linux-stable.git/fs, branch v4.4.6

ovl: fix getcwd() failure after unsuccessful rmdir

2016-03-16T15:43:01+00:00

commit ce9113bbcbf45a57c082d6603b9a9f342be3ef74 upstream.

ovl_remove_upper() should do d_drop() only after it successfully
removes the dir, otherwise a subsequent getcwd() system call will
fail, breaking userspace programs.

This is to fix: https://bugzilla.kernel.org/show_bug.cgi?id=110491

Signed-off-by: Rui Wang 
Reviewed-by: Konstantin Khlebnikov 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

ovl: copy new uid/gid into overlayfs runtime inode

2016-03-16T15:43:01+00:00

commit b81de061fa59f17d2730aabb1b84419ef3913810 upstream.

Overlayfs must update uid/gid after chown, otherwise functions
like inode_owner_or_capable() will check user against stale uid.
Catched by xfstests generic/087, it chowns file and calls utimes.

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

userfaultfd: don't block on the last VM updates at exit time

2016-03-16T15:43:01+00:00

commit 39680f50ae54cbbb6e72ac38b8329dd3eb9105f4 upstream.

The exit path will do some final updates to the VM of an exiting process
to inform others of the fact that the process is going away.

That happens, for example, for robust futex state cleanup, but also if
the parent has asked for a TID update when the process exits (we clear
the child tid field in user space).

However, at the time we do those final VM accesses, we've already
stopped accepting signals, so the usual "stop waiting for userfaults on
signal" code in fs/userfaultfd.c no longer works, and the process can
become an unkillable zombie waiting for something that will never
happen.

To solve this, just make handle_userfault() abort any user fault
handling if we're already in the exit path past the signal handling
state being dead (marked by PF_EXITING).

This VM special case is pretty ugly, and it is possible that we should
look at finalizing signals later (or move the VM final accesses
earlier).  But in the meantime this is a fairly minimally intrusive fix.

Reported-and-tested-by: Dmitry Vyukov 
Acked-by: Andrea Arcangeli 
Signed-off-by: Linus Torvalds 
Cc: Sedat Dilek 
Signed-off-by: Greg Kroah-Hartman

ovl: fix working on distributed fs as lower layer

2016-03-16T15:42:59+00:00

commit b5891cfab08fe3144a616e8e734df7749fb3b7d0 upstream.

This adds missing .d_select_inode into alternative dentry_operations.

Signed-off-by: Konstantin Khlebnikov 
Fixes: 7c03b5d45b8e ("ovl: allow distributed fs as lower layer")
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Reviewed-by: Nikolay Borisov 
Tested-by: Nikolay Borisov 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

ovl: ignore lower entries when checking purity of non-directory entries

2016-03-16T15:42:59+00:00

commit 45d11738969633ec07ca35d75d486bf2d8918df6 upstream.

After rename file dentry still holds reference to lower dentry from
previous location. This doesn't matter for data access because data comes
from upper dentry. But this stale lower dentry taints dentry at new
location and turns it into non-pure upper. Such file leaves visible
whiteout entry after remove in directory which shouldn't have whiteouts at
all.

Overlayfs already tracks pureness of file location in oe->opaque.  This
patch just uses that for detecting actual path type.

Comment from Vivek Goyal's patch:

Here are the details of the problem. Do following.

$ mkdir upper lower work merged upper/dir/
$ touch lower/test
$ sudo mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=
work merged
$ mv merged/test merged/dir/
$ rm merged/dir/test
$ ls -l merged/dir/
/usr/bin/ls: cannot access merged/dir/test: No such file or directory
total 0
c????????? ? ? ? ?            ? test

Basic problem seems to be that once a file has been unlinked, a whiteout
has been left behind which was not needed and hence it becomes visible.

Whiteout is visible because parent dir is of not type MERGE, hence
od->is_real is set during ovl_dir_open(). And that means ovl_iterate()
passes on iterate handling directly to underlying fs. Underlying fs does
not know/filter whiteouts so it becomes visible to user.

