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A number of filesystems were potentially triggering kernel bugs due to
corrupted symlink names on disk. This function helps safely terminate
the names.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Duane Griffin <duaneg@dghda.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This adds LOOKUP_RENAME_TARGET intent for lookup of rename destination.
LOOKUP_RENAME_TARGET is going to be used like LOOKUP_CREATE. But since
the destination of rename() can be existing directory entry, so it has a
difference. Although that difference doesn't matter in my usage, this
tells it to user of this intent.
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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New flag: LOOKUP_EXCL. Set before doing the final step of pathname
resolution on the paths that have LOOKUP_CREATE and O_EXCL.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Analog of lookup_path(), takes struct path *.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* do not pass nameidata; struct path is all the callers want.
* switch to new helpers:
user_path_at(dfd, pathname, flags, &path)
user_path(pathname, &path)
user_lpath(pathname, &path)
user_path_dir(pathname, &path) (fail if not a directory)
The last 3 are trivial macro wrappers for the first one.
* remove nameidata in callers.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* MAY_CHDIR is redundant - it's an equivalent of MAY_ACCESS
* MAY_ACCESS on fuse should affect only the last step of pathname resolution
* fchdir() and chroot() should pass MAY_ACCESS, for the same reason why
chdir() needs that.
* now that we pass MAY_ACCESS explicitly in all cases, LOOKUP_ACCESS can be
removed; it has no business being in nameidata.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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long overdue...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... so we ought to pass MAY_CHDIR to vfs_permission() instead of having
it triggered on every step of preceding pathname resolution. LOOKUP_CHDIR
is killed by that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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* Add path_put() functions for releasing a reference to the dentry and
vfsmount of a struct path in the right order
* Switch from path_release(nd) to path_put(&nd->path)
* Rename dput_path() to path_put_conditional()
[akpm@linux-foundation.org: fix cifs]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is the central patch of a cleanup series. In most cases there is no good
reason why someone would want to use a dentry for itself. This series reflects
that fact and embeds a struct path into nameidata.
Together with the other patches of this series
- it enforced the correct order of getting/releasing the reference count on
<dentry,vfsmount> pairs
- it prepares the VFS for stacking support since it is essential to have a
struct path in every place where the stack can be traversed
- it reduces the overall code size:
without patch series:
text data bss dec hex filename
5321639 858418 715768 6895825 6938d1 vmlinux
with patch series:
text data bss dec hex filename
5320026 858418 715768 6894212 693284 vmlinux
This patch:
Switch from nd->{dentry,mnt} to nd->path.{dentry,mnt} everywhere.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix cifs]
[akpm@linux-foundation.org: fix smack]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Move the definition of struct path into its own header file for further
patches.
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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path_release_on_umount() should only be called from sys_umount(). I merged the
function into sys_umount() instead of having in in namei.c.
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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FASTCALL() is always expanded to empty, remove it.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Try to fix the mess created by sysfs braindamage.
- refactor code internal to fs/namei.c a little to avoid too much
duplication:
o __lookup_hash_kern is renamed back to __lookup_hash
o the old __lookup_hash goes away, permission checks moves to
the two callers
o useless inline qualifiers on above functions go away
- lookup_one_len_kern loses it's last argument and is renamed to
lookup_one_noperm to make it's useage a little more clear
- added kerneldoc comments to describe lookup_one_len aswell as
lookup_one_noperm and make it very clear that no one should use
the latter ever.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Stackable file systems, among others, frequently need to lookup paths or
path components starting from an arbitrary point in the namespace
(identified by a dentry and a vfsmount). Currently, such file systems use
lookup_one_len, which is frowned upon [1] as it does not pass the lookup
intent along; not passing a lookup intent, for example, can trigger BUG_ON's
when stacking on top of NFSv4.
The first patch introduces a new lookup function to allow lookup starting
from an arbitrary point in the namespace. This approach has been suggested
by Christoph Hellwig [2].
The second patch changes sunrpc to use vfs_path_lookup.
The third patch changes nfsctl.c to use vfs_path_lookup.
The fourth patch marks link_path_walk static.
The fifth, and last patch, unexports path_walk because it is no longer
unnecessary to call it directly, and using the new vfs_path_lookup is
cleaner.
For example, the following snippet of code, looks up "some/path/component"
in a directory pointed to by parent_{dentry,vfsmnt}:
err = vfs_path_lookup(parent_dentry, parent_vfsmnt,
"some/path/component", 0, &nd);
if (!err) {
/* exits */
...
/* once done, release the references */
path_release(&nd);
} else if (err == -ENOENT) {
/* doesn't exist */
} else {
/* other error */
}
VFS functions such as lookup_create can be used on the nameidata structure
to pass the create intent to the file system.
Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Prevent permission checking from being performed when the kernel wants to
unconditionally remove a sysfs group, by introducing an kernel-only variant
of lookup_one_len(), lookup_one_len_kern().
Additionally, as sysfs_remove_group() does not check the return value of
the lookup before using it, a BUG_ON has been added to pinpoint the cause
of any problems potentially caused by this (and as a form of annotation).
