forked from Minki/linux
File locking changes for v5.16
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This commit is contained in:
Linus Torvalds
commit
9ac211426f
@ -29,7 +29,6 @@ algorithms work.
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fiemap
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files
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locks
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mandatory-locking
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mount_api
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quota
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seq_file
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@ -57,16 +57,9 @@ fcntl(), with all the problems that implies.
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1.3 Mandatory Locking As A Mount Option
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---------------------------------------
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Mandatory locking, as described in
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'Documentation/filesystems/mandatory-locking.rst' was prior to this release a
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general configuration option that was valid for all mounted filesystems. This
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had a number of inherent dangers, not the least of which was the ability to
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freeze an NFS server by asking it to read a file for which a mandatory lock
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existed.
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From this release of the kernel, mandatory locking can be turned on and off
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on a per-filesystem basis, using the mount options 'mand' and 'nomand'.
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The default is to disallow mandatory locking. The intention is that
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mandatory locking only be enabled on a local filesystem as the specific need
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arises.
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Mandatory locking was prior to this release a general configuration option
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that was valid for all mounted filesystems. This had a number of inherent
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dangers, not the least of which was the ability to freeze an NFS server by
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asking it to read a file for which a mandatory lock existed.
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Such option was dropped in Kernel v5.14.
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@ -302,9 +302,6 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
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if (!(fl->fl_flags & FL_FLOCK))
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return -ENOLCK;
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/* No mandatory locks */
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if (fl->fl_type & LOCK_MAND)
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return -EOPNOTSUPP;
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dout("ceph_flock, fl_file: %p\n", fl->fl_file);
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@ -1338,8 +1338,6 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
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{
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if (!(fl->fl_flags & FL_FLOCK))
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return -ENOLCK;
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if (fl->fl_type & LOCK_MAND)
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return -EOPNOTSUPP;
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if (fl->fl_type == F_UNLCK) {
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do_unflock(file, fl);
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161
fs/locks.c
161
fs/locks.c
@ -2,117 +2,11 @@
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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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* We implement four types of file locks: BSD locks, posix locks, open
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* file description locks, and leases. For details about BSD locks,
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* see the flock(2) man page; for details about the other three, see
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* fcntl(2).
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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.rst' 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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@ -461,8 +355,6 @@ static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
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}
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static inline int flock_translate_cmd(int cmd) {
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if (cmd & LOCK_MAND)
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return cmd & (LOCK_MAND | LOCK_RW);
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switch (cmd) {
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case LOCK_SH:
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return F_RDLCK;
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@ -942,8 +834,6 @@ static bool flock_locks_conflict(struct file_lock *caller_fl,
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*/
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if (caller_fl->fl_file == sys_fl->fl_file)
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return false;
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if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
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return false;
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return locks_conflict(caller_fl, sys_fl);
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}
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@ -2116,11 +2006,9 @@ EXPORT_SYMBOL(locks_lock_inode_wait);
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* - %LOCK_SH -- a shared lock.
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* - %LOCK_EX -- an exclusive lock.
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* - %LOCK_UN -- remove an existing lock.
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* - %LOCK_MAND -- a 'mandatory' flock.
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* This exists to emulate Windows Share Modes.
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* - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED)
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*
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* %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
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* processes read and write access respectively.
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* %LOCK_MAND support has been removed from the kernel.
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*/
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SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
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{
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@ -2137,10 +2025,23 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
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cmd &= ~LOCK_NB;
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unlock = (cmd == LOCK_UN);
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if (!unlock && !(cmd & LOCK_MAND) &&
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!(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
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if (!unlock && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
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goto out_putf;
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/*
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* LOCK_MAND locks were broken for a long time in that they never
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* conflicted with one another and didn't prevent any sort of open,
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* read or write activity.
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*
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* Just ignore these requests now, to preserve legacy behavior, but
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* throw a warning to let people know that they don't actually work.
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*/
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if (cmd & LOCK_MAND) {
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pr_warn_once("Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n");
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error = 0;
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goto out_putf;
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}
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lock = flock_make_lock(f.file, cmd, NULL);
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if (IS_ERR(lock)) {
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error = PTR_ERR(lock);
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@ -2718,6 +2619,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
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struct inode *inode = NULL;
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unsigned int fl_pid;
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struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
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int type;
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fl_pid = locks_translate_pid(fl, proc_pidns);
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/*
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@ -2745,11 +2647,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
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seq_printf(f, " %s ",
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(inode == NULL) ? "*NOINODE*" : "ADVISORY ");
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} else if (IS_FLOCK(fl)) {
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if (fl->fl_type & LOCK_MAND) {
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seq_puts(f, "FLOCK MSNFS ");
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} else {
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seq_puts(f, "FLOCK ADVISORY ");
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}
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seq_puts(f, "FLOCK ADVISORY ");
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} else if (IS_LEASE(fl)) {
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if (fl->fl_flags & FL_DELEG)
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seq_puts(f, "DELEG ");
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@ -2765,17 +2663,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
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} else {
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seq_puts(f, "UNKNOWN UNKNOWN ");
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}
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if (fl->fl_type & LOCK_MAND) {
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seq_printf(f, "%s ",
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(fl->fl_type & LOCK_READ)
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? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ "
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: (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
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} else {
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int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
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type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
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seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
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(type == F_RDLCK) ? "READ" : "UNLCK");
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}
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seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
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(type == F_RDLCK) ? "READ" : "UNLCK");
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if (inode) {
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/* userspace relies on this representation of dev_t */
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seq_printf(f, "%d %02x:%02x:%lu ", fl_pid,
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@ -3076,9 +3076,7 @@ static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp)
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int error = get_write_access(inode);
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if (error)
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return error;
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/*
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* Refuse to truncate files with mandatory locks held on them.
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*/
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error = security_path_truncate(path);
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if (!error) {
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error = do_truncate(mnt_userns, path->dentry, 0,
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@ -843,15 +843,6 @@ int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
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if (!(fl->fl_flags & FL_FLOCK))
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return -ENOLCK;
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/*
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* The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
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* any standard. In principle we might be able to support LOCK_MAND
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* on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
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* NFS code is not set up for it.
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*/
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if (fl->fl_type & LOCK_MAND)
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return -EINVAL;
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if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
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is_local = 1;
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@ -368,10 +368,6 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
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if (unlikely((ssize_t) count < 0))
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return -EINVAL;
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/*
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* ranged mandatory locking does not apply to streams - it makes sense
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* only for files where position has a meaning.
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*/
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if (ppos) {
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loff_t pos = *ppos;
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@ -181,6 +181,10 @@ struct f_owner_ex {
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blocking */
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#define LOCK_UN 8 /* remove lock */
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/*
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* LOCK_MAND support has been removed from the kernel. We leave the symbols
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* here to not break legacy builds, but these should not be used in new code.
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*/
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#define LOCK_MAND 32 /* This is a mandatory flock ... */
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#define LOCK_READ 64 /* which allows concurrent read operations */
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#define LOCK_WRITE 128 /* which allows concurrent write operations */
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