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![Linus Torvalds](/assets/img/avatar_default.png)
There is measurable performance impact in some synthetic tests due to commit6d390e4b5d
(locks: fix a potential use-after-free problem when wakeup a waiter). Fix the race condition instead by clearing the fl_blocker pointer after the wake_up, using explicit acquire/release semantics. This does mean that we can no longer use the clearing of fl_blocker as the wait condition, so switch the waiters over to checking whether the fl_blocked_member list_head is empty. Reviewed-by: yangerkun <yangerkun@huawei.com> Reviewed-by: NeilBrown <neilb@suse.de> Fixes:6d390e4b5d
(locks: fix a potential use-after-free problem when wakeup a waiter) Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
3019 lines
80 KiB
C
3019 lines
80 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/fs/locks.c
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*
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* Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
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* Doug Evans (dje@spiff.uucp), August 07, 1992
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*
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* Deadlock detection added.
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* FIXME: one thing isn't handled yet:
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* - mandatory locks (requires lots of changes elsewhere)
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* Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
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*
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* Miscellaneous edits, and a total rewrite of posix_lock_file() code.
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* Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
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*
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* Converted file_lock_table to a linked list from an array, which eliminates
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* the limits on how many active file locks are open.
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* Chad Page (pageone@netcom.com), November 27, 1994
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*
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* Removed dependency on file descriptors. dup()'ed file descriptors now
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* get the same locks as the original file descriptors, and a close() on
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* any file descriptor removes ALL the locks on the file for the current
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* process. Since locks still depend on the process id, locks are inherited
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* after an exec() but not after a fork(). This agrees with POSIX, and both
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* BSD and SVR4 practice.
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* Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
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*
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* Scrapped free list which is redundant now that we allocate locks
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* dynamically with kmalloc()/kfree().
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* Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
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*
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* Implemented two lock personalities - FL_FLOCK and FL_POSIX.
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*
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* FL_POSIX locks are created with calls to fcntl() and lockf() through the
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* fcntl() system call. They have the semantics described above.
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*
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* FL_FLOCK locks are created with calls to flock(), through the flock()
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* system call, which is new. Old C libraries implement flock() via fcntl()
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* and will continue to use the old, broken implementation.
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*
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* FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
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* with a file pointer (filp). As a result they can be shared by a parent
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* process and its children after a fork(). They are removed when the last
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* file descriptor referring to the file pointer is closed (unless explicitly
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* unlocked).
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*
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* FL_FLOCK locks never deadlock, an existing lock is always removed before
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* upgrading from shared to exclusive (or vice versa). When this happens
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* any processes blocked by the current lock are woken up and allowed to
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* run before the new lock is applied.
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* Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
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*
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* Removed some race conditions in flock_lock_file(), marked other possible
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* races. Just grep for FIXME to see them.
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* Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
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*
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* Addressed Dmitry's concerns. Deadlock checking no longer recursive.
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* Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
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* once we've checked for blocking and deadlocking.
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* Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
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*
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* Initial implementation of mandatory locks. SunOS turned out to be
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* a rotten model, so I implemented the "obvious" semantics.
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* See 'Documentation/filesystems/mandatory-locking.txt' for details.
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* Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
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*
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* Don't allow mandatory locks on mmap()'ed files. Added simple functions to
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* check if a file has mandatory locks, used by mmap(), open() and creat() to
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* see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
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* Manual, Section 2.
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* Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
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*
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* Tidied up block list handling. Added '/proc/locks' interface.
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* Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
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*
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* Fixed deadlock condition for pathological code that mixes calls to
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* flock() and fcntl().
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* Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
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*
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* Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
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* for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
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* guarantee sensible behaviour in the case where file system modules might
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* be compiled with different options than the kernel itself.
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* Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
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*
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* Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
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* (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
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* Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
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*
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* Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
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* locks. Changed process synchronisation to avoid dereferencing locks that
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* have already been freed.
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* Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
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*
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* Made the block list a circular list to minimise searching in the list.
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* Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
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*
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* Made mandatory locking a mount option. Default is not to allow mandatory
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* locking.
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* Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
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*
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* Some adaptations for NFS support.
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* Olaf Kirch (okir@monad.swb.de), Dec 1996,
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*
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* Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
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* Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
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*
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* Use slab allocator instead of kmalloc/kfree.
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* Use generic list implementation from <linux/list.h>.
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* Sped up posix_locks_deadlock by only considering blocked locks.
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* Matthew Wilcox <willy@debian.org>, March, 2000.
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*
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* Leases and LOCK_MAND
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* Matthew Wilcox <willy@debian.org>, June, 2000.
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* Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
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*
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* Locking conflicts and dependencies:
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* If multiple threads attempt to lock the same byte (or flock the same file)
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* only one can be granted the lock, and other must wait their turn.
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* The first lock has been "applied" or "granted", the others are "waiting"
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* and are "blocked" by the "applied" lock..
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*
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* Waiting and applied locks are all kept in trees whose properties are:
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*
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* - the root of a tree may be an applied or waiting lock.
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* - every other node in the tree is a waiting lock that
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* conflicts with every ancestor of that node.
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*
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* Every such tree begins life as a waiting singleton which obviously
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* satisfies the above properties.
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*
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* The only ways we modify trees preserve these properties:
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*
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* 1. We may add a new leaf node, but only after first verifying that it
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* conflicts with all of its ancestors.
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* 2. We may remove the root of a tree, creating a new singleton
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* tree from the root and N new trees rooted in the immediate
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* children.
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* 3. If the root of a tree is not currently an applied lock, we may
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* apply it (if possible).
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* 4. We may upgrade the root of the tree (either extend its range,
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* or upgrade its entire range from read to write).
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*
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* When an applied lock is modified in a way that reduces or downgrades any
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* part of its range, we remove all its children (2 above). This particularly
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* happens when a lock is unlocked.
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*
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* For each of those child trees we "wake up" the thread which is
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* waiting for the lock so it can continue handling as follows: if the
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* root of the tree applies, we do so (3). If it doesn't, it must
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* conflict with some applied lock. We remove (wake up) all of its children
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* (2), and add it is a new leaf to the tree rooted in the applied
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* lock (1). We then repeat the process recursively with those
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* children.
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*
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*/
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/security.h>
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#include <linux/slab.h>
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#include <linux/syscalls.h>
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#include <linux/time.h>
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#include <linux/rcupdate.h>
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#include <linux/pid_namespace.h>
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#include <linux/hashtable.h>
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#include <linux/percpu.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/filelock.h>
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#include <linux/uaccess.h>
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#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX)
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#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
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#define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
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#define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK)
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#define IS_REMOTELCK(fl) (fl->fl_pid <= 0)
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static bool lease_breaking(struct file_lock *fl)
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{
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return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
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}
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static int target_leasetype(struct file_lock *fl)
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{
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if (fl->fl_flags & FL_UNLOCK_PENDING)
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return F_UNLCK;
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if (fl->fl_flags & FL_DOWNGRADE_PENDING)
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return F_RDLCK;
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return fl->fl_type;
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}
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int leases_enable = 1;
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int lease_break_time = 45;
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/*
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* The global file_lock_list is only used for displaying /proc/locks, so we
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* keep a list on each CPU, with each list protected by its own spinlock.
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* Global serialization is done using file_rwsem.
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*
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* Note that alterations to the list also require that the relevant flc_lock is
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* held.
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*/
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struct file_lock_list_struct {
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spinlock_t lock;
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struct hlist_head hlist;
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};
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static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
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DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
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/*
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* The blocked_hash is used to find POSIX lock loops for deadlock detection.
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* It is protected by blocked_lock_lock.
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*
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* We hash locks by lockowner in order to optimize searching for the lock a
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* particular lockowner is waiting on.
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*
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* FIXME: make this value scale via some heuristic? We generally will want more
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* buckets when we have more lockowners holding locks, but that's a little
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* difficult to determine without knowing what the workload will look like.
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*/
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#define BLOCKED_HASH_BITS 7
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static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
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/*
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* This lock protects the blocked_hash. Generally, if you're accessing it, you
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* want to be holding this lock.
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*
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* In addition, it also protects the fl->fl_blocked_requests list, and the
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* fl->fl_blocker pointer for file_lock structures that are acting as lock
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* requests (in contrast to those that are acting as records of acquired locks).
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*
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* Note that when we acquire this lock in order to change the above fields,
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* we often hold the flc_lock as well. In certain cases, when reading the fields
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* protected by this lock, we can skip acquiring it iff we already hold the
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* flc_lock.
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*/
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static DEFINE_SPINLOCK(blocked_lock_lock);
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static struct kmem_cache *flctx_cache __read_mostly;
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static struct kmem_cache *filelock_cache __read_mostly;
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static struct file_lock_context *
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locks_get_lock_context(struct inode *inode, int type)
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{
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struct file_lock_context *ctx;
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/* paired with cmpxchg() below */
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ctx = smp_load_acquire(&inode->i_flctx);
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if (likely(ctx) || type == F_UNLCK)
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goto out;
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ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
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if (!ctx)
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goto out;
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spin_lock_init(&ctx->flc_lock);
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INIT_LIST_HEAD(&ctx->flc_flock);
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INIT_LIST_HEAD(&ctx->flc_posix);
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INIT_LIST_HEAD(&ctx->flc_lease);
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/*
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* Assign the pointer if it's not already assigned. If it is, then
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* free the context we just allocated.
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*/
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if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
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kmem_cache_free(flctx_cache, ctx);
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ctx = smp_load_acquire(&inode->i_flctx);
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}
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out:
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trace_locks_get_lock_context(inode, type, ctx);
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return ctx;
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}
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static void
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locks_dump_ctx_list(struct list_head *list, char *list_type)
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{
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struct file_lock *fl;
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list_for_each_entry(fl, list, fl_list) {
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pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
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}
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}
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static void
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locks_check_ctx_lists(struct inode *inode)
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{
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struct file_lock_context *ctx = inode->i_flctx;
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if (unlikely(!list_empty(&ctx->flc_flock) ||
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!list_empty(&ctx->flc_posix) ||
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!list_empty(&ctx->flc_lease))) {
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pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
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MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
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inode->i_ino);
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locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
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locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
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locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
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}
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}
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static void
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locks_check_ctx_file_list(struct file *filp, struct list_head *list,
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char *list_type)
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{
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struct file_lock *fl;
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struct inode *inode = locks_inode(filp);
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list_for_each_entry(fl, list, fl_list)
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if (fl->fl_file == filp)
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pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
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" fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
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list_type, MAJOR(inode->i_sb->s_dev),
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MINOR(inode->i_sb->s_dev), inode->i_ino,
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fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
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}
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void
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locks_free_lock_context(struct inode *inode)
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{
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struct file_lock_context *ctx = inode->i_flctx;
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if (unlikely(ctx)) {
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locks_check_ctx_lists(inode);
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kmem_cache_free(flctx_cache, ctx);
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}
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}
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static void locks_init_lock_heads(struct file_lock *fl)
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{
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INIT_HLIST_NODE(&fl->fl_link);
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INIT_LIST_HEAD(&fl->fl_list);
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INIT_LIST_HEAD(&fl->fl_blocked_requests);
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INIT_LIST_HEAD(&fl->fl_blocked_member);
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init_waitqueue_head(&fl->fl_wait);
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}
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/* Allocate an empty lock structure. */
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struct file_lock *locks_alloc_lock(void)
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{
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struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
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if (fl)
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locks_init_lock_heads(fl);
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return fl;
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}
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EXPORT_SYMBOL_GPL(locks_alloc_lock);
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void locks_release_private(struct file_lock *fl)
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{
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BUG_ON(waitqueue_active(&fl->fl_wait));
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BUG_ON(!list_empty(&fl->fl_list));
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BUG_ON(!list_empty(&fl->fl_blocked_requests));
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BUG_ON(!list_empty(&fl->fl_blocked_member));
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BUG_ON(!hlist_unhashed(&fl->fl_link));
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if (fl->fl_ops) {
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if (fl->fl_ops->fl_release_private)
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fl->fl_ops->fl_release_private(fl);
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fl->fl_ops = NULL;
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}
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if (fl->fl_lmops) {
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if (fl->fl_lmops->lm_put_owner) {
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fl->fl_lmops->lm_put_owner(fl->fl_owner);
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fl->fl_owner = NULL;
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}
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fl->fl_lmops = NULL;
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}
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}
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EXPORT_SYMBOL_GPL(locks_release_private);
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/* Free a lock which is not in use. */
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void locks_free_lock(struct file_lock *fl)
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{
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locks_release_private(fl);
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kmem_cache_free(filelock_cache, fl);
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}
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EXPORT_SYMBOL(locks_free_lock);
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static void
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locks_dispose_list(struct list_head *dispose)
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{
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struct file_lock *fl;
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while (!list_empty(dispose)) {
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fl = list_first_entry(dispose, struct file_lock, fl_list);
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list_del_init(&fl->fl_list);
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locks_free_lock(fl);
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}
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}
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void locks_init_lock(struct file_lock *fl)
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{
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memset(fl, 0, sizeof(struct file_lock));
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locks_init_lock_heads(fl);
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}
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EXPORT_SYMBOL(locks_init_lock);
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/*
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* Initialize a new lock from an existing file_lock structure.