Signed-off-by: James Morris <jmorris@namei.org>
Cc: Nagendra Singh Tomar <nagendra_tomar@adaptec.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Moved struct path from fs/namei.c to include/linux/namei.h. This allows many
places in the VFS, as well as any stackable filesystem to easily keep track of
dentry-vfsmount pairs.
Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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* fs/open.c is getting bit crowdy
* preparation to lutimes(2)
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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In the "operation does permission checking" model used by fuse, chdir
permission is not checked, since there's no chdir method.
For this case set a lookup flag, which will be passed to ->permission(), so
fuse can distinguish it from permission checks for other operations.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It's way past time to bump it to 8. Everyone had been warned - for
months now.
RH kernels have had this for more than a year.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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As announced, lookup_hash() can now become static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name. These functions, openat etc, have been discussed on numerous
occasions. They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.
We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic. But this code is rather expensive. Here are some
results (similar to what Jim Meyering posted before).
The test creates a deep directory hierarchy on a tmpfs filesystem. Then
rm -fr is used to remove all directories. Without syscall support I get
this:
real 0m31.921s
user 0m0.688s
sys 0m31.234s
With syscall support the results are much better:
real 0m20.699s
user 0m0.536s
sys 0m20.149s
The interfaces are for obvious reasons currently not much used. But they'll
be used. coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them. I expect a patch to make follow soon. Every program which is walking
the filesystem tree will benefit.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch __deprecated_for_modules the lookup_hash() prototype.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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->permission and ->lookup have a struct nameidata * argument these days to
pass down lookup intents. Unfortunately some callers of lookup_hash don't
actually pass this one down. For lookup_one_len() we don't have a struct
nameidata to pass down, but as this function is a library function only
used by filesystem code this is an acceptable limitation. All other
callers should pass down the nameidata, so this patch changes the
lookup_hash interface to only take a struct nameidata argument and derives
the other two arguments to __lookup_hash from it. All callers already have
the nameidata argument available so this is not a problem.
At the same time I'd like to deprecate the lookup_hash interface as there
are better exported interfaces for filesystem usage. Before it can
actually be removed I need to fix up rpc_pipefs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This is needed by NFSv4 for atomicity reasons: our open command is in
fact a lookup+open, so we need to be able to propagate open context
information from lookup() into the resulting struct file's
private_data field.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Add a mechanism for the VFS layer to retry pathname resolution if a file
system returns ESTALE at any point during the resolution process. Pathname
resolution is retried once from the first component, using all real lookup
requests.
This provides effective recovery for most cases where files or directories
have been replaced by other remote file system clients. It also provides
a foundation to build a mechanism by which file system clients can fail
over transparently to a replicated server.
Test-plan:
Combinations of rsync and "ls -l" on multiple clients. No stale file handles
should be after directory trees are replaced. Standard performance tests;
little or no loss of performance is expected.
Created: Fri, 11 Feb 2005 16:46:19 -0500
Signed-off-by: Chuck Lever <cel@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Here's a patch that I worked out with Al Viro that adds support for a
filesystem (such as kAFS) to perform automounting intrinsically without the
need for a userspace daemon. It also adds support for such mountpoints to be
degraded at the filesystem's behest until they've been untouched long enough
that they'll be removed.
I've a patch (to follow) that removes some #ifdef's from fs/afs/* thus
allowing it to make use of this facility.
There are five pieces to this:
(1) Any interested filesystem needs to have at least one list to which
expirable mountpoints can be added.
Access to this list is governed by the vfsmount_lock.
(2) When a filesystem wants to create an expirable mount, it calls
do_kern_mount() to get a handle on the filesystem it wants mounting, and
then calls do_add_mount() to mount that filesystem on the designated
mountpoint, supplying the list mentioned in (1) to which the vfsmount
will be added.
In kAFS's case, the mountpoint is a directory with a follow_link() method
defined (fs/afs/mntpt.c). This uses the struct nameidata supplied as an
argument as a determination of where the new filesystem should be
mounted.
(3) When something using a vfsmount finishes dealing with it, it calls
mntput(). This unmarks the vfsmount for immediate expiry.
There are two criteria for determining if a vfsmount may be expired - it
mustn't be marked as in use for anything other than being a child of
another vfsmount, and it must have an expiry mark against it already.
(4) The filesystem then determines the policy on expiring the mounts created
in (2). When it feels the need to, it passes the list mentioned in (1) to
mark_mounts_for_expiry() to request everything on the list be expired.
This function examines each mount listed. If the vfsmount meets the
criteria mentioned in (3), then the vfsmount is deleted from the
namespace and disposed of as for unmounting; otherwise the vfsmount is
left untouched apart from now bearing an expiration mark if it didn't
before.
kAFS's expiration policy is simply to invoke this process at regular
intervals for all the mounts on its list.
(5) An expiration facility is also provided to userspace: by calling umount()
with a MNT_EXPIRE flag, it can make a request to unmount only if the
mountpoint hasn't been used since the last request and isn't in use now.
