behavioural difference for existing callers at this stage. > > > > Signed-off-by: Daniel P. Berrangé > > --- > > include/qemu/osdep.h | 1 + > > util/osdep.c | 71 +++++++++++++++++++++++++++++++++++--------- > > 2 files changed, 58 insertions(+), 14 deletions(-) > > > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > > index 0d26a1b9bd..e41701a308 100644 > > --- a/include/qemu/osdep.h > > +++ b/include/qemu/osdep.h > > @@ -483,6 +483,7 @@ int qemu_madvise(void *addr, size_t len, int advice); > > int qemu_mprotect_rwx(void *addr, size_t size); > > int qemu_mprotect_none(void *addr, size_t size); > > > > +int qemu_open_err(const char *name, int flags, Error **errp, ...); > > int qemu_open(const char *name, int flags, ...); > > int qemu_close(int fd); > > int qemu_unlink(const char *name); > > diff --git a/util/osdep.c b/util/osdep.c > > index 4bdbe81cec..450b3a5da3 100644 > > --- a/util/osdep.c > > +++ b/util/osdep.c > > @@ -22,6 +22,7 @@ > > * THE SOFTWARE. > > */ > > #include "qemu/osdep.h" > > +#include "qapi/error.h" > > > > /* Needed early for CONFIG_BSD etc. */ > > > > @@ -282,7 +283,7 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive) > > /* > > * Opens a file with FD_CLOEXEC set > > */ > > -int qemu_open(const char *name, int flags, ...) > > +static int qemu_openv(const char *name, int flags, Error **errp, va_list ap) > > { > > int ret; > > int mode = 0; > > @@ -297,24 +298,31 @@ int qemu_open(const char *name, int flags, ...) > > > > fdset_id = qemu_parse_fdset(fdset_id_str); > > if (fdset_id == -1) { > > + error_setg(errp, "Unable to parse fdset %s", name); > > errno = EINVAL; > > return -1; > > } > > > > fd = monitor_fdset_get_fd(fdset_id, flags); > > if (fd < 0) { > > + error_setg_errno(errp, -fd, "Unable acquire FD for %s flags %x", > > + name, flags); > > errno = -fd; > > return -1; > > } > > > > dupfd = qemu_dup_flags(fd, flags); > > if (dupfd == -1) { > > + error_setg_errno(errp, errno, "Unable dup FD for %s flags %x", > > + name, flags); > > return -1; > > } > > > > ret = monitor_fdset_dup_fd_add(fdset_id, dupfd); > > if (ret == -1) { > > close(dupfd); > > + error_setg(errp, "Unable save FD for %s flags %x", > > + name, flags); > > errno = EINVAL; > > return -1; > > } > > @@ -324,11 +332,7 @@ int qemu_open(const char *name, int flags, ...) > > #endif > > > > if (flags & O_CREAT) { > > - va_list ap; > > - > > - va_start(ap, flags); > > mode = va_arg(ap, int); > > - va_end(ap); > > } > > > > #ifdef O_CLOEXEC > > @@ -340,25 +344,64 @@ int qemu_open(const char *name, int flags, ...) > > } > > #endif > > > > + if (ret == -1) { > > + const char *action = "open"; > > + if (flags & O_CREAT) { > > + action = "create"; > > + } > > #ifdef O_DIRECT > > - if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) { > > - int newflags = flags & ~O_DIRECT; > > + if (errno == EINVAL && (flags & O_DIRECT)) { > > + int newflags = flags & ~O_DIRECT; > > # ifdef O_CLOEXEC > > - ret = open(name, newflags | O_CLOEXEC, mode); > > + ret = open(name, newflags | O_CLOEXEC, mode); > > # else > > - ret = open(name, newflags, mode); > > + ret = open(name, newflags, mode); > > # endif > > - if (ret != -1) { > > - close(ret); > > - error_report("file system does not support O_DIRECT"); > > - errno = EINVAL; > > + if (ret != -1) { > > + close(ret); > > + error_setg(errp, "Unable to %s '%s' flags 0x%x: " > > + "filesystem does not support O_DIRECT", > > + action, name, flags); > > + if (!errp) { > > If the caller ignores errors, ... > > > + error_report("file system does not support O_DIRECT"); > > ... we report this error to stderr (but not any of the other ones). > This is weird. I figure you do it here to reproduce the weirdness of > qemu_open() before the patch. Goes back to > > commit a5813077aac7865f69b7ee46a594f3705429f7cd > Author: Stefan Hajnoczi > Date: Thu Aug 22 11:29:03 2013 +0200 > > osdep: warn if open(O_DIRECT) on fails with EINVAL > > Print a warning when opening a file O_DIRECT fails with EINVAL. This > saves users a lot of time trying to figure out the EINVAL error, which > is typical when attempting to open a file O_DIRECT on Linux tmpfs. > > Reported-by: Deepak C Shetty > Signed-off-by: Stefan Hajnoczi > Reviewed-by: Eric Blake > > The message isn't phrased as a warning, though. Should it use > warn_report()? Stefan? I was really in two minds as to whether to keep this error_report or not. It depends depends on whether any other callers of qemu_open still need it. In fact if nothing outside the block layer uses O_DIRECT then I think we can remove the error_report line. > > +int qemu_open_err(const char *name, int flags, Error **errp, ...) > > +{ > > + va_list ap; > > + int rv; > > + > > + va_start(ap, errp); > > + rv = qemu_openv(name, flags, errp, ap); > > + va_end(ap); > > + > > + return rv; > > +} > > + > > +int qemu_open(const char *name, int flags, ...) > > +{ > > + va_list ap; > > + int rv; > > + > > + va_start(ap, flags); > > + rv = qemu_openv(name, flags, NULL, ap); > > + va_end(ap); > > + > > + return rv; > > +} > > I'd rename this to qemu_open_with_bad_error_messages(). My goal was to avoid a big bang conversion of all callers. > > For better ones, callers can use > > if (qemu_open_err(name, flags, &err) < 0) { > error_report_err(err); > ... > } > > or, where the error is fatal > > qemu_open_err(name, flags, &error_fatal); > > If you prefer not to rename it now, please add a comment why it should > not be used in new code, and existing uses should be converted. > > If you rename, call the new one qemu_open(). Maybe it is better to rename upfront though, instead of waiting till everything uses the qemu_open_err and then renaming back to qemu_open. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|