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authorLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 09:06:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-01 09:06:53 -0700
commit9ac211426fb6747c92d570647e2ce889e33cbffd (patch)
treec9d021ff260415fa63071b37ae01f01e81334bb5
parentad98a9246616e736504d1ebc2f3f35c2c0dcb806 (diff)
parent482e00075d660a16de822686a4be4f7c0e11e5e2 (diff)
Merge tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull file locking updates from Jeff Layton: "Most of this is just follow-on cleanup work of documentation and comments from the mandatory locking removal in v5.15. The only real functional change is that LOCK_MAND flock() support is also being removed, as it has basically been non-functional since the v2.5 days" * tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux: fs: remove leftover comments from mandatory locking removal locks: remove changelog comments docs: fs: locks.rst: update comment about mandatory file locking Documentation: remove reference to now removed mandatory-locking doc locks: remove LOCK_MAND flock lock support
-rw-r--r--Documentation/filesystems/index.rst1
-rw-r--r--Documentation/filesystems/locks.rst17
-rw-r--r--fs/ceph/locks.c3
-rw-r--r--fs/gfs2/file.c2
-rw-r--r--fs/locks.c161
-rw-r--r--fs/namei.c4
-rw-r--r--fs/nfs/file.c9
-rw-r--r--fs/read_write.c4
-rw-r--r--include/uapi/asm-generic/fcntl.h4
9 files changed, 36 insertions, 169 deletions
diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
index c0ad233963ae..bee63d42e5ec 100644
--- a/Documentation/filesystems/index.rst
+++ b/Documentation/filesystems/index.rst
@@ -29,7 +29,6 @@ algorithms work.
fiemap
files
locks
- mandatory-locking
mount_api
quota
seq_file
diff --git a/Documentation/filesystems/locks.rst b/Documentation/filesystems/locks.rst
index c5ae858b1aac..26429317dbbc 100644
--- a/Documentation/filesystems/locks.rst
+++ b/Documentation/filesystems/locks.rst
@@ -57,16 +57,9 @@ fcntl(), with all the problems that implies.
1.3 Mandatory Locking As A Mount Option
---------------------------------------
-Mandatory locking, as described in
-'Documentation/filesystems/mandatory-locking.rst' was prior to this release a
-general configuration option that was valid for all mounted filesystems. This
-had a number of inherent dangers, not the least of which was the ability to
-freeze an NFS server by asking it to read a file for which a mandatory lock
-existed.
-
-From this release of the kernel, mandatory locking can be turned on and off
-on a per-filesystem basis, using the mount options 'mand' and 'nomand'.
-The default is to disallow mandatory locking. The intention is that
-mandatory locking only be enabled on a local filesystem as the specific need
-arises.
+Mandatory locking was prior to this release a general configuration option
+that was valid for all mounted filesystems. This had a number of inherent
+dangers, not the least of which was the ability to freeze an NFS server by
+asking it to read a file for which a mandatory lock existed.
+Such option was dropped in Kernel v5.14.
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index bdeb271f47d9..d8c31069fbf2 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -302,9 +302,6 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;
- /* No mandatory locks */
- if (fl->fl_type & LOCK_MAND)
- return -EOPNOTSUPP;
dout("ceph_flock, fl_file: %p\n", fl->fl_file);
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index c559827cb6f9..078ef29e31bc 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -1338,8 +1338,6 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl)
{
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;
- if (fl->fl_type & LOCK_MAND)
- return -EOPNOTSUPP;
if (fl->fl_type == F_UNLCK) {
do_unflock(file, fl);
diff --git a/fs/locks.c b/fs/locks.c
index 3d6fb4ae847b..0fca9d680978 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2,117 +2,11 @@
/*
* linux/fs/locks.c
*
- * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
- * Doug Evans (dje@spiff.uucp), August 07, 1992
+ * We implement four types of file locks: BSD locks, posix locks, open
+ * file description locks, and leases. For details about BSD locks,
+ * see the flock(2) man page; for details about the other three, see
+ * fcntl(2).
