Mounting a FUSE file system remotely using SSH in combination with
pseudo-terminal allocation (-t), results in "Transport endpoint is
not connected" errors when trying to access the file system contents.
For example:
# ssh -t root@localhost "cmsfs-fuse /dev/disk/by-path/ccw-0.0.0190 /CMSFS"
Connection to localhost closed.
# ls /CMSFS
ls: cannot access '/CMSFS': Transport endpoint is not connected
The cmsfs-fuse main program (which can also be any other FUSE file
system) calls into the fuse_main() libfuse library function.
The fuse_main() function later calls fuse_daemonize() to fork the
daemon process to handle the FUSE file system I/O.
The fuse_daemonize() function calls fork() as usual. The child
proceeds with setsid() and then redirecting its file descriptors
to /dev/null etc. The parent process, simply exits.
The child's functions and the parent's exit creates a subtle race.
This is seen with an SSH connection. The SSH command above calls
cmsfs-fuse on an allocated pseudo-terminal device (-t option).
If the parent exits, SSH receives the command completion and closes
the connection, that means, it closes the master side of the
pseudo-terminal. This causes a HUP signal being sent to the process
group on the pseudo-terminal. At this point in time, the child might
not have completed the setsid() call and, hence, becomes terminated.
Note that fuse daemon sets up its signal handlers after fuse_daemonize()
has completed.
Even if the child has the chance to disassociate from its parent process
group to become it's own process group with setsid(), the child still
has the pseudo-terminal opened as stdin, stdout, and stderr. So the
pseudo-terminal still behave as controlling terminal and might cause a
SIGHUP at closing the the master side.
To solve the problem, the parent has to wait until the child (the fuse
daemon process) has completed its processing, that means, has become
its own process group with setsid() and closed any file descriptors
pointing to the pseudo-terminal.
Closes: #27
Reported-by: Ofer Baruch <oferba@il.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Mount can be used with an "-o context=" option in order to specify a
mountpoint-wide SELinux security context different from the default context
provided by the active SELinux policy.
This is useful in order to enable users to mount multiple sshfs targets under
distinct contexts, which is my main motivation for getting this patch mainlined.
Closes: #36
- fuse_kern_unmount closes handle (e.g. 19)
- a thread in my process opens a file - the OS assigns newly freed
handle (i.e. 19)
- fuse_kern_chan_destroy closes the same handle (i.e. 19)
- a thread in my process opens another file - the OS assigns newly
freed handle (i.e. 19)
- * MAYHEM *
Reported by Dan Greenfield
The lru list was not initialized for the "/" path. This resulted in
remove_node_lru() crashing on LOOKUP-DOTDOT.
Patch by Madan Valluri.
--
ChangeLog | 4 ++++
lib/fuse.c | 4 ++++
2 files changed, 8 insertions(+)
Patch by Ratna Manoj.
queue_element_unlock() should set ->first_locked and ->second_locked to false.
Discovered with 'fs_racer'. The assert(wnode->treelock == TREELOCK_WRITE) in
unlock_path() was hit within minutes.
Miklos: simplified patch
Due to an oversight, splice will never actually be used for i/o. Someone forgot
to #include "config.h" in lib/buffer.c (in fact almost no files include that
header). As a result, even though configure detects splice support and puts
HAVE_SPLICE in config.h, buffer.c is always compiled as if there is no splice
support.
Also add #include "config.h" to fuse.c and fuse_lowlevel.c. These currently
include it indirectly through fuse_misc.h, but we don't want to depend on that.
Reported by Matthew Gabeler-Lee
Commit 4dc7e675bb (Don't unhash name in FORGET) broke the forget logic in a
subtle way, resulting in "fuse internal error: node NNN not found" and causing
the filesystem daemon to abort.
Fix by incrementing the node refcount if nlookup goes from zero to one.
Reported by Kyle Lippincott
The failure path of try_get_path2() erronously tried to free the "path1" value
(an address on the stack) instead of the allocated string pointed to by "path1".
This caused the library to crash.
Reported by Itay Perl
fallocate filesystem operation preallocates media space for the given file.
If fallocate returns success then any subsequent write to the given range
never fails with 'not enough space' error.
Linking to a library that uses threads requires the application to be linked
with -pthreads otherwise some pthread functions will be linked to stubs in
glibc. So move -pthread from Libs.private to Libs in fuse.pc.
Reported by Werner Fink
This partially reverts commit 4b2157c44e.
Remove mmap/munmap suppor as this missed the interface changes for Linux-3.3
(API version 7.18).
Only revert the mmap/munmap bits and leave the retrieve_reply API fix in place
as well as the optimization in fuse_send_data_iov_fallback().
This resulted in ENOENT being returned for unlinked but still open files if the
kernel sent a FORGET request for the parent directory.
Discovered with fs_racer in LTP.
Ville Silventoinen reported that fs_racer in LTP triggered a hang in
wait_on_path(). This bug was caused by try_get_path() not resetting "ticket" on
permanent failure.
libfuse part to allow a FUSE file-system to tell the kernel when a
file or directory is deleted. If the specified dentry has the
specified inode number, the kernel will unhash it.
Signed-off-by: John Muir <john@jmuir.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reply to request with ENOMEM in case of failure to allocate request
structure. Otherwise the task issuing the request will just freeze up
until the filesystem daemon is killed. Reported by Stephan Kulow
daemon() is a BSD-ism. Although it is available on many platforms
it is not a standard function. Some platforms (e.g. MacOSX) deprecated
it.
It is safer just to use fork() function that is a part of POSIX.
