Al Viro [Wed, 13 May 2015 13:12:02 +0000 (09:12 -0400)]
turn user_{path_at,path,lpath,path_dir}() into static inlines
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 13 May 2015 11:28:08 +0000 (07:28 -0400)]
namei: move saved_nd pointer into struct nameidata
these guys are always declared next to each other; might as well put
the former (pointer to previous instance) into the latter and simplify
the calling conventions for {set,restore}_nameidata()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 13 May 2015 11:00:28 +0000 (07:00 -0400)]
inline user_path_create()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 13 May 2015 10:57:49 +0000 (06:57 -0400)]
inline user_path_parent()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 22:44:32 +0000 (18:44 -0400)]
namei: trim do_last() arguments
now that struct filename is stashed in nameidata we have no need to
pass it in
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 22:43:07 +0000 (18:43 -0400)]
namei: stash dfd and name into nameidata
fewer arguments to pass around...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 21:35:52 +0000 (17:35 -0400)]
namei: fold path_cleanup() into terminate_walk()
they are always called next to each other; moreover,
terminate_walk() is more symmetrical that way.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 21:32:54 +0000 (17:32 -0400)]
namei: saner calling conventions for filename_parentat()
a) make it reject ERR_PTR() for name
b) make it putname(name) on all other failure exits
c) make it return name on success
again, simplifies the callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 21:21:25 +0000 (17:21 -0400)]
namei: saner calling conventions for filename_create()
a) make it reject ERR_PTR() for name
b) make it putname(name) upon return in all other cases.
seriously simplifies the callers...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 15:19:16 +0000 (11:19 -0400)]
namei: shift nameidata down into filename_parentat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 20:53:42 +0000 (16:53 -0400)]
namei: make filename_lookup() reject ERR_PTR() passed as name
makes for much easier life in callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 20:44:39 +0000 (16:44 -0400)]
namei: shift nameidata inside filename_lookup()
pass root instead; non-NULL => copy to nd.root and
set LOOKUP_ROOT in flags
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 20:40:39 +0000 (16:40 -0400)]
namei: move putname() call into filename_lookup()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 20:36:12 +0000 (16:36 -0400)]
namei: pass the struct path to store the result down into path_lookupat()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 20:32:34 +0000 (16:32 -0400)]
namei: uninline set_root{,_rcu}()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 16:22:47 +0000 (12:22 -0400)]
namei: be careful with mountpoint crossings in follow_dotdot_rcu()
Otherwise we are risking a hard error where nonlazy restart would be the right
thing to do; it's a very narrow race with mount --move and most of the time it
ends up being completely harmless, but it's possible to construct a case when
we'll get a bogus hard error instead of falling back to non-lazy walk...
For one thing, when crossing _into_ overmount of parent we need to check for
mount_lock bumps when we get NULL from __lookup_mnt() as well.
For another, and less exotically, we need to make sure that the data fetched
in follow_up_rcu() had been consistent. ->mnt_mountpoint is pinned for as
long as it is a mountpoint, but we need to check mount_lock after fetching
to verify that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NeilBrown [Mon, 23 Mar 2015 02:37:38 +0000 (13:37 +1100)]
Documentation: remove outdated information from automount-support.txt
The guidelines for adding automount support to a filesystem
in filesystems/automount-support.txt is out or date.
filesystems/autofs4.txt contains more current text, so replace
the out-of-date content with a reference to that.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 12:29:38 +0000 (08:29 -0400)]
get rid of assorted nameidata-related debris
pointless forward declarations, stale comments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 12:29:13 +0000 (08:29 -0400)]
lustre: kill unused helper
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 23 Feb 2015 05:20:40 +0000 (00:20 -0500)]
lustre: kill unused macro (LOOKUP_CONTINUE)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 12 May 2015 04:10:18 +0000 (00:10 -0400)]
namei: unlazy_walk() doesn't need to mess with current->fs anymore
now that we have ->root_seq, legitimize_path(&nd->root, nd->root_seq)
will do just fine...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 11 May 2015 12:29:30 +0000 (08:29 -0400)]
update Documentation/filesystems/ regarding the follow_link/put_link changes
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 23:02:01 +0000 (19:02 -0400)]
namei: handle absolute symlinks without dropping out of RCU mode
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 22:15:21 +0000 (18:15 -0400)]
enable passing fast relative symlinks without dropping out of RCU mode
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NeilBrown [Mon, 23 Mar 2015 02:37:40 +0000 (13:37 +1100)]
VFS/namei: make the use of touch_atime() in get_link() RCU-safe.
touch_atime is not RCU-safe, and so cannot be called on an RCU walk.
