I believe that there is a problem with the handling of POSIX locks, which
the attached patch should address.
The problem appears to be a race between fcntl(2) and close(2). A
multithreaded application could close a file descriptor at the same time as
it is trying to acquire a lock using the same file descriptor. I would
suggest that that multithreaded application is not providing the proper
synchronization for itself, but the OS should still behave correctly.
SUS3 (Single UNIX Specification Version 3, read: POSIX) indicates that when
a file descriptor is closed, that all POSIX locks on the file, owned by the
process which closed the file descriptor, should be released.
The trick here is when those locks are released. The current code releases
all locks which exist when close is processing, but any locks in progress
are handled when the last reference to the open file is released.
There are three cases to consider.
One is the simple case, a multithreaded (mt) process has a file open and
races to close it and acquire a lock on it. In this case, the close will
release one reference to the open file and when the fcntl is done, it will
release the other reference. For this situation, no locks should exist on
the file when both the close and fcntl operations are done. The current
system will handle this case because the last reference to the open file is
being released.
The second case is when the mt process has dup(2)'d the file descriptor.
The close will release one reference to the file and the fcntl, when done,
will release another, but there will still be at least one more reference
to the open file. One could argue that the existence of a lock on the file
after the close has completed is okay, because it was acquired after the
close operation and there is still a way for the application to release the
lock on the file, using an existing file descriptor.
The third case is when the mt process has forked, after opening the file
and either before or after becoming an mt process. In this case, each
process would hold a reference to the open file. For each process, this
degenerates to first case above. However, the lock continues to exist
until both processes have released their references to the open file. This
lock could block other lock requests.
The changes to release the lock when the last reference to the open file
aren't quite right because they would allow the lock to exist as long as
there was a reference to the open file. This is too long.
The new proposed solution is to add support in the fcntl code path to
detect a race with close and then to release the lock which was just
acquired when such as race is detected. This causes locks to be released
in a timely fashion and for the system to conform to the POSIX semantic
specification.
This was tested by instrumenting a kernel to detect the handling locks and
then running a program which generates case #3 above. A dangling lock
could be reliably generated. When the changes to detect the close/fcntl
race were added, a dangling lock could no longer be generated.
Cc: Matthew Wilcox <willy@debian.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Oliver Paukstadt from our test department is testing the xip patches in
Linus' git-tree. He found a problem that shows when reading a file that
contains sparse blocks (holes) on a -o xip mounted ext2 filesystem: the
BUG_ON() in fs/ext2/xip.c:40 triggers where it should not. The problem was
introduced by a cleanup in my previous patch, this patch fixes it.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
If the automount daemon receives a signal which causes it to sumarily
terminate the autofs4 module leaks dentries. The same problem exists with
detached mount requests without the warning.
This patch cleans these dentries at umount.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We must drop references to quota structures before releasing the inode.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We must drop references to quota structures before releasing the inode.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
reiserfs_new_inode() can call iput() with the xattr lock held. This will
cause a deadlock to occur when reiserfs_delete_xattrs() is called to clean
up.
The following patch releases the lock and reacquires it after the iput.
This is safe because interaction with xattrs is complete, and the relock is
just to balance out the release in the caller.
The locking needs some reworking to be more sane, but that's more intrusive
and I was just looking to fix this bug.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Here's a patch to fix a missing refrigerator call in jffs2.
Signed-off-by: Nigel Cunningham <nigel@suspend2.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Check for (unlikely) errors in the filesystem initialization stuff in
our module_init() function.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Change default inotify limits: Maximum instances per user to 128 and
maximum events per queue to 16k. The max instances used to be 128; the
change to 8 was a mistake. Memory consumption is fine.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Handle error out paths better.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Bug fix: Ensure that the fd passed to inotify_add_watch() and
inotify_rm_watch() belongs to inotify.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
As an optimization, use fget_light() and fput_light() where possible.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Miscellaneous invariant clean up, comment fixes, and so on. Trivial
stuff.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch includes feedback from Andrew and Christoph. Thanks for
taking time to review.
Use of empty_zero_page was eliminated to fix compilation for architectures
that don't have it.
This patch removes setting pages up-to-date in ext2_get_xip_page and all
bug checks to verify that the page is indeed up to date. Setting the page
state on mapping to userland is bogus. None of the code patchs involved
with these pages in mm cares about the page state.
still on my ToDo list: identify a place outside second extended where
__inode_direct_access should reside
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In the rare case of failing to write the cleanmarker
the allocated node was not freed.
Pointed out by Forrest Zhao
Initial cleanup by Joern Engel
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Minimal patch removing uses of ROOT_DEV; next patch unexports it. I've
opposed this, but I've planned to reintroduce the functionality without using
ROOT_DEV.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix the error message to refer to the error code, i.e. err, not count, plus
add some cosmetical fixes.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Allow the setting of NLM timeouts and grace periods through the proc and
sysclt interfaces on x86_64 architectures
Signed-off-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Something has changed in the core kernel such that we now get concurrent
inode write outs, one e.g via pdflush and one via sys_sync or whatever.