This allows expiration to be driven by userspace instead of by the
kernel if that is desirable.
This also means that do_umount() has to use a different version of
path_release() to everyone else... it can't call mntput() as that clears
the expiration flag, thus rendering this unachievable; so it's version of
path_release() calls _mntput(), which doesn't do the clear.
My original idea was to give the kernel more knowledge of automounted
things. This avoids a certain problem with stat() on a mountpoint causing it
to mount (for example, do "ls -l /afs" on a machine with kAFS), but Al wanted
it done this way.
> Why is autofs unsuitable?
Because:
(1) Autofs is flat; AFS requires a tree - mounts on mounts on mounts on
mounts...
(2) AFS holds the data as to what the mountpoints are and where they go, and
these may be cross-links to subtrees beyond your control. It's also not
trivial to extract a list of mountpoints as is required for autofs.
(3) Autofs is not namespace safe.
(4) Ducking back to userspace to get that to do the mount is pretty tricky if
namespaces are involved.
In fact, autofs may well want to make use of this facility.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch-kit gets past the limit on nested symlinks, without
incompatible API changes _and_ with killing code duplication in most of
the readlink/follow_link pairs. And no, it's not the old ->getlink()
crap - procfs et.al. are not special-cased there.
Here's how it works:
* ->follow_link() still does what it used to do - replaces
vfsmount/dentry in the nameidata it got from caller. However, it can
also leave a pathname to be resolved by caller.
* we add an array of char * into nameidata; we always work with
nd->saved_names[current->link_count]. nd_set_link() sets it,
nd_get_link() returns it.
* callers of ->follow_link() (all two of them) check if ->follow_link()
had left us something to do. If it had (return value was zero and
nd_get_link() is non-NULL), they do __vfs_follow_link() on that name.
Then they call a new method (->put_link()) that frees whatever has to
be freed, etc.
Note that absolute majority of symlinks have "resolve a pathname" as
part of their ->follow_link(); they can do something else and some don't
do that at all, but having that pathname resolution is very, very
common.
With that change we allow them to shift pathname resolution part to
caller. They don't have to - it's perfectly OK to do all work in
->follow_link(). However, leaving the pathname resolution to caller
will
a) exclude foo_follow_link() stack frame from the picture
b) kill 2 stack frames - all callers are in fs/namei.c
and they can use inlined variant of vfs_follow_link().
That reduction of stack use is enough to push the limit on nested
symlinks from 5 to 8 (actually, even beyond that, but since 8 is common
for other Unices it will do fine).
For those who have "pure" ->follow_link() (i.e. "find a string that
would be symlink contents and say nd_set_link(nd, string)") we also get
a common helper implementing ->readlink() - it just calls
->follow_link() on a dummy nameidata, calls vfs_readlink() on result of
nd_get_link() and does ->put_link(). Using (or not using) it is up to
filesystem; it's a helper that can be used as a ->readlink() for many
filesystems, not a reimplementation of sys_readlink(). However, that's
_MANY_ filesystems - practically all of them.
Note that we don't put any crap like "if this is a normal symlink, do
this; otherwise call ->follow_link() and let it do its magic" into
callers - all symlinks are handled the same way. Which was the main
problem with getlink proposal back then.
That covers almost everything; the only cases left are nfs, ncpfs and
cifs. Those will go later - we are backwards compatible, so it's not a
problem.
First patch: infrastructure - helpers allowing ->follow_link() to leave
a pathname to be traversed by caller + corresponding code in callers.
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- Make the VFS pass the struct nameidata as an optional parameter
to the permission() inode operation.
- Patch may_create()/may_open() so it passes the struct nameidata from
vfs_create()/open_namei() as an argument to permission().
- Add an intent flag for the sys_access() function.
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- Add open intent information to the 'struct nameidata'.
- Pass the struct nameidata as an optional parameter to the
lookup() inode operation.
- Pass the struct nameidata as an optional parameter to the
d_revalidate() dentry operation.
- Make link_path_walk() set the LOOKUP_CONTINUE flag in nd->flags instead
of passing it as an extra parameter to d_revalidate().
- Make open_namei(), and sys_uselib() set the open()/create() intent
data.
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type evaluation. This tags the system call interfaces in
fs/open.c, fs/dcache.c and mm/swapfile.c - and tags the path
walking helper functions.
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Patch from Maneesh Soni <maneesh@in.ibm.com>
Revert the fast-walk dcache code in preparation for dcache_rcu.
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Damn it, use the normal "-p1" format for patches!
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- Include dcache.h/namei.h in fs/autofs/autofs_i.h not dirhash.c
- Include list.h and spinlock.h in dcache.h
- Include list.h in mount.h and namei.h
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Currently fs.h is full of unrelated declarations and included in almost
any source file. Thus it makes sense to spilt certain aspects out that are
only used by few users.
This patch starts with the namei/path lookup interface and splits it into
<linux/namei.h> which is now directly included by the 24 files that actually
need it.
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