However, in situations where RCU-walk makes a difference, the symlink
will likely to accessed much more often than it is useful to update
the atime.
So split out the test of "Does the atime actually need to be updated"
into atime_needs_update(), and have get_link() unlazy if it finds that
it will need to do that update.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 17:04:24 +0000 (13:04 -0400)]
namei: don't unlazy until get_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 16:55:43 +0000 (12:55 -0400)]
namei: make unlazy_walk and terminate_walk handle nd->stack, add unlazy_link
We are almost done - primitives for leaving RCU mode are aware of nd->stack
now, a new primitive for going to non-RCU mode when we have a symlink on hands
added.
The thing we are heavily relying upon is that *any* unlazy failure will be
shortly followed by terminate_walk(), with no access to nameidata in between.
So it's enough to leave the things in a state terminate_walk() would cope with.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 17:23:53 +0000 (13:23 -0400)]
namei: store seq numbers in nd->stack[]
we'll need them for unlazy_walk()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 15:43:53 +0000 (11:43 -0400)]
new helper: __legitimize_mnt()
same as legitimize_mnt(), except that it does *not* drop and regain
rcu_read_lock; return values are
0 => grabbed a reference, we are fine
1 => failed, just go away
-1 => failed, go away and mntput(bastard) when outside of rcu_read_lock
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 00:37:40 +0000 (20:37 -0400)]
namei: make may_follow_link() safe in RCU mode
We *can't* call that audit garbage in RCU mode - it's doing a weird
mix of allocations (GFP_NOFS, immediately followed by GFP_KERNEL)
and I'm not touching that... thing again.
So if this security sclero^Whardening feature gets triggered when
we are in RCU mode, tough - we'll fail with -ECHILD and have
everything restarted in non-RCU mode. Only to hit the same test
and fail, this time with EACCES and with (oh, rapture) an audit spew
produced.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 00:32:22 +0000 (20:32 -0400)]
namei: make put_link() RCU-safe
very simple - just make path_put() conditional on !RCU.
Note that right now it doesn't get called in RCU mode -
we leave it before getting anything into stack.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Thu, 7 May 2015 15:19:14 +0000 (11:19 -0400)]
new helper: free_page_put_link()
similar to kfree_put_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Thu, 7 May 2015 15:14:26 +0000 (11:14 -0400)]
switch ->put_link() from dentry to inode
only one instance looks at that argument at all; that sole
exception wants inode rather than dentry.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NeilBrown [Mon, 23 Mar 2015 02:37:39 +0000 (13:37 +1100)]
security: make inode_follow_link RCU-walk aware
inode_follow_link now takes an inode and rcu flag as well as the
dentry.
inode is used in preference to d_backing_inode(dentry), particularly
in RCU-walk mode.
selinux_inode_follow_link() gets dentry_has_perm() and
inode_has_perm() open-coded into it so that it can call
avc_has_perm_flags() in way that is safe if LOOKUP_RCU is set.
Calling avc_has_perm_flags() with rcu_read_lock() held means
that when avc_has_perm_noaudit calls avc_compute_av(), the attempt
to rcu_read_unlock() before calling security_compute_av() will not
actually drop the RCU read-lock.
However as security_compute_av() is completely in a read_lock()ed
region, it should be safe with the RCU read-lock held.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NeilBrown [Mon, 23 Mar 2015 02:37:39 +0000 (13:37 +1100)]
security/selinux: pass 'flags' arg to avc_audit() and avc_has_perm_flags()
This allows MAY_NOT_BLOCK to be passed, in RCU-walk mode, through
the new avc_has_perm_flags() to avc_audit() and thence the slow_avc_audit.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Thu, 7 May 2015 23:54:34 +0000 (19:54 -0400)]
namei: pick_link() callers already have inode
no need to refetch (and once we move unlazy out of there, recheck ->d_seq).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
David Howells [Wed, 6 May 2015 14:59:00 +0000 (15:59 +0100)]
VFS: Handle lower layer dentry/inode in pathwalk
Make use of d_backing_inode() in pathwalk to gain access to an
inode or dentry that's on a lower layer.
Signed-off-by: David Howells <dhowells@redhat.com>
Al Viro [Thu, 7 May 2015 13:21:14 +0000 (09:21 -0400)]
namei: store inode in nd->stack[]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 5 May 2015 13:40:46 +0000 (09:40 -0400)]
namei: don't mangle nd->seq in lookup_fast()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 5 May 2015 13:26:05 +0000 (09:26 -0400)]
namei: explicitly pass seq number to unlazy_walk() when dentry != NULL
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 9 May 2015 20:54:45 +0000 (16:54 -0400)]
link_path_walk: use explicit returns for failure exits
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 22:05:21 +0000 (18:05 -0400)]
namei: lift terminate_walk() all the way up
Lift it from link_path_walk(), trailing_symlink(), lookup_last(),
mountpoint_last(), complete_walk() and do_last(). A _lot_ of
those suckers merge.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 21:37:07 +0000 (17:37 -0400)]
namei: lift link_path_walk() call out of trailing_symlink()
Make trailing_symlink() return the pathname to traverse or ERR_PTR(-E...).
A subtle point is that for "magic" symlinks it returns "" now - that
leads to link_path_walk("", nd), which is immediately returning 0 and
we are back to the treatment of the last component, at whereever the
damn thing has left us.
Reduces the stack footprint - link_path_walk() called on more shallow
stack now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 21:19:59 +0000 (17:19 -0400)]
namei: path_init() calling conventions change
* lift link_path_walk() into callers; moving it down into path_init()
had been a mistake. Stack footprint, among other things...
* do _not_ call path_cleanup() after path_init() failure; on all failure
exits out of it we have nothing for path_cleanup() to do
* have path_init() return pathname or ERR_PTR(-E...)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 11 May 2015 12:05:05 +0000 (08:05 -0400)]
namei: get rid of nameidata->base
we can do fdput() under rcu_read_lock() just fine; all we need to take
care of is fetching nd->inode value first.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 20:59:20 +0000 (16:59 -0400)]
namei: split off filename_lookupat() with LOOKUP_PARENT
new functions: filename_parentat() and path_parentat() resp.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 20:38:31 +0000 (16:38 -0400)]
namei: may_follow_link() - lift terminate_walk() on failures into caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 10 May 2015 15:50:01 +0000 (11:50 -0400)]
namei: take increment of nd->depth into pick_link()
Makes the situation much more regular - we avoid a strange state
when the element just after the top of stack is used to store
struct path of symlink, but isn't counted in nd->depth. This
is much more regular, so the normal failure exits, etc., work
fine.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 6 May 2015 20:01:56 +0000 (16:01 -0400)]
namei: kill nd->link
Just store it in nd->stack[nd->depth].link right in pick_link().
Now that we make sure of stack expansion in pick_link(), we can
do so...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 6 May 2015 19:58:18 +0000 (15:58 -0400)]
may_follow_link(): trim arguments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Tue, 5 May 2015 14:52:35 +0000 (10:52 -0400)]
namei: move bumping the refcount of link->mnt into pick_link()
update the failure cleanup in may_follow_link() to match that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Fri, 8 May 2015 20:28:42 +0000 (16:28 -0400)]
namei: fold put_link() into the failure case of complete_walk()
... and don't open-code unlazy_walk() in there - the only reason
for that is to avoid verfication of cached nd->root, which is
trivially avoided by discarding said cached nd->root first.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 10 May 2015 15:01:00 +0000 (11:01 -0400)]
namei: take the treatment of absolute symlinks to get_link()
rather than letting the callers handle the jump-to-root part of
semantics, do it right in get_link() and return the rest of the
body for the caller to deal with - at that point it's treated
the same way as relative symlinks would be. And return NULL
when there's no "rest of the body" - those are treated the same
as pure jump symlink would be.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 10 May 2015 14:50:41 +0000 (10:50 -0400)]
namei: simpler treatment of symlinks with nothing other that / in the body
Instead of saving name and branching to OK:, where we'll immediately restore
it, and call walk_component() with WALK_PUT|WALK_GET and nd->last_type being
LAST_BIND, which is equivalent to put_link(nd), err = 0, we can just treat
that the same way we'd treat procfs-style "jump" symlinks - do put_link(nd)
and move on.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 10 May 2015 14:43:46 +0000 (10:43 -0400)]
namei: simplify failure exits in get_link()
when cookie is NULL, put_link() is equivalent to path_put(), so
as soon as we'd set last->cookie to NULL, we can bump nd->depth and
let the normal logics in terminate_walk() to take care of cleanups.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 2 May 2015 17:37:52 +0000 (13:37 -0400)]
don't pass nameidata to ->follow_link()
its only use is getting passed to nd_jump_link(), which can obtain
it from current->nameidata
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 22 Apr 2015 14:30:08 +0000 (10:30 -0400)]
namei: simplify the callers of follow_managed()
now that it gets nameidata, no reason to have setting LOOKUP_JUMPED on
mountpoint crossing and calling path_put_conditional() on failures
done in every caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NeilBrown [Mon, 23 Mar 2015 02:37:38 +0000 (13:37 +1100)]
VFS: replace {, total_}link_count in task_struct with pointer to nameidata
task_struct currently contains two ad-hoc members for use by the VFS:
link_count and total_link_count. These are only interesting to fs/namei.c,
so exposing them explicitly is poor layering. Incidentally, link_count
isn't used anymore, so it can just die.
This patches replaces those with a single pointer to 'struct nameidata'.
This structure represents the current filename lookup of which
there can only be one per process, and is a natural place to
store total_link_count.
This will allow the current "nameidata" argument to all
follow_link operations to be removed as current->nameidata
can be used instead in the _very_ few instances that care about
it at all.
As there are occasional circumstances where pathname lookup can
recurse, such as through kern_path_locked, we always save and old
current->nameidata (if there is one) when setting a new value, and
make sure any active link_counts are preserved.
follow_mount and follow_automount now get a 'struct nameidata *'
rather than 'int flags' so that they can directly access
total_link_count, rather than going through 'current'.
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 18 Apr 2015 03:02:40 +0000 (23:02 -0400)]
lustre: rip the private symlink nesting limit out
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 22:26:59 +0000 (18:26 -0400)]
namei: move link count check and stack allocation into pick_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 22:13:23 +0000 (18:13 -0400)]
namei: make should_follow_link() store the link in nd->link
... if it decides to follow, that is.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 21:47:11 +0000 (17:47 -0400)]
namei: new calling conventions for walk_component()
instead of a single flag (!= 0 => we want to follow symlinks) pass
two bits - WALK_GET (want to follow symlinks) and WALK_PUT (put_link()
once we are done looking at the name). The latter matters only for
success exits - on failure the caller will discard everything anyway.
Suggestions for better variant are welcome; what this thing aims for
is making sure that pending put_link() is done *before* walk_component()
decides to pick a symlink up, rather than between picking it up and
acting upon it. See the next commit for payoff.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 12:58:35 +0000 (08:58 -0400)]
link_path_walk: move the OK: inside the loop
fewer labels that way; in particular, resuming after the end of
nested symlink is straight-line.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 12:34:59 +0000 (08:34 -0400)]
namei: have terminate_walk() do put_link() on everything left
All callers of terminate_walk() are followed by more or less
open-coded eqiuvalent of "do put_link() on everything left
in nd->stack". Better done in terminate_walk() itself, and
when we go for RCU symlink traversal we'll have to do it
there anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 12:26:45 +0000 (08:26 -0400)]
namei: take put_link() into {lookup,mountpoint,do}_last()
rationale: we'll need to have terminate_walk() do put_link() on
everything, which will mean that in some cases ..._last() will do
put_link() anyway. Easier to have them do it in all cases.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 12:15:36 +0000 (08:15 -0400)]
namei: lift (open-coded) terminate_walk() into callers of get_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 11:59:30 +0000 (07:59 -0400)]
lift terminate_walk() into callers of walk_component()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 11:53:00 +0000 (07:53 -0400)]
namei: lift (open-coded) terminate_walk() in follow_dotdot_rcu() into callers
follow_dotdot_rcu() does an equivalent of terminate_walk() on failure;
shifting it into callers makes for simpler rules and those callers
already have terminate_walk() on other failure exits.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:30:27 +0000 (21:30 -0400)]
namei: we never need more than MAXSYMLINKS entries in nd->stack
The only reason why we needed one more was that purely nested
MAXSYMLINKS symlinks could lead to path_init() using that many
entries in addition to nd->stack[0] which it left unused.