This causes a nasty deadlock in ntfs. The only clean solution
unfortunately requires a minor vfs api extension.
First the deadlock analysis:
Prerequisive knowledge: NTFS has a file $MFT (inode 0) loaded at mount
time. The NTFS driver uses the page cache for storing the file contents as
usual. More interestingly this file contains the table of on-disk inodes
as a sequence of MFT_RECORDs. Thus NTFS driver accesses the on-disk inodes
by accessing the MFT_RECORDs in the page cache pages of the loaded inode
$MFT.
The situation: VFS inode X on a mounted ntfs volume is dirty. For same
inode X, the ntfs_inode is dirty and thus corresponding on-disk inode,
which is as explained above in a dirty PAGE_CACHE_PAGE belonging to the
table of inodes ($MFT, inode 0).
What happens:
Process 1: sys_sync()/umount()/whatever... calls __sync_single_inode() for
$MFT -> do_writepages() -> write_page for the dirty page containing the
on-disk inode X, the page is now locked -> ntfs_write_mst_block() which
clears PageUptodate() on the page to prevent anyone else getting hold of it
whilst it does the write out (this is necessary as the on-disk inode needs
"fixups" applied before the write to disk which are removed again after the
write and PageUptodate is then set again). It then analyses the page
looking for dirty on-disk inodes and when it finds one it calls
ntfs_may_write_mft_record() to see if it is safe to write this on-disk
inode. This then calls ilookup5() to check if the corresponding VFS inode
is in icache(). This in turn calls ifind() which waits on the inode lock
via wait_on_inode whilst holding the global inode_lock.
Process 2: pdflush results in a call to __sync_single_inode for the same
VFS inode X on the ntfs volume. This locks the inode (I_LOCK) then calls
write-inode -> ntfs_write_inode -> map_mft_record() -> read_cache_page() of
the page (in page cache of table of inodes $MFT, inode 0) containing the
on-disk inode. This page has PageUptodate() clear because of Process 1
(see above) so read_cache_page() blocks when tries to take the page lock
for the page so it can call ntfs_read_page().
Thus Process 1 is holding the page lock on the page containing the on-disk
inode X and it is waiting on the inode X to be unlocked in ifind() so it
can write the page out and then unlock the page.
And Process 2 is holding the inode lock on inode X and is waiting for the
page to be unlocked so it can call ntfs_readpage() or discover that
Process 1 set PageUptodate() again and use the page.
Thus we have a deadlock due to ifind() waiting on the inode lock.
The only sensible solution: NTFS does not care whether the VFS inode is
locked or not when it calls ilookup5() (it doesn't use the VFS inode at
all, it just uses it to find the corresponding ntfs_inode which is of
course attached to the VFS inode (both are one single struct); and it uses
the ntfs_inode which is subject to its own locking so I_LOCK is irrelevant)
hence we want a modified ilookup5_nowait() which is the same as ilookup5()
but it does not wait on the inode lock.
Without such functionality I would have to keep my own ntfs_inode cache in
the NTFS driver just so I can find ntfs_inodes independent of their VFS
inodes which would be slow, memory and cpu cycle wasting, and incredibly
stupid given the icache already exists in the VFS.
Below is a patch that does the ilookup5_nowait() implementation in
fs/inode.c and exports it.
ilookup5_nowait.diff:
Introduce ilookup5_nowait() which is basically the same as ilookup5() but
it does not wait on the inode's lock (i.e. it omits the wait_on_inode()
done in ifind()).
This is needed to avoid a nasty deadlock in NTFS.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This moves the inotify sysctl knobs to "/proc/sys/fs/inotify" from
"/proc/sys/fs". Also some related cleanup.
Signed-off-by: Robert Love <rml@novell.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
All of the different xattr namespaces have different rules.
user.* and ACL's are not allowed on symlinks, and since these were the
first xattrs implemented, I assumed there was no need to support xattrs
on symlinks. This one-line patch should fix it.
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:
* dnotify requires the opening of one fd per each directory
that you intend to watch. This quickly results in too many
open files and pins removable media, preventing unmount.
* dnotify is directory-based. You only learn about changes to
directories. Sure, a change to a file in a directory affects
the directory, but you are then forced to keep a cache of
stat structures.
* dnotify's interface to user-space is awful. Signals?
inotify provides a more usable, simple, powerful solution to file change
notification:
* inotify's interface is a system call that returns a fd, not SIGIO.
You get a single fd, which is select()-able.
* inotify has an event that says "the filesystem that the item
you were watching is on was unmounted."
* inotify can watch directories or files.
Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.
See Documentation/filesystems/inotify.txt.
Signed-off-by: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This was a pure indentation change, using:
scripts/Lindent fs/reiserfs/*.c include/linux/reiserfs_*.h
to make reiserfs match the regular Linux indentation style. As Jeff
Mahoney <jeffm@suse.com> writes:
The ReiserFS code is a mix of a number of different coding styles, sometimes
different even from line-to-line. Since the code has been relatively stable
for quite some time and there are few outstanding patches to be applied, it
is time to reformat the code to conform to the Linux style standard outlined
in Documentation/CodingStyle.
