Commit Graph

223 Commits

Author SHA1 Message Date
Jeff Layton
6e129d0068 locks: flock_make_lock should return a struct file_lock (or PTR_ERR)
Eliminate the need for a return pointer.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:13 -04:00
Jeff Layton
7ca76311fe locks: set fl_owner for leases to filp instead of current->files
Like flock locks, leases are owned by the file description. Now that the
i_have_this_lease check in __break_lease is gone, we don't actually use
the fl_owner for leases for anything. So, it's now safe to set this more
appropriately to the same value as the fl_file.

While we're at it, fix up the comments over the fl_owner_t definition
since they're rather out of date.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-10-07 14:06:13 -04:00
Jeff Layton
4d01b7f5e7 locks: give lm_break a return value
Christoph suggests:

   "Add a return value to lm_break so that the lock manager can tell the
    core code "you can delete this lease right now".  That gets rid of
    the games with the timeout which require all kinds of race avoidance
    code in the users."

Do that here and have the nfsd lease break routine use it when it detects
that there was a race between setting up the lease and it being broken.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:13 -04:00
Jeff Layton
03d12ddf84 locks: __break_lease cleanup in preparation of allowing direct removal of leases
Eliminate an unneeded "flock" variable. We can use "fl" as a loop cursor
everywhere. Add a any_leases_conflict helper function as well to
consolidate a bit of code.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:13 -04:00
Jeff Layton
843c6b2f4c locks: remove i_have_this_lease check from __break_lease
I think that the intent of this code was to ensure that a process won't
deadlock if it has one fd open with a lease on it and then breaks that
lease by opening another fd. In that case it'll treat the __break_lease
call as if it were non-blocking.

This seems wrong -- the process could (for instance) be multithreaded
and managing different fds via different threads. I also don't see any
mention of this limitation in the (somewhat sketchy) documentation.

Remove the check and the non-blocking behavior when i_have_this_lease
is true.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-10-07 14:06:13 -04:00
Jeff Layton
c45198eda2 locks: move freeing of leases outside of i_lock
There was only one place where we still could free a file_lock while
holding the i_lock -- lease_modify. Add a new list_head argument to the
lm_change operation, pass in a private list when calling it, and fix
those callers to dispose of the list once the lock has been dropped.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:13 -04:00
Jeff Layton
f82b4b6780 locks: move i_lock acquisition into generic_*_lease handlers
Now that we have a saner internal API for managing leases, we no longer
need to mandate that the inode->i_lock be held over most of the lease
code. Push it down into generic_add_lease and generic_delete_lease.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:13 -04:00
Jeff Layton
1c7dd2ff43 locks: define a lm_setup handler for leases
...and move the fasync setup into it for fcntl lease calls. At the same
time, change the semantics of how the file_lock double-pointer is
handled. Up until now, on a successful lease return you got a pointer to
the lock on the list. This is bad, since that pointer can no longer be
relied on as valid once the inode->i_lock has been released.

Change the code to instead just zero out the pointer if the lease we
passed in ended up being used. Then the callers can just check to see
if it's NULL after the call and free it if it isn't.

The priv argument has the same semantics. The lm_setup function can
zero the pointer out to signal to the caller that it should not be
freed after the function returns.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:12 -04:00
Jeff Layton
e6f5c78930 locks: plumb a "priv" pointer into the setlease routines
In later patches, we're going to add a new lock_manager_operation to
finish setting up the lease while still holding the i_lock.  To do
this, we'll need to pass a little bit of info in the fcntl setlease
case (primarily an fasync structure). Plumb the extra pointer into
there in advance of that.

We declare this pointer as a void ** to make it clear that this is
private info, and that the caller isn't required to set this unless
the lm_setup specifically requires it.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:12 -04:00
Jeff Layton
e51673aa5d locks: clean up vfs_setlease kerneldoc comments
Some of the latter paragraphs seem ambiguous and just plain wrong.
In particular the break_lease comment makes no sense. We call
break_lease (and break_deleg) from all sorts of vfs-layer functions,
so there is clearly such a method.