That can't happen now - path_init() starts with entry 0 (and
trailing_symlink() is called only when we'd already encountered
one symlink, so no more than MAXSYMLINKS-1 are left).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:27:36 +0000 (21:27 -0400)]
link_path_walk: end of nd->depth massage
get rid of orig_depth - we only use it on error exit to tell whether
to stop doing put_link() when depth reaches 0 (call from path_init())
or when it reaches 1 (call from trailing_symlink()). However, in
the latter case the caller would immediately follow with one more
put_link(). Just keep doing it until the depth reaches zero (and
simplify trailing_symlink() as the result).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:21:44 +0000 (21:21 -0400)]
link_path_walk: nd->depth massage, part 10
Get rid of orig_depth checks in OK: logics. If nd->depth is
zero, we had been called from path_init() and we are done.
If it is greater than 1, we are not done, whether we'd been
called from path_init() or trailing_symlink(). And in
case when it's 1, we might have been called from path_init()
and reached the end of nested symlink (in which case
nd->stack[0].name will point to the rest of pathname and
we are not done) or from trailing_symlink(), in which case
we are done.
Just have trailing_symlink() leave NULL in nd->stack[0].name
and use that to discriminate between those cases.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:16:35 +0000 (21:16 -0400)]
link_path_walk: nd->depth massage, part 9
Make link_path_walk() work with any value of nd->depth on entry -
memorize it and use it in tests instead of comparing with 1.
Don't bother with increment/decrement in path_init().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:06:24 +0000 (21:06 -0400)]
put_link: nd->depth massage, part 8
all calls are preceded by decrement of nd->depth; move it into
put_link() itself.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:04:07 +0000 (21:04 -0400)]
trailing_symlink: nd->depth massage, part 7
move decrement of nd->depth on successful returns into the callers.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 01:02:40 +0000 (21:02 -0400)]
get_link: nd->depth massage, part 6
make get_link() increment nd->depth on successful exit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 00:59:58 +0000 (20:59 -0400)]
trailing_symlink: nd->depth massage, part 5
move increment of ->depth to the point where we'd discovered
that get_link() has not returned an error, adjust exits
accordingly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 00:54:27 +0000 (20:54 -0400)]
link_path_walk: nd->depth massage, part 4
lift increment/decrement into link_path_walk() callers.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 00:52:15 +0000 (20:52 -0400)]
link_path_walk: nd->depth massage, part 3
remove decrement/increment surrounding nd_alloc_stack(), adjust the
test in it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 00:46:54 +0000 (20:46 -0400)]
link_path_walk: nd->depth massage, part 2
collapse adjacent increment/decrement pairs.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Mon, 4 May 2015 00:01:27 +0000 (20:01 -0400)]
link_path_walk: nd->depth massage, part 1
nd->stack[0] is unused until the handling of trailing symlinks and
we want to get rid of that. Having fucked that transformation up
several times, I went for bloody pedantic series of provably equivalent
transformations. Sorry.
Step 1: keep nd->depth higher by one in link_path_walk() - increment upon
entry, decrement on exits, adjust the arithmetics inside and surround the
calls of functions that care about nd->depth value (nd_alloc_stack(),
get_link(), put_link()) with decrement/increment pairs.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 2 May 2015 11:16:16 +0000 (07:16 -0400)]
namei: remove restrictions on nesting depth
The only restriction is that on the total amount of symlinks
crossed; how they are nested does not matter
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 04:53:50 +0000 (00:53 -0400)]
namei: trim the arguments of get_link()
same story as the previous commit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 3 May 2015 00:19:23 +0000 (20:19 -0400)]
namei: trim redundant arguments of fs/namei.c:put_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 2 May 2015 23:48:56 +0000 (19:48 -0400)]
namei: trim redundant arguments of trailing_symlink()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 2 May 2015 23:38:35 +0000 (19:38 -0400)]
namei: move link/cookie pairs into nameidata
Array of MAX_NESTED_LINKS + 1 elements put into nameidata;
what used to be a local array in link_path_walk() occupies
entries 1 .. MAX_NESTED_LINKS in it, link and cookie from
the trailing symlink handling loops - entry 0.
This is _not_ the final arrangement; just an easily verified
incremental step.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:44:34 +0000 (20:44 -0400)]
link_path_walk: cleanup - turn goto start; into continue;
Deal with skipping leading slashes before what used to be the
recursive call. That way we can get rid of that goto completely.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:40:04 +0000 (20:40 -0400)]
link_path_walk: split "return from recursive call" path
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:30:49 +0000 (20:30 -0400)]
link_path_walk: kill the recursion
absolutely straightforward now - the only variables we need to preserve
across the recursive call are name, link and cookie, and recursion depth
is limited (and can is equal to nd->depth). So arrange an array of
triples to hold instances of those and be done with that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:21:40 +0000 (20:21 -0400)]
link_path_walk: final preparations to killing recursion
reduce the number of returns in there - turn all places
where it returns zero into goto OK and places where it
returns non-zero into goto Err. The only non-trivial
detail is that all breaks in the loop are guaranteed
to be with non-zero err.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:14:20 +0000 (20:14 -0400)]
link_path_walk: get rid of duplication
What we do after the second walk_component() + put_link() + depth
decrement in there is exactly equivalent to what's done right
after the first walk_component(). Easy to verify and not at all
surprising, seeing that there we have just walked the last
component of nested symlink.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:09:08 +0000 (20:09 -0400)]
link_path_walk: massage a bit more
Pull the block after the if-else in the end of what used to be do-while
body into all branches there. We are almost done with the massage...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 00:03:03 +0000 (20:03 -0400)]
link_path_walk: turn inner loop into explicit goto
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 18 Apr 2015 23:19:01 +0000 (19:19 -0400)]
link_path_walk: don't bother with walk_component() after jumping link
... it does nothing if nd->last_type is LAST_BIND.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 18 Apr 2015 23:10:36 +0000 (19:10 -0400)]
link_path_walk: handle get_link() returning ERR_PTR() immediately
If we get ERR_PTR() from get_link(), we are guaranteed to get err != 0
when we break out of do-while, so we are going to hit if (err) return err;
shortly after it. Pull that into the if (IS_ERR(s)) body.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 22 Apr 2015 17:46:57 +0000 (13:46 -0400)]
namei: rename follow_link to trailing_symlink, move it down
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sun, 19 Apr 2015 04:16:37 +0000 (00:16 -0400)]
namei: move the calls of may_follow_link() into follow_link()
All remaining callers of the former are preceded by the latter
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 18 Apr 2015 22:45:16 +0000 (18:45 -0400)]
namei: expand the call of follow_link() in link_path_walk()
... and strip __always_inline from follow_link() - remaining callers
don't need that.
Now link_path_walk() recursion is a direct one.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Sat, 18 Apr 2015 03:44:45 +0000 (23:44 -0400)]
namei: expand nested_symlink() in its only caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 22 Apr 2015 22:02:17 +0000 (18:02 -0400)]
do_last: move path there from caller's stack frame
We used to need it to feed to follow_link(). No more...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Al Viro [Wed, 22 Apr 2015 21:52:47 +0000 (17:52 -0400)]
namei: introduce nameidata->link
shares space with nameidata->next, walk_component() et.al. store
the struct path of symlink instead of returning it into a variable
passed by caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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