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*/
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void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
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{
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new->fl_owner = fl->fl_owner;
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new->fl_pid = fl->fl_pid;
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new->fl_file = NULL;
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new->fl_flags = fl->fl_flags;
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new->fl_type = fl->fl_type;
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new->fl_start = fl->fl_start;
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new->fl_end = fl->fl_end;
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new->fl_lmops = fl->fl_lmops;
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new->fl_ops = NULL;
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if (fl->fl_lmops) {
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if (fl->fl_lmops->lm_get_owner)
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fl->fl_lmops->lm_get_owner(fl->fl_owner);
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}
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}
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EXPORT_SYMBOL(locks_copy_conflock);
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void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
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{
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/* "new" must be a freshly-initialized lock */
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WARN_ON_ONCE(new->fl_ops);
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locks_copy_conflock(new, fl);
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new->fl_file = fl->fl_file;
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new->fl_ops = fl->fl_ops;
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if (fl->fl_ops) {
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if (fl->fl_ops->fl_copy_lock)
|
|
fl->fl_ops->fl_copy_lock(new, fl);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(locks_copy_lock);
|
|
|
|
static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
|
|
{
|
|
struct file_lock *f;
|
|
|
|
/*
|
|
* As ctx->flc_lock is held, new requests cannot be added to
|
|
* ->fl_blocked_requests, so we don't need a lock to check if it
|
|
* is empty.
|
|
*/
|
|
if (list_empty(&fl->fl_blocked_requests))
|
|
return;
|
|
spin_lock(&blocked_lock_lock);
|
|
list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests);
|
|
list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member)
|
|
f->fl_blocker = new;
|
|
spin_unlock(&blocked_lock_lock);
|
|
}
|
|
|
|
static inline int flock_translate_cmd(int cmd) {
|
|
if (cmd & LOCK_MAND)
|
|
return cmd & (LOCK_MAND | LOCK_RW);
|
|
switch (cmd) {
|
|
case LOCK_SH:
|
|
return F_RDLCK;
|
|
case LOCK_EX:
|
|
return F_WRLCK;
|
|
case LOCK_UN:
|
|
return F_UNLCK;
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Fill in a file_lock structure with an appropriate FLOCK lock. */
|
|
static struct file_lock *
|
|
flock_make_lock(struct file *filp, unsigned int cmd, struct file_lock *fl)
|
|
{
|
|
int type = flock_translate_cmd(cmd);
|
|
|
|
if (type < 0)
|
|
return ERR_PTR(type);
|
|
|
|
if (fl == NULL) {
|
|
fl = locks_alloc_lock();
|
|
if (fl == NULL)
|
|
return ERR_PTR(-ENOMEM);
|
|
} else {
|
|
locks_init_lock(fl);
|
|
}
|
|
|
|
fl->fl_file = filp;
|
|
fl->fl_owner = filp;
|
|
fl->fl_pid = current->tgid;
|
|
fl->fl_flags = FL_FLOCK;
|
|
fl->fl_type = type;
|
|
fl->fl_end = OFFSET_MAX;
|
|
|
|
return fl;
|
|
}
|
|
|
|
static int assign_type(struct file_lock *fl, long type)
|
|
{
|
|
switch (type) {
|
|
case F_RDLCK:
|
|
case F_WRLCK:
|
|
case F_UNLCK:
|
|
fl->fl_type = type;
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
|
|
struct flock64 *l)
|
|
{
|
|
switch (l->l_whence) {
|
|
case SEEK_SET:
|
|
fl->fl_start = 0;
|
|
break;
|
|
case SEEK_CUR:
|
|
fl->fl_start = filp->f_pos;
|
|
break;
|
|
case SEEK_END:
|
|
fl->fl_start = i_size_read(file_inode(filp));
|
|
break;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
if (l->l_start > OFFSET_MAX - fl->fl_start)
|
|
return -EOVERFLOW;
|
|
fl->fl_start += l->l_start;
|
|
if (fl->fl_start < 0)
|
|
return -EINVAL;
|
|
|
|
/* POSIX-1996 leaves the case l->l_len < 0 undefined;
|
|
POSIX-2001 defines it. */
|
|
if (l->l_len > 0) {
|
|
if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
|
|
return -EOVERFLOW;
|
|
fl->fl_end = fl->fl_start + l->l_len - 1;
|
|
|
|
} else if (l->l_len < 0) {
|
|
if (fl->fl_start + l->l_len < 0)
|
|
return -EINVAL;
|
|
fl->fl_end = fl->fl_start - 1;
|
|
fl->fl_start += l->l_len;
|
|
} else
|
|
fl->fl_end = OFFSET_MAX;
|
|
|
|
fl->fl_owner = current->files;
|
|
fl->fl_pid = current->tgid;
|
|
fl->fl_file = filp;
|
|
fl->fl_flags = FL_POSIX;
|
|
fl->fl_ops = NULL;
|
|
fl->fl_lmops = NULL;
|
|
|
|
return assign_type(fl, l->l_type);
|
|
}
|
|
|
|
/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
|
|
* style lock.
|
|
*/
|
|
static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
|
|
struct flock *l)
|
|
{
|
|
struct flock64 ll = {
|
|
.l_type = l->l_type,
|
|
.l_whence = l->l_whence,
|
|
.l_start = l->l_start,
|
|
.l_len = l->l_len,
|
|
};
|
|
|
|
return flock64_to_posix_lock(filp, fl, &ll);
|
|
}
|
|
|
|
/* default lease lock manager operations */
|
|
static bool
|
|
lease_break_callback(struct file_lock *fl)
|
|
{
|
|
kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
|
|
return false;
|
|
}
|
|
|
|
static void
|
|
lease_setup(struct file_lock *fl, void **priv)
|
|
{
|
|
struct file *filp = fl->fl_file;
|
|
struct fasync_struct *fa = *priv;
|
|
|
|
/*
|
|
* fasync_insert_entry() returns the old entry if any. If there was no
|
|
* old entry, then it used "priv" and inserted it into the fasync list.
|
|
* Clear the pointer to indicate that it shouldn't be freed.
|
|
*/
|
|
if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
|
|
*priv = NULL;
|
|
|
|
__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
|
|
}
|
|
|
|
static const struct lock_manager_operations lease_manager_ops = {
|
|
.lm_break = lease_break_callback,
|
|
.lm_change = lease_modify,
|
|
.lm_setup = lease_setup,
|
|
};
|
|
|
|
/*
|
|
* Initialize a lease, use the default lock manager operations
|
|
*/
|
|
static int lease_init(struct file *filp, long type, struct file_lock *fl)
|
|
{
|
|
if (assign_type(fl, type) != 0)
|
|
return -EINVAL;
|
|
|
|
fl->fl_owner = filp;
|
|
fl->fl_pid = current->tgid;
|
|
|
|
fl->fl_file = filp;
|
|
fl->fl_flags = FL_LEASE;
|
|
fl->fl_start = 0;
|
|
fl->fl_end = OFFSET_MAX;
|
|
fl->fl_ops = NULL;
|
|
fl->fl_lmops = &lease_manager_ops;
|
|
return 0;
|
|
}
|
|
|
|
/* Allocate a file_lock initialised to this type of lease */
|
|
static struct file_lock *lease_alloc(struct file *filp, long type)
|
|
{
|
|
struct file_lock *fl = locks_alloc_lock();
|
|
int error = -ENOMEM;
|
|
|
|
if (fl == NULL)
|
|
return ERR_PTR(error);
|
|
|
|
error = lease_init(filp, type, fl);
|
|
if (error) {
|
|
locks_free_lock(fl);
|
|
return ERR_PTR(error);
|
|
}
|
|
return fl;
|
|
}
|
|
|
|
/* Check if two locks overlap each other.
|
|
*/
|
|
static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
|
|
{
|
|
return ((fl1->fl_end >= fl2->fl_start) &&
|
|
(fl2->fl_end >= fl1->fl_start));
|
|
}
|
|
|
|
/*
|
|
* Check whether two locks have the same owner.
|
|
*/
|
|
static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
|
|
{
|
|
return fl1->fl_owner == fl2->fl_owner;
|
|
}
|
|
|
|
/* Must be called with the flc_lock held! */
|
|
static void locks_insert_global_locks(struct file_lock *fl)
|
|
{
|
|
struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
|
|
|
|
percpu_rwsem_assert_held(&file_rwsem);
|
|
|
|
spin_lock(&fll->lock);
|
|
fl->fl_link_cpu = smp_processor_id();
|
|
hlist_add_head(&fl->fl_link, &fll->hlist);
|
|
spin_unlock(&fll->lock);
|
|
}
|
|
|
|
/* Must be called with the flc_lock held! */
|
|
static void locks_delete_global_locks(struct file_lock *fl)
|
|
{
|
|
struct file_lock_list_struct *fll;
|
|
|
|
percpu_rwsem_assert_held(&file_rwsem);
|
|
|
|
/*
|
|
* Avoid taking lock if already unhashed. This is safe since this check
|
|
* is done while holding the flc_lock, and new insertions into the list
|
|
* also require that it be held.
|
|
*/
|
|
if (hlist_unhashed(&fl->fl_link))
|
|
return;
|
|
|
|
fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
|
|
spin_lock(&fll->lock);
|
|
hlist_del_init(&fl->fl_link);
|
|
spin_unlock(&fll->lock);
|
|
}
|
|
|
|
static unsigned long
|
|
posix_owner_key(struct file_lock *fl)
|
|
{
|
|
return (unsigned long)fl->fl_owner;
|
|
}
|
|
|
|
static void locks_insert_global_blocked(struct file_lock *waiter)
|
|
{
|
|
lockdep_assert_held(&blocked_lock_lock);
|
|
|
|
hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
|
|
}
|
|
|
|
static void locks_delete_global_blocked(struct file_lock *waiter)
|
|
{
|
|
lockdep_assert_held(&blocked_lock_lock);
|
|
|
|
hash_del(&waiter->fl_link);
|
|
}
|
|
|
|
/* Remove waiter from blocker's block list.
|
|
* When blocker ends up pointing to itself then the list is empty.
|
|
*
|
|
* Must be called with blocked_lock_lock held.
|
|
*/
|
|
static void __locks_delete_block(struct file_lock *waiter)
|
|
{
|
|
locks_delete_global_blocked(waiter);
|
|
list_del_init(&waiter->fl_blocked_member);
|
|
}
|
|
|
|
static void __locks_wake_up_blocks(struct file_lock *blocker)
|
|
{
|
|
while (!list_empty(&blocker->fl_blocked_requests)) {
|
|
struct file_lock *waiter;
|
|
|
|
waiter = list_first_entry(&blocker->fl_blocked_requests,
|
|
struct file_lock, fl_blocked_member);
|
|
__locks_delete_block(waiter);
|
|
if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
|
|
waiter->fl_lmops->lm_notify(waiter);
|
|
else
|
|
wake_up(&waiter->fl_wait);
|
|
|
|
/*
|
|
* The setting of fl_blocker to NULL marks the "done"
|
|
* point in deleting a block. Paired with acquire at the top
|
|
* of locks_delete_block().
|
|
*/
|
|
smp_store_release(&waiter->fl_blocker, NULL);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* locks_delete_lock - stop waiting for a file lock
|
|
* @waiter: the lock which was waiting
|
|
*
|
|
* lockd/nfsd need to disconnect the lock while working on it.
|
|
*/
|
|
int locks_delete_block(struct file_lock *waiter)
|
|
{
|
|
int status = -ENOENT;
|
|
|
|
/*
|
|
* If fl_blocker is NULL, it won't be set again as this thread "owns"
|
|
* the lock and is the only one that might try to claim the lock.
|
|
*
|
|
* We use acquire/release to manage fl_blocker so that we can
|
|
* optimize away taking the blocked_lock_lock in many cases.
|
|
*
|
|
* The smp_load_acquire guarantees two things:
|
|
*
|
|
* 1/ that fl_blocked_requests can be tested locklessly. If something
|
|
* was recently added to that list it must have been in a locked region
|
|
* *before* the locked region when fl_blocker was set to NULL.
|
|
*
|
|
* 2/ that no other thread is accessing 'waiter', so it is safe to free
|
|
* it. __locks_wake_up_blocks is careful not to touch waiter after
|
|
* fl_blocker is released.
|
|
*
|
|
* If a lockless check of fl_blocker shows it to be NULL, we know that
|
|
* no new locks can be inserted into its fl_blocked_requests list, and
|
|
* can avoid doing anything further if the list is empty.
|
|
*/
|
|
if (!smp_load_acquire(&waiter->fl_blocker) &&
|
|
list_empty(&waiter->fl_blocked_requests))
|
|
return status;
|
|
|
|
spin_lock(&blocked_lock_lock);
|
|
if (waiter->fl_blocker)
|
|
status = 0;
|
|
__locks_wake_up_blocks(waiter);
|
|
__locks_delete_block(waiter);
|
|
|
|
/*
|
|
* The setting of fl_blocker to NULL marks the "done" point in deleting
|
|
* a block. Paired with acquire at the top of this function.
|
|
*/
|
|
smp_store_release(&waiter->fl_blocker, NULL);
|
|
spin_unlock(&blocked_lock_lock);
|
|
return status;
|
|
}
|
|
EXPORT_SYMBOL(locks_delete_block);
|
|
|
|
/* Insert waiter into blocker's block list.
|
|
* We use a circular list so that processes can be easily woken up in
|
|
* the order they blocked. The documentation doesn't require this but
|
|
* it seems like the reasonable thing to do.
|
|
*
|
|
* Must be called with both the flc_lock and blocked_lock_lock held. The
|
|
* fl_blocked_requests list itself is protected by the blocked_lock_lock,
|
|
* but by ensuring that the flc_lock is also held on insertions we can avoid
|
|
* taking the blocked_lock_lock in some cases when we see that the
|
|
* fl_blocked_requests list is empty.
|
|
*
|
|
* Rather than just adding to the list, we check for conflicts with any existing
|
|
* waiters, and add beneath any waiter that blocks the new waiter.
|
|
* Thus wakeups don't happen until needed.
|
|
*/
|
|
static void __locks_insert_block(struct file_lock *blocker,
|
|
struct file_lock *waiter,
|
|
bool conflict(struct file_lock *,
|
|
struct file_lock *))
|
|
{
|
|
struct file_lock *fl;
|
|
BUG_ON(!list_empty(&waiter->fl_blocked_member));
|
|
|
|
new_blocker:
|
|
list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member)
|
|
if (conflict(fl, waiter)) {
|
|
blocker = fl;
|
|
goto new_blocker;
|
|
}
|
|
waiter->fl_blocker = blocker;
|
|
list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
|
|
if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
|
|
locks_insert_global_blocked(waiter);
|
|
|
|
/* The requests in waiter->fl_blocked are known to conflict with
|
|
* waiter, but might not conflict with blocker, or the requests
|
|
* and lock which block it. So they all need to be woken.
|
|
*/
|
|
__locks_wake_up_blocks(waiter);
|
|
}
|
|
|
|
/* Must be called with flc_lock held. */
|
|
static void locks_insert_block(struct file_lock *blocker,
|
|
struct file_lock *waiter,
|
|
bool conflict(struct file_lock *,
|
|
struct file_lock *))
|
|
{
|
|
spin_lock(&blocked_lock_lock);
|
|
__locks_insert_block(blocker, waiter, conflict);
|
|
spin_unlock(&blocked_lock_lock);
|
|
}
|
|
|
|
/*
|
|
* Wake up processes blocked waiting for blocker.
|
|
*
|
|
* Must be called with the inode->flc_lock held!
|
|
*/
|
|
static void locks_wake_up_blocks(struct file_lock *blocker)
|
|
{
|
|
/*
|
|
* Avoid taking global lock if list is empty. This is safe since new
|
|
* blocked requests are only added to the list under the flc_lock, and
|
|
* the flc_lock is always held here. Note that removal from the
|
|
* fl_blocked_requests list does not require the flc_lock, so we must
|
|
* recheck list_empty() after acquiring the blocked_lock_lock.
|
|
*/
|
|
if (list_empty(&blocker->fl_blocked_requests))
|
|
return;
|
|
|
|
spin_lock(&blocked_lock_lock);
|
|
__locks_wake_up_blocks(blocker);
|
|
spin_unlock(&blocked_lock_lock);
|
|
}
|
|
|
|
static void
|
|
locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
|
|
{
|
|
list_add_tail(&fl->fl_list, before);
|
|
locks_insert_global_locks(fl);
|
|
}
|
|
|
|
static void
|
|
locks_unlink_lock_ctx(struct file_lock *fl)
|
|
{
|
|
locks_delete_global_locks(fl);
|
|
list_del_init(&fl->fl_list);
|
|
locks_wake_up_blocks(fl);
|
|
}
|
|
|
|
static void
|
|
locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
|
|
{
|
|
locks_unlink_lock_ctx(fl);
|
|
if (dispose)
|
|
list_add(&fl->fl_list, dispose);
|
|
else
|
|
locks_free_lock(fl);
|
|
}
|
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
|
|
* checks for shared/exclusive status of overlapping locks.
|
|
*/
|
|
static bool locks_conflict(struct file_lock *caller_fl,
|
|
struct file_lock *sys_fl)
|
|
{
|
|
if (sys_fl->fl_type == F_WRLCK)
|
|
return true;
|
|
if (caller_fl->fl_type == F_WRLCK)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
|
|
* checking before calling the locks_conflict().
|
|
*/
|
|
static bool posix_locks_conflict(struct file_lock *caller_fl,
|
|
struct file_lock *sys_fl)
|
|
{
|
|
/* POSIX locks owned by the same process do not conflict with
|
|
* each other.
|
|
*/
|
|
if (posix_same_owner(caller_fl, sys_fl))
|
|
return false;
|
|
|
|
/* Check whether they overlap */
|
|
if (!locks_overlap(caller_fl, sys_fl))
|
|
return false;
|
|
|
|
return locks_conflict(caller_fl, sys_fl);
|
|
}
|
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
|
|
* checking before calling the locks_conflict().
|
|
*/
|
|
static bool flock_locks_conflict(struct file_lock *caller_fl,
|
|
struct file_lock *sys_fl)
|
|
{
|
|
/* FLOCK locks referring to the same filp do not conflict with
|
|
* each other.
|
|
*/
|
|
if (caller_fl->fl_file == sys_fl->fl_file)
|
|
return false;
|
|
if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
|
|
return false;
|
|
|
|
return locks_conflict(caller_fl, sys_fl);
|
|
}
|
|
|
|
void
|
|
posix_test_lock(struct file *filp, struct file_lock *fl)
|
|
{
|
|
struct file_lock *cfl;
|
|
struct file_lock_context *ctx;
|
|
struct inode *inode = locks_inode(filp);
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx || list_empty_careful(&ctx->flc_posix)) {
|
|
fl->fl_type = F_UNLCK;
|
|
return;
|
|
}
|
|
|
|
spin_lock(&ctx->flc_lock);
|
|
list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
|
|
if (posix_locks_conflict(fl, cfl)) {
|
|
locks_copy_conflock(fl, cfl);
|
|
goto out;
|
|
}
|
|
}
|
|
fl->fl_type = F_UNLCK;
|
|
out:
|
|
spin_unlock(&ctx->flc_lock);
|
|
return;
|
|
}
|
|
EXPORT_SYMBOL(posix_test_lock);
|
|
|
|
/*
|
|
* Deadlock detection:
|
|
*
|
|
* We attempt to detect deadlocks that are due purely to posix file
|
|
* locks.
|
|
*
|
|
* We assume that a task can be waiting for at most one lock at a time.
|
|
* So for any acquired lock, the process holding that lock may be
|
|
* waiting on at most one other lock. That lock in turns may be held by
|
|
* someone waiting for at most one other lock. Given a requested lock
|
|
* caller_fl which is about to wait for a conflicting lock block_fl, we
|
|
* follow this chain of waiters to ensure we are not about to create a
|
|
* cycle.
|
|
*
|
|
* Since we do this before we ever put a process to sleep on a lock, we
|
|
* are ensured that there is never a cycle; that is what guarantees that
|
|
* the while() loop in posix_locks_deadlock() eventually completes.
|
|
*
|
|
* Note: the above assumption may not be true when handling lock
|
|
* requests from a broken NFS client. It may also fail in the presence
|
|
* of tasks (such as posix threads) sharing the same open file table.
|
|
* To handle those cases, we just bail out after a few iterations.
|
|
*
|
|
* For FL_OFDLCK locks, the owner is the filp, not the files_struct.
|
|
* Because the owner is not even nominally tied to a thread of
|
|
* execution, the deadlock detection below can't reasonably work well. Just
|
|
* skip it for those.
|
|
*
|
|
* In principle, we could do a more limited deadlock detection on FL_OFDLCK
|
|
* locks that just checks for the case where two tasks are attempting to
|
|
* upgrade from read to write locks on the same inode.
|
|
*/
|
|
|
|
#define MAX_DEADLK_ITERATIONS 10
|
|
|
|
/* Find a lock that the owner of the given block_fl is blocking on. */
|
|
static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
|
|
{
|
|
struct file_lock *fl;
|
|
|
|
hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
|
|
if (posix_same_owner(fl, block_fl)) {
|
|
while (fl->fl_blocker)
|
|
fl = fl->fl_blocker;
|
|
return fl;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/* Must be called with the blocked_lock_lock held! */
|
|
static int posix_locks_deadlock(struct file_lock *caller_fl,
|
|
struct file_lock *block_fl)
|
|
{
|
|
int i = 0;
|
|
|
|
lockdep_assert_held(&blocked_lock_lock);
|
|
|
|
/*
|
|
* This deadlock detector can't reasonably detect deadlocks with
|
|
* FL_OFDLCK locks, since they aren't owned by a process, per-se.
|
|
*/
|
|
if (IS_OFDLCK(caller_fl))
|
|
return 0;
|
|
|
|
while ((block_fl = what_owner_is_waiting_for(block_fl))) {
|
|
if (i++ > MAX_DEADLK_ITERATIONS)
|
|
return 0;
|
|
if (posix_same_owner(caller_fl, block_fl))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
|
|
* after any leases, but before any posix locks.
|
|
*
|
|
* Note that if called with an FL_EXISTS argument, the caller may determine
|
|
* whether or not a lock was successfully freed by testing the return
|
|
* value for -ENOENT.
