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Tue, 08 Dec 2020 20:54:37 -0800 (PST) Received: from 64-217.abest.vip ([129.227.156.200]) by smtp.gmail.com with ESMTPSA id d4sm425850pjz.28.2020.12.08.20.54.34 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Dec 2020 20:54:36 -0800 (PST) From: Li Feng To: Kevin Wolf , Max Reitz , qemu-block@nongnu.org (open list:raw), qemu-devel@nongnu.org (open list:All patches CC here) Subject: [PATCH v2] file-posix: detect the lock using the real file Date: Wed, 9 Dec 2020 12:54:48 +0800 Message-Id: <1607489688-37088-1-git-send-email-fengli@smartx.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1607432377-87084-1-git-send-email-fengli@smartx.com> References: <1607432377-87084-1-git-send-email-fengli@smartx.com> Received-SPF: none client-ip=2607:f8b0:4864:20::441; envelope-from=fengli@smartx.com; helo=mail-pf1-x441.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=unavailable 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: , Cc: lifeng1519@gmail.com, Li Feng , kyle@smartx.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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; @@ -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;