* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
mm: export generic_pipe_buf_*() to modules
fuse: support splice() reading from fuse device
fuse: allow splice to move pages
mm: export remove_from_page_cache() to modules
mm: export lru_cache_add_*() to modules
fuse: support splice() writing to fuse device
fuse: get page reference for readpages
fuse: use get_user_pages_fast()
fuse: remove unneeded variable
This adds:
alias: devname:<name>
to some common kernel modules, which will allow the on-demand loading
of the kernel module when the device node is accessed.
Ideally all these modules would be compiled-in, but distros seems too
much in love with their modularization that we need to cover the common
cases with this new facility. It will allow us to remove a bunch of pretty
useless init scripts and modprobes from init scripts.
The static device node aliases will be carried in the module itself. The
program depmod will extract this information to a file in the module directory:
$ cat /lib/modules/2.6.34-00650-g537b60d-dirty/modules.devname
# Device nodes to trigger on-demand module loading.
microcode cpu/microcode c10:184
fuse fuse c10:229
ppp_generic ppp c108:0
tun net/tun c10:200
dm_mod mapper/control c10:235
Udev will pick up the depmod created file on startup and create all the
static device nodes which the kernel modules specify, so that these modules
get automatically loaded when the device node is accessed:
$ /sbin/udevd --debug
...
static_dev_create_from_modules: mknod '/dev/cpu/microcode' c10:184
static_dev_create_from_modules: mknod '/dev/fuse' c10:229
static_dev_create_from_modules: mknod '/dev/ppp' c108:0
static_dev_create_from_modules: mknod '/dev/net/tun' c10:200
static_dev_create_from_modules: mknod '/dev/mapper/control' c10:235
udev_rules_apply_static_dev_perms: chmod '/dev/net/tun' 0666
udev_rules_apply_static_dev_perms: chmod '/dev/fuse' 0666
A few device nodes are switched to statically allocated numbers, to allow
the static nodes to work. This might also useful for systems which still run
a plain static /dev, which is completely unsafe to use with any dynamic minor
numbers.
Note:
The devname aliases must be limited to the *common* and *single*instance*
device nodes, like the misc devices, and never be used for conceptually limited
systems like the loop devices, which should rather get fixed properly and get a
control node for losetup to talk to, instead of creating a random number of
device nodes in advance, regardless if they are ever used.
This facility is to hide the mess distros are creating with too modualized
kernels, and just to hide that these modules are not compiled-in, and not to
paper-over broken concepts. Thanks! :)
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Cc: Ian Kent <raven@themaw.net>
Signed-Off-By: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Allow userspace filesystem implementation to use splice() to read from
the fuse device.
The userspace filesystem can now transfer data coming from a WRITE
request to an arbitrary file descriptor (regular file, block device or
socket) without having to go through a userspace buffer.
The semantics of using splice() to read messages are:
1) with a single splice() call move the whole message from the fuse
device to a temporary pipe
2) read the header from the pipe and determine the message type
3a) if message is a WRITE then splice data from pipe to destination
3b) else read rest of message to userspace buffer
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
When splicing buffers to the fuse device with SPLICE_F_MOVE, try to
move pages from the pipe buffer into the page cache. This allows
populating the fuse filesystem's cache without ever touching the page
contents, i.e. zero copy read capability.
The following steps are performed when trying to move a page into the
page cache:
- buf->ops->confirm() to make sure the new page is uptodate
- buf->ops->steal() to try to remove the new page from it's previous place
- remove_from_page_cache() on the old page
- add_to_page_cache_locked() on the new page
If any of the above steps fail (non fatally) then the code falls back
to copying the page. In particular ->steal() will fail if there are
external references (other than the page cache and the pipe buffer) to
the page.
Also since the remove_from_page_cache() + add_to_page_cache_locked()
are non-atomic it is possible that the page cache is repopulated in
between the two and add_to_page_cache_locked() will fail. This could
be fixed by creating a new atomic replace_page_cache_page() function.
fuse_readpages_end() needed to be reworked so it works even if
page->mapping is NULL for some or all pages which can happen if the
add_to_page_cache_locked() failed.
A number of sanity checks were added to make sure the stolen pages
don't have weird flags set, etc... These could be moved into generic
splice/steal code.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Allow userspace filesystem implementation to use splice() to write to
the fuse device. The semantics of using splice() are:
1) buffer the message header and data in a temporary pipe
2) with a *single* splice() call move the message from the temporary pipe
to the fuse device
The READ reply message has the most interesting use for this, since
now the data from an arbitrary file descriptor (which could be a
regular file, a block device or a socket) can be tranferred into the
fuse device without having to go through a userspace buffer. It will
also allow zero copy moving of pages.
One caveat is that the protocol on the fuse device requires the length
of the whole message to be written into the header. But the length of
the data transferred into the temporary pipe may not be known in
advance. The current library implementation works around this by
using vmplice to write the header and modifying the header after
splicing the data into the pipe (error handling omitted):
struct fuse_out_header out;
iov.iov_base = &out;
iov.iov_len = sizeof(struct fuse_out_header);
vmsplice(pip[1], &iov, 1, 0);
len = splice(input_fd, input_offset, pip[1], NULL, len, 0);
/* retrospectively modify the header: */
out.len = len + sizeof(struct fuse_out_header);
splice(pip[0], NULL, fuse_chan_fd(req->ch), NULL, out.len, flags);
This works since vmsplice only saves a pointer to the data, it does
not copy the data itself.
Since pipes are currently limited to 16 pages and messages need to be
spliced atomically, the length of the data is limited to 15 pages (or
60kB for 4k pages).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Replace uses of get_user_pages() with get_user_pages_fast(). It looks
nicer and should be faster in most cases.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
gcc 4.4 warns about:
fs/fuse/dev.c: In function ‘fuse_notify_inval_entry’:
fs/fuse/dev.c:925: warning: the frame size of 1060 bytes is larger than 1024 bytes
The problem is we declare two structures and a large array on the stack,
I move the array alway from the stack and allocate memory for it dynamically.
Signed-off-by: Fang Wenqi <antonf@turbolinux.com.cn>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: add fusectl interface to max_background
fuse: limit user-specified values of max background requests
fuse: use drop_nlink() instead of direct nlink manipulation
fuse: document protocol version negotiation
fuse: make the number of max background requests and congestion threshold tunable
This reverts commit 097041e576.
Trond had a better fix, which is the parent of this one ("Fix compile
error due to congestion_wait() changes")
Requested-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When building v2.6.31-rc2-344-g69ca06c, the following build errors are
found due to missing includes:
CC [M] fs/fuse/dev.o
fs/fuse/dev.c: In function ‘request_end’:
fs/fuse/dev.c:289: error: ‘BLK_RW_SYNC’ undeclared (first use in this function)
...
fs/nfs/write.c: In function ‘nfs_set_page_writeback’:
fs/nfs/write.c:207: error: ‘BLK_RW_ASYNC’ undeclared (first use in this function)
Signed-off-by: Larry Finger@lwfinger.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1faa16d228 accidentally broke
the bdi congestion wait queue logic, causing us to wait on congestion
for WRITE (== 1) when we really wanted BLK_RW_ASYNC (== 0) instead.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
The practical values for these limits depend on the design of the
filesystem server so let userspace set them at initialization time.
Signed-off-by: Csaba Henk <csaba@gluster.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Add notification messages that allow the filesystem to invalidate VFS
caches.
Two notifications are added:
1) inode invalidation
- invalidate cached attributes
- invalidate a range of pages in the page cache (this is optional)
2) dentry invalidation
- try to invalidate a subtree in the dentry cache
Care must be taken while accessing the 'struct super_block' for the
mount, as it can go away while an invalidation is in progress. To
prevent this, introduce a rw-semaphore, that is taken for read during
the invalidation and taken for write in the ->kill_sb callback.
Cc: Csaba Henk <csaba@gluster.com>
Cc: Anand Avati <avati@zresearch.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
On 64 bit systems -- where sizeof(ssize_t) > sizeof(int) -- the following test
exposes a bug due to a non-careful return of an int or unsigned value:
implement a FUSE filesystem which sends an unsolicited notification to
the kernel with invalid opcode. The respective write to /dev/fuse
will return (1 << 32) - EINVAL with errno == 0 instead of -1 with
errno == EINVAL.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
Update fuse_conn_init() such that it doesn't take @sb and move bdi
registration into a separate function. Also separate out
fuse_conn_kill() from fuse_put_super().
These will be used to implement cuse.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Move fuse_copy_finish() to before calling fuse_notify_poll_wakeup().
This is not a big issue because fuse_notify_poll_wakeup() should be
atomic, but it's cleaner this way, and later uses of notification will
need to be able to finish the copying before performing some actions.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
If a fuse filesystem is unmounted but the device file descriptor
remains open and a new mount reuses the old device number, then the
mount fails with EEXIST and the following warning is printed in the
kernel log:
WARNING: at fs/sysfs/dir.c:462 sysfs_add_one+0x35/0x3d()
sysfs: duplicate filename '0:15' can not be created
The cause is that the bdi belonging to the fuse filesystem was
destoryed only after the device file was released. Fix this by
calling bdi_destroy() from fuse_put_super() instead.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: clean up annotations of fc->lock
fuse: fix sparse warning in ioctl
fuse: update interface version
fuse: add fuse_conn->release()
fuse: separate out fuse_conn_init() from new_conn()
fuse: add fuse_ prefix to several functions
fuse: implement poll support
fuse: implement unsolicited notification
fuse: add file kernel handle
fuse: implement ioctl support
fuse: don't let fuse_req->end() put the base reference
fuse: move FUSE_MINOR to miscdevice.h
fuse: style fixes
Makes the existing annotations match the more common one per line style
and adds a few missing annotations.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Add fuse_ prefix to request_send*() and get_root_inode() as some of
those functions will be exported for CUSE. With or without CUSE
export, having the function names scoped is a good idea for
debuggability.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Implement poll support. Polled files are indexed using kh in a RB
tree rooted at fuse_conn->polled_files.
Client should send FUSE_NOTIFY_POLL notification once after processing
FUSE_POLL which has FUSE_POLL_SCHEDULE_NOTIFY set. Sending
notification unconditionally after the latest poll or everytime file
content might have changed is inefficient but won't cause malfunction.
fuse_file_poll() can sleep and requires patches from the following
thread which allows f_op->poll() to sleep.
http://thread.gmane.org/gmane.linux.kernel/726176
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Clients always used to write only in response to read requests. To
implement poll efficiently, clients should be able to issue
unsolicited notifications. This patch implements basic notification
support.
Zero fuse_out_header.unique is now accepted and considered unsolicited
notification and the error field contains notification code. This
patch doesn't implement any actual notification.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
fuse_req->end() was supposed to be put the base reference but there's
no reason why it should. It only makes things more complex. Move it
out of ->end() and make it the responsibility of request_end().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Wrap access to task credentials so that they can be separated more easily from
the task_struct during the introduction of COW creds.
Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id().
Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more
sense to use RCU directly rather than a convenient wrapper; these will be
addressed by later patches.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: fuse-devel@lists.sourceforge.net
Signed-off-by: James Morris <jmorris@namei.org>
As it is, all instances of ->release() for files that have ->fasync()
need to remember to evict file from fasync lists; forgetting that
creates a hole and we actually have a bunch that *does* forget.
So let's keep our lives simple - let __fput() check FASYNC in
file->f_flags and call ->fasync() there if it's been set. And lose that
crap in ->release() instances - leaving it there is still valid, but we
don't have to bother anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Quoting Linus (3 years ago, FUSE inclusion discussions):
"User-space filesystems are hard to get right. I'd claim that they
are almost impossible, unless you limit them somehow (shared
writable mappings are the nastiest part - if you don't have those,
you can reasonably limit your problems by limiting the number of
dirty pages you accept through normal "write()" calls)."
Instead of attempting the impossible, I've just waited for the dirty page
accounting infrastructure to materialize (thanks to Peter Zijlstra and
others). This nicely solved the biggest problem: limiting the number of pages
used for write caching.
Some small details remained, however, which this largish patch attempts to
address. It provides a page writeback implementation for fuse, which is
completely safe against VM related deadlocks. Performance may not be very
good for certain usage patterns, but generally it should be acceptable.
It has been tested extensively with fsx-linux and bash-shared-mapping.
Fuse page writeback design
--------------------------
fuse_writepage() allocates a new temporary page with GFP_NOFS|__GFP_HIGHMEM.
It copies the contents of the original page, and queues a WRITE request to the
userspace filesystem using this temp page.
The writeback is finished instantly from the MM's point of view: the page is
removed from the radix trees, and the PageDirty and PageWriteback flags are
cleared.
For the duration of the actual write, the NR_WRITEBACK_TEMP counter is
incremented. The per-bdi writeback count is not decremented until the actual
write completes.
On dirtying the page, fuse waits for a previous write to finish before
proceeding. This makes sure, there can only be one temporary page used at a
time for one cached page.
This approach is wasteful in both memory and CPU bandwidth, so why is this
complication needed?
The basic problem is that there can be no guarantee about the time in which
the userspace filesystem will complete a write. It may be buggy or even
malicious, and fail to complete WRITE requests. We don't want unrelated parts
of the system to grind to a halt in such cases.
Also a filesystem may need additional resources (particularly memory) to
complete a WRITE request. There's a great danger of a deadlock if that
allocation may wait for the writepage to finish.
Currently there are several cases where the kernel can block on page
writeback:
- allocation order is larger than PAGE_ALLOC_COSTLY_ORDER
- page migration
- throttle_vm_writeout (through NR_WRITEBACK)
- sync(2)
Of course in some cases (fsync, msync) we explicitly want to allow blocking.
So for these cases new code has to be added to fuse, since the VM is not
tracking writeback pages for us any more.
As an extra safetly measure, the maximum dirty ratio allocated to a single
fuse filesystem is set to 1% by default. This way one (or several) buggy or
malicious fuse filesystems cannot slow down the rest of the system by hogging
dirty memory.
