autofs: make the autofsv5 packet file descriptor use a packetized pipe

commit 64f371bc3107e69efce563a3d0f0e6880de0d537 upstream.

The autofs packet size has had a very unfortunate size problem on x86:
because the alignment of 'u64' differs in 32-bit and 64-bit modes, and
because the packet data was not 8-byte aligned, the size of the autofsv5
packet structure differed between 32-bit and 64-bit modes despite
looking otherwise identical (300 vs 304 bytes respectively).

We first fixed that up by making the 64-bit compat mode know about this
problem in commit a32744d4abae ("autofs: work around unhappy compat
problem on x86-64"), and that made a 32-bit 'systemd' work happily on a
64-bit kernel because everything then worked the same way as on a 32-bit
kernel.

But it turned out that 'automount' had actually known and worked around
this problem in user space, so fixing the kernel to do the proper 32-bit
compatibility handling actually *broke* 32-bit automount on a 64-bit
kernel, because it knew that the packet sizes were wrong and expected
those incorrect sizes.

As a result, we ended up reverting that compatibility mode fix, and
thus breaking systemd again, in commit fcbf94b9dedd.

With both automount and systemd doing a single read() system call, and
verifying that they get *exactly* the size they expect but using
different sizes, it seemed that fixing one of them inevitably seemed to
break the other.  At one point, a patch I seriously considered applying
from Michael Tokarev did a "strcmp()" to see if it was automount that
was doing the operation.  Ugly, ugly.

However, a prettier solution exists now thanks to the packetized pipe
mode.  By marking the communication pipe as being packetized (by simply
setting the O_DIRECT flag), we can always just write the bigger packet
size, and if user-space does a smaller read, it will just get that
partial end result and the extra alignment padding will simply be thrown
away.

This makes both automount and systemd happy, since they now get the size
they asked for, and the kernel side of autofs simply no longer needs to
care - it could pad out the packet arbitrarily.

Of course, if there is some *other* user of autofs (please, please,
please tell me it ain't so - and we haven't heard of any) that tries to
read the packets with multiple writes, that other user will now be