Commit Graph

368 Commits

Author SHA1 Message Date
Al Viro
52094c8a06 take RCU-dependent stuff around exec_permission() into a new helper
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-14 09:15:23 -04:00
Al Viro
c9c6cac0c2 kill path_lookup()
all remaining callers pass LOOKUP_PARENT to it, so
flags argument can die; renamed to kern_path_parent()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-14 09:15:23 -04:00
Al Viro
b306419ae0 nd->inode is not set on the second attempt in path_walk()
We leave it at whatever it had been pointing to after the
first link_path_walk() had failed with -ESTALE.  Things
do not work well after that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-08 21:16:28 -05:00
Al Viro
1858efd471 minimal fix for do_filp_open() race
failure exits on the no-O_CREAT side of do_filp_open() merge with
those of O_CREAT one; unfortunately, if do_path_lookup() returns
-ESTALE, we'll get out_filp:, notice that we are about to return
-ESTALE without having trying to create the sucker with LOOKUP_REVAL
and jump right into the O_CREAT side of code.  And proceed to try
and create a file.  Usually that'll fail with -ESTALE again, but
we can race and get that attempt of pathname resolution to succeed.

open() without O_CREAT really shouldn't end up creating files, races
or not.  The real fix is to rearchitect the whole do_filp_open(),
but for now splitting the failure exits will do.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-04 13:14:21 -05:00
Linus Torvalds
3abb17e82f vfs: fix BUG_ON() in fs/namei.c:1461
When Al moved the nameidata_dentry_drop_rcu_maybe() call into the
do_follow_link function in commit 844a391799 ("nothing in
do_follow_link() is going to see RCU"), he mistakenly left the

	BUG_ON(inode != path->dentry->d_inode);

behind.  Which would otherwise be ok, but that BUG_ON() really needs to
be _after_ dropping RCU, since the dentry isn't necessarily stable
otherwise.

So complete the code movement in that commit, and move the BUG_ON() into
do_follow_link() too.  This means that we need to pass in 'inode' as an
argument (just for this one use), but that's a small thing.  And
eventually we may be confident enough in our path lookup that we can
just remove the BUG_ON() and the unnecessary inode argument.

Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-16 08:56:55 -08:00
Al Viro
4e924a4f53 get rid of nameidata_dentry_drop_rcu() calling nameidata_drop_rcu()
can't happen anymore and didn't work right anyway

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-02-15 02:26:54 -05:00
Al Viro
f60aef7ec6 drop out of RCU in return_reval
... thus killing the need to handle drop-from-RCU in d_revalidate()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-02-15 02:26:54 -05:00
Al Viro
f5e1c1c1af split do_revalidate() into RCU and non-RCU cases
fixing oopsen in lookup_one_len()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-02-15 02:26:54 -05:00
Al Viro
24643087e7 in do_lookup() split RCU and non-RCU cases of need_revalidate
and use unlikely() instead of gotos, for fsck sake...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-02-15 02:26:54 -05:00
Al Viro
844a391799 nothing in do_follow_link() is going to see RCU
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-02-15 02:26:53 -05:00
Linus Torvalds
2dab597441 Fix possible filp_cachep memory corruption
In commit 31e6b01f41 ("fs: rcu-walk for path lookup") we started doing
path lookup using RCU, which then falls back to a careful non-RCU lookup
in case of problems (LOOKUP_REVAL).  So do_filp_open() has this "re-do
the lookup carefully" looping case.

However, that means that we must not release the open-intent file data
if we are going to loop around and use it once more!

Fix this by moving the release of the open-intent data to the function
that allocates it (do_filp_open() itself) rather than the helper
functions that can get called multiple times (finish_open() and
do_last()).  This makes the logic for the lifetime of that field much
more obvious, and avoids the possible double free.

Reported-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-11 15:53:38 -08:00
Ian Kent
8931221411 vfs - fix dentry ref count in do_lookup()
There is a ref count problem in fs/namei.c:do_lookup().

When walking in ref-walk mode, if follow_managed() returns a fail we
need to drop dentry and possibly vfsmount.  Clean up properly,
as we do in the other caller of follow_managed().

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-18 01:21:26 -05:00
Al Viro
19a167af7c Take the completion of automount into new helper
... and shift it from namei.c to namespace.c

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-17 01:35:23 -05:00
Al Viro
f03c65993b sanitize vfsmount refcounting changes
Instead of splitting refcount between (per-cpu) mnt_count
and (SMP-only) mnt_longrefs, make all references contribute
to mnt_count again and keep track of how many are longterm
ones.

Accounting rules for longterm count:
	* 1 for each fs_struct.root.mnt
	* 1 for each fs_struct.pwd.mnt
	* 1 for having non-NULL ->mnt_ns
	* decrement to 0 happens only under vfsmount lock exclusive

That allows nice common case for mntput() - since we can't drop the
final reference until after mnt_longterm has reached 0 due to the rules
above, mntput() can grab vfsmount lock shared and check mnt_longterm.
If it turns out to be non-zero (which is the common case), we know
that this is not the final mntput() and can just blindly decrement
percpu mnt_count.  Otherwise we grab vfsmount lock exclusive and
do usual decrement-and-check of percpu mnt_count.

For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm();
namespace.c uses the latter in places where we don't already hold
vfsmount lock exclusive and opencodes a few remaining spots where
we need to manipulate mnt_longterm.

Note that we mostly revert the code outside of fs/namespace.c back
to what we used to have; in particular, normal code doesn't need
to care about two kinds of references, etc.  And we get to keep
the optimization Nick's variant had bought us...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-16 13:47:07 -05:00
David Howells
ea5b778a8b Unexport do_add_mount() and add in follow_automount(), not ->d_automount()
Unexport do_add_mount() and make ->d_automount() return the vfsmount to be
added rather than calling do_add_mount() itself.  follow_automount() will then
do the addition.