With appropriate privileges, this limit can be raised through
'/sys/class/bdi/<bdi>/max_ratio'.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Libfuse basically creates a new thread for each new request. This is fine for
synchronous requests, which are naturally limited. However background
requests (especially writepage) can cause a thread creation storm.
To avoid this, limit the number of background requests available to userspace.
This is done by introducing another queue for background requests, and a
counter for the number of "active" requests, which are currently available for
userspace.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't return -ENOENT for a read() on the fuse device when the request was
aborted. Instead return -ENODEV, meaning the filesystem has been
force-umounted or aborted.
Previously ENOENT meant that the request was interrupted, but now the
'aborted' flag is not set in case of interrupts.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't set 'aborted' flag on a request if it's interrupted. We have to wait
for the answer anyway, and this would only a very little time while copying
the reply.
This means, that write() on the fuse device will not return -ENOENT during
normal operation, only if the filesystem is aborted by a forced umount or
through the fusectl interface.
This could simplify userspace code somewhat when backward compatibility with
earlier kernel versions is not required.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move dput/mntput pair from request_end() to fuse_release_end(), because
there's no other place they are used.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make lifetime of 'struct fuse_file' independent from 'struct file' by adding a
reference counter and destructor.
This will enable asynchronous page writeback, where it cannot be guaranteed,
that the file is not released while a request with this file handle is being
served.
The actual RELEASE request is only sent when there are no more references to
the fuse_file.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use wake_up_all instead of wake_up in put_reserved_req(), otherwise it is
possible that the right task is not woken up.
Also create a separate reserved_req_waitq in addition to the blocked_waitq,
since they fulfill totally separate functions.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Set the read and write congestion state if the request queue is close to
blocking, and clear it when it's not.
This prevents unnecessary blocking in readahead and (when writable mmaps are
allowed) writeback.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Slab destructors were no longer supported after Christoph's
c59def9f22 change. They've been
BUGs for both slab and slub, and slob never supported them
either.
This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Replace all uses of kmem_cache_t with struct kmem_cache.
The patch was generated using the following script:
#!/bin/sh
#
# Replace one string by another in all the kernel sources.
#
set -e
for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do
quilt add $file
sed -e "1,\$s/$1/$2/g" $file >/tmp/$$
mv /tmp/$$ $file
quilt refresh
done
The script was run like this
sh replace kmem_cache_t "struct kmem_cache"
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
SLAB_KERNEL is an alias of GFP_KERNEL.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch removes readv() and writev() methods and replaces them with
aio_read()/aio_write() methods.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
request_end and fuse_read_interrupt release fc->lock. Add lock annotations
to these two functions so that sparse can check callers for lock pairing,
and so that sparse will not complain about these functions since they
intentionally use locks in this manner.
Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add synchronous request interruption. This is needed for file locking
operations which have to be interruptible. However filesystem may implement
interruptibility of other operations (e.g. like NFS 'intr' mount option).
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Rename the 'interrupted' flag to 'aborted', since it indicates exactly that,
and next patch will introduce an 'interrupted' flag for a
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
All POSIX locks owned by the current task are removed on close(). If the
FLUSH request resulting initiated by close() fails to reach userspace, there
might be locks remaining, which cannot be removed.
The only reason it could fail, is if allocating the request fails. In this
case use the request reserved for RELEASE, or if that is currently used by
another FLUSH, wait for it to become available.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add a control filesystem to fuse, replacing the attributes currently exported
through sysfs. An empty directory '/sys/fs/fuse/connections' is still created
in sysfs, and mounting the control filesystem here provides backward
compatibility.
Advantages of the control filesystem over the previous solution:
- allows the object directory and the attributes to be owned by the
filesystem owner, hence letting unpriviled users abort the
filesystem connection
- does not suffer from module unload race
[akpm@osdl.org: fix this fs for recent dhowells depredations]
[akpm@osdl.org: fix 64-bit printk warnings]
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Don't put requests into the background when a fatal interrupt occurs while the
request is in userspace. This removes a major wart from the implementation.
Backgrounding of requests was introduced to allow breaking of deadlocks.
However now the same can be achieved by aborting the filesystem through the
'abort' sysfs attribute.
This is a change in the interface, but should not cause problems, since these
kinds of deadlocks never happen during normal operation.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
A deadlock was possible, when the last reference to the superblock was
held due to a background request containing a file reference.
Releasing the file would release the vfsmount which in turn would
release the superblock. Since sbput_sem is held during the fput() and
fuse_put_super() tries to acquire this same semaphore, a deadlock
results.
The solution is to move the fput() outside the region protected by
sbput_sem.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
This reverts 73ce8355c2 commit.
It was wrong, because it didn't take into account the requirement,
that iput() for background requests must be performed synchronously
with ->put_super(), otherwise active inodes may remain after unmount.
The right solution is to keep the sbput_sem and perform iput() within
the locked region, but move fput() outside sbput_sem.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