This patch contains the result of running scripts/Lindent against
fs/reiserfs/*.c and include/linux/reiserfs_*.h. There are places where the
code can be made to look better, but I'd rather keep those patches separate
so that there isn't a subtle by-hand hand accident in the middle of a huge
patch. To be clear: This patch is reformatting *only*.
A number of patches may follow that continue to make the code more consistent
with the Linux coding style.
Hans wasn't particularly enthusiastic about these patches, but said he
wouldn't really oppose them either.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
indent(1) doesn't know how to handle the "do not compile" error. It results
in the item_ops array declaration being indented a tab stop in when it should
not be. This patch replaces it with a #error that describes why it's failing.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
While fixing an oops in the st driver in a dirty release path, I
encountered an oops in cdev_put for cdevs allocated using cdev_alloc. If
cdev_del is called when the cdev kobject still has an open user, when the
last cdev_put is called, the cdev_put will call kobject_put, which will end
up ultimately releasing the cdev in cdev_dynamic_release. Patch fixes the
oops by preventing cdev_put from accessing freed memory.
Signed-off-by: Brian King <brking@us.ibm.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Restore old set of ext2 mount options when remounting of a filesystem
fails.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Fix a problem with ext3 mount option parsing. When remount of a filesystem
fails, old options are now restored.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
When a noninitial thread does exec, it becomes the new group leader. If
there is a ITIMER_REAL timer running, it points at the old group leader and
when it fires it can follow a stale pointer. The timer data needs to be
reset to point at the exec'ing thread that is becoming the group leader.
This has to synchronize with any concurrent firing of the timer to make
sure that it_real_fn can never run when the data points to a thread that
might have been reaped already.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Bug symptoms
~~~~~~~~~~~~
For the same inode VFS calls read_inode() twice and doesn't call
clear_inode() between the two read_inode() invocations.
Bug description
~~~~~~~~~~~~~~~
Suppose we have an inode which has zero reference count but is still in
the inode cache. Suppose kswapd invokes shrink_icache_memory() to free
some RAM. In prune_icache() inodes are removed from i_hash. prune_icache
() is then going to call clear_inode(), but drops the inode_lock
spinlock before this. If in this moment another task calls iget() for an
inode which was just removed from i_hash by prune_icache(), then iget()
invokes read_inode() for this inode, because it is *already removed*
from i_hash.
The end result is: we call iget(#N) then iput(#N); inode #N has zero
i_count now and is in the inode cache; kswapd starts. kswapd removes the
inode #N from i_hash ans is preempted; we call iget(#N) again;
read_inode() is invoked as the result; but we expect clear_inode()
before.
Fix
~~~~~~~
To fix the bug I remove inodes from i_hash later, when clear_inode() is
actually called. I remove them from i_hash under spinlock protection.
Since the i_state is set to I_FREEING, it is safe to do this. The others
will sleep waiting for the inode state change.
I also postpone removing inodes from i_sb_list. It is not compulsory to
do so but I do it for readability reasons. Inodes are added/removed to
the lists together everywhere in the code and there is no point to
change this rule. This is harmless because the only user of i_sb_list
which somehow may interfere with me (invalidate_list()) is excluded by
the iprune_sem mutex.
The same race is possible in invalidate_list() so I do the same for it.
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch fixes queer behavior in __wait_on_freeing_inode().
If I_LOCK was not set it called yield(), effectively busy waiting for the
removal of the inode from the hash. This change was introduced within
"[PATCH] eliminate inode waitqueue hashtable" Changeset 1.1938.166.16 last
october by wli.
The solution is to restore the old behavior, of unconditionally waiting on
the waitqueue. It doesn't matter if I_LOCK is not set initally, the task
will go to sleep, and wake up when wake_up_inode() is called from
generic_delete_inode() after removing the inode from the hash chain.
Comment is also updated to better reflect current behavior.
This condition is very hard to trigger normally (simultaneous clear_inode()
with iget()) so probably only heavy stress testing can reveal any change of
behavior.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In case of a mount error locks might be uninitialized but
accessed by the resulting call to jffs2_kill_sb().
Signed-off-by: Artem B. Bityuckiy <dedekind@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We recently changed the method of collecting and sorting of
tmp_dnode objects to use a temporary RB-tree instead of a
temporary list. Rename function and update comments.
Signed-off-by: Artem B. Bityuckiy <dedekind@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
After discussion at the recent NFSv4 bake-a-thon, I realized that my
assumption that NFS4_FH_PERSISTENT required filehandles to persist was a
misreading of the spec. This also fixes an interoperability problem with the
Solaris client.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We shouldn't be allowing, e.g., write locks on files not open for read. To
enforce this, we add a pointer from the lock stateid back to the open stateid
it came from, so that the check will continue to be correct even after the
open is upgraded or downgraded.
Signed-off-by: Andy Adamson <andros@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
As long as we're here, do some miscellaneous cleanup.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The handling of close_lru in preprocess_stateid_op was a source of some
confusion here recently. Try to make the logic a little clearer, by renaming
find_openstateowner_id to make its purpose clearer and untangling some
unnecessarily complicated goto's.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