This slightly complicates things as ->d_automount() normally wants to add the
new vfsmount to an expiration list and start an expiration timer.  The problem
with that is that the vfsmount will be deleted if it has a refcount of 1 and
the timer will not repeat if the expiration list is empty.

To this end, we require the vfsmount to be returned from d_automount() with a
refcount of (at least) 2.  One of these refs will be dropped unconditionally.
In addition, follow_automount() must get a 3rd ref around the call to
do_add_mount() lest it eat a ref and return an error, leaving the mount we
have open to being expired as we would otherwise have only 1 ref on it.

d_automount() should also add the the vfsmount to the expiration list (by
calling mnt_set_expiry()) and start the expiration timer before returning, if
this mechanism is to be used.  The vfsmount will be unlinked from the
expiration list by follow_automount() if do_add_mount() fails.

This patch also fixes the call to do_add_mount() for AFS to propagate the mount
flags from the parent vfsmount.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:48 -05:00
David Howells
ab90911ff9 Allow d_manage() to be used in RCU-walk mode
Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well
as when it is in Ref-walk mode.  This permits __follow_mount_rcu() to call
d_manage() directly.  d_manage() needs a parameter to indicate that it is in
RCU-walk mode as it isn't allowed to sleep if in that mode (but should return
-ECHILD instead).

autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon
accesses it and otherwise request dropping back to ref-walk mode.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:47 -05:00
David Howells
87556ef199 Remove a further kludge from __do_follow_link()
Remove a further kludge from __do_follow_link() as it's no longer required with
the automount code.

This reverts the non-helper-function parts of
051d381259, which breaks union mounts.

Reported-by: vaurora@redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:46 -05:00
David Howells
db3729153e Remove the automount through follow_link() kludge code from pathwalk
Remove the automount through follow_link() kludge code from pathwalk in favour
of using d_automount().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:36 -05:00
David Howells
6f45b65672 Add an AT_NO_AUTOMOUNT flag to suppress terminal automount
Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of automount
point directories.  This can be used by fstatat() users to permit the
gathering of attributes on an automount point and also prevent
mass-automounting of a directory of automount points by ls.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:33 -05:00
David Howells
cc53ce53c8 Add a dentry op to allow processes to be held during pathwalk transit
Add a dentry op (d_manage) to permit a filesystem to hold a process and make it
sleep when it tries to transit away from one of that filesystem's directories
during a pathwalk.  The operation is keyed off a new dentry flag
(DCACHE_MANAGE_TRANSIT).

The filesystem is allowed to be selective about which processes it holds and
which it permits to continue on or prohibits from transiting from each flagged
directory.  This will allow autofs to hold up client processes whilst letting
its userspace daemon through to maintain the directory or the stuff behind it
or mounted upon it.

The ->d_manage() dentry operation:

	int (*d_manage)(struct path *path, bool mounting_here);

takes a pointer to the directory about to be transited away from and a flag
indicating whether the transit is undertaken by do_add_mount() or
do_move_mount() skipping through a pile of filesystems mounted on a mountpoint.

It should return 0 if successful and to let the process continue on its way;
-EISDIR to prohibit the caller from skipping to overmounted filesystems or
automounting, and to use this directory; or some other error code to return to
the user.

->d_manage() is called with namespace_sem writelocked if mounting_here is true
and no other locks held, so it may sleep.  However, if mounting_here is true,
it may not initiate or wait for a mount or unmount upon the parameter
directory, even if the act is actually performed by userspace.

Within fs/namei.c, follow_managed() is extended to check with d_manage() first
on each managed directory, before transiting away from it or attempting to
automount upon it.

follow_down() is renamed follow_down_one() and should only be used where the
filesystem deliberately intends to avoid management steps (e.g. autofs).

A new follow_down() is added that incorporates the loop done by all other
callers of follow_down() (do_add/move_mount(), autofs and NFSD; whilst AFS, NFS
and CIFS do use it, their use is removed by converting them to use
d_automount()).  The new follow_down() calls d_manage() as appropriate.  It
also takes an extra parameter to indicate if it is being called from mount code
(with namespace_sem writelocked) which it passes to d_manage().  follow_down()
ignores automount points so that it can be used to mount on them.

__follow_mount_rcu() is made to abort rcu-walk mode if it hits a directory with
DCACHE_MANAGE_TRANSIT set on the basis that we're probably going to have to
sleep.  It would be possible to enter d_manage() in rcu-walk mode too, and have
that determine whether to abort or not itself.  That would allow the autofs
daemon to continue on in rcu-walk mode.

Note that DCACHE_MANAGE_TRANSIT on a directory should be cleared when it isn't
required as every tranist from that directory will cause d_manage() to be
invoked.  It can always be set again when necessary.

==========================
WHAT THIS MEANS FOR AUTOFS
==========================

Autofs currently uses the lookup() inode op and the d_revalidate() dentry op to
trigger the automounting of indirect mounts, and both of these can be called
with i_mutex held.

autofs knows that the i_mutex will be held by the caller in lookup(), and so
can drop it before invoking the daemon - but this isn't so for d_revalidate(),
since the lock is only held on _some_ of the code paths that call it.  This
means that autofs can't risk dropping i_mutex from its d_revalidate() function
before it calls the daemon.