Why did we leave a whiteout to begin with when we should not have.
ovl_do_remove() checks for OVL_TYPE_PURE_UPPER() and does not leave
whiteout if file is pure upper. In this case file is not found to be pure
upper hence whiteout is left.

So why file was not PURE_UPPER in this case? I think because dentry is
still carrying some leftover state which was valid before rename. For
example, od->numlower was set to 1 as it was a lower file. After rename,
this state is not valid anymore as there is no such file in lower.

Signed-off-by: Konstantin Khlebnikov 
Reported-by: Viktor Stanchev 
Suggested-by: Vivek Goyal 
Link: https://bugzilla.kernel.org/show_bug.cgi?id=109611
Acked-by: Vivek Goyal 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

ncpfs: fix a braino in OOM handling in ncp_fill_cache()

2016-03-16T15:42:59+00:00

commit 803c00123a8012b3a283c0530910653973ef6d8f upstream.

Failing to allocate an inode for child means that cache for *parent* is
incompletely populated.  So it's parent directory inode ('dir') that
needs NCPI_DIR_CACHE flag removed, *not* the child inode ('inode', which
is what we'd failed to allocate in the first place).

Fucked-up-in: commit 5e993e25 ("ncpfs: get rid of d_validate() nonsense")
Fucked-up-by: Al Viro 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

jffs2: reduce the breakage on recovery from halfway failed rename()

2016-03-16T15:42:58+00:00

commit f93812846f31381d35c04c6c577d724254355e7f upstream.

d_instantiate(new_dentry, old_inode) is absolutely wrong thing to
do - it will oops if new_dentry used to be positive, for starters.
What we need is d_invalidate() the target and be done with that.

Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

Fix directory hardlinks from deleted directories

2016-03-09T23:34:53+00:00

commit be629c62a603e5935f8177fd8a19e014100a259e upstream.

When a directory is deleted, we don't take too much care about killing off
all the dirents that belong to it — on the basis that on remount, the scan
will conclude that the directory is dead anyway.

This doesn't work though, when the deleted directory contained a child
directory which was moved *out*. In the early stages of the fs build
we can then end up with an apparent hard link, with the child directory
appearing both in its true location, and as a child of the original
directory which are this stage of the mount process we don't *yet* know
is defunct.

To resolve this, take out the early special-casing of the "directories
shall not have hard links" rule in jffs2_build_inode_pass1(), and let the
normal nlink processing happen for directories as well as other inodes.

Then later in the build process we can set ic->pino_nlink to the parent
inode#, as is required for directories during normal operaton, instead
of the nlink. And complain only *then* about hard links which are still
in evidence even after killing off all the unreachable paths.

Reported-by: Liu Song 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

jffs2: Fix page lock / f->sem deadlock

2016-03-09T23:34:53+00:00

commit 49e91e7079febe59a20ca885a87dd1c54240d0f1 upstream.

With this fix, all code paths should now be obtaining the page lock before
f->sem.

Reported-by: Szabó Tamás 
Tested-by: Thomas Betker 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

Revert "jffs2: Fix lock acquisition order bug in jffs2_write_begin"

2016-03-09T23:34:53+00:00

commit 157078f64b8a9cd7011b6b900b2f2498df850748 upstream.

This reverts commit 5ffd3412ae55
("jffs2: Fix lock acquisition order bug in jffs2_write_begin").

The commit modified jffs2_write_begin() to remove a deadlock with
jffs2_garbage_collect_live(), but this introduced new deadlocks found
by multiple users. page_lock() actually has to be called before
mutex_lock(&c->alloc_sem) or mutex_lock(&f->sem) because
jffs2_write_end() and jffs2_readpage() are called with the page locked,
and they acquire c->alloc_sem and f->sem, resp.

In other words, the lock order in jffs2_write_begin() was correct, and
it is the jffs2_garbage_collect_live() path that has to be changed.

Revert the commit to get rid of the new deadlocks, and to clear the way
for a better fix of the original deadlock.

Reported-by: Deng Chao 
Reported-by: Ming Liu 
Reported-by: wangzaiwei 
Signed-off-by: Thomas Betker 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman