From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48345) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aqGog-0006bM-9T for qemu-devel@nongnu.org; Wed, 13 Apr 2016 05:10:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aqGof-0001oL-1l for qemu-devel@nongnu.org; Wed, 13 Apr 2016 05:10:30 -0400 From: Fam Zheng Date: Wed, 13 Apr 2016 17:09:54 +0800 Message-Id: <1460538604-12132-6-git-send-email-famz@redhat.com> In-Reply-To: <1460538604-12132-1-git-send-email-famz@redhat.com> References: <1460538604-12132-1-git-send-email-famz@redhat.com> Subject: [Qemu-devel] [PATCH for-2.7 05/15] raw-posix: Implement .bdrv_lockf List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Max Reitz , Jeff Cody , Markus Armbruster , Eric Blake , John Snow , qemu-block@nongnu.org, berrange@redhat.com, pbonzini@redhat.com, den@openvz.org Because virtlockd in libvirt already uses the fcntl lock on the image file, we have to workaround this by locking a digest-mapped temporary file. Signed-off-by: Fam Zheng --- block/raw-posix.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) diff --git a/block/raw-posix.c b/block/raw-posix.c index 906d5c9..277f20d 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -35,6 +35,7 @@ #include "raw-aio.h" #include "qapi/util.h" #include "qapi/qmp/qstring.h" +#include "glib.h" #if defined(__APPLE__) && (__MACH__) #include @@ -149,6 +150,9 @@ typedef struct BDRVRawState { bool discard_zeroes:1; bool has_fallocate; bool needs_alignment; + bool image_locked; + int lock_file_fd; + char *lock_file_name; } BDRVRawState; typedef struct BDRVRawReopenState { @@ -397,6 +401,87 @@ static void raw_attach_aio_context(BlockDriverState *bs, #endif } +static int raw_do_lockf(int fd, BdrvLockfCmd cmd) +{ + int ret; + struct flock fl = (struct flock) { + .l_start = 0, + .l_whence = SEEK_SET, + .l_len = 0, + }; + switch (cmd) { + case BDRV_LOCKF_RWLOCK: + fl.l_type = F_WRLCK; + break; + case BDRV_LOCKF_ROLOCK: + fl.l_type = F_RDLCK; + break; + case BDRV_LOCKF_UNLOCK: + fl.l_type = F_UNLCK; + break; + default: + abort(); + } + ret = fcntl(fd, F_SETLK, &fl); + return ret == -1 ? -errno : 0; +} + +static char *raw_get_lock_file_name(BlockDriverState *bs) +{ + GChecksum *cksm; + const char *digest; + char *lock_file = NULL; + char *fullpath = g_malloc(PATH_MAX); + + if (!realpath(bs->filename, fullpath)) { + pstrcpy(fullpath, PATH_MAX, bs->filename); + } + cksm = g_checksum_new(G_CHECKSUM_SHA1); + g_checksum_update(cksm, (const guchar *)fullpath, strlen(fullpath)); + g_free(fullpath); + digest = g_checksum_get_string(cksm); + if (digest) { + lock_file = g_strdup_printf("/var/tmp/.qemu-%s.lock", digest); + } + g_checksum_free(cksm); + return lock_file; +} + +static int raw_lockf(BlockDriverState *bs, BdrvLockfCmd cmd, Error **errp) +{ + + BDRVRawState *s = bs->opaque; + int ret; + + if ((cmd == BDRV_LOCKF_UNLOCK) == (!s->image_locked)) { + return 0; + } + if (s->lock_file_fd == -1) { + /* Create and open the lock file if necessary. */ + + assert(cmd != BDRV_LOCKF_UNLOCK); + + s->lock_file_name = raw_get_lock_file_name(bs); + + s->lock_file_fd = qemu_open(s->lock_file_name, O_RDWR | O_CREAT, 0644); + if (s->lock_file_fd == -1) { + error_setg_errno(errp, errno, "Failed to open file"); + ret = -EIO; + goto out; + } + } + + ret = raw_do_lockf(s->lock_file_fd, cmd); + if (ret) { + error_setg_errno(errp, errno, + "Failed to lock file: %s", s->lock_file_name); + } else { + s->image_locked = cmd != BDRV_LOCKF_UNLOCK; + } +out: + return ret; +} + #ifdef CONFIG_LINUX_AIO static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags) { @@ -585,6 +670,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags, int ret; s->type = FTYPE_FILE; + s->lock_file_fd = -1; ret = raw_open_common(bs, options, flags, 0, &local_err); if (local_err) { error_propagate(errp, local_err); @@ -1393,6 +1479,15 @@ static void raw_close(BlockDriverState *bs) raw_detach_aio_context(bs); + if (s->lock_file_fd != -1) { + qemu_close(s->lock_file_fd); + s->lock_file_fd = -1; + } + if (s->lock_file_name) { + unlink(s->lock_file_name); + g_free(s->lock_file_name); + s->lock_file_name = NULL; + } #ifdef CONFIG_LINUX_AIO if (s->use_aio) { laio_cleanup(s->aio_ctx); @@ -1960,6 +2055,8 @@ BlockDriver bdrv_file = { .bdrv_detach_aio_context = raw_detach_aio_context, .bdrv_attach_aio_context = raw_attach_aio_context, + .bdrv_lockf = raw_lockf, + .create_opts = &raw_create_opts, }; -- 2.8.0