Also get rid of some of the other comments about what's needed for
a full implementation.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:12 -04:00
Jeff Layton
0efaa7e82f locks: generic_delete_lease doesn't need a file_lock at all
Ensure that it's OK to pass in a NULL file_lock double pointer on
a F_UNLCK request and convert the vfs_setlease F_UNLCK callers to
do just that.

Finally, turn the BUG_ON in generic_setlease into a WARN_ON_ONCE
with an error return. That's a problem we can handle without
crashing the box if it occurs.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:12 -04:00
Jeff Layton
bfe8602436 locks: close potential race in lease_get_mtime
lease_get_mtime is called without the i_lock held, so there's no
guarantee about the stability of the list. Between the time when we
assign "flock" and then dereference it to check whether it's a lease
and for write, the lease could be freed.

Ensure that that doesn't occur by taking the i_lock before trying
to check the lease.

Cc: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-10-07 14:06:12 -04:00
Jeff Layton
e0b93eddfe security: make security_file_set_fowner, f_setown and __f_setown void return
security_file_set_fowner always returns 0, so make it f_setown and
__f_setown void return functions and fix up the error handling in the
callers.

Cc: linux-security-module@vger.kernel.org
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-09-09 16:01:36 -04:00
Jeff Layton
699688a416 locks: remove lock_may_read and lock_may_write
There are no callers of these functions.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-09-09 16:01:09 -04:00
Kinglong Mee
f328296e27 locks: Copy fl_lmops information for conflock in locks_copy_conflock()
Commit d5b9026a67 ([PATCH] knfsd: locks: flag NFSv4-owned locks) using
fl_lmops field in file_lock for checking nfsd4 lockowner.

But, commit 1a747ee0cc (locks: don't call ->copy_lock methods on return
of conflicting locks) causes the fl_lmops of conflock always be NULL.

Also, commit 0996905f93 (lockd: posix_test_lock() should not call
locks_copy_lock()) caused the fl_lmops of conflock always be NULL too.

Make sure copy the private information by fl_copy_lock() in struct
file_lock_operations, merge __locks_copy_lock() to fl_copy_lock().

Jeff advice, "Set fl_lmops on conflocks, but don't set fl_ops.
fl_ops are superfluous, since they are callbacks into the filesystem.
There should be no need to bother the filesystem at all with info
in a conflock. But, lock _ownership_ matters for conflocks and that's
indicated by the fl_lmops. So you really do want to copy the fl_lmops
for conflocks I think."

v5: add missing calling of locks_release_private() in nlmsvc_testlock()
v4: only copy fl_lmops for conflock, don't copy fl_ops

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-09-09 16:01:09 -04:00
Kinglong Mee
5c97d7b147 locks: New ops in lock_manager_operations for get/put owner
NFSD or other lockmanager may increase the owner's reference,
so adds two new options for copying and releasing owner.

v5: change order from 2/6 to 3/6
v4: rename lm_copy_owner/lm_release_owner to lm_get_owner/lm_put_owner

Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-09-09 16:01:09 -04:00
Kinglong Mee
3fe0fff18f locks: Rename __locks_copy_lock() to locks_copy_conflock()
Jeff advice, " Right now __locks_copy_lock is only used to copy
conflocks. It would be good to rename that to something more
distinct (i.e.locks_copy_conflock), to make it clear that we're
generating a conflock there."

v5: change order from 3/6 to 2/6
v4: new patch only renaming function name

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-09-09 16:01:09 -04:00
Jeff Layton
f39b913cee locks: pass correct "before" pointer to locks_unlink_lock in generic_add_lease
The argument to locks_unlink_lock can't be just any pointer to a
pointer. It must be a pointer to the fl_next field in the previous
lock in the list.

Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2014-09-09 16:00:51 -04:00
Jeff Layton
2dfb928f7e locks: move locks_free_lock calls in do_fcntl_add_lease outside spinlock
There's no need to call locks_free_lock here while still holding the
i_lock. Defer that until the lock has been dropped.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-08-14 10:07:47 -04:00
Jeff Layton
ed9814d858 locks: defer freeing locks in locks_delete_lock until after i_lock has been dropped
In commit 72f98e7255 (locks: turn lock_flocks into a spinlock), we
moved from using the BKL to a global spinlock. With this change, we lost
the ability to block in the fl_release_private operation.

This is problematic for NFS (and probably some other filesystems as
well). Add a new list_head argument to locks_delete_lock. If that
argument is non-NULL, then queue any locks that we want to free to the
list instead of freeing them.

Then, add a new locks_dispose_list function that will walk such a list
and call locks_free_lock on them after the i_lock has been dropped.

Finally, change all of the callers of locks_delete_lock to pass in a
list_head, except for lease_modify. That function can be called long
after the i_lock has been acquired. Deferring the freeing of a lease
after unlocking it in that function is non-trivial until we overhaul
some of the spinlocking in the lease code.

Currently though, no filesystem that sets fl_release_private supports
leases, so this is not currently a problem. We'll eventually want to
make the same change in the lease code, but it needs a lot more work
before we can reasonably do so.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-08-14 10:07:47 -04:00
Jeff Layton
b84d49f944 locks: don't reuse file_lock in __posix_lock_file
Currently in the case where a new file lock completely replaces the old
one, we end up overwriting the existing lock with the new info. This
means that we have to call fl_release_private inside i_lock. Change the
code to instead copy the info to new_fl, insert that lock into the
correct spot and then delete the old lock. In a later patch, we'll defer
the freeing of the old lock until after the i_lock has been dropped.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-08-14 10:07:47 -04:00
Jeff Layton
566709bd62 locks: don't call locks_release_private from locks_copy_lock
All callers of locks_copy_lock pass in a brand new file_lock struct, so
there's no need to call locks_release_private on it. Replace that with
a warning that fires in the event that we receive a target lock that
doesn't look like it's properly initialized.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-08-11 14:24:22 -04:00
Jeff Layton
8144f1f699 locks: show delegations as "DELEG" in /proc/locks
Now that they are a distinct lease type, show them as such.

Cc: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-08-11 13:36:54 -04:00
Christoph Hellwig
73a8f5f7e6 locks: purge fl_owner_t from fs/locks.c
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-07-13 21:39:07 -04:00
Jeff Layton
0c27362998 locks: set fl_owner for leases back to current->files
This fixes a regression due to commit 130d1f956a (locks: ensure that
fl_owner is always initialized properly in flock and lease codepaths). I
had mistakenly thought that the fl_owner wasn't used in the lease code,
but I missed the place in __break_lease that does use it.

The i_have_this_lease check in generic_add_lease uses it. While I'm not
sure that check is terribly helpful [1], reset it back to using
current->files in order to ensure that there's no behavior change here.

[1]: leases are owned by the file description. It's possible that this
     is a threaded program, and the lease breaker and the task that
     would handle the signal are different, even if they have the same
     file table. So, there is the potential for false positives with
     this check.

Fixes: 130d1f956a (locks: ensure that fl_owner is always initialized properly in flock and lease codepaths)
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
2014-06-10 12:29:05 -04:00
Jeff Layton
62af4f1f7d locks: add some tracepoints in the lease handling code
v2: add a __break_lease tracepoint for non-blocking case

Recently, I needed these to help track down a softlockup when recalling a
delegation, but they might be helpful in other situations as well.

Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
2014-06-02 08:09:30 -04:00
Fabian Frederick
5315c26a6c fs/locks.c: replace seq_printf by seq_puts
Replace seq_printf where possible

Cc: Jeff Layton <jlayton@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
2014-06-02 08:09:29 -04:00
Jeff Layton
130d1f956a locks: ensure that fl_owner is always initialized properly in flock and lease codepaths
Currently, the fl_owner isn't set for flock locks. Some filesystems use
byte-range locks to simulate flock locks and there is a common idiom in
those that does:

    fl->fl_owner = (fl_owner_t)filp;
    fl->fl_start = 0;
    fl->fl_end = OFFSET_MAX;

Since flock locks are generally "owned" by the open file description,
move this into the common flock lock setup code. The fl_start and fl_end
fields are already set appropriately, so remove the unneeded setting of
that in flock ops in those filesystems as well.

Finally, the lease code also sets the fl_owner as if they were owned by
the process and not the open file description. This is incorrect as
leases have the same ownership semantics as flock locks. Set them the
same way. The lease code doesn't actually use the fl_owner value for
anything, so this is more for consistency's sake than a bugfix.

Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (Staging portion)
Acked-by: J. Bruce Fields <bfields@fieldses.org>
2014-06-02 08:09:29 -04:00
Jeff Layton
cf01f4eef9 locks: only validate the lock vs. f_mode in F_SETLK codepaths
v2: replace missing break in switch statement (as pointed out by Dave
    Jones)

commit bce7560d49 (locks: consolidate checks for compatible
filp->f_mode values in setlk handlers) introduced a regression in the
F_GETLK handler.

flock64_to_posix_lock is a shared codepath between F_GETLK and F_SETLK,
but the f_mode checks should only be applicable to the F_SETLK codepaths
according to POSIX.

Instead of just reverting the patch, add a new function to do this
checking and have the F_SETLK handlers call it.

Cc: Dave Jones <davej@redhat.com>
Reported-and-Tested-by: Reuben Farrelly <reuben@reub.net>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
2014-05-09 11:41:54 -04:00
Jeff Layton
cff2fce58b locks: rename FL_FILE_PVT and IS_FILE_PVT to use "*_OFDLCK" instead
File-private locks have been re-christened as "open file description"
locks.  Finish the symbol name cleanup in the internal implementation.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-04-23 16:17:03 -04:00
Jeff Layton
0d3f7a2dd2 locks: rename file-private locks to "open file description locks"
File-private locks have been merged into Linux for v3.15, and *now*
people are commenting that the name and macro definitions for the new
file-private locks suck.

...and I can't even disagree. The names and command macros do suck.

We're going to have to live with these for a long time, so it's
important that we be happy with the names before we're stuck with them.
The consensus on the lists so far is that they should be rechristened as
"open file description locks".

The name isn't a big deal for the kernel, but the command macros are not
visually distinct enough from the traditional POSIX lock macros. The
glibc and documentation folks are recommending that we change them to
look like F_OFD_{GETLK|SETLK|SETLKW}. That lessens the chance that a
programmer will typo one of the commands wrong, and also makes it easier
to spot this difference when reading code.

This patch makes the following changes that I think are necessary before
v3.15 ships:

1) rename the command macros to their new names. These end up in the uapi
   headers and so are part of the external-facing API. It turns out that
   glibc doesn't actually use the fcntl.h uapi header, but it's hard to
   be sure that something else won't. Changing it now is safest.

2) make the the /proc/locks output display these as type "OFDLCK"

Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Carlos O'Donell <carlos@redhat.com>
Cc: Stefan Metzmacher <metze@samba.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Frank Filz <ffilzlnx@mindspring.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-04-22 08:23:58 -04:00
Jeff Layton
f1c6bb2cb8 locks: allow __break_lease to sleep even when break_time is 0
A fl->fl_break_time of 0 has a special meaning to the lease break code
that basically means "never break the lease". knfsd uses this to ensure
that leases don't disappear out from under it.

Unfortunately, the code in __break_lease can end up passing this value
to wait_event_interruptible as a timeout, which prevents it from going
to sleep at all. This makes __break_lease to spin in a tight loop and
causes soft lockups.

Fix this by ensuring that we pass a minimum value of 1 as a timeout
instead.

Cc: <stable@vger.kernel.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Reported-by: Terry Barnaby <terry1@beam.ltd.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-04-15 06:17:49 -04:00
Jeff Layton
29723adee1 locks: make locks_mandatory_area check for file-private locks
Allow locks_mandatory_area() to handle file-private locks correctly.
If there is a file-private lock set on an open file and we're doing I/O
via the same, then that should not cause anything to block.