The bug could manifest itself as, for example, a process that's trying to
validate an automount dentry that gets made to wait because that dentry is
expired and needs cleaning up:

	mkdir         S ffffffff8014e05a     0 32580  24956
	Call Trace:
	 [<ffffffff885371fd>] :autofs4:autofs4_wait+0x674/0x897
	 [<ffffffff80127f7d>] avc_has_perm+0x46/0x58
	 [<ffffffff8009fdcf>] autoremove_wake_function+0x0/0x2e
	 [<ffffffff88537be6>] :autofs4:autofs4_expire_wait+0x41/0x6b
	 [<ffffffff88535cfc>] :autofs4:autofs4_revalidate+0x91/0x149
	 [<ffffffff80036d96>] __lookup_hash+0xa0/0x12f
	 [<ffffffff80057a2f>] lookup_create+0x46/0x80
	 [<ffffffff800e6e31>] sys_mkdirat+0x56/0xe4

versus the automount daemon which wants to remove that dentry, but can't
because the normal process is holding the i_mutex lock:

	automount     D ffffffff8014e05a     0 32581      1              32561
	Call Trace:
	 [<ffffffff80063c3f>] __mutex_lock_slowpath+0x60/0x9b
	 [<ffffffff8000ccf1>] do_path_lookup+0x2ca/0x2f1
	 [<ffffffff80063c89>] .text.lock.mutex+0xf/0x14
	 [<ffffffff800e6d55>] do_rmdir+0x77/0xde
	 [<ffffffff8005d229>] tracesys+0x71/0xe0
	 [<ffffffff8005d28d>] tracesys+0xd5/0xe0

which means that the system is deadlocked.

This patch allows autofs to hold up normal processes whilst the daemon goes
ahead and does things to the dentry tree behind the automouter point without
risking a deadlock as almost no locks are held in d_manage() and none in
d_automount().

Signed-off-by: David Howells <dhowells@redhat.com>
Was-Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:07:31 -05:00
David Howells
9875cf8064 Add a dentry op to handle automounting rather than abusing follow_link()
Add a dentry op (d_automount) to handle automounting directories rather than
abusing the follow_link() inode operation.  The operation is keyed off a new
dentry flag (DCACHE_NEED_AUTOMOUNT).

This also makes it easier to add an AT_ flag to suppress terminal segment
automount during pathwalk and removes the need for the kludge code in the
pathwalk algorithm to handle directories with follow_link() semantics.

The ->d_automount() dentry operation:

	struct vfsmount *(*d_automount)(struct path *mountpoint);

takes a pointer to the directory to be mounted upon, which is expected to
provide sufficient data to determine what should be mounted.  If successful, it
should return the vfsmount struct it creates (which it should also have added
to the namespace using do_add_mount() or similar).  If there's a collision with
another automount attempt, NULL should be returned.  If the directory specified
by the parameter should be used directly rather than being mounted upon,
-EISDIR should be returned.  In any other case, an error code should be
returned.

The ->d_automount() operation is called with no locks held and may sleep.  At
this point the pathwalk algorithm will be in ref-walk mode.

Within fs/namei.c itself, a new pathwalk subroutine (follow_automount()) is
added to handle mountpoints.  It will return -EREMOTE if the automount flag was
set, but no d_automount() op was supplied, -ELOOP if we've encountered too many
symlinks or mountpoints, -EISDIR if the walk point should be used without
mounting and 0 if successful.  The path will be updated to point to the mounted
filesystem if a successful automount took place.

__follow_mount() is replaced by follow_managed() which is more generic
(especially with the patch that adds ->d_manage()).  This handles transits from
directories during pathwalk, including automounting and skipping over
mountpoints (and holding processes with the next patch).

__follow_mount_rcu() will jump out of RCU-walk mode if it encounters an
automount point with nothing mounted on it.

follow_dotdot*() does not handle automounts as you don't want to trigger them
whilst following "..".

I've also extracted the mount/don't-mount logic from autofs4 and included it
here.  It makes the mount go ahead anyway if someone calls open() or creat(),
tries to traverse the directory, tries to chdir/chroot/etc. into the directory,
or sticks a '/' on the end of the pathname.  If they do a stat(), however,
they'll only trigger the automount if they didn't also say O_NOFOLLOW.

I've also added an inode flag (S_AUTOMOUNT) so that filesystems can mark their
inodes as automount points.  This flag is automatically propagated to the
dentry as DCACHE_NEED_AUTOMOUNT by __d_instantiate().  This saves NFS and could
save AFS a private flag bit apiece, but is not strictly necessary.  It would be
preferable to do the propagation in d_set_d_op(), but that doesn't normally
have access to the inode.

[AV: fixed breakage in case if __follow_mount_rcu() fails and nameidata_drop_rcu()
succeeds in RCU case of do_lookup(); we need to fall through to non-RCU case after
that, rather than just returning with ungrabbed *path]

Signed-off-by: David Howells <dhowells@redhat.com>
Was-Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:05:03 -05:00
Al Viro
1a8edf40e7 do_lookup() fix
do_lookup() has a path leading from LOOKUP_RCU case to non-RCU
crossing of mountpoints, which breaks things badly.  If we
hit need_revalidate: and do nothing in there, we need to come
back into LOOKUP_RCU half of things, not to done: in non-RCU
one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15 20:03:39 -05:00
Linus Torvalds
acda4721ae Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin
* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
  kernel: fix hlist_bl again
  cgroups: Fix a lockdep warning at cgroup removal
  fs: namei fix ->put_link on wrong inode in do_filp_open
2011-01-14 09:08:29 -08:00
Nick Piggin
7b9337aaf9 fs: namei fix ->put_link on wrong inode in do_filp_open
J. R. Okajima noticed that ->put_link is being attempted on the
wrong inode, and suggested the way to fix it. I changed it a bit
according to Al's suggestion to keep an explicit link path around.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-14 08:42:43 +00:00
Linus Torvalds
db9effe99a Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin
* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
  fs: fix do_last error case when need_reval_dot
  nfs: add missing rcu-walk check
  fs: hlist UP debug fixup
  fs: fix dropping of rcu-walk from force_reval_path
  fs: force_reval_path drop rcu-walk before d_invalidate
  fs: small rcu-walk documentation fixes

Fixed up trivial conflicts in Documentation/filesystems/porting
2011-01-13 20:14:13 -08:00
J. R. Okajima
f20877d94a fs: fix do_last error case when need_reval_dot
When open(2) without O_DIRECTORY opens an existing dir, it should return
EISDIR. In do_last(), the variable 'error' is initialized EISDIR, but it
is changed by d_revalidate() which returns any positive to represent
'the target dir is valid.'

Should we keep and return the initialized 'error' in this case.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-14 03:56:04 +00:00
Nick Piggin
90dbb77ba4 fs: fix dropping of rcu-walk from force_reval_path
As J. R. Okajima noted, force_reval_path passes in the same dentry to
d_revalidate as the one in the nameidata structure (other callers pass in a
child), so the locking breaks. This can oops with a chrooted nfs mount, for
example. Similarly there can be other problems with revalidating a dentry
which is already in nameidata of the path walk.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-14 02:36:19 +00:00
Nick Piggin
bb20c18db6 fs: force_reval_path drop rcu-walk before d_invalidate
d_revalidate can return in rcu-walk mode even when it returns 0.  We can't just
call any old dcache function on rcu-walk dentry (the dentry is unstable, so
even through d_lock can safely be taken, the result may no longer be what we
expect -- careful re-checks would be required). So just drop rcu in this case.

(I missed this conversion when switching to the rcu-walk convention that Linus
suggested)

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-14 02:35:53 +00:00
Jeff Layton
e1181ee657 vfs: pass struct file to do_truncate on O_TRUNC opens (try #2)
When a file is opened with O_TRUNC, the truncate processing is handled
by handle_truncate(). This function however doesn't receive any info
about the newly instantiated filp, and therefore can't pass that info
along so that the setattr can use it.

This makes NFSv4 misbehave. The client does an open and gets a valid
stateid, and then doesn't use that stateid on the subsequent truncate.
It uses the zero-stateid instead. Most servers ignore this fact and
just do the truncate anyway, but some don't like it (notably, RHEL4).

It seems more correct that since we have a fully instantiated file at
the time that handle_truncate is called, that we pass that along so
that the truncate operation can properly use it.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-12 20:06:59 -05:00
Randy Dunlap
39191628ed fs: fix namei.c kernel-doc notation
Fix new kernel-doc notation warnings in fs/namei.c and spell
ECHILD correctly.

  Warning(fs/namei.c:218): No description found for parameter 'flags'
  Warning(fs/namei.c:425): Excess function parameter 'Returns' description in 'nameidata_drop_rcu'
  Warning(fs/namei.c:478): Excess function parameter 'Returns' description in 'nameidata_dentry_drop_rcu'
  Warning(fs/namei.c:540): Excess function parameter 'Returns' description in 'nameidata_drop_rcu_last'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc:	Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-10 07:38:53 -08:00
Nick Piggin
b3e19d924b fs: scale mntget/mntput
The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.

The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.

We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.

- check the global sum once every interval (this will delay zero detection
  for some interval, so it's probably a showstopper for vfsmounts).

- keep a local count and only taking the global sum when local reaches 0 (this
  is difficult for vfsmounts, because we can't hold preempt off for the life of
  a reference, so a counter would need to be per-thread or tied strongly to a
  particular CPU which requires more locking).

- keep a local difference of increments and decrements, which allows us to sum
  the total difference and hence find the refcount when summing all CPUs. Then,
  keep a single integer "long" refcount for slow and long lasting references,
  and only take the global sum of local counters when the long refcount is 0.

This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.

This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.

This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:33 +11:00
Nick Piggin
b74c79e993 fs: provide rcu-walk aware permission i_ops
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:29 +11:00
Nick Piggin
34286d6662 fs: rcu-walk aware d_revalidate method
Require filesystems be aware of .d_revalidate being called in rcu-walk
mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning
-ECHILD from all implementations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:29 +11:00
Nick Piggin
fb045adb99 fs: dcache reduce branches in lookup path
Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.

Patched with:

git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:28 +11:00
Nick Piggin
c28cc36469 fs: fs_struct use seqlock
Use a seqlock in the fs_struct to enable us to take an atomic copy of the
complete cwd and root paths. Use this in the RCU lookup path to avoid a
thread-shared spinlock in RCU lookup operations.

Multi-threaded apps may now perform path lookups with scalability matching
multi-process apps. Operations such as stat(2) become very scalable for
multi-threaded workload.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:27 +11:00
Nick Piggin
31e6b01f41 fs: rcu-walk for path lookup
Perform common cases of path lookups without any stores or locking in the
ancestor dentry elements. This is called rcu-walk, as opposed to the current
algorithm which is a refcount based walk, or ref-walk.

This results in far fewer atomic operations on every path element,
significantly improving path lookup performance. It also avoids cacheline
bouncing on common dentries, significantly improving scalability.

The overall design is like this:
* LOOKUP_RCU is set in nd->flags, which distinguishes rcu-walk from ref-walk.
* Take the RCU lock for the entire path walk, starting with the acquiring
  of the starting path (eg. root/cwd/fd-path). So now dentry refcounts are
  not required for dentry persistence.
* synchronize_rcu is called when unregistering a filesystem, so we can
  access d_ops and i_ops during rcu-walk.
* Similarly take the vfsmount lock for the entire path walk. So now mnt
  refcounts are not required for persistence. Also we are free to perform mount
  lookups, and to assume dentry mount points and mount roots are stable up and
  down the path.
* Have a per-dentry seqlock to protect the dentry name, parent, and inode,
  so we can load this tuple atomically, and also check whether any of its
  members have changed.
* Dentry lookups (based on parent, candidate string tuple) recheck the parent
  sequence after the child is found in case anything changed in the parent
  during the path walk.
* inode is also RCU protected so we can load d_inode and use the inode for
  limited things.
* i_mode, i_uid, i_gid can be tested for exec permissions during path walk.
* i_op can be loaded.

When we reach the destination dentry, we lock it, recheck lookup sequence,
and increment its refcount and mountpoint refcount. RCU and vfsmount locks
are dropped. This is termed "dropping rcu-walk". If the dentry refcount does
not match, we can not drop rcu-walk gracefully at the current point in the
lokup, so instead return -ECHILD (for want of a better errno). This signals the
path walking code to re-do the entire lookup with a ref-walk.

Aside from the final dentry, there are other situations that may be encounted
where we cannot continue rcu-walk. In that case, we drop rcu-walk (ie. take
a reference on the last good dentry) and continue with a ref-walk. Again, if
we can drop rcu-walk gracefully, we return -ECHILD and do the whole lookup
using ref-walk. But it is very important that we can continue with ref-walk
for most cases, particularly to avoid the overhead of double lookups, and to
gain the scalability advantages on common path elements (like cwd and root).

The cases where rcu-walk cannot continue are:
* NULL dentry (ie. any uncached path element)
* parent with d_inode->i_op->permission or ACLs
* dentries with d_revalidate
* Following links

In future patches, permission checks and d_revalidate become rcu-walk aware. It
may be possible eventually to make following links rcu-walk aware.

Uncached path elements will always require dropping to ref-walk mode, at the
very least because i_mutex needs to be grabbed, and objects allocated.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:27 +11:00
Nick Piggin
b5c84bf6f6 fs: dcache remove dcache_lock
dcache_lock no longer protects anything. remove it.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:23 +11:00
Nick Piggin
b7ab39f631 fs: dcache scale dentry refcount
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:21 +11:00
Nick Piggin
b1e6a015a5 fs: change d_hash for rcu-walk
Change d_hash so it may be called from lock-free RCU lookups. See similar
patch for d_compare for details.

For in-tree filesystems, this is just a mechanical change.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 17:50:20 +11:00
Lino Sanfilippo
b1085ba80c fanotify: if set by user unset FMODE_NONOTIFY before fsnotify_perm() is called
Unsetting FMODE_NONOTIFY in fsnotify_open() is too late, since fsnotify_perm()
is called before. If FMODE_NONOTIFY is set fsnotify_perm() will skip permission
checks, so a user can still disable permission checks by setting this flag
in an open() call.
This patch corrects this by unsetting the flag before fsnotify_perm is called.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
2010-12-07 16:14:21 -05:00
Al Viro
d893f1bc2a fix open/umount race
nameidata_to_filp() drops nd->path or transfers it to opened
file.  In the former case it's a Bad Idea(tm) to do mnt_drop_write()
on nd->path.mnt, since we might race with umount and vfsmount in
question might be gone already.

Fix: don't drop it, then...  IOW, have nameidata_to_filp() grab nd->path
in case it transfers it to file and do path_drop() in callers.  After
they are through with accessing nd->path...

Reported-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-10-29 04:14:56 -04:00
Al Viro
7de9c6ee3e new helper: ihold()
Clones an existing reference to inode; caller must already hold one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-10-25 21:26:11 -04:00
Christoph Hellwig
81fca44400 fs: move permission check back into __lookup_hash
The caller that didn't need it is gone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-10-25 21:18:19 -04:00
Nick Piggin
99b7db7b8f fs: brlock vfsmount_lock
fs: brlock vfsmount_lock

Use a brlock for the vfsmount lock. It must be taken for write whenever
modifying the mount hash or associated fields, and may be taken for read when
performing mount hash lookups.

A new lock is added for the mnt-id allocator, so it doesn't need to take
the heavy vfsmount write-lock.

The number of atomics should remain the same for fastpath rlock cases, though
code would be slightly slower due to per-cpu access. Scalability is not not be
much improved in common cases yet, due to other locks (ie. dcache_lock) getting
in the way. However path lookups crossing mountpoints should be one case where
scalability is improved (currently requiring the global lock).

The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node
Altix system (high latency to remote nodes), a simple umount microbenchmark
(mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it
took 6.8s, afterwards took 7.1s, about 5% slower.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-18 08:35:48 -04:00
Nick Piggin
b04f784e5d fs: remove extra lookup in __lookup_hash
fs: remove extra lookup in __lookup_hash

Optimize lookup for create operations, where no dentry should often be
common-case. In cases where it is not, such as unlink, the added overhead
is much smaller than the removed.

Also, move comments about __d_lookup racyness to the __d_lookup call site.
d_lookup is intuitive; __d_lookup is what needs commenting. So in that same
vein, add kerneldoc comments to __d_lookup and clean up some of the comments:

- We are interested in how the RCU lookup works here, particularly with
  renames. Make that explicit, and point to the document where it is explained
  in more detail.
- RCU is pretty standard now, and macros make implementations pretty mindless.
  If we want to know about RCU barrier details, we look in RCU code.
- Delete some boring legacy comments because we don't care much about how the
  code used to work, more about the interesting parts of how it works now. So
  comments about lazy LRU may be interesting, but would better be done in the
  LRU or refcount management code.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-18 08:35:47 -04:00
Nick Piggin
baa0389073 fs: dentry allocation consolidation
fs: dentry allocation consolidation

There are 2 duplicate copies of code in dentry allocation in path lookup.
Consolidate them into a single function.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-18 08:35:45 -04:00
Nick Piggin
2e2e88ea8c fs: fix do_lookup false negative
fs: fix do_lookup false negative

In do_lookup, if we initially find no dentry, we take the directory i_mutex and
re-check the lookup. If we find a dentry there, then we revalidate it if
needed. However if that revalidate asks for the dentry to be invalidated, we
return -ENOENT from do_lookup. What should happen instead is an attempt to
allocate and lookup a new dentry.

This is probably not noticed because it is rare. It is only reached if a
concurrent create races in first (in which case, the dentry probably won't be
invalidated anyway), or if the racy __d_lookup has failed due to a
false-negative (which is very rare).

Fix this by removing code and have it use the normal reval path.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-18 08:35:45 -04:00
Miklos Szeredi
f7ad3c6be9 vfs: add helpers to get root and pwd
Add three helpers that retrieve a refcounted copy of the root and cwd
from the supplied fs_struct.

 get_fs_root()
 get_fs_pwd()
 get_fs_root_and_pwd()

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-08-11 00:28:20 -04:00
Linus Torvalds
8c8946f509 Merge branch 'for-linus' of git://git.infradead.org/users/eparis/notify
* 'for-linus' of git://git.infradead.org/users/eparis/notify: (132 commits)
  fanotify: use both marks when possible
  fsnotify: pass both the vfsmount mark and inode mark
  fsnotify: walk the inode and vfsmount lists simultaneously
  fsnotify: rework ignored mark flushing
  fsnotify: remove global fsnotify groups lists
  fsnotify: remove group->mask
  fsnotify: remove the global masks
  fsnotify: cleanup should_send_event
  fanotify: use the mark in handler functions
  audit: use the mark in handler functions
  dnotify: use the mark in handler functions
  inotify: use the mark in handler functions
  fsnotify: send fsnotify_mark to groups in event handling functions
  fsnotify: Exchange list heads instead of moving elements
  fsnotify: srcu to protect read side of inode and vfsmount locks
  fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called
  fsnotify: use _rcu functions for mark list traversal
  fsnotify: place marks on object in order of group memory address
  vfs/fsnotify: fsnotify_close can delay the final work in fput
  fsnotify: store struct file not struct path
  ...

Fix up trivial delete/modify conflict in fs/notify/inotify/inotify.c.
2010-08-10 11:39:13 -07:00
Eric Paris
d09ca73979 security: make LSMs explicitly mask off permissions
SELinux needs to pass the MAY_ACCESS flag so it can handle auditting
correctly.  Presently the masking of MAY_* flags is done in the VFS.  In
order to allow LSMs to decide what flags they care about and what flags
they don't just pass them all and the each LSM mask off what they don't
need.  This patch should contain no functional changes to either the VFS or
any LSM.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02 15:35:07 +10:00
Tetsuo Handa
ea0d3ab239 LSM: Remove unused arguments from security_path_truncate().
When commit be6d3e56a6 "introduce new LSM hooks
where vfsmount is available." was proposed, regarding security_path_truncate(),
only "struct file *" argument (which AppArmor wanted to use) was removed.
But length and time_attrs arguments are not used by TOMOYO nor AppArmor.
Thus, let's remove these arguments.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02 15:33:40 +10:00
Eric Paris
59b0df211b fsnotify: use unsigned char * for dentry->d_name.name
fsnotify was using char * when it passed around the d_name.name string
internally but it is actually an unsigned char *.  This patch switches
fsnotify to use unsigned and should silence some pointer signess warnings
which have popped out of xfs.  I do not add -Wpointer-sign to the fsnotify
code as there are still issues with kstrdup and strlen which would pop
out needless warnings.

Signed-off-by: Eric Paris <eparis@redhat.com>
2010-07-28 09:59:01 -04:00
Neil Brown
176306f59a VFS: fix recent breakage of FS_REVAL_DOT
Commit 1f36f774b2 broke FS_REVAL_DOT semantics.

In particular, before this patch, the command
   ls -l
in an NFS mounted directory would always check if the directory on the server
had changed and if so would flush and refill the pagecache for the dir.
After this patch, the same "ls -l" will repeatedly return stale date until
the cached attributes for the directory time out.

The following patch fixes this by ensuring the d_revalidate is called by
do_last when "." is being looked-up.
link_path_walk has already called d_revalidate, but in that case LOOKUP_OPEN
is not set so nfs_lookup_verify_inode chooses not to do any validation.

The following patch restores the original behaviour.

Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-27 22:03:06 -04:00
Huang Shijie
9a2296832c namei.c : update mnt when it needed
update the mnt of the path when it is not equal to the new one.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-21 18:31:22 -04:00
Al Viro
d83c49f3e3 Fix the regression created by "set S_DEAD on unlink()..." commit
1) i_flags simply doesn't work for mount/unlink race prevention;
we may have many links to file and rm on one of those obviously
shouldn't prevent bind on top of another later on.  To fix it
right way we need to mark _dentry_ as unsuitable for mounting
upon; new flag (DCACHE_CANT_MOUNT) is protected by d_flags and
i_mutex on the inode in question.  Set it (with dont_mount(dentry))
in unlink/rmdir/etc., check (with cant_mount(dentry)) in places
in namespace.c that used to check for S_DEAD.  Setting S_DEAD
is still needed in places where we used to set it (for directories
getting killed), since we rely on it for readdir/rmdir race
prevention.

2) rename()/mount() protection has another bogosity - we unhash
the target before we'd checked that it's not a mountpoint.  Fixed.

3) ancient bogosity in pivot_root() - we locked i_mutex on the
right directory, but checked S_DEAD on the different (and wrong)
one.  Noticed and fixed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-15 07:16:33 -04:00
Jan Kara
002baeecf5 vfs: Fix O_NOFOLLOW behavior for paths with trailing slashes
According to specification

	mkdir d; ln -s d a; open("a/", O_NOFOLLOW | O_RDONLY)

should return success but currently it returns ELOOP.  This is a
regression caused by path lookup cleanup patch series.