*
- * Deadlock detection added.
- * FIXME: one thing isn't handled yet:
- * - mandatory locks (requires lots of changes elsewhere)
- * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
- *
- * Miscellaneous edits, and a total rewrite of posix_lock_file() code.
- * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
- *
- * Converted file_lock_table to a linked list from an array, which eliminates
- * the limits on how many active file locks are open.
- * Chad Page (pageone@netcom.com), November 27, 1994
- *
- * Removed dependency on file descriptors. dup()'ed file descriptors now
- * get the same locks as the original file descriptors, and a close() on
- * any file descriptor removes ALL the locks on the file for the current
- * process. Since locks still depend on the process id, locks are inherited
- * after an exec() but not after a fork(). This agrees with POSIX, and both
- * BSD and SVR4 practice.
- * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
- *
- * Scrapped free list which is redundant now that we allocate locks
- * dynamically with kmalloc()/kfree().
- * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
- *
- * Implemented two lock personalities - FL_FLOCK and FL_POSIX.
- *
- * FL_POSIX locks are created with calls to fcntl() and lockf() through the
- * fcntl() system call. They have the semantics described above.
- *
- * FL_FLOCK locks are created with calls to flock(), through the flock()
- * system call, which is new. Old C libraries implement flock() via fcntl()
- * and will continue to use the old, broken implementation.
- *
- * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
- * with a file pointer (filp). As a result they can be shared by a parent
- * process and its children after a fork(). They are removed when the last
- * file descriptor referring to the file pointer is closed (unless explicitly
- * unlocked).
- *
- * FL_FLOCK locks never deadlock, an existing lock is always removed before
- * upgrading from shared to exclusive (or vice versa). When this happens
- * any processes blocked by the current lock are woken up and allowed to
- * run before the new lock is applied.
- * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
- *
- * Removed some race conditions in flock_lock_file(), marked other possible
- * races. Just grep for FIXME to see them.
- * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
- *
- * Addressed Dmitry's concerns. Deadlock checking no longer recursive.
- * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
- * once we've checked for blocking and deadlocking.
- * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
- *
- * Initial implementation of mandatory locks. SunOS turned out to be
- * a rotten model, so I implemented the "obvious" semantics.
- * See 'Documentation/filesystems/mandatory-locking.rst' for details.
- * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
- *
- * Don't allow mandatory locks on mmap()'ed files. Added simple functions to
- * check if a file has mandatory locks, used by mmap(), open() and creat() to
- * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
- * Manual, Section 2.
- * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
- *
- * Tidied up block list handling. Added '/proc/locks' interface.
- * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
- *
- * Fixed deadlock condition for pathological code that mixes calls to
- * flock() and fcntl().
- * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
- *
- * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
- * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
- * guarantee sensible behaviour in the case where file system modules might
- * be compiled with different options than the kernel itself.
- * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
- *
- * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
- * (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
- * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
- *
- * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
- * locks. Changed process synchronisation to avoid dereferencing locks that
- * have already been freed.
- * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
- *
- * Made the block list a circular list to minimise searching in the list.
- * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
- *
- * Made mandatory locking a mount option. Default is not to allow mandatory
- * locking.
- * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
- *
- * Some adaptations for NFS support.
- * Olaf Kirch (okir@monad.swb.de), Dec 1996,
- *
- * Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
- * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
- *
- * Use slab allocator instead of kmalloc/kfree.
- * Use generic list implementation from <linux/list.h>.
- * Sped up posix_locks_deadlock by only considering blocked locks.
- * Matthew Wilcox <willy@debian.org>, March, 2000.
- *
- * Leases and LOCK_MAND
- * Matthew Wilcox <willy@debian.org>, June, 2000.
- * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
*
* Locking conflicts and dependencies:
* If multiple threads attempt to lock the same byte (or flock the same file)
@@ -461,8 +355,6 @@ static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
}
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;
@@ -942,8 +834,6 @@ static bool flock_locks_conflict(struct file_lock *caller_fl,
*/
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);
}
@@ -2116,11 +2006,9 @@ EXPORT_SYMBOL(locks_lock_inode_wait);
* - %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 -- a 'mandatory' flock. (DEPRECATED)
*
- * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
- * processes read and write access respectively.
+ * %LOCK_MAND support has been removed from the kernel.
*/
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
{
@@ -2137,9 +2025,22 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
cmd &= ~LOCK_NB;
unlock = (cmd == LOCK_UN);
- if (!unlock && !(cmd & LOCK_MAND) &&
- !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
+ if (!unlock && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
+ goto out_putf;
+
+ /*
+ * LOCK_MAND locks were broken for a long time in that they never
+ * conflicted with one another and didn't prevent any sort of open,
+ * read or write activity.
+ *
+ * Just ignore these requests now, to preserve legacy behavior, but
+ * throw a warning to let people know that they don't actually work.
+ */
+ if (cmd & LOCK_MAND) {
+ pr_warn_once("Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n");
+ error = 0;
goto out_putf;
+ }
lock = flock_make_lock(f.file, cmd, NULL);
if (IS_ERR(lock)) {
@@ -2718,6 +2619,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
struct inode *inode = NULL;
unsigned int fl_pid;
struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
+ int type;
fl_pid = locks_translate_pid(fl, proc_pidns);
/*
@@ -2745,11 +2647,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
seq_printf(f, " %s ",
(inode == NULL) ? "*NOINODE*" : "ADVISORY ");
} else if (IS_FLOCK(fl)) {
- if (fl->fl_type & LOCK_MAND) {
- seq_puts(f, "FLOCK MSNFS ");
- } else {
- seq_puts(f, "FLOCK ADVISORY ");
- }
+ seq_puts(f, "FLOCK ADVISORY ");
} else if (IS_LEASE(fl)) {
if (fl->fl_flags & FL_DELEG)
seq_puts(f, "DELEG ");
@@ -2765,17 +2663,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
} 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;
+ type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
- seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
- (type == F_RDLCK) ? "READ" : "UNLCK");
- }
+ 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,
diff --git a/fs/namei.c b/fs/namei.c
index 1946d9667790..1f9d2187c765 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3076,9 +3076,7 @@ static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp)
int error = get_write_access(inode);
if (error)
return error;
- /*
- * Refuse to truncate files with mandatory locks held on them.
- */
+
error = security_path_truncate(path);
if (!error) {
error = do_truncate(mnt_userns, path->dentry, 0,
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index aa353fd58240..24e7dccce355 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -843,15 +843,6 @@ int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
if (!(fl->fl_flags & FL_FLOCK))
return -ENOLCK;
- /*
- * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of
- * any standard. In principle we might be able to support LOCK_MAND
- * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the
- * NFS code is not set up for it.
- */
- if (fl->fl_type & LOCK_MAND)
- return -EINVAL;
-
if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK)
is_local = 1;
diff --git a/fs/read_write.c b/fs/read_write.c
index af057c57bdc6..0074afa7ecb3 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -368,10 +368,6 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
if (unlikely((ssize_t) count < 0))
return -EINVAL;
- /*
- * ranged mandatory locking does not apply to streams - it makes sense
- * only for files where position has a meaning.
- */
if (ppos) {
loff_t pos = *ppos;
diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h
index 9dc0bf0c5a6e..ecd0f5bdfc1d 100644
--- a/include/uapi/asm-generic/fcntl.h
+++ b/include/uapi/asm-generic/fcntl.h
@@ -181,6 +181,10 @@ struct f_owner_ex {
blocking */
#define LOCK_UN 8 /* remove lock */
+/*
+ * LOCK_MAND support has been removed from the kernel. We leave the symbols
+ * here to not break legacy builds, but these should not be used in new code.
+ */
#define LOCK_MAND 32 /* This is a mandatory flock ... */
#define LOCK_READ 64 /* which allows concurrent read operations */
#define LOCK_WRITE 128 /* which allows concurrent write operations */