Handle this by first doing a non-blocking FL_ACCESS check for a
file-private lock, and then fall back to checking for a classic POSIX
lock (and possibly blocking).

Note that this approach is subject to the same races that have always
plagued mandatory locking on Linux.

Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
d7a06983a0 locks: fix locks_mandatory_locked to respect file-private locks
As Trond pointed out, you can currently deadlock yourself by setting a
file-private lock on a file that requires mandatory locking and then
trying to do I/O on it.

Avoid this problem by plumbing some knowledge of file-private locks into
the mandatory locking code. In order to do this, we must pass down
information about the struct file that's being used to
locks_verify_locked.

Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
90478939dc locks: require that flock->l_pid be set to 0 for file-private locks
Neil Brown suggested potentially overloading the l_pid value as a "lock
context" field for file-private locks. While I don't think we will
probably want to do that here, it's probably a good idea to ensure that
in the future we could extend this API without breaking existing
callers.

Typically the l_pid value is ignored for incoming struct flock
arguments, serving mainly as a place to return the pid of the owner if
there is a conflicting lock. For file-private locks, require that it
currently be set to 0 and return EINVAL if it isn't. If we eventually
want to make a non-zero l_pid mean something, then this will help ensure
that we don't break legacy programs that are using file-private locks.

Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
5d50ffd7c3 locks: add new fcntl cmd values for handling file private locks
Due to some unfortunate history, POSIX locks have very strange and
unhelpful semantics. The thing that usually catches people by surprise
is that they are dropped whenever the process closes any file descriptor
associated with the inode.

This is extremely problematic for people developing file servers that
need to implement byte-range locks. Developers often need a "lock
management" facility to ensure that file descriptors are not closed
until all of the locks associated with the inode are finished.

Additionally, "classic" POSIX locks are owned by the process. Locks
taken between threads within the same process won't conflict with one
another, which renders them useless for synchronization between threads.

This patchset adds a new type of lock that attempts to address these
issues. These locks conflict with classic POSIX read/write locks, but
have semantics that are more like BSD locks with respect to inheritance
and behavior on close.

This is implemented primarily by changing how fl_owner field is set for
these locks. Instead of having them owned by the files_struct of the
process, they are instead owned by the filp on which they were acquired.
Thus, they are inherited across fork() and are only released when the
last reference to a filp is put.

These new semantics prevent them from being merged with classic POSIX
locks, even if they are acquired by the same process. These locks will
also conflict with classic POSIX locks even if they are acquired by
the same process or on the same file descriptor.

The new locks are managed using a new set of cmd values to the fcntl()
syscall. The initial implementation of this converts these values to
"classic" cmd values at a fairly high level, and the details are not
exposed to the underlying filesystem. We may eventually want to push
this handing out to the lower filesystem code but for now I don't
see any need for it.

Also, note that with this implementation the new cmd values are only
available via fcntl64() on 32-bit arches. There's little need to
add support for legacy apps on a new interface like this.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
57b65325fe locks: skip deadlock detection on FL_FILE_PVT locks
It's not really feasible to do deadlock detection with FL_FILE_PVT
locks since they aren't owned by a single task, per-se. Deadlock
detection also tends to be rather expensive so just skip it for
these sorts of locks.

Also, add a FIXME comment about adding more limited deadlock detection
that just applies to ro -> rw upgrades, per Andy's request.

Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
c1e62b8fc3 locks: pass the cmd value to fcntl_getlk/getlk64
Once we introduce file private locks, we'll need to know what cmd value
was used, as that affects the ownership and whether a conflict would
arise.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:43 -04:00
Jeff Layton
3fd80cddc6 locks: report l_pid as -1 for FL_FILE_PVT locks
FL_FILE_PVT locks are no longer tied to a particular pid, and are
instead inheritable by child processes. Report a l_pid of '-1' for
these sorts of locks since the pid is somewhat meaningless for them.

This precedent comes from FreeBSD. There, POSIX and flock() locks can
conflict with one another. If fcntl(F_GETLK, ...) returns a lock set
with flock() then the l_pid member cannot be a process ID because the
lock is not held by a process as such.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
c918d42a27 locks: make /proc/locks show IS_FILE_PVT locks as type "FLPVT"
In a later patch, we'll be adding a new type of lock that's owned by
the struct file instead of the files_struct. Those sorts of locks
will be flagged with a new FL_FILE_PVT flag.

Report these types of locks as "FLPVT" in /proc/locks to distinguish
them from "classic" POSIX locks.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
78ed8a1338 locks: rename locks_remove_flock to locks_remove_file
This function currently removes leases in addition to flock locks and in
a later patch we'll have it deal with file-private locks too. Rename it
to locks_remove_file to indicate that it removes locks that are
associated with a particular struct file, and not just flock locks.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
bce7560d49 locks: consolidate checks for compatible filp->f_mode values in setlk handlers
Move this check into flock64_to_posix_lock instead of duplicating it in
two places. This also fixes a minor wart in the code where we continue
referring to the struct flock after converting it to struct file_lock.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
J. Bruce Fields
ef12e72a01 locks: fix posix lock range overflow handling
In the 32-bit case fcntl assigns the 64-bit f_pos and i_size to a 32-bit
off_t.

The existing range checks also seem to depend on signed arithmetic
wrapping when it overflows.  In practice maybe that works, but we can be
more careful.  That also allows us to make a more reliable distinction
between -EINVAL and -EOVERFLOW.

Note that in the 32-bit case SEEK_CUR or SEEK_END might allow the caller
to set a lock with starting point no longer representable as a 32-bit
value.  We could return -EOVERFLOW in such cases, but the locks code is
capable of handling such ranges, so we choose to be lenient here.  The
only problem is that subsequent GETLK calls on such a lock will fail
with EOVERFLOW.

While we're here, do some cleanup including consolidating code for the
flock and flock64 cases.

Signed-off-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
8c3cac5e6a locks: eliminate BUG() call when there's an unexpected lock on file close
A leftover lock on the list is surely a sign of a problem of some sort,
but it's not necessarily a reason to panic the box. Instead, just log a
warning with some info about the lock, and then delete it like we would
any other lock.

In the event that the filesystem declares a ->lock f_op, we may end up
leaking something, but that's generally preferable to an immediate
panic.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
b03dfdec03 locks: add __acquires and __releases annotations to locks_start and locks_stop
...to make sparse happy.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
6ca10ed8ed locks: remove "inline" qualifier from fl_link manipulation functions
It's best to let the compiler decide that.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
46dad7603f locks: clean up comment typo
Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31 08:24:42 -04:00
Jeff Layton
24cbe7845e locks: close potential race between setlease and open
As Al Viro points out, there is an unlikely, but possible race between
opening a file and setting a lease on it. generic_add_lease is done with
the i_lock held, but the inode->i_flock check in break_lease is
lockless. It's possible for another task doing an open to do the entire
pathwalk and call break_lease between the point where generic_add_lease
checks for a conflicting open and adds the lease to the list. If this
occurs, we can end up with a lease set on the file with a conflicting
open.

To guard against that, check again for a conflicting open after adding
the lease to the i_flock list. If the above race occurs, then we can
simply unwind the lease setting and return -EAGAIN.

Because we take dentry references and acquire write access on the file
before calling break_lease, we know that if the i_flock list is empty
when the open caller goes to check it then the necessary refcounts have
already been incremented. Thus the additional check for a conflicting
open will see that there is one and the setlease call will fail.

Cc: Bruce Fields <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@fieldses.org>
2014-03-31 08:24:42 -04:00
Dan Carpenter
4fdb793ffe locks: missing unlock on error in generic_add_lease()
We should unlock here before returning.

Fixes: df4e8d2c1d ('locks: implement delegations')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-13 07:30:53 -05:00
J. Bruce Fields
df4e8d2c1d locks: implement delegations
Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock
type.

Note nfsd is the only delegation user and is only using read
delegations.  Warn on any attempt to set a write delegation for now.
We'll come back to that case later.

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09 00:16:41 -05:00