Fix the code to ignore O_NOFOLLOW in case the provided path has trailing
slashes.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Marius Tolzmann <tolzmann@molgen.mpg.de>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-05-13 08:46:04 -07:00
Al Viro
3e297b6134 Restore LOOKUP_DIRECTORY hint handling in final lookup on open()
Lose want_dir argument, while we are at it - since now
nd->flags & LOOKUP_DIRECTORY is equivalent to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-26 12:41:05 -04:00
Jiri Kosina
318ae2edc3 Merge branch 'for-next' into for-linus
Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c
2010-03-08 16:55:37 +01:00
Al Viro
781b16775b Fix a dumb typo - use of & instead of &&
We managed to lose O_DIRECTORY testing due to a stupid typo in commit
1f36f774b2 ("Switch !O_CREAT case to use of do_last()")

Reported-by: Walter Sheets <w41ter@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06 10:54:48 -08:00
Linus Torvalds
e213e26ab3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6: (33 commits)
  quota: stop using QUOTA_OK / NO_QUOTA
  dquot: cleanup dquot initialize routine
  dquot: move dquot initialization responsibility into the filesystem
  dquot: cleanup dquot drop routine
  dquot: move dquot drop responsibility into the filesystem
  dquot: cleanup dquot transfer routine
  dquot: move dquot transfer responsibility into the filesystem
  dquot: cleanup inode allocation / freeing routines
  dquot: cleanup space allocation / freeing routines
  ext3: add writepage sanity checks
  ext3: Truncate allocated blocks if direct IO write fails to update i_size
  quota: Properly invalidate caches even for filesystems with blocksize < pagesize
  quota: generalize quota transfer interface
  quota: sb_quota state flags cleanup
  jbd: Delay discarding buffers in journal_unmap_buffer
  ext3: quota_write cross block boundary behaviour
  quota: drop permission checks from xfs_fs_set_xstate/xfs_fs_set_xquota
  quota: split out compat_sys_quotactl support from quota.c
  quota: split out netlink notification support from quota.c
  quota: remove invalid optimization from quota_sync_all
  ...

Fixed trivial conflicts in fs/namei.c and fs/ufs/inode.c
2010-03-05 13:20:53 -08:00
Al Viro
1f36f774b2 Switch !O_CREAT case to use of do_last()
... and now we have all intents crap well localized

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:22:25 -05:00
Al Viro
def4af30cf Get rid of symlink body copying
Now that nd->last stays around until ->put_link() is called, we can
just postpone that ->put_link() in do_filp_open() a bit and don't
bother with copying.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:40 -05:00
Al Viro
3866248e5f Finish pulling of -ESTALE handling to upper level in do_filp_open()
Don't bother with path_walk() (and its retry loop); link_path_walk()
will do it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:38 -05:00
Al Viro
806b681cbe Turn do_link spaghetty into a normal loop
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:36 -05:00
Al Viro
10fa8e62f2 Unify exits in O_CREAT handling
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:35 -05:00
Al Viro
9e67f36169 Kill is_link argument of do_last()
We set it to 1 iff we return NULL

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:33 -05:00
Al Viro
67ee3ad21d Pull handling of LAST_BIND into do_last(), clean up ok: part in do_filp_open()
Note that in case of !O_CREAT we know that nd.root has already been given up

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:31 -05:00
Al Viro
4296e2cbf2 Leave mangled flag only for setting nd.intent.open.flag
Nothing else uses it anymore

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:29 -05:00
Al Viro
5b369df826 Get rid of passing mangled flag to do_last()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:27 -05:00
Al Viro
9a66179e13 Don't pass mangled open_flag to finish_open()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:25 -05:00
Al Viro
a2c36b450e pull more into do_last()
Handling of LAST_DOT/LAST_ROOT/LAST_DOTDOT/terminating slash
can be pulled in as well

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:24 -05:00
Al Viro
c99658fe97 bail out with ELOOP earlier in do_link loop
If we'd passed through 32 trailing symlinks already, there's
no sense following the 33rd - we'll bail out anyway.  Better
bugger off earlier.

It *does* change behaviour, after a fashion - if the 33rd happens
to be a procfs-style symlink, original code *would* allow it.
This one will not.  Cry me a river if that hurts you.  Please, do.
And post a video of that, while you are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:22 -05:00
Al Viro
a1e28038df pull the common predecessors into do_last()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:20 -05:00
Al Viro
c41c140562 postpone __putname() until after do_last()
Since do_last() doesn't mangle nd->last_name, we can safely postpone
__putname() done in handling of trailing symlinks until after the
call of do_last()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:18 -05:00
Al Viro
27bff34300 unroll do_last: loop in do_filp_open()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:16 -05:00
Al Viro
3343eb8209 Shift releasing nd->root from do_last() to its caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:15 -05:00
Al Viro
fb1cc555d5 gut do_filp_open() a bit more (do_last separation)
Brute-force separation of stuff reachable from do_last: with
the exception of do_link:; just take all that crap to a helper
function as-is and have it tell the caller if it has to go
to do_link.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:13 -05:00
Al Viro
648fa8611d beginning to untangle do_filp_open()
That's going to be a long and painful series.  The first step:
take the stuff reachable from 'ok' label in do_filp_open() into
a new helper (finish_open()).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-05 09:01:11 -05:00
Christoph Hellwig
907f4554e2 dquot: move dquot initialization responsibility into the filesystem
Currently various places in the VFS call vfs_dq_init directly.  This means
we tie the quota code into the VFS.  Get rid of that and make the
filesystem responsible for the initialization.   For most metadata operations
this is a straight forward move into the methods, but for truncate and
open it's a bit more complicated.

For truncate we currently only call vfs_dq_init for the sys_truncate case
because open already takes care of it for ftruncate and open(O_TRUNC) - the
new code causes an additional vfs_dq_init for those which is harmless.

For open the initialization is moved from do_filp_open into the open method,
which means it happens slightly earlier now, and only for regular files.
The latter is fine because we don't need to initialize it for operations
on special files, and we already do it as part of the namespace operations
for directories.

Add a dquot_file_open helper that filesystems that support generic quotas
can use to fill in ->open.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
2010-03-05 00:20:30 +01:00
Al Viro
9643f5d94a Merge branch 'for-fsnotify' into for-linus 2010-03-03 17:12:40 -05:00
Al Viro
bec1052e5b set S_DEAD on unlink() and non-directory rename() victims
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-03 14:12:08 -05:00
Al Viro
3088dd7080 Clean follow_dotdot() up a bit
No need to open-code follow_up() in it and locking can be lighter.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-03 14:07:56 -05:00
Al Viro
8737c9305b Switch may_open() and break_lease() to passing O_...
... instead of mixing FMODE_ and O_

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-03-03 13:00:21 -05:00
Al Viro
ac278a9c50 fix LOOKUP_FOLLOW on automount "symlinks"
Make sure that automount "symlinks" are followed regardless of LOOKUP_FOLLOW;
it should have no effect on them.

