From 9faf31b68f049ca6432a1ef086a76344ff2a2357 Mon Sep 17 00:00:00 2001 From: Michael Tokarev Date: Mon, 16 Jan 2012 18:37:44 +0400 Subject: [PATCH 1/3] do not chdir(/) in qemu-nbd before opening all files When qemu-nbd becomes a daemon it calls daemon(3) with nochdir=0, so daemon(3) changes current directory to /. But at this time, qemu-nbd did not open any user-specified files yet, so by changing current directory, all non-absolute paths becomes wrong. The solution is to pass nochdir=1 to daemon(3) function, and to chdir("/") after all init has been performed, before entering the main loop, -- just like a good daemon should do. This patch is applicable for -stable. Signed-off-by: Michael Tokarev Signed-off-by: Paolo Bonzini --- qemu-nbd.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index eb61c33acd..e189cf86f4 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -429,7 +429,7 @@ int main(int argc, char **argv) pid = fork(); if (pid == 0) { close(stderr_fd[0]); - ret = qemu_daemon(0, 0); + ret = qemu_daemon(1, 0); /* Temporarily redirect stderr to the parent's pipe... */ dup2(stderr_fd[1], STDERR_FILENO); @@ -527,6 +527,12 @@ int main(int argc, char **argv) qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL, (void *)(uintptr_t)fd); + /* now when the initialization is (almost) complete, chdir("/") + * to free any busy filesystems */ + if (chdir("/") < 0) { + err(EXIT_FAILURE, "Could not chdir to root directory"); + } + do { main_loop_wait(false); } while (!sigterm_reported && (persistent || !nbd_started || nb_fds > 0)); From a6ac2313a83a6c3ed69c221ef8bed91676f078e9 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Tue, 6 Dec 2011 09:07:00 +0100 Subject: [PATCH 2/3] open /dev/nbd in nbd_client_thread Signed-off-by: Paolo Bonzini --- qemu-nbd.c | 34 ++++++++++++++++------------------ 1 file changed, 16 insertions(+), 18 deletions(-) diff --git a/qemu-nbd.c b/qemu-nbd.c index e189cf86f4..d4e70410fc 100644 --- a/qemu-nbd.c +++ b/qemu-nbd.c @@ -37,7 +37,6 @@ static NBDExport *exp; static int verbose; -static char *device; static char *srcpath; static char *sockpath; static bool sigterm_reported; @@ -178,6 +177,7 @@ static void termsig_handler(int signum) static void *show_parts(void *arg) { + char *device = arg; int nbd; /* linux just needs an open() to trigger @@ -194,11 +194,11 @@ static void *show_parts(void *arg) static void *nbd_client_thread(void *arg) { - int fd = *(int *)arg; + char *device = arg; off_t size; size_t blocksize; uint32_t nbdflags; - int sock; + int fd, sock; int ret; pthread_t show_parts_thread; @@ -213,13 +213,20 @@ static void *nbd_client_thread(void *arg) goto out; } + fd = open(device, O_RDWR); + if (fd == -1) { + /* Linux-only, we can use %m in printf. */ + fprintf(stderr, "Failed to open %s: %m", device); + goto out; + } + ret = nbd_init(fd, sock, nbdflags, size, blocksize); if (ret == -1) { goto out; } /* update partition table */ - pthread_create(&show_parts_thread, NULL, show_parts, NULL); + pthread_create(&show_parts_thread, NULL, show_parts, device); if (verbose) { fprintf(stderr, "NBD device %s is now connected to %s\n", @@ -273,6 +280,7 @@ int main(int argc, char **argv) uint32_t nbdflags = 0; bool disconnect = false; const char *bindto = "0.0.0.0"; + char *device = NULL; int port = NBD_DEFAULT_PORT; off_t fd_size; const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t"; @@ -466,19 +474,9 @@ int main(int argc, char **argv) } } - if (device) { - /* Open before spawning new threads. In the future, we may - * drop privileges after opening. - */ - fd = open(device, O_RDWR); - if (fd == -1) { - err(EXIT_FAILURE, "Failed to open %s", device); - } - - if (sockpath == NULL) { - sockpath = g_malloc(128); - snprintf(sockpath, 128, SOCKET_PATH, basename(device)); - } + if (device != NULL && sockpath == NULL) { + sockpath = g_malloc(128); + snprintf(sockpath, 128, SOCKET_PATH, basename(device)); } bdrv_init(); @@ -513,7 +511,7 @@ int main(int argc, char **argv) if (device) { int ret; - ret = pthread_create(&client_thread, NULL, nbd_client_thread, &fd); + ret = pthread_create(&client_thread, NULL, nbd_client_thread, device); if (ret != 0) { errx(EXIT_FAILURE, "Failed to create client thread: %s", strerror(ret)); From e5950790cb8c447867752faa62d8471d55298d58 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 18 Jan 2012 12:48:19 +0100 Subject: [PATCH 3/3] nbd: add git tree to MAINTAINERS Signed-off-by: Paolo Bonzini --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) diff --git a/MAINTAINERS b/MAINTAINERS index 173e893a62..6a9c981c4c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -510,6 +510,7 @@ S: Odd Fixes F: block/nbd.c F: nbd.* F: qemu-nbd.c +T: git://github.com/bonzini/qemu.git nbd-next SLIRP M: Jan Kiszka