|
|
*/
|
|
static int flock_lock_inode(struct inode *inode, struct file_lock *request)
|
|
{
|
|
struct file_lock *new_fl = NULL;
|
|
struct file_lock *fl;
|
|
struct file_lock_context *ctx;
|
|
int error = 0;
|
|
bool found = false;
|
|
LIST_HEAD(dispose);
|
|
|
|
ctx = locks_get_lock_context(inode, request->fl_type);
|
|
if (!ctx) {
|
|
if (request->fl_type != F_UNLCK)
|
|
return -ENOMEM;
|
|
return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
|
|
}
|
|
|
|
if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
|
|
new_fl = locks_alloc_lock();
|
|
if (!new_fl)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
if (request->fl_flags & FL_ACCESS)
|
|
goto find_conflict;
|
|
|
|
list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
|
|
if (request->fl_file != fl->fl_file)
|
|
continue;
|
|
if (request->fl_type == fl->fl_type)
|
|
goto out;
|
|
found = true;
|
|
locks_delete_lock_ctx(fl, &dispose);
|
|
break;
|
|
}
|
|
|
|
if (request->fl_type == F_UNLCK) {
|
|
if ((request->fl_flags & FL_EXISTS) && !found)
|
|
error = -ENOENT;
|
|
goto out;
|
|
}
|
|
|
|
find_conflict:
|
|
list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
|
|
if (!flock_locks_conflict(request, fl))
|
|
continue;
|
|
error = -EAGAIN;
|
|
if (!(request->fl_flags & FL_SLEEP))
|
|
goto out;
|
|
error = FILE_LOCK_DEFERRED;
|
|
locks_insert_block(fl, request, flock_locks_conflict);
|
|
goto out;
|
|
}
|
|
if (request->fl_flags & FL_ACCESS)
|
|
goto out;
|
|
locks_copy_lock(new_fl, request);
|
|
locks_move_blocks(new_fl, request);
|
|
locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
|
|
new_fl = NULL;
|
|
error = 0;
|
|
|
|
out:
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
if (new_fl)
|
|
locks_free_lock(new_fl);
|
|
locks_dispose_list(&dispose);
|
|
trace_flock_lock_inode(inode, request, error);
|
|
return error;
|
|
}
|
|
|
|
static int posix_lock_inode(struct inode *inode, struct file_lock *request,
|
|
struct file_lock *conflock)
|
|
{
|
|
struct file_lock *fl, *tmp;
|
|
struct file_lock *new_fl = NULL;
|
|
struct file_lock *new_fl2 = NULL;
|
|
struct file_lock *left = NULL;
|
|
struct file_lock *right = NULL;
|
|
struct file_lock_context *ctx;
|
|
int error;
|
|
bool added = false;
|
|
LIST_HEAD(dispose);
|
|
|
|
ctx = locks_get_lock_context(inode, request->fl_type);
|
|
if (!ctx)
|
|
return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
|
|
|
|
/*
|
|
* We may need two file_lock structures for this operation,
|
|
* so we get them in advance to avoid races.
|
|
*
|
|
* In some cases we can be sure, that no new locks will be needed
|
|
*/
|
|
if (!(request->fl_flags & FL_ACCESS) &&
|
|
(request->fl_type != F_UNLCK ||
|
|
request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
|
|
new_fl = locks_alloc_lock();
|
|
new_fl2 = locks_alloc_lock();
|
|
}
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
/*
|
|
* New lock request. Walk all POSIX locks and look for conflicts. If
|
|
* there are any, either return error or put the request on the
|
|
* blocker's list of waiters and the global blocked_hash.
|
|
*/
|
|
if (request->fl_type != F_UNLCK) {
|
|
list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
|
|
if (!posix_locks_conflict(request, fl))
|
|
continue;
|
|
if (conflock)
|
|
locks_copy_conflock(conflock, fl);
|
|
error = -EAGAIN;
|
|
if (!(request->fl_flags & FL_SLEEP))
|
|
goto out;
|
|
/*
|
|
* Deadlock detection and insertion into the blocked
|
|
* locks list must be done while holding the same lock!
|
|
*/
|
|
error = -EDEADLK;
|
|
spin_lock(&blocked_lock_lock);
|
|
/*
|
|
* Ensure that we don't find any locks blocked on this
|
|
* request during deadlock detection.
|
|
*/
|
|
__locks_wake_up_blocks(request);
|
|
if (likely(!posix_locks_deadlock(request, fl))) {
|
|
error = FILE_LOCK_DEFERRED;
|
|
__locks_insert_block(fl, request,
|
|
posix_locks_conflict);
|
|
}
|
|
spin_unlock(&blocked_lock_lock);
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* If we're just looking for a conflict, we're done. */
|
|
error = 0;
|
|
if (request->fl_flags & FL_ACCESS)
|
|
goto out;
|
|
|
|
/* Find the first old lock with the same owner as the new lock */
|
|
list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
|
|
if (posix_same_owner(request, fl))
|
|
break;
|
|
}
|
|
|
|
/* Process locks with this owner. */
|
|
list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
|
|
if (!posix_same_owner(request, fl))
|
|
break;
|
|
|
|
/* Detect adjacent or overlapping regions (if same lock type) */
|
|
if (request->fl_type == fl->fl_type) {
|
|
/* In all comparisons of start vs end, use
|
|
* "start - 1" rather than "end + 1". If end
|
|
* is OFFSET_MAX, end + 1 will become negative.
|
|
*/
|
|
if (fl->fl_end < request->fl_start - 1)
|
|
continue;
|
|
/* If the next lock in the list has entirely bigger
|
|
* addresses than the new one, insert the lock here.
|
|
*/
|
|
if (fl->fl_start - 1 > request->fl_end)
|
|
break;
|
|
|
|
/* If we come here, the new and old lock are of the
|
|
* same type and adjacent or overlapping. Make one
|
|
* lock yielding from the lower start address of both
|
|
* locks to the higher end address.
|
|
*/
|
|
if (fl->fl_start > request->fl_start)
|
|
fl->fl_start = request->fl_start;
|
|
else
|
|
request->fl_start = fl->fl_start;
|
|
if (fl->fl_end < request->fl_end)
|
|
fl->fl_end = request->fl_end;
|
|
else
|
|
request->fl_end = fl->fl_end;
|
|
if (added) {
|
|
locks_delete_lock_ctx(fl, &dispose);
|
|
continue;
|
|
}
|
|
request = fl;
|
|
added = true;
|
|
} else {
|
|
/* Processing for different lock types is a bit
|
|
* more complex.
|
|
*/
|
|
if (fl->fl_end < request->fl_start)
|
|
continue;
|
|
if (fl->fl_start > request->fl_end)
|
|
break;
|
|
if (request->fl_type == F_UNLCK)
|
|
added = true;
|
|
if (fl->fl_start < request->fl_start)
|
|
left = fl;
|
|
/* If the next lock in the list has a higher end
|
|
* address than the new one, insert the new one here.
|
|
*/
|
|
if (fl->fl_end > request->fl_end) {
|
|
right = fl;
|
|
break;
|
|
}
|
|
if (fl->fl_start >= request->fl_start) {
|
|
/* The new lock completely replaces an old
|
|
* one (This may happen several times).
|
|
*/
|
|
if (added) {
|
|
locks_delete_lock_ctx(fl, &dispose);
|
|
continue;
|
|
}
|
|
/*
|
|
* Replace the old lock with new_fl, and
|
|
* remove the old one. It's safe to do the
|
|
* insert here since we know that we won't be
|
|
* using new_fl later, and that the lock is
|
|
* just replacing an existing lock.
|
|
*/
|
|
error = -ENOLCK;
|
|
if (!new_fl)
|
|
goto out;
|
|
locks_copy_lock(new_fl, request);
|
|
request = new_fl;
|
|
new_fl = NULL;
|
|
locks_insert_lock_ctx(request, &fl->fl_list);
|
|
locks_delete_lock_ctx(fl, &dispose);
|
|
added = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The above code only modifies existing locks in case of merging or
|
|
* replacing. If new lock(s) need to be inserted all modifications are
|
|
* done below this, so it's safe yet to bail out.
|
|
*/
|
|
error = -ENOLCK; /* "no luck" */
|
|
if (right && left == right && !new_fl2)
|
|
goto out;
|
|
|
|
error = 0;
|
|
if (!added) {
|
|
if (request->fl_type == F_UNLCK) {
|
|
if (request->fl_flags & FL_EXISTS)
|
|
error = -ENOENT;
|
|
goto out;
|
|
}
|
|
|
|
if (!new_fl) {
|
|
error = -ENOLCK;
|
|
goto out;
|
|
}
|
|
locks_copy_lock(new_fl, request);
|
|
locks_move_blocks(new_fl, request);
|
|
locks_insert_lock_ctx(new_fl, &fl->fl_list);
|
|
fl = new_fl;
|
|
new_fl = NULL;
|
|
}
|
|
if (right) {
|
|
if (left == right) {
|
|
/* The new lock breaks the old one in two pieces,
|
|
* so we have to use the second new lock.
|
|
*/
|
|
left = new_fl2;
|
|
new_fl2 = NULL;
|
|
locks_copy_lock(left, right);
|
|
locks_insert_lock_ctx(left, &fl->fl_list);
|
|
}
|
|
right->fl_start = request->fl_end + 1;
|
|
locks_wake_up_blocks(right);
|
|
}
|
|
if (left) {
|
|
left->fl_end = request->fl_start - 1;
|
|
locks_wake_up_blocks(left);
|
|
}
|
|
out:
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
/*
|
|
* Free any unused locks.
|
|
*/
|
|
if (new_fl)
|
|
locks_free_lock(new_fl);
|
|
if (new_fl2)
|
|
locks_free_lock(new_fl2);
|
|
locks_dispose_list(&dispose);
|
|
trace_posix_lock_inode(inode, request, error);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* posix_lock_file - Apply a POSIX-style lock to a file
|
|
* @filp: The file to apply the lock to
|
|
* @fl: The lock to be applied
|
|
* @conflock: Place to return a copy of the conflicting lock, if found.
|
|
*
|
|
* Add a POSIX style lock to a file.
|
|
* We merge adjacent & overlapping locks whenever possible.
|
|
* POSIX locks are sorted by owner task, then by starting address
|
|
*
|
|
* Note that if called with an FL_EXISTS argument, the caller may determine
|
|
* whether or not a lock was successfully freed by testing the return
|
|
* value for -ENOENT.
|
|
*/
|
|
int posix_lock_file(struct file *filp, struct file_lock *fl,
|
|
struct file_lock *conflock)
|
|
{
|
|
return posix_lock_inode(locks_inode(filp), fl, conflock);
|
|
}
|
|
EXPORT_SYMBOL(posix_lock_file);
|
|
|
|
/**
|
|
* posix_lock_inode_wait - Apply a POSIX-style lock to a file
|
|
* @inode: inode of file to which lock request should be applied
|
|
* @fl: The lock to be applied
|
|
*
|
|
* Apply a POSIX style lock request to an inode.
|
|
*/
|
|
static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
|
|
{
|
|
int error;
|
|
might_sleep ();
|
|
for (;;) {
|
|
error = posix_lock_inode(inode, fl, NULL);
|
|
if (error != FILE_LOCK_DEFERRED)
|
|
break;
|
|
error = wait_event_interruptible(fl->fl_wait,
|
|
list_empty(&fl->fl_blocked_member));
|
|
if (error)
|
|
break;
|
|
}
|
|
locks_delete_block(fl);
|
|
return error;
|
|
}
|
|
|
|
#ifdef CONFIG_MANDATORY_FILE_LOCKING
|
|
/**
|
|
* locks_mandatory_locked - Check for an active lock
|
|
* @file: the file to check
|
|
*
|
|
* Searches the inode's list of locks to find any POSIX locks which conflict.
|
|
* This function is called from locks_verify_locked() only.
|
|
*/
|
|
int locks_mandatory_locked(struct file *file)
|
|
{
|
|
int ret;
|
|
struct inode *inode = locks_inode(file);
|
|
struct file_lock_context *ctx;
|
|
struct file_lock *fl;
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx || list_empty_careful(&ctx->flc_posix))
|
|
return 0;
|
|
|
|
/*
|
|
* Search the lock list for this inode for any POSIX locks.
|
|
*/
|
|
spin_lock(&ctx->flc_lock);
|
|
ret = 0;
|
|
list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
|
|
if (fl->fl_owner != current->files &&
|
|
fl->fl_owner != file) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
}
|
|
spin_unlock(&ctx->flc_lock);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* locks_mandatory_area - Check for a conflicting lock
|
|
* @inode: the file to check
|
|
* @filp: how the file was opened (if it was)
|
|
* @start: first byte in the file to check
|
|
* @end: lastbyte in the file to check
|
|
* @type: %F_WRLCK for a write lock, else %F_RDLCK
|
|
*
|
|
* Searches the inode's list of locks to find any POSIX locks which conflict.
|
|
*/
|
|
int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
|
|
loff_t end, unsigned char type)
|
|
{
|
|
struct file_lock fl;
|
|
int error;
|
|
bool sleep = false;
|
|
|
|
locks_init_lock(&fl);
|
|
fl.fl_pid = current->tgid;
|
|
fl.fl_file = filp;
|
|
fl.fl_flags = FL_POSIX | FL_ACCESS;
|
|
if (filp && !(filp->f_flags & O_NONBLOCK))
|
|
sleep = true;
|
|
fl.fl_type = type;
|
|
fl.fl_start = start;
|
|
fl.fl_end = end;
|
|
|
|
for (;;) {
|
|
if (filp) {
|
|
fl.fl_owner = filp;
|
|
fl.fl_flags &= ~FL_SLEEP;
|
|
error = posix_lock_inode(inode, &fl, NULL);
|
|
if (!error)
|
|
break;
|
|
}
|
|
|
|
if (sleep)
|
|
fl.fl_flags |= FL_SLEEP;
|
|
fl.fl_owner = current->files;
|
|
error = posix_lock_inode(inode, &fl, NULL);
|
|
if (error != FILE_LOCK_DEFERRED)
|
|
break;
|
|
error = wait_event_interruptible(fl.fl_wait,
|
|
list_empty(&fl.fl_blocked_member));
|
|
if (!error) {
|
|
/*
|
|
* If we've been sleeping someone might have
|
|
* changed the permissions behind our back.