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-19 03:56:42 -05:00
Al Viro
cccc6bba3f Lose the first argument of audit_inode_child()
it's always equal to ->d_name.name of the second argument

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-08 14:38:36 -05:00
Al Viro
123df2944c Lose the new_name argument of fsnotify_move()
it's always new_dentry->d_name.name

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-08 14:38:36 -05:00
Mimi Zohar
9bbb6cad01 ima: rename ima_path_check to ima_file_check
ima_path_check actually deals with files!  call it ima_file_check instead.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-07 03:06:22 -05:00
Mimi Zohar
8eb988c70e fix ima breakage
The "Untangling ima mess, part 2 with counters" patch messed
up the counters.  Based on conversations with Al Viro, this patch
streamlines ima_path_check() by removing the counter maintaince.
The counters are now updated independently, from measuring the file,
in __dentry_open() and alloc_file() by calling ima_counts_get().
ima_path_check() is called from nfsd and do_filp_open().
It also did not measure all files that should have been measured.
Reason: ima_path_check() got bogus value passed as mask.
[AV: mea culpa]
[AV: add missing nfsd bits]

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-02-07 03:06:22 -05:00
Adam Buchbinder
c41b20e721 Fix misspellings of "truly" in comments.
Some comments misspell "truly"; this fixes them. No code changes.

Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-02-04 11:55:45 +01:00
Al Viro
9850c05655 Fix the -ESTALE handling in do_filp_open()
Instead of playing sick games with path saving, cleanups, just retry
the entire thing once with LOOKUP_REVAL added.  Post-.34 we'll convert
all -ESTALE handling in there to that style, rather than playing with
many retry loops deep in the call chain.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-01-14 09:05:26 -05:00
Al Viro
6d125529c6 Fix ACC_MODE() for real
commit 5300990c03 had stepped on a rather
nasty mess: definitions of ACC_MODE used to be different.  Fixed the
resulting breakage, converting them to variant that takes O_... value;
all callers have that and it actually simplifies life (see tomoyo part
of changes).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-01-14 09:05:26 -05:00
Al Viro
86acdca1b6 fix autofs/afs/etc. magic mountpoint breakage
We end up trying to kfree() nd.last.name on open("/mnt/tmp", O_CREAT)
if /mnt/tmp is an autofs direct mount.  The reason is that nd.last_type
is bogus here; we want LAST_BIND for everything of that kind and we
get LAST_NORM left over from finding parent directory.

So make sure that it *is* set properly; set to LAST_BIND before
doing ->follow_link() - for normal symlinks it will be changed
by __vfs_follow_link() and everything else needs it set that way.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-01-14 09:05:25 -05:00
Serge E. Hallyn
7ea6600148 generic_permission: MAY_OPEN is not write access
generic_permission was refusing CAP_DAC_READ_SEARCH-enabled
processes from opening DAC-protected files read-only, because
do_filp_open adds MAY_OPEN to the open mask.

Ignore MAY_OPEN.  After this patch, CAP_DAC_READ_SEARCH is
again sufficient to open(fname, O_RDONLY) on a file to which
DAC otherwise refuses us read permission.

Reported-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-30 12:35:44 -08:00
Al Viro
5300990c03 Sanitize f_flags helpers
* pull ACC_MODE to fs.h; we have several copies all over the place
* nightmarish expression calculating f_mode by f_flags deserves a helper
too (OPEN_FMODE(flags))

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-22 12:27:34 -05:00
Al Viro
482928d59d Fix f_flags/f_mode in case of lookup_instantiate_filp() from open(pathname, 3)
Just set f_flags when shoving struct file into nameidata; don't
postpone that until __dentry_open().  do_filp_open() has correct
value; lookup_instantiate_filp() doesn't - we lose the difference
between O_RDWR and 3 by that point.

We still set .intent.open.flags, so no fs code needs to be changed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-22 12:27:34 -05:00
Jeff Layton
cb59861f03 vfs: remove extraneous NULL d_inode check from do_filp_open
We can't get to this point unless it's a valid pointer.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-17 10:52:34 -05:00
Jeff Layton
39159de2a0 vfs: force reval of target when following LAST_BIND symlinks (try #7)
procfs-style symlinks return a last_type of LAST_BIND without an actual
path string. This causes __follow_link to skip calling __vfs_follow_link
and so the dentry isn't revalidated.

This is a problem when the link target sits on NFSv4 as it depends on
the VFS to revalidate the dentry before using it on an open call. Ensure
that this occurs by forcing a revalidation of the target dentry of
LAST_BIND symlinks.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:48 -05:00
Al Viro
1429b3eca2 Untangling ima mess, part 3: kill dead code in ima
Kill the 'update' argument of ima_path_check(), kill
dead code in ima.

Current rules: ima counters are bumped at the same time
when the file switches from put_filp() fodder to fput()
one.  Which happens exactly in two places - alloc_file()
and __dentry_open().  Nothing else needs to do that at
all.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:47 -05:00
Al Viro
b65a9cfc2c Untangling ima mess, part 2: deal with counters
* do ima_get_count() in __dentry_open()
* stop doing that in followups
* move ima_path_check() to right after nameidata_to_filp()
* don't bump counters on it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:47 -05:00
Al Viro
7715b52122 O_TRUNC open shouldn't fail after file truncation
* take truncate logics into a helper (handle_truncate())
* rip it out of may_open()
* call it from the only caller of may_open() that might pass
O_TRUNC
* and do that after we'd finished with opening.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-16 12:16:47 -05:00