path: root/glusterfsd
diff options
authorCsaba Henk <>2012-05-14 17:07:28 +0530
committerAnand Avati <>2012-05-21 13:47:09 -0700
commit439d0426dd60ef6c1f4af13fcbbe73f1d206acc6 (patch)
treeab9b7637bd223bf7862e2861dd562faa541687eb /glusterfsd
parenta2b7f11f279b9acc74c1a3b6d893fda7c160683d (diff)
fuse, glusterfsd: mount logic fixes
Commit 7d0397c2 introduced two issues: i) broke the libfuse derived mount logic (details below) ii) in case of a daemonized glusterfs client is ran as daemon, parent process can return earlier than the mount is in place, which breaks agents that programmatically do a gluster mount via a direct call to glusterfs (ie. not via mount(8)). This patch fixes these issues by a refactor that merges the approaches sported by commits 7d0397c2 fuse: allow requests during mount (needed for SELinux labels) c5d781e0 upon daemonizing, wait on mtab update to terminate in parent Original daemonized libfuse event flow is as follows: try: fd = open("/dev/fuse") mount("-oopts,fd=%s" % fd ...) mount(8) -f # manipulate mtab except: sp = socketpair() env _FUSE_COMMFD=sp fusermount -oopts fd = receive_fd(sp) where fusermount(1) does: fd = open("/dev/fuse") mount("-oopts,fd=%d" % fd ...) sp = atoi(getenv("_FUSE_COMMFD")) send_fd(sp, fd) daemonize( # in child fuse_loop(fd) ) # in parent exit() As of 013850c9 (instead of adopting FUSE's 47e61004¹), we went for async mtab manipulation, and as of c5d781e0, still wanted keep that in sync with termination of daemon parent, so we changed it to: try: fd = open("/dev/fuse") mount("-oopts,fd=%s" % fd ...) pid = fork( # in child mount(8) -f ) except: sp = socketpair() env _FUSE_COMMFD=sp fusermount -oopts fd = receive_fd(sp) daemonize( fuse_loop(fd) ) waitpid(pid) exit() (Note the new approch came only to direct [privileged] mount, so fusermount based mounting was already partially broken.) As of 7d0397c2, with the purpose of facilitating async mount, the event flow was practically reduced to: fd = open("/dev/fuse") fork( mount("-oopts,fd=%s" % fd ...) fork( mount(8) -n ) ) daemonize( fuse_loop(fd) ) exit() Thus fusermount based mounting become defunct; however, the dead code was still kept around. So, we should either drop it or fix it. Also, the mtab manipulator is forked into yet another child with no purpose, while syncing with it in daemon parent is broken. mount(2) is neither synced with parent. Now we are coming to the following scheme: fd = open("/dev/fuse") pid = fork( try: mount("-oopts,fd=%s" % fd ...) mount(8) -n except: env _FUSE_DEVFD=fd fusermount -oopts ) where fusermount(1) does: fd = getenv("_FUSE_DEVFD") mount("-oopts,fd=%s" % fd ...) daemonize( fuse_loop(fd) ) waitpid(pid) exit() Nb.: - We can't help losing compatibility with upstream fusermount, as it sends back the fd only when mount(2) is completed, thus defeating the async mount approach. The 'getenv("_FUSE_DEVFD")' mechanism is specfic to glusterfs' fusermount (at the moment -- sure we can talk about it with upstream) - fusermount opens /dev/fuse at same privilege level as of original process², so we can bravely go on with doing the open unconditionally in original process - Original mounting code actually tries to mount through fusermount _twice_: if first attempt fails, then, assuming subtype support is missing in kernel, it tries again subtype stripped. However, this is redundant, as fusermount internally also performs the subtype check³. Therefore we simplified the logic to have just a single fusermount call. - we revert the changes to mount.glusterfs as of 7d0397c2, as now there is no issue with glusterfs to work around in that scope ¹;a=blobdiff;f=ChangeLog;h=47e61004;hb=4c3d9b19;hpb=e61b775a ²;a=blob;f=util/fusermount.c;h=b2e87d95#l1023 ³;a=blob;f=util/fusermount.c;h=b2e87d95#l839 Change-Id: I0c4ab70e0c5ad7b27337228749b266bcd0ba941d BUG: 811217 Signed-off-by: Csaba Henk <> Reviewed-on: Tested-by: Gluster Build System <> Reviewed-by: Jeff Darcy <> Reviewed-by: Anand Avati <>
Diffstat (limited to 'glusterfsd')
1 files changed, 5 insertions, 5 deletions
diff --git a/glusterfsd/src/glusterfsd.c b/glusterfsd/src/glusterfsd.c
index 8fbbb2f..903eac7 100644
--- a/glusterfsd/src/glusterfsd.c
+++ b/glusterfsd/src/glusterfsd.c
@@ -386,7 +386,7 @@ create_fuse_mount (glusterfs_ctx_t *ctx)
if (!cmd_args->no_daemon_mode) {
- ret = dict_set_static_ptr (master->options, "sync-mtab",
+ ret = dict_set_static_ptr (master->options, "sync-to-mount",
if (ret < 0) {
gf_log ("glusterfsd", GF_LOG_ERROR,
@@ -1502,11 +1502,11 @@ daemonize (glusterfs_ctx_t *ctx)
case 0:
- if (ctx->mtab_pid > 0) {
- ret = waitpid (ctx->mtab_pid, &cstatus, 0);
- if (!(ret == ctx->mtab_pid && cstatus == 0)) {
+ if (ctx->mnt_pid > 0) {
+ ret = waitpid (ctx->mnt_pid, &cstatus, 0);
+ if (!(ret == ctx->mnt_pid && cstatus == 0)) {
gf_log ("daemonize", GF_LOG_ERROR,
- "/etc/mtab update failed");
+ "mount failed");
exit (1);