a) instead of storing the symlink body (via nd_set_link()) and returning
an opaque pointer later passed to ->put_link(), ->follow_link() _stores_
that opaque pointer (into void * passed by address by caller) and returns
the symlink body.  Returning ERR_PTR() on error, NULL on jump (procfs magic
symlinks) and pointer to symlink body for normal symlinks.  Stored pointer
is ignored in all cases except the last one.

Storing NULL for opaque pointer (or not storing it at all) means no call
of ->put_link().

b) the body used to be passed to ->put_link() implicitly (via nameidata).
Now only the opaque pointer is.  In the cases when we used the symlink body
to free stuff, ->follow_link() now should store it as opaque pointer in addition
to returning it.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

that's the bulk of filesystem drivers dealing with inodes of their own
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Convert the following where appropriate:

 (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).

 (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).

 (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry).  This is actually more
     complicated than it appears as some calls should be converted to
     d_can_lookup() instead.  The difference is whether the directory in
     question is a real dir with a ->lookup op or whether it's a fake dir with
     a ->d_automount op.

In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).

Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer.  In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.

However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.

There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE.  Strictly, this was
intended for special directory entry types that don't have attached inodes.

The following perl+coccinelle script was used:

use strict;

my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
    die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
    print "No matches\n";
    exit(0);
}

my @cocci = (
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISLNK(E->d_inode->i_mode)',
    '+ d_is_symlink(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISDIR(E->d_inode->i_mode)',
    '+ d_is_dir(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISREG(E->d_inode->i_mode)',
    '+ d_is_reg(E)' );

my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);

foreach my $file (@callers) {
    chomp $file;
    print "Processing ", $file, "\n";
    system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
	die "spatch failed";
}

[AV: overlayfs parts skipped]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Analysis from Marc:

 "Commit 7078187a ("fuse: introduce fuse_simple_request() helper")
  from the above pull request triggers some EIO errors for me in some tests
  that rely on fuse

  Looking at the code changes and a bit of debugging info I think there's a
  general problem here that fuse_get_req checks and possibly waits for
  fc->initialized, and this was always called first.  But this commit
  changes the ordering and in many places fc->minor is now possibly used
  before fuse_get_req, and we can't be sure that fc has been initialized.
  In my case fuse_lookup_init sets req->out.args[0].size to the wrong size
  because fc->minor at that point is still 0, leading to the EIO error."

Fix by moving the compat adjustments into fuse_simple_request() to after
fuse_get_req().

This is also more readable than the original, since now compatibility is
handled in a single function instead of cluttering each operation.
Reported-by: NMarc Dionne <marc.c.dionne@gmail.com>
Tested-by: NMarc Dionne <marc.c.dionne@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Fixes: 7078187a ("fuse: introduce fuse_simple_request() helper")

The following pattern is repeated many times:

	req = fuse_get_req_nopages(fc);
	/* Initialize req->(in|out).args */
	fuse_request_send(fc, req);
	err = req->out.h.error;
	fuse_put_request(req);

Create a new replacement helper:

	/* Initialize args */
	err = fuse_simple_request(fc, &args);

In addition to reducing the code size, this will ease moving from the
complex arg-based to a simpler page-based I/O on the fuse device.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Now that d_invalidate can no longer fail, stop returning a useless
return code.  For the few callers that checked the return code update
remove the handling of d_invalidate failure.
Reviewed-by: NMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Now that check_submounts_and_drop can not fail and is called from
d_invalidate there is no longer a need to call check_submounts_and_drom
from filesystem d_revalidate methods so remove it.
Reviewed-by: NMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Christoph Hellwig suggests:

1) make vfs_rename call ->rename2 if it exists instead of ->rename
2) switch all filesystems that you're adding NOREPLACE support for to
   use ->rename2
3) see how many ->rename instances we'll have left after a few
   iterations of 2.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Make ->rename2() universal, i.e. able to handle zero flags.  This is to
make future change of the API easier.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The following test case demonstrates the bug:

  sh# mount -t glusterfs localhost:meta-test /mnt/one

  sh# mount -t glusterfs localhost:meta-test /mnt/two

  sh# echo stuff > /mnt/one/file; rm -f /mnt/two/file; echo stuff > /mnt/one/file
  bash: /mnt/one/file: Stale file handle

  sh# echo stuff > /mnt/one/file; rm -f /mnt/two/file; sleep 1; echo stuff > /mnt/one/file

On the second open() on /mnt/one, FUSE would have used the old
nodeid (file handle) trying to re-open it. Gluster is returning
-ESTALE. The ESTALE propagates back to namei.c:filename_lookup()
where lookup is re-attempted with LOOKUP_REVAL. The right
behavior now, would be for FUSE to ignore the entry-timeout and
and do the up-call revalidation. Instead FUSE is ignoring
LOOKUP_REVAL, succeeding the revalidation (because entry-timeout
has not passed), and open() is again retried on the old file
handle and finally the ESTALE is going back to the application.

