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bh=QFCv/dkVItlKNLeUqV+j8mABtIRLwYg9S19bowBNNFk=; b=WCFsngwuPG5A9c6tqlnfb1bUVe/8KJdAlPY01xdWqcsvpImY6/G3LLCVyLD4L0lhrRr55E 6OwloStKIBuOhbYozGkIIQ7zlN+KHHTqsQ+/nHHi2071Xg/T6/gV4S77MKu6NIwf3dteRO mORtwiKx5QVGKOGJ169bnUAc08b0pAA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-30-SDYd-8FTOBaBB2ZVTxXJoQ-1; Thu, 10 Dec 2020 10:59:46 -0500 X-MC-Unique: SDYd-8FTOBaBB2ZVTxXJoQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E2219805F0B; Thu, 10 Dec 2020 15:59:15 +0000 (UTC) Received: from redhat.com (ovpn-115-31.ams2.redhat.com [10.36.115.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 534AE5C559; Thu, 10 Dec 2020 15:59:13 +0000 (UTC) Date: Thu, 10 Dec 2020 15:59:10 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Li Feng Subject: Re: [PATCH v2] file-posix: detect the lock using the real file Message-ID: <20201210155910.GN24855@redhat.com> References: <1607432377-87084-1-git-send-email-fengli@smartx.com> <1607489688-37088-1-git-send-email-fengli@smartx.com> MIME-Version: 1.0 In-Reply-To: <1607489688-37088-1-git-send-email-fengli@smartx.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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 , lifeng1519@gmail.com, "open list:raw" , "open list:All patches CC here" , Max Reitz , kyle@smartx.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Dec 09, 2020 at 12:54:48PM +0800, Li Feng wrote: > This patch addresses this issue: > When accessing a volume on an NFS filesystem without supporting the file lock, > tools, like qemu-img, will complain "Failed to lock byte 100". > > In the original code, the qemu_has_ofd_lock will test the lock on the > "/dev/null" pseudo-file. Actually, the file.locking is per-drive property, > which depends on the underlay filesystem. > > In this patch, make the 'qemu_has_ofd_lock' with a filename be more > generic and reasonable. > > Signed-off-by: Li Feng > --- > v2: remove the refactoring. > --- > block/file-posix.c | 32 ++++++++++++++++++-------------- > include/qemu/osdep.h | 2 +- > tests/test-image-locking.c | 2 +- > util/osdep.c | 19 ++++++++++++------- > 4 files changed, 32 insertions(+), 23 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index 806764f7e3..03be1b188c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -595,7 +595,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, > switch (locking) { > case ON_OFF_AUTO_ON: > s->use_lock = true; > - if (!qemu_has_ofd_lock()) { > + if (!qemu_has_ofd_lock(filename)) { > warn_report("File lock requested but OFD locking syscall is " > "unavailable, falling back to POSIX file locks"); > error_printf("Due to the implementation, locks can be lost " > @@ -606,7 +606,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, > s->use_lock = false; > break; > case ON_OFF_AUTO_AUTO: > - s->use_lock = qemu_has_ofd_lock(); > + s->use_lock = qemu_has_ofd_lock(filename); > break; > default: > abort(); > @@ -2388,6 +2388,7 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp) > int fd; > uint64_t perm, shared; > int result = 0; > + bool use_lock; > > /* Validate options and set default values */ > assert(options->driver == BLOCKDEV_DRIVER_FILE); > @@ -2428,19 +2429,22 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp) > perm = BLK_PERM_WRITE | BLK_PERM_RESIZE; > shared = BLK_PERM_ALL & ~BLK_PERM_RESIZE; > > - /* Step one: Take locks */ > - result = raw_apply_lock_bytes(NULL, fd, perm, ~shared, false, errp); > - if (result < 0) { > - goto out_close; > - } > + use_lock = qemu_has_ofd_lock(file_opts->filename); > + if (use_lock) { > + /* Step one: Take locks */ > + result = raw_apply_lock_bytes(NULL, fd, perm, ~shared, false, errp); > + if (result < 0) { > + goto out_close; > + } > > - /* Step two: Check that nobody else has taken conflicting locks */ > - result = raw_check_lock_bytes(fd, perm, shared, errp); > - if (result < 0) { > - error_append_hint(errp, > - "Is another process using the image [%s]?\n", > - file_opts->filename); > - goto out_unlock; > + /* Step two: Check that nobody else has taken conflicting locks */ > + result = raw_check_lock_bytes(fd, perm, shared, errp); > + if (result < 0) { > + error_append_hint(errp, > + "Is another process using the image [%s]?\n", > + file_opts->filename); > + goto out_unlock; > + } > } > > /* Clear the file by truncating it to 0 */ > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index f9ec8c84e9..349adad465 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -512,7 +512,7 @@ int qemu_dup(int fd); > int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive); > int qemu_unlock_fd(int fd, int64_t start, int64_t len); > int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive); > -bool qemu_has_ofd_lock(void); > +bool qemu_has_ofd_lock(const char *filename); > #endif > > #if defined(__HAIKU__) && defined(__i386__) > diff --git a/tests/test-image-locking.c b/tests/test-image-locking.c > index ba057bd66c..3e80246081 100644 > --- a/tests/test-image-locking.c > +++ b/tests/test-image-locking.c > @@ -149,7 +149,7 @@ int main(int argc, char **argv) > > g_test_init(&argc, &argv, NULL); > > - if (qemu_has_ofd_lock()) { > + if (qemu_has_ofd_lock(NULL)) { > g_test_add_func("/image-locking/basic", test_image_locking_basic); > g_test_add_func("/image-locking/set-perm-abort", test_set_perm_abort); > } > diff --git a/util/osdep.c b/util/osdep.c > index 66d01b9160..20119aa9ae 100644 > --- a/util/osdep.c > +++ b/util/osdep.c > @@ -187,7 +187,7 @@ static int qemu_parse_fdset(const char *param) > return qemu_parse_fd(param); > } > > -static void qemu_probe_lock_ops(void) > +static void qemu_probe_lock_ops(const char *filename) > { > if (fcntl_op_setlk == -1) { > #ifdef F_OFD_SETLK > @@ -200,10 +200,15 @@ static void qemu_probe_lock_ops(void) > .l_type = F_WRLCK, > }; > > - fd = open("/dev/null", O_RDWR); > + if (filename) { > + fd = open(filename, O_RDWR); > + } else { > + fd = open("/dev/null", O_RDONLY); > + } > if (fd < 0) { > fprintf(stderr, > - "Failed to open /dev/null for OFD lock probing: %s\n", > + "Failed to open %s for OFD lock probing: %s\n", > + filename ? filename : "/dev/null", > strerror(errno)); > fcntl_op_setlk = F_SETLK; > fcntl_op_getlk = F_GETLK; This is still just as broken as v1, because it is setting a global variable fcntl_op_getlk, based on result of an operation whose result will vary depending on the filename parameter. If you want to test whether a filesystem supports fcntl locks in general, don't touch qemu_has_ofd_lock or qemu_probe_lock_ops methods at all. Those are just for probing regular fcntl vs OFD fcntl locks. > @@ -225,9 +230,9 @@ static void qemu_probe_lock_ops(void) > } > } > > -bool qemu_has_ofd_lock(void) > +bool qemu_has_ofd_lock(const char *filename) > { > - qemu_probe_lock_ops(); > + qemu_probe_lock_ops(filename); > #ifdef F_OFD_SETLK > return fcntl_op_setlk == F_OFD_SETLK; > #else > @@ -244,7 +249,7 @@ static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type) > .l_len = len, > .l_type = fl_type, > }; > - qemu_probe_lock_ops(); > + qemu_probe_lock_ops(NULL); > do { > ret = fcntl(fd, fcntl_op_setlk, &fl); > } while (ret == -1 && errno == EINTR); > @@ -270,7 +275,7 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive) > .l_len = len, > .l_type = exclusive ? F_WRLCK : F_RDLCK, > }; > - qemu_probe_lock_ops(); > + qemu_probe_lock_ops(NULL); > ret = fcntl(fd, fcntl_op_getlk, &fl); > if (ret == -1) { > return -errno; > -- > 2.24.3 > > 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 :|