|
|
*/
|
|
if (__mandatory_lock(inode))
|
|
continue;
|
|
}
|
|
|
|
break;
|
|
}
|
|
locks_delete_block(&fl);
|
|
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(locks_mandatory_area);
|
|
#endif /* CONFIG_MANDATORY_FILE_LOCKING */
|
|
|
|
static void lease_clear_pending(struct file_lock *fl, int arg)
|
|
{
|
|
switch (arg) {
|
|
case F_UNLCK:
|
|
fl->fl_flags &= ~FL_UNLOCK_PENDING;
|
|
/* fall through */
|
|
case F_RDLCK:
|
|
fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
|
|
}
|
|
}
|
|
|
|
/* We already had a lease on this file; just change its type */
|
|
int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
|
|
{
|
|
int error = assign_type(fl, arg);
|
|
|
|
if (error)
|
|
return error;
|
|
lease_clear_pending(fl, arg);
|
|
locks_wake_up_blocks(fl);
|
|
if (arg == F_UNLCK) {
|
|
struct file *filp = fl->fl_file;
|
|
|
|
f_delown(filp);
|
|
filp->f_owner.signum = 0;
|
|
fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
|
|
if (fl->fl_fasync != NULL) {
|
|
printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
|
|
fl->fl_fasync = NULL;
|
|
}
|
|
locks_delete_lock_ctx(fl, dispose);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(lease_modify);
|
|
|
|
static bool past_time(unsigned long then)
|
|
{
|
|
if (!then)
|
|
/* 0 is a special value meaning "this never expires": */
|
|
return false;
|
|
return time_after(jiffies, then);
|
|
}
|
|
|
|
static void time_out_leases(struct inode *inode, struct list_head *dispose)
|
|
{
|
|
struct file_lock_context *ctx = inode->i_flctx;
|
|
struct file_lock *fl, *tmp;
|
|
|
|
lockdep_assert_held(&ctx->flc_lock);
|
|
|
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
|
|
trace_time_out_leases(inode, fl);
|
|
if (past_time(fl->fl_downgrade_time))
|
|
lease_modify(fl, F_RDLCK, dispose);
|
|
if (past_time(fl->fl_break_time))
|
|
lease_modify(fl, F_UNLCK, dispose);
|
|
}
|
|
}
|
|
|
|
static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
|
|
{
|
|
bool rc;
|
|
|
|
if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
|
|
rc = false;
|
|
goto trace;
|
|
}
|
|
if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
|
|
rc = false;
|
|
goto trace;
|
|
}
|
|
|
|
rc = locks_conflict(breaker, lease);
|
|
trace:
|
|
trace_leases_conflict(rc, lease, breaker);
|
|
return rc;
|
|
}
|
|
|
|
static bool
|
|
any_leases_conflict(struct inode *inode, struct file_lock *breaker)
|
|
{
|
|
struct file_lock_context *ctx = inode->i_flctx;
|
|
struct file_lock *fl;
|
|
|
|
lockdep_assert_held(&ctx->flc_lock);
|
|
|
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
|
|
if (leases_conflict(fl, breaker))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* __break_lease - revoke all outstanding leases on file
|
|
* @inode: the inode of the file to return
|
|
* @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
|
|
* break all leases
|
|
* @type: FL_LEASE: break leases and delegations; FL_DELEG: break
|
|
* only delegations
|
|
*
|
|
* break_lease (inlined for speed) has checked there already is at least
|
|
* some kind of lock (maybe a lease) on this file. Leases are broken on
|
|
* a call to open() or truncate(). This function can sleep unless you
|
|
* specified %O_NONBLOCK to your open().
|
|
*/
|
|
int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
|
|
{
|
|
int error = 0;
|
|
struct file_lock_context *ctx;
|
|
struct file_lock *new_fl, *fl, *tmp;
|
|
unsigned long break_time;
|
|
int want_write = (mode & O_ACCMODE) != O_RDONLY;
|
|
LIST_HEAD(dispose);
|
|
|
|
new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
|
|
if (IS_ERR(new_fl))
|
|
return PTR_ERR(new_fl);
|
|
new_fl->fl_flags = type;
|
|
|
|
/* typically we will check that ctx is non-NULL before calling */
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx) {
|
|
WARN_ON_ONCE(1);
|
|
goto free_lock;
|
|
}
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
|
|
time_out_leases(inode, &dispose);
|
|
|
|
if (!any_leases_conflict(inode, new_fl))
|
|
goto out;
|
|
|
|
break_time = 0;
|
|
if (lease_break_time > 0) {
|
|
break_time = jiffies + lease_break_time * HZ;
|
|
if (break_time == 0)
|
|
break_time++; /* so that 0 means no break time */
|
|
}
|
|
|
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
|
|
if (!leases_conflict(fl, new_fl))
|
|
continue;
|
|
if (want_write) {
|
|
if (fl->fl_flags & FL_UNLOCK_PENDING)
|
|
continue;
|
|
fl->fl_flags |= FL_UNLOCK_PENDING;
|
|
fl->fl_break_time = break_time;
|
|
} else {
|
|
if (lease_breaking(fl))
|
|
continue;
|
|
fl->fl_flags |= FL_DOWNGRADE_PENDING;
|
|
fl->fl_downgrade_time = break_time;
|
|
}
|
|
if (fl->fl_lmops->lm_break(fl))
|
|
locks_delete_lock_ctx(fl, &dispose);
|
|
}
|
|
|
|
if (list_empty(&ctx->flc_lease))
|
|
goto out;
|
|
|
|
if (mode & O_NONBLOCK) {
|
|
trace_break_lease_noblock(inode, new_fl);
|
|
error = -EWOULDBLOCK;
|
|
goto out;
|
|
}
|
|
|
|
restart:
|
|
fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
|
|
break_time = fl->fl_break_time;
|
|
if (break_time != 0)
|
|
break_time -= jiffies;
|
|
if (break_time == 0)
|
|
break_time++;
|
|
locks_insert_block(fl, new_fl, leases_conflict);
|
|
trace_break_lease_block(inode, new_fl);
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
|
|
locks_dispose_list(&dispose);
|
|
error = wait_event_interruptible_timeout(new_fl->fl_wait,
|
|
list_empty(&new_fl->fl_blocked_member),
|
|
break_time);
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
trace_break_lease_unblock(inode, new_fl);
|
|
locks_delete_block(new_fl);
|
|
if (error >= 0) {
|
|
/*
|
|
* Wait for the next conflicting lease that has not been
|
|
* broken yet
|
|
*/
|
|
if (error == 0)
|
|
time_out_leases(inode, &dispose);
|
|
if (any_leases_conflict(inode, new_fl))
|
|
goto restart;
|
|
error = 0;
|
|
}
|
|
out:
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
locks_dispose_list(&dispose);
|
|
free_lock:
|
|
locks_free_lock(new_fl);
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(__break_lease);
|
|
|
|
/**
|
|
* lease_get_mtime - update modified time of an inode with exclusive lease
|
|
* @inode: the inode
|
|
* @time: pointer to a timespec which contains the last modified time
|
|
*
|
|
* This is to force NFS clients to flush their caches for files with
|
|
* exclusive leases. The justification is that if someone has an
|
|
* exclusive lease, then they could be modifying it.
|
|
*/
|
|
void lease_get_mtime(struct inode *inode, struct timespec64 *time)
|
|
{
|
|
bool has_lease = false;
|
|
struct file_lock_context *ctx;
|
|
struct file_lock *fl;
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (ctx && !list_empty_careful(&ctx->flc_lease)) {
|
|
spin_lock(&ctx->flc_lock);
|
|
fl = list_first_entry_or_null(&ctx->flc_lease,
|
|
struct file_lock, fl_list);
|
|
if (fl && (fl->fl_type == F_WRLCK))
|
|
has_lease = true;
|
|
spin_unlock(&ctx->flc_lock);
|
|
}
|
|
|
|
if (has_lease)
|
|
*time = current_time(inode);
|
|
}
|
|
EXPORT_SYMBOL(lease_get_mtime);
|
|
|
|
/**
|
|
* fcntl_getlease - Enquire what lease is currently active
|
|
* @filp: the file
|
|
*
|
|
* The value returned by this function will be one of
|
|
* (if no lease break is pending):
|
|
*
|
|
* %F_RDLCK to indicate a shared lease is held.
|
|
*
|
|
* %F_WRLCK to indicate an exclusive lease is held.
|
|
*
|
|
* %F_UNLCK to indicate no lease is held.
|
|
*
|
|
* (if a lease break is pending):
|
|
*
|
|
* %F_RDLCK to indicate an exclusive lease needs to be
|
|
* changed to a shared lease (or removed).
|
|
*
|
|
* %F_UNLCK to indicate the lease needs to be removed.
|
|
*
|
|
* XXX: sfr & willy disagree over whether F_INPROGRESS
|
|
* should be returned to userspace.
|
|
*/
|
|
int fcntl_getlease(struct file *filp)
|
|
{
|
|
struct file_lock *fl;
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file_lock_context *ctx;
|
|
int type = F_UNLCK;
|
|
LIST_HEAD(dispose);
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (ctx && !list_empty_careful(&ctx->flc_lease)) {
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
time_out_leases(inode, &dispose);
|
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
|
|
if (fl->fl_file != filp)
|
|
continue;
|
|
type = target_leasetype(fl);
|
|
break;
|
|
}
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
|
|
locks_dispose_list(&dispose);
|
|
}
|
|
return type;
|
|
}
|
|
|
|
/**
|
|
* check_conflicting_open - see if the given file points to an inode that has
|
|
* an existing open that would conflict with the
|
|
* desired lease.
|
|
* @filp: file to check
|
|
* @arg: type of lease that we're trying to acquire
|
|
* @flags: current lock flags
|
|
*
|
|
* Check to see if there's an existing open fd on this file that would
|
|
* conflict with the lease we're trying to set.
|
|
*/
|
|
static int
|
|
check_conflicting_open(struct file *filp, const long arg, int flags)
|
|
{
|
|
struct inode *inode = locks_inode(filp);
|
|
int self_wcount = 0, self_rcount = 0;
|
|
|
|
if (flags & FL_LAYOUT)
|
|
return 0;
|
|
|
|
if (arg == F_RDLCK)
|
|
return inode_is_open_for_write(inode) ? -EAGAIN : 0;
|
|
else if (arg != F_WRLCK)
|
|
return 0;
|
|
|
|
/*
|
|
* Make sure that only read/write count is from lease requestor.
|
|
* Note that this will result in denying write leases when i_writecount
|
|
* is negative, which is what we want. (We shouldn't grant write leases
|
|
* on files open for execution.)
|
|
*/
|
|
if (filp->f_mode & FMODE_WRITE)
|
|
self_wcount = 1;
|
|
else if (filp->f_mode & FMODE_READ)
|
|
self_rcount = 1;
|
|
|
|
if (atomic_read(&inode->i_writecount) != self_wcount ||
|
|
atomic_read(&inode->i_readcount) != self_rcount)
|
|
return -EAGAIN;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
|
|
{
|
|
struct file_lock *fl, *my_fl = NULL, *lease;
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file_lock_context *ctx;
|
|
bool is_deleg = (*flp)->fl_flags & FL_DELEG;
|
|
int error;
|
|
LIST_HEAD(dispose);
|
|
|
|
lease = *flp;
|
|
trace_generic_add_lease(inode, lease);
|
|
|
|
/* Note that arg is never F_UNLCK here */
|
|
ctx = locks_get_lock_context(inode, arg);
|
|
if (!ctx)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* In the delegation case we need mutual exclusion with
|
|
* a number of operations that take the i_mutex. We trylock
|
|
* because delegations are an optional optimization, and if
|
|
* there's some chance of a conflict--we'd rather not
|
|
* bother, maybe that's a sign this just isn't a good file to
|
|
* hand out a delegation on.