Fix: if revalidation is happening with LOOKUP_REVAL, then ignore
entry-timeout and always do the up-call.
Signed-off-by: NAnand Avati <avati@redhat.com>
Reviewed-by: NNiels de Vos <ndevos@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

As suggested by checkpatch.pl, use time_before64() instead of direct
comparison of jiffies64 values.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: <stable@vger.kernel.org>

Support RENAME_EXCHANGE and RENAME_NOREPLACE flags on the userspace ABI.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The patch addresses two use-cases when the flag may be safely cleared:

1. fuse_do_setattr() is called with ATTR_CTIME flag set in attr->ia_valid.
In this case attr->ia_ctime bears actual value. In-kernel fuse must send it
to the userspace server and then assign the value to inode->i_ctime.

2. fuse_do_setattr() is called with ATTR_SIZE flag set in attr->ia_valid,
whereas ATTR_CTIME is not set (truncate(2)).
In this case in-kernel fuse must sent "now" to the userspace server and then
assign the value to inode->i_ctime.

In both cases we could clear I_DIRTY_SYNC, but that needs more thought.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Let the kernel maintain i_ctime locally: update i_ctime explicitly on
truncate, fallocate, open(O_TRUNC), setxattr, removexattr, link, rename,
unlink.

The inode flag I_DIRTY_SYNC serves as indication that local i_ctime should
be flushed to the server eventually.  The patch sets the flag and updates
i_ctime in course of operations listed above.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

This implements updating ctime as well as mtime on file_update_time().
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The patch extends fuse_setattr_in, and extends the flush procedure
(fuse_flush_times()) called on ->write_inode() to send the ctime as well as
mtime.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

...and flush mtime from this.  This allows us to use the kernel
infrastructure for writing out dirty metadata (mtime at this point, but
ctime in the next patches and also maybe atime).
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Handling truncate(2), VFS doesn't set ATTR_MTIME bit in iattr structure;
only ATTR_SIZE bit is set. In-kernel fuse must handle the case by setting
mtime fields of struct fuse_setattr_in to "now" and set FATTR_MTIME bit
even though ATTR_MTIME was not set.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Let the kernel maintain i_mtime locally:
 - clear S_NOCMTIME
 - implement i_op->update_time()
 - flush mtime on fsync and last close
 - update i_mtime explicitly on truncate and fallocate

Fuse inode flag FUSE_I_MTIME_DIRTY serves as indication that local i_mtime
should be flushed to the server eventually.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Make fuse think that when writeback is on the inode's i_size is always
up-to-date and not update it with the value received from the userspace.
This is done because the page cache code may update i_size without letting
the FS know.

This assumption implies fixing the previously introduced short-read helper --
when a short read occurs the 'hole' is filled with zeroes.

fuse_file_fallocate() is also fixed because now we should keep i_size up to
date, so it must be updated if FUSE_FALLOCATE request succeeded.
Signed-off-by: NMaxim V. Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Various read operations (e.g. readlink, readdir) invalidate the cached
attrs for atime changes.  This patch adds a new function
'fuse_invalidate_atime', which checks for a read-only super block and
avoids the attr invalidation in that case.
Signed-off-by: NAndrew Gallagher <andrewjcg@fb.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

...which just returns -EBUSY if a directory alias would be created.

This is to be used by fuse mkdir to make sure that a buggy or malicious
userspace filesystem doesn't do anything nasty.  Previously fuse used a
private mutex for this purpose, which can now go away.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

fuse_access() is never called in RCU walk, only on the final component of
access(2) and chdir(2)...
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Doing dput(parent) is not valid in RCU walk mode.  In RCU mode it would
probably be okay to update the parent flags, but it's actually not
necessary most of the time...

So only set the FUSE_I_ADVISE_RDPLUS flag on the parent when the entry was
recently initialized by READDIRPLUS.

This is achieved by setting FUSE_I_INIT_RDPLUS on entries added by
READDIRPLUS and only dropping out of RCU mode if this flag is set.
FUSE_I_INIT_RDPLUS is cleared once the FUSE_I_ADVISE_RDPLUS flag is set in
the parent.
Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

If revalidate finds an invalid dentry in RCU walk mode, let the VFS deal
with it instead of calling check_submounts_and_drop() which is not prepared
for being called from RCU walk.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

truncate_pagecache() doesn't care about old size since commit
cedabed4 ("vfs: Fix vmtruncate() regression").  Let's drop it.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Drop a subtree when we find that it has moved or been delated.  This can be
done as long as there are no submounts under this location.

If the directory was moved and we come across the same directory in a
future lookup it will be reconnected by d_materialise_unique().
Signed-off-by: NAnand Avati <avati@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

On errors unrelated to the filesystem's state (ENOMEM, ENOTCONN) return the
error itself from ->d_revalidate() insted of returning zero (invalid).

Also make a common label for invalidating the dentry.  This will be used by
the next patch.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Use d_materialise_unique() instead of d_splice_alias().  This allows dentry
subtrees to be moved to a new place if there moved, even if something is
referencing a dentry in the subtree (open fd, cwd, etc..).