|
|
*/
|
|
if (is_deleg && !inode_trylock(inode))
|
|
return -EAGAIN;
|
|
|
|
if (is_deleg && arg == F_WRLCK) {
|
|
/* Write delegations are not currently supported: */
|
|
inode_unlock(inode);
|
|
WARN_ON_ONCE(1);
|
|
return -EINVAL;
|
|
}
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
time_out_leases(inode, &dispose);
|
|
error = check_conflicting_open(filp, arg, lease->fl_flags);
|
|
if (error)
|
|
goto out;
|
|
|
|
/*
|
|
* At this point, we know that if there is an exclusive
|
|
* lease on this file, then we hold it on this filp
|
|
* (otherwise our open of this file would have blocked).
|
|
* And if we are trying to acquire an exclusive lease,
|
|
* then the file is not open by anyone (including us)
|
|
* except for this filp.
|
|
*/
|
|
error = -EAGAIN;
|
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
|
|
if (fl->fl_file == filp &&
|
|
fl->fl_owner == lease->fl_owner) {
|
|
my_fl = fl;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* No exclusive leases if someone else has a lease on
|
|
* this file:
|
|
*/
|
|
if (arg == F_WRLCK)
|
|
goto out;
|
|
/*
|
|
* Modifying our existing lease is OK, but no getting a
|
|
* new lease if someone else is opening for write:
|
|
*/
|
|
if (fl->fl_flags & FL_UNLOCK_PENDING)
|
|
goto out;
|
|
}
|
|
|
|
if (my_fl != NULL) {
|
|
lease = my_fl;
|
|
error = lease->fl_lmops->lm_change(lease, arg, &dispose);
|
|
if (error)
|
|
goto out;
|
|
goto out_setup;
|
|
}
|
|
|
|
error = -EINVAL;
|
|
if (!leases_enable)
|
|
goto out;
|
|
|
|
locks_insert_lock_ctx(lease, &ctx->flc_lease);
|
|
/*
|
|
* The check in break_lease() is lockless. It's possible for another
|
|
* open to race in after we did the earlier check for a conflicting
|
|
* open but before the lease was inserted. Check again for a
|
|
* conflicting open and cancel the lease if there is one.
|
|
*
|
|
* We also add a barrier here to ensure that the insertion of the lock
|
|
* precedes these checks.
|
|
*/
|
|
smp_mb();
|
|
error = check_conflicting_open(filp, arg, lease->fl_flags);
|
|
if (error) {
|
|
locks_unlink_lock_ctx(lease);
|
|
goto out;
|
|
}
|
|
|
|
out_setup:
|
|
if (lease->fl_lmops->lm_setup)
|
|
lease->fl_lmops->lm_setup(lease, priv);
|
|
out:
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
locks_dispose_list(&dispose);
|
|
if (is_deleg)
|
|
inode_unlock(inode);
|
|
if (!error && !my_fl)
|
|
*flp = NULL;
|
|
return error;
|
|
}
|
|
|
|
static int generic_delete_lease(struct file *filp, void *owner)
|
|
{
|
|
int error = -EAGAIN;
|
|
struct file_lock *fl, *victim = NULL;
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file_lock_context *ctx;
|
|
LIST_HEAD(dispose);
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx) {
|
|
trace_generic_delete_lease(inode, NULL);
|
|
return error;
|
|
}
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
|
|
if (fl->fl_file == filp &&
|
|
fl->fl_owner == owner) {
|
|
victim = fl;
|
|
break;
|
|
}
|
|
}
|
|
trace_generic_delete_lease(inode, victim);
|
|
if (victim)
|
|
error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
locks_dispose_list(&dispose);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* generic_setlease - sets a lease on an open file
|
|
* @filp: file pointer
|
|
* @arg: type of lease to obtain
|
|
* @flp: input - file_lock to use, output - file_lock inserted
|
|
* @priv: private data for lm_setup (may be NULL if lm_setup
|
|
* doesn't require it)
|
|
*
|
|
* The (input) flp->fl_lmops->lm_break function is required
|
|
* by break_lease().
|
|
*/
|
|
int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
|
|
void **priv)
|
|
{
|
|
struct inode *inode = locks_inode(filp);
|
|
int error;
|
|
|
|
if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
|
|
return -EACCES;
|
|
if (!S_ISREG(inode->i_mode))
|
|
return -EINVAL;
|
|
error = security_file_lock(filp, arg);
|
|
if (error)
|
|
return error;
|
|
|
|
switch (arg) {
|
|
case F_UNLCK:
|
|
return generic_delete_lease(filp, *priv);
|
|
case F_RDLCK:
|
|
case F_WRLCK:
|
|
if (!(*flp)->fl_lmops->lm_break) {
|
|
WARN_ON_ONCE(1);
|
|
return -ENOLCK;
|
|
}
|
|
|
|
return generic_add_lease(filp, arg, flp, priv);
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(generic_setlease);
|
|
|
|
#if IS_ENABLED(CONFIG_SRCU)
|
|
/*
|
|
* Kernel subsystems can register to be notified on any attempt to set
|
|
* a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
|
|
* to close files that it may have cached when there is an attempt to set a
|
|
* conflicting lease.
|
|
*/
|
|
static struct srcu_notifier_head lease_notifier_chain;
|
|
|
|
static inline void
|
|
lease_notifier_chain_init(void)
|
|
{
|
|
srcu_init_notifier_head(&lease_notifier_chain);
|
|
}
|
|
|
|
static inline void
|
|
setlease_notifier(long arg, struct file_lock *lease)
|
|
{
|
|
if (arg != F_UNLCK)
|
|
srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
|
|
}
|
|
|
|
int lease_register_notifier(struct notifier_block *nb)
|
|
{
|
|
return srcu_notifier_chain_register(&lease_notifier_chain, nb);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lease_register_notifier);
|
|
|
|
void lease_unregister_notifier(struct notifier_block *nb)
|
|
{
|
|
srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lease_unregister_notifier);
|
|
|
|
#else /* !IS_ENABLED(CONFIG_SRCU) */
|
|
static inline void
|
|
lease_notifier_chain_init(void)
|
|
{
|
|
}
|
|
|
|
static inline void
|
|
setlease_notifier(long arg, struct file_lock *lease)
|
|
{
|
|
}
|
|
|
|
int lease_register_notifier(struct notifier_block *nb)
|
|
{
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lease_register_notifier);
|
|
|
|
void lease_unregister_notifier(struct notifier_block *nb)
|
|
{
|
|
}
|
|
EXPORT_SYMBOL_GPL(lease_unregister_notifier);
|
|
|
|
#endif /* IS_ENABLED(CONFIG_SRCU) */
|
|
|
|
/**
|
|
* vfs_setlease - sets a lease on an open file
|
|
* @filp: file pointer
|
|
* @arg: type of lease to obtain
|
|
* @lease: file_lock to use when adding a lease
|
|
* @priv: private info for lm_setup when adding a lease (may be
|
|
* NULL if lm_setup doesn't require it)
|
|
*
|
|
* Call this to establish a lease on the file. The "lease" argument is not
|
|
* used for F_UNLCK requests and may be NULL. For commands that set or alter
|
|
* an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
|
|
* set; if not, this function will return -ENOLCK (and generate a scary-looking
|
|
* stack trace).
|
|
*
|
|
* The "priv" pointer is passed directly to the lm_setup function as-is. It
|
|
* may be NULL if the lm_setup operation doesn't require it.
|
|
*/
|
|
int
|
|
vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
|
|
{
|
|
if (lease)
|
|
setlease_notifier(arg, *lease);
|
|
if (filp->f_op->setlease)
|
|
return filp->f_op->setlease(filp, arg, lease, priv);
|
|
else
|
|
return generic_setlease(filp, arg, lease, priv);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_setlease);
|
|
|
|
static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
|
|
{
|
|
struct file_lock *fl;
|
|
struct fasync_struct *new;
|
|
int error;
|
|
|
|
fl = lease_alloc(filp, arg);
|
|
if (IS_ERR(fl))
|
|
return PTR_ERR(fl);
|
|
|
|
new = fasync_alloc();
|
|
if (!new) {
|
|
locks_free_lock(fl);
|
|
return -ENOMEM;
|
|
}
|
|
new->fa_fd = fd;
|
|
|
|
error = vfs_setlease(filp, arg, &fl, (void **)&new);
|
|
if (fl)
|
|
locks_free_lock(fl);
|
|
if (new)
|
|
fasync_free(new);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* fcntl_setlease - sets a lease on an open file
|
|
* @fd: open file descriptor
|
|
* @filp: file pointer
|
|
* @arg: type of lease to obtain
|
|
*
|
|
* Call this fcntl to establish a lease on the file.
|
|
* Note that you also need to call %F_SETSIG to
|
|
* receive a signal when the lease is broken.
|
|
*/
|
|
int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
|
|
{
|
|
if (arg == F_UNLCK)
|
|
return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
|
|
return do_fcntl_add_lease(fd, filp, arg);
|
|
}
|
|
|
|
/**
|
|
* flock_lock_inode_wait - Apply a FLOCK-style lock to a file
|
|
* @inode: inode of the file to apply to
|
|
* @fl: The lock to be applied
|
|
*
|
|
* Apply a FLOCK style lock request to an inode.
|
|
*/
|
|
static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
|
|
{
|
|
int error;
|
|
might_sleep();
|
|
for (;;) {
|
|
error = flock_lock_inode(inode, fl);
|
|
if (error != FILE_LOCK_DEFERRED)
|
|
break;
|
|
error = wait_event_interruptible(fl->fl_wait,
|
|
list_empty(&fl->fl_blocked_member));
|
|
if (error)
|
|
break;
|
|
}
|
|
locks_delete_block(fl);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* locks_lock_inode_wait - Apply a lock to an inode
|
|
* @inode: inode of the file to apply to
|
|
* @fl: The lock to be applied
|
|
*
|
|
* Apply a POSIX or FLOCK style lock request to an inode.
|
|
*/
|
|
int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
|
|
{
|
|
int res = 0;
|
|
switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
|
|
case FL_POSIX:
|
|
res = posix_lock_inode_wait(inode, fl);
|
|
break;
|
|
case FL_FLOCK:
|
|
res = flock_lock_inode_wait(inode, fl);
|
|
break;
|
|
default:
|
|
BUG();
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(locks_lock_inode_wait);
|
|
|
|
/**
|
|
* sys_flock: - flock() system call.
|
|
* @fd: the file descriptor to lock.
|
|
* @cmd: the type of lock to apply.
|
|
*
|
|
* Apply a %FL_FLOCK style lock to an open file descriptor.
|
|
* The @cmd can be one of:
|
|
*
|
|
* - %LOCK_SH -- a shared lock.
|
|
* - %LOCK_EX -- an exclusive lock.
|
|
* - %LOCK_UN -- remove an existing lock.
|
|
* - %LOCK_MAND -- a 'mandatory' flock.
|
|
* This exists to emulate Windows Share Modes.
|
|
*
|
|
* %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
|
|
* processes read and write access respectively.
|
|
*/
|
|
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
struct file_lock *lock;
|
|
int can_sleep, unlock;
|
|
int error;
|
|
|
|
error = -EBADF;
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
can_sleep = !(cmd & LOCK_NB);
|
|
cmd &= ~LOCK_NB;
|
|
unlock = (cmd == LOCK_UN);
|
|
|
|
if (!unlock && !(cmd & LOCK_MAND) &&
|
|
!(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
|
|
goto out_putf;
|
|
|
|
lock = flock_make_lock(f.file, cmd, NULL);
|
|
if (IS_ERR(lock)) {
|
|
error = PTR_ERR(lock);
|
|
goto out_putf;
|
|
}
|
|
|
|
if (can_sleep)
|
|
lock->fl_flags |= FL_SLEEP;
|
|
|
|
error = security_file_lock(f.file, lock->fl_type);
|
|
if (error)
|
|
goto out_free;
|
|
|
|
if (f.file->f_op->flock)
|
|
error = f.file->f_op->flock(f.file,
|
|
(can_sleep) ? F_SETLKW : F_SETLK,
|
|
lock);
|
|
else
|
|
error = locks_lock_file_wait(f.file, lock);
|
|
|
|
out_free:
|
|
locks_free_lock(lock);
|
|
|
|
out_putf:
|
|
fdput(f);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* vfs_test_lock - test file byte range lock
|
|
* @filp: The file to test lock for
|
|
* @fl: The lock to test; also used to hold result
|
|
*
|
|
* Returns -ERRNO on failure. Indicates presence of conflicting lock by
|
|
* setting conf->fl_type to something other than F_UNLCK.