This will also allow us to drop a subtree if it is found to be replaced by
something else.  In this case the disconnected subtree can later be
reconnected to its new location.

d_materialise_unique() ensures that a directory entry only ever has one
alias.  We keep fc->inst_mutex around the calls for d_materialise_unique()
on directories to prevent a race with mkdir "stealing" the inode.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Userspace can add names containing a slash character to the directory
listing.  Don't allow this as it could cause all sorts of trouble.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

The way how fuse calls truncate_pagecache() from fuse_change_attributes()
is completely wrong. Because, w/o i_mutex held, we never sure whether
'oldsize' and 'attr->size' are valid by the time of execution of
truncate_pagecache(inode, oldsize, attr->size). In fact, as soon as we
released fc->lock in the middle of fuse_change_attributes(), we completely
loose control of actions which may happen with given inode until we reach
truncate_pagecache. The list of potentially dangerous actions includes
mmap-ed reads and writes, ftruncate(2) and write(2) extending file size.

The typical outcome of doing truncate_pagecache() with outdated arguments
is data corruption from user point of view. This is (in some sense)
acceptable in cases when the issue is triggered by a change of the file on
the server (i.e. externally wrt fuse operation), but it is absolutely
intolerable in scenarios when a single fuse client modifies a file without
any external intervention. A real life case I discovered by fsx-linux
looked like this:

1. Shrinking ftruncate(2) comes to fuse_do_setattr(). The latter sends
FUSE_SETATTR to the server synchronously, but before getting fc->lock ...
2. fuse_dentry_revalidate() is asynchronously called. It sends FUSE_LOOKUP
to the server synchronously, then calls fuse_change_attributes(). The
latter updates i_size, releases fc->lock, but before comparing oldsize vs
attr->size..
3. fuse_do_setattr() from the first step proceeds by acquiring fc->lock and
updating attributes and i_size, but now oldsize is equal to
outarg.attr.size because i_size has just been updated (step 2). Hence,
fuse_do_setattr() returns w/o calling truncate_pagecache().
4. As soon as ftruncate(2) completes, the user extends file size by
write(2) making a hole in the middle of file, then reads data from the hole
either by read(2) or mmap-ed read. The user expects to get zero data from
the hole, but gets stale data because truncate_pagecache() is not executed
yet.

The scenario above illustrates one side of the problem: not truncating the
page cache even though we should. Another side corresponds to truncating
page cache too late, when the state of inode changed significantly.
Theoretically, the following is possible:

1. As in the previous scenario fuse_dentry_revalidate() discovered that
i_size changed (due to our own fuse_do_setattr()) and is going to call
truncate_pagecache() for some 'new_size' it believes valid right now. But
by the time that particular truncate_pagecache() is called ...
2. fuse_do_setattr() returns (either having called truncate_pagecache() or
not -- it doesn't matter).
3. The file is extended either by write(2) or ftruncate(2) or fallocate(2).
4. mmap-ed write makes a page in the extended region dirty.

The result will be the lost of data user wrote on the fourth step.

The patch is a hotfix resolving the issue in a simplistic way: let's skip
dangerous i_size update and truncate_pagecache if an operation changing
file size is in progress. This simplistic approach looks correct for the
cases w/o external changes. And to handle them properly, more sophisticated
and intrusive techniques (e.g. NFS-like one) would be required. I'd like to
postpone it until the issue is well discussed on the mailing list(s).

Changed in v2:
 - improved patch description to cover both sides of the issue.
Signed-off-by: NMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

Calls like setxattr and removexattr result in updation of ctime.
Therefore invalidate inode attributes to force a refresh.
Signed-off-by: NAnand Avati <avati@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org

Niels noted that we don't need the 'dentry = NULL' line.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: Niels de Vos <ndevos@redhat.com>

If we got the inode through fuse_iget() then the attributes are already
up-to-date.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Fuse does instantiation slightly differently from NFS/CIFS which use
d_materialise_unique().
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org

Add sanity checks before adding or updating an entry with data received
from readdirplus.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org

In case d_lookup() returns a dentry with d_inode == NULL, the dentry is not
returned with dput(). This results in triggering a BUG() in
shrink_dcache_for_umount_subtree():

  BUG: Dentry ...{i=0,n=...} still in use (1) [unmount of fuse fuse]

[SzM: need to d_drop() as well]
Reported-by: NJustin Clift <jclift@redhat.com>
Signed-off-by: NNiels de Vos <ndevos@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Tested-by: NBrian Foster <bfoster@redhat.com>
Tested-by: NNiels de Vos <ndevos@redhat.com>
CC: stable@vger.kernel.org

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Fix bug introduced by commit 4582a4ab "FUSE: Adapt readdirplus to application
usage patterns".

We need to check for a positive dentry; negative dentries are not added by
readdirplus.  Secondly we need to advise the use of readdirplus on the *parent*,
otherwise the whole thing is useless.  Thirdly all this is only relevant if
"readdirplus_auto" mode is selected by the filesystem.

We advise the use of readdirplus only if the dentry was still valid.  If we had
to redo the lookup then there was no use in doing the -plus version.
Reported-by: NBernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
CC: Feng Shuo <steve.shuo.feng@gmail.com>
CC: stable@vger.kernel.org