|
|
*/
|
|
int vfs_test_lock(struct file *filp, struct file_lock *fl)
|
|
{
|
|
if (filp->f_op->lock)
|
|
return filp->f_op->lock(filp, F_GETLK, fl);
|
|
posix_test_lock(filp, fl);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_test_lock);
|
|
|
|
/**
|
|
* locks_translate_pid - translate a file_lock's fl_pid number into a namespace
|
|
* @fl: The file_lock who's fl_pid should be translated
|
|
* @ns: The namespace into which the pid should be translated
|
|
*
|
|
* Used to tranlate a fl_pid into a namespace virtual pid number
|
|
*/
|
|
static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
|
|
{
|
|
pid_t vnr;
|
|
struct pid *pid;
|
|
|
|
if (IS_OFDLCK(fl))
|
|
return -1;
|
|
if (IS_REMOTELCK(fl))
|
|
return fl->fl_pid;
|
|
/*
|
|
* If the flock owner process is dead and its pid has been already
|
|
* freed, the translation below won't work, but we still want to show
|
|
* flock owner pid number in init pidns.
|
|
*/
|
|
if (ns == &init_pid_ns)
|
|
return (pid_t)fl->fl_pid;
|
|
|
|
rcu_read_lock();
|
|
pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
|
|
vnr = pid_nr_ns(pid, ns);
|
|
rcu_read_unlock();
|
|
return vnr;
|
|
}
|
|
|
|
static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
|
|
{
|
|
flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
|
|
#if BITS_PER_LONG == 32
|
|
/*
|
|
* Make sure we can represent the posix lock via
|
|
* legacy 32bit flock.
|
|
*/
|
|
if (fl->fl_start > OFFT_OFFSET_MAX)
|
|
return -EOVERFLOW;
|
|
if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
|
|
return -EOVERFLOW;
|
|
#endif
|
|
flock->l_start = fl->fl_start;
|
|
flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
|
|
fl->fl_end - fl->fl_start + 1;
|
|
flock->l_whence = 0;
|
|
flock->l_type = fl->fl_type;
|
|
return 0;
|
|
}
|
|
|
|
#if BITS_PER_LONG == 32
|
|
static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
|
|
{
|
|
flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
|
|
flock->l_start = fl->fl_start;
|
|
flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
|
|
fl->fl_end - fl->fl_start + 1;
|
|
flock->l_whence = 0;
|
|
flock->l_type = fl->fl_type;
|
|
}
|
|
#endif
|
|
|
|
/* Report the first existing lock that would conflict with l.
|
|
* This implements the F_GETLK command of fcntl().
|
|
*/
|
|
int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
|
|
{
|
|
struct file_lock *fl;
|
|
int error;
|
|
|
|
fl = locks_alloc_lock();
|
|
if (fl == NULL)
|
|
return -ENOMEM;
|
|
error = -EINVAL;
|
|
if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
|
|
goto out;
|
|
|
|
error = flock_to_posix_lock(filp, fl, flock);
|
|
if (error)
|
|
goto out;
|
|
|
|
if (cmd == F_OFD_GETLK) {
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_GETLK;
|
|
fl->fl_flags |= FL_OFDLCK;
|
|
fl->fl_owner = filp;
|
|
}
|
|
|
|
error = vfs_test_lock(filp, fl);
|
|
if (error)
|
|
goto out;
|
|
|
|
flock->l_type = fl->fl_type;
|
|
if (fl->fl_type != F_UNLCK) {
|
|
error = posix_lock_to_flock(flock, fl);
|
|
if (error)
|
|
goto out;
|
|
}
|
|
out:
|
|
locks_free_lock(fl);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* vfs_lock_file - file byte range lock
|
|
* @filp: The file to apply the lock to
|
|
* @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
|
|
* @fl: The lock to be applied
|
|
* @conf: Place to return a copy of the conflicting lock, if found.
|
|
*
|
|
* A caller that doesn't care about the conflicting lock may pass NULL
|
|
* as the final argument.
|
|
*
|
|
* If the filesystem defines a private ->lock() method, then @conf will
|
|
* be left unchanged; so a caller that cares should initialize it to
|
|
* some acceptable default.
|
|
*
|
|
* To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
|
|
* locks, the ->lock() interface may return asynchronously, before the lock has
|
|
* been granted or denied by the underlying filesystem, if (and only if)
|
|
* lm_grant is set. Callers expecting ->lock() to return asynchronously
|
|
* will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
|
|
* the request is for a blocking lock. When ->lock() does return asynchronously,
|
|
* it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
|
|
* request completes.
|
|
* If the request is for non-blocking lock the file system should return
|
|
* FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
|
|
* with the result. If the request timed out the callback routine will return a
|
|
* nonzero return code and the file system should release the lock. The file
|
|
* system is also responsible to keep a corresponding posix lock when it
|
|
* grants a lock so the VFS can find out which locks are locally held and do
|
|
* the correct lock cleanup when required.
|
|
* The underlying filesystem must not drop the kernel lock or call
|
|
* ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
|
|
* return code.
|
|
*/
|
|
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
|
|
{
|
|
if (filp->f_op->lock)
|
|
return filp->f_op->lock(filp, cmd, fl);
|
|
else
|
|
return posix_lock_file(filp, fl, conf);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_lock_file);
|
|
|
|
static int do_lock_file_wait(struct file *filp, unsigned int cmd,
|
|
struct file_lock *fl)
|
|
{
|
|
int error;
|
|
|
|
error = security_file_lock(filp, fl->fl_type);
|
|
if (error)
|
|
return error;
|
|
|
|
for (;;) {
|
|
error = vfs_lock_file(filp, cmd, fl, NULL);
|
|
if (error != FILE_LOCK_DEFERRED)
|
|
break;
|
|
error = wait_event_interruptible(fl->fl_wait,
|
|
list_empty(&fl->fl_blocked_member));
|
|
if (error)
|
|
break;
|
|
}
|
|
locks_delete_block(fl);
|
|
|
|
return error;
|
|
}
|
|
|
|
/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
|
|
static int
|
|
check_fmode_for_setlk(struct file_lock *fl)
|
|
{
|
|
switch (fl->fl_type) {
|
|
case F_RDLCK:
|
|
if (!(fl->fl_file->f_mode & FMODE_READ))
|
|
return -EBADF;
|
|
break;
|
|
case F_WRLCK:
|
|
if (!(fl->fl_file->f_mode & FMODE_WRITE))
|
|
return -EBADF;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Apply the lock described by l to an open file descriptor.
|
|
* This implements both the F_SETLK and F_SETLKW commands of fcntl().
|
|
*/
|
|
int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
|
|
struct flock *flock)
|
|
{
|
|
struct file_lock *file_lock = locks_alloc_lock();
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file *f;
|
|
int error;
|
|
|
|
if (file_lock == NULL)
|
|
return -ENOLCK;
|
|
|
|
/* Don't allow mandatory locks on files that may be memory mapped
|
|
* and shared.
|
|
*/
|
|
if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
|
|
error = -EAGAIN;
|
|
goto out;
|
|
}
|
|
|
|
error = flock_to_posix_lock(filp, file_lock, flock);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = check_fmode_for_setlk(file_lock);
|
|
if (error)
|
|
goto out;
|
|
|
|
/*
|
|
* If the cmd is requesting file-private locks, then set the
|
|
* FL_OFDLCK flag and override the owner.
|
|
*/
|
|
switch (cmd) {
|
|
case F_OFD_SETLK:
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_SETLK;
|
|
file_lock->fl_flags |= FL_OFDLCK;
|
|
file_lock->fl_owner = filp;
|
|
break;
|
|
case F_OFD_SETLKW:
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_SETLKW;
|
|
file_lock->fl_flags |= FL_OFDLCK;
|
|
file_lock->fl_owner = filp;
|
|
/* Fallthrough */
|
|
case F_SETLKW:
|
|
file_lock->fl_flags |= FL_SLEEP;
|
|
}
|
|
|
|
error = do_lock_file_wait(filp, cmd, file_lock);
|
|
|
|
/*
|
|
* Attempt to detect a close/fcntl race and recover by releasing the
|
|
* lock that was just acquired. There is no need to do that when we're
|
|
* unlocking though, or for OFD locks.
|
|
*/
|
|
if (!error && file_lock->fl_type != F_UNLCK &&
|
|
!(file_lock->fl_flags & FL_OFDLCK)) {
|
|
/*
|
|
* We need that spin_lock here - it prevents reordering between
|
|
* update of i_flctx->flc_posix and check for it done in
|
|
* close(). rcu_read_lock() wouldn't do.
|
|
*/
|
|
spin_lock(¤t->files->file_lock);
|
|
f = fcheck(fd);
|
|
spin_unlock(¤t->files->file_lock);
|
|
if (f != filp) {
|
|
file_lock->fl_type = F_UNLCK;
|
|
error = do_lock_file_wait(filp, cmd, file_lock);
|
|
WARN_ON_ONCE(error);
|
|
error = -EBADF;
|
|
}
|
|
}
|
|
out:
|
|
trace_fcntl_setlk(inode, file_lock, error);
|
|
locks_free_lock(file_lock);
|
|
return error;
|
|
}
|
|
|
|
#if BITS_PER_LONG == 32
|
|
/* Report the first existing lock that would conflict with l.
|
|
* This implements the F_GETLK command of fcntl().
|
|
*/
|
|
int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
|
|
{
|
|
struct file_lock *fl;
|
|
int error;
|
|
|
|
fl = locks_alloc_lock();
|
|
if (fl == NULL)
|
|
return -ENOMEM;
|
|
|
|
error = -EINVAL;
|
|
if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
|
|
goto out;
|
|
|
|
error = flock64_to_posix_lock(filp, fl, flock);
|
|
if (error)
|
|
goto out;
|
|
|
|
if (cmd == F_OFD_GETLK) {
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_GETLK64;
|
|
fl->fl_flags |= FL_OFDLCK;
|
|
fl->fl_owner = filp;
|
|
}
|
|
|
|
error = vfs_test_lock(filp, fl);
|
|
if (error)
|
|
goto out;
|
|
|
|
flock->l_type = fl->fl_type;
|
|
if (fl->fl_type != F_UNLCK)
|
|
posix_lock_to_flock64(flock, fl);
|
|
|
|
out:
|
|
locks_free_lock(fl);
|
|
return error;
|
|
}
|
|
|
|
/* Apply the lock described by l to an open file descriptor.
|
|
* This implements both the F_SETLK and F_SETLKW commands of fcntl().
|
|
*/
|
|
int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
|
|
struct flock64 *flock)
|
|
{
|
|
struct file_lock *file_lock = locks_alloc_lock();
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file *f;
|
|
int error;
|
|
|
|
if (file_lock == NULL)
|
|
return -ENOLCK;
|
|
|
|
/* Don't allow mandatory locks on files that may be memory mapped
|
|
* and shared.
|
|
*/
|
|
if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
|
|
error = -EAGAIN;
|
|
goto out;
|
|
}
|
|
|
|
error = flock64_to_posix_lock(filp, file_lock, flock);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = check_fmode_for_setlk(file_lock);
|
|
if (error)
|
|
goto out;
|
|
|
|
/*
|
|
* If the cmd is requesting file-private locks, then set the
|
|
* FL_OFDLCK flag and override the owner.
|
|
*/
|
|
switch (cmd) {
|
|
case F_OFD_SETLK:
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_SETLK64;
|
|
file_lock->fl_flags |= FL_OFDLCK;
|
|
file_lock->fl_owner = filp;
|
|
break;
|
|
case F_OFD_SETLKW:
|
|
error = -EINVAL;
|
|
if (flock->l_pid != 0)
|
|
goto out;
|
|
|
|
cmd = F_SETLKW64;
|
|
file_lock->fl_flags |= FL_OFDLCK;
|
|
file_lock->fl_owner = filp;
|
|
/* Fallthrough */
|
|
case F_SETLKW64:
|
|
file_lock->fl_flags |= FL_SLEEP;
|
|
}
|
|
|
|
error = do_lock_file_wait(filp, cmd, file_lock);
|
|
|
|
/*
|
|
* Attempt to detect a close/fcntl race and recover by releasing the
|
|
* lock that was just acquired. There is no need to do that when we're
|
|
* unlocking though, or for OFD locks.
|
|
*/
|
|
if (!error && file_lock->fl_type != F_UNLCK &&
|
|
!(file_lock->fl_flags & FL_OFDLCK)) {
|
|
/*
|
|
* We need that spin_lock here - it prevents reordering between
|
|
* update of i_flctx->flc_posix and check for it done in
|
|
* close(). rcu_read_lock() wouldn't do.
|
|
*/
|
|
spin_lock(¤t->files->file_lock);
|
|
f = fcheck(fd);
|
|
spin_unlock(¤t->files->file_lock);
|
|
if (f != filp) {
|
|
file_lock->fl_type = F_UNLCK;
|
|
error = do_lock_file_wait(filp, cmd, file_lock);
|
|
WARN_ON_ONCE(error);
|
|
error = -EBADF;
|
|
}
|
|
}
|
|
out:
|
|
locks_free_lock(file_lock);
|
|
return error;
|
|
}
|
|
#endif /* BITS_PER_LONG == 32 */
|
|
|
|
/*
|
|
* This function is called when the file is being removed
|
|
* from the task's fd array. POSIX locks belonging to this task
|
|
* are deleted at this time.
|
|
*/
|
|
void locks_remove_posix(struct file *filp, fl_owner_t owner)
|
|
{
|
|
int error;
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file_lock lock;
|
|
struct file_lock_context *ctx;
|
|
|
|
/*
|
|
* If there are no locks held on this file, we don't need to call
|
|
* posix_lock_file(). Another process could be setting a lock on this
|
|
* file at the same time, but we wouldn't remove that lock anyway.
|
|
*/
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx || list_empty(&ctx->flc_posix))
|
|
return;
|
|
|
|
locks_init_lock(&lock);
|
|
lock.fl_type = F_UNLCK;
|
|
lock.fl_flags = FL_POSIX | FL_CLOSE;
|
|
lock.fl_start = 0;
|
|
lock.fl_end = OFFSET_MAX;
|
|
lock.fl_owner = owner;
|
|
lock.fl_pid = current->tgid;
|
|
lock.fl_file = filp;
|
|
lock.fl_ops = NULL;
|
|
lock.fl_lmops = NULL;
|
|
|
|
error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
|
|
|
|
if (lock.fl_ops && lock.fl_ops->fl_release_private)
|
|
lock.fl_ops->fl_release_private(&lock);
|
|
trace_locks_remove_posix(inode, &lock, error);
|
|
}
|
|
EXPORT_SYMBOL(locks_remove_posix);
|
|
|
|
/* The i_flctx must be valid when calling into here */
|
|
static void
|
|
locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
|
|
{
|
|
struct file_lock fl;
|
|
struct inode *inode = locks_inode(filp);
|
|
|
|
if (list_empty(&flctx->flc_flock))
|
|
return;
|
|
|
|
flock_make_lock(filp, LOCK_UN, &fl);
|
|
fl.fl_flags |= FL_CLOSE;
|
|
|
|
if (filp->f_op->flock)
|
|
filp->f_op->flock(filp, F_SETLKW, &fl);
|
|
else
|
|
flock_lock_inode(inode, &fl);
|
|
|
|
if (fl.fl_ops && fl.fl_ops->fl_release_private)
|
|
fl.fl_ops->fl_release_private(&fl);
|
|
}
|
|
|
|
/* The i_flctx must be valid when calling into here */
|
|
static void
|
|
locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
|
|
{
|
|
struct file_lock *fl, *tmp;
|
|
LIST_HEAD(dispose);
|
|
|
|
if (list_empty(&ctx->flc_lease))
|
|
return;
|
|
|
|
percpu_down_read(&file_rwsem);
|
|
spin_lock(&ctx->flc_lock);
|
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
|
|
if (filp == fl->fl_file)
|
|
lease_modify(fl, F_UNLCK, &dispose);
|
|
spin_unlock(&ctx->flc_lock);
|
|
percpu_up_read(&file_rwsem);
|
|
|
|
locks_dispose_list(&dispose);
|
|
}
|
|
|
|
/*
|
|
* This function is called on the last close of an open file.
|
|
*/
|
|
void locks_remove_file(struct file *filp)
|
|
{
|
|
struct file_lock_context *ctx;
|
|
|
|
ctx = smp_load_acquire(&locks_inode(filp)->i_flctx);
|
|
if (!ctx)
|
|
return;
|
|
|
|
/* remove any OFD locks */
|
|
locks_remove_posix(filp, filp);
|
|
|
|
/* remove flock locks */
|
|
locks_remove_flock(filp, ctx);
|
|
|
|
/* remove any leases */
|
|
locks_remove_lease(filp, ctx);
|
|
|
|
spin_lock(&ctx->flc_lock);
|
|
locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
|
|
locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
|
|
locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
|
|
spin_unlock(&ctx->flc_lock);
|
|
}
|
|
|
|
/**
|
|
* vfs_cancel_lock - file byte range unblock lock
|
|
* @filp: The file to apply the unblock to
|
|
* @fl: The lock to be unblocked
|
|
*
|
|
* Used by lock managers to cancel blocked requests
|
|
*/
|
|
int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
|
|
{
|
|
if (filp->f_op->lock)
|
|
return filp->f_op->lock(filp, F_CANCELLK, fl);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_cancel_lock);
|
|
|
|
#ifdef CONFIG_PROC_FS
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/seq_file.h>
|
|
|
|
struct locks_iterator {
|
|
int li_cpu;
|
|
loff_t li_pos;
|
|
};
|
|
|
|
static void lock_get_status(struct seq_file *f, struct file_lock *fl,
|
|
loff_t id, char *pfx)
|
|
{
|
|
struct inode *inode = NULL;
|
|
unsigned int fl_pid;
|
|
struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
|
|
|
|
fl_pid = locks_translate_pid(fl, proc_pidns);
|
|
/*
|
|
* If lock owner is dead (and pid is freed) or not visible in current
|
|
* pidns, zero is shown as a pid value. Check lock info from
|
|
* init_pid_ns to get saved lock pid value.
|
|
*/
|
|
|
|
if (fl->fl_file != NULL)
|
|
inode = locks_inode(fl->fl_file);
|
|
|
|
seq_printf(f, "%lld:%s ", id, pfx);
|
|
if (IS_POSIX(fl)) {
|
|
if (fl->fl_flags & FL_ACCESS)
|
|
seq_puts(f, "ACCESS");
|
|
else if (IS_OFDLCK(fl))
|
|
seq_puts(f, "OFDLCK");
|
|
else
|
|
seq_puts(f, "POSIX ");
|
|
|
|
seq_printf(f, " %s ",
|
|
(inode == NULL) ? "*NOINODE*" :
|
|
mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
|
|
} else if (IS_FLOCK(fl)) {
|
|
if (fl->fl_type & LOCK_MAND) {
|
|
seq_puts(f, "FLOCK MSNFS ");
|
|
} else {
|
|
seq_puts(f, "FLOCK ADVISORY ");
|
|
}
|
|
} else if (IS_LEASE(fl)) {
|
|
if (fl->fl_flags & FL_DELEG)
|
|
seq_puts(f, "DELEG ");
|
|
else
|
|
seq_puts(f, "LEASE ");
|
|
|
|
if (lease_breaking(fl))
|
|
seq_puts(f, "BREAKING ");
|
|
else if (fl->fl_file)
|
|
seq_puts(f, "ACTIVE ");
|
|
else
|
|
seq_puts(f, "BREAKER ");
|
|
} else {
|
|
seq_puts(f, "UNKNOWN UNKNOWN ");
|
|
}
|
|
if (fl->fl_type & LOCK_MAND) {
|
|
seq_printf(f, "%s ",
|
|
(fl->fl_type & LOCK_READ)
|
|
? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
|
|
: (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
|
|
} else {
|
|
int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
|
|
|
|
seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
|
|
(type == F_RDLCK) ? "READ" : "UNLCK");
|
|
}
|
|
if (inode) {
|
|
/* userspace relies on this representation of dev_t */
|
|
seq_printf(f, "%d %02x:%02x:%lu ", fl_pid,
|
|
MAJOR(inode->i_sb->s_dev),
|
|
MINOR(inode->i_sb->s_dev), inode->i_ino);
|
|
} else {
|
|
seq_printf(f, "%d <none>:0 ", fl_pid);
|
|
}
|
|
if (IS_POSIX(fl)) {
|
|
if (fl->fl_end == OFFSET_MAX)
|
|
seq_printf(f, "%Ld EOF\n", fl->fl_start);
|
|
else
|
|
seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
|
|
} else {
|
|
seq_puts(f, "0 EOF\n");
|
|
}
|
|
}
|
|
|
|
static int locks_show(struct seq_file *f, void *v)
|
|
{
|
|
struct locks_iterator *iter = f->private;
|
|
struct file_lock *fl, *bfl;
|
|
struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
|
|
|
|
fl = hlist_entry(v, struct file_lock, fl_link);
|
|
|
|
if (locks_translate_pid(fl, proc_pidns) == 0)
|
|
return 0;
|
|
|
|
lock_get_status(f, fl, iter->li_pos, "");
|
|
|
|
list_for_each_entry(bfl, &fl->fl_blocked_requests, fl_blocked_member)
|
|
lock_get_status(f, bfl, iter->li_pos, " ->");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __show_fd_locks(struct seq_file *f,
|
|
struct list_head *head, int *id,
|
|
struct file *filp, struct files_struct *files)
|
|
{
|
|
struct file_lock *fl;
|
|
|
|
list_for_each_entry(fl, head, fl_list) {
|
|
|
|
if (filp != fl->fl_file)
|
|
continue;
|
|
if (fl->fl_owner != files &&
|
|
fl->fl_owner != filp)
|
|
continue;
|
|
|
|
(*id)++;
|
|
seq_puts(f, "lock:\t");
|
|
lock_get_status(f, fl, *id, "");
|
|
}
|
|
}
|
|
|
|
void show_fd_locks(struct seq_file *f,
|
|
struct file *filp, struct files_struct *files)
|
|
{
|
|
struct inode *inode = locks_inode(filp);
|
|
struct file_lock_context *ctx;
|
|
int id = 0;
|
|
|
|
ctx = smp_load_acquire(&inode->i_flctx);
|
|
if (!ctx)
|
|
return;
|
|
|
|
spin_lock(&ctx->flc_lock);
|
|
__show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
|
|
__show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
|
|
__show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
|
|
spin_unlock(&ctx->flc_lock);
|
|
}
|
|
|
|
static void *locks_start(struct seq_file *f, loff_t *pos)
|
|
__acquires(&blocked_lock_lock)
|
|
{
|
|
struct locks_iterator *iter = f->private;
|
|
|
|
iter->li_pos = *pos + 1;
|
|
percpu_down_write(&file_rwsem);
|
|
spin_lock(&blocked_lock_lock);
|
|
return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
|
|
}
|
|
|
|
static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
|
|
{
|
|
struct locks_iterator *iter = f->private;
|
|
|
|
++iter->li_pos;
|
|
return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
|
|
}
|
|
|
|
static void locks_stop(struct seq_file *f, void *v)
|
|
__releases(&blocked_lock_lock)
|
|
{
|
|
spin_unlock(&blocked_lock_lock);
|
|
percpu_up_write(&file_rwsem);
|
|
}
|
|
|
|
static const struct seq_operations locks_seq_operations = {
|
|
.start = locks_start,
|
|
.next = locks_next,
|
|
.stop = locks_stop,
|
|
.show = locks_show,
|
|
};
|
|
|
|
static int __init proc_locks_init(void)
|
|
{
|
|
proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
|
|
sizeof(struct locks_iterator), NULL);
|
|
return 0;
|
|
}
|
|
fs_initcall(proc_locks_init);
|
|
#endif
|
|
|
|
static int __init filelock_init(void)
|
|
{
|
|
int i;
|
|
|
|
flctx_cache = kmem_cache_create("file_lock_ctx",
|
|
sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
|
|
|
|
filelock_cache = kmem_cache_create("file_lock_cache",
|
|
sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
|
|
|
|
spin_lock_init(&fll->lock);
|
|
INIT_HLIST_HEAD(&fll->hlist);
|
|
}
|
|
|
|
lease_notifier_chain_init();
|
|
return 0;
|
|
}
|
|
core_initcall(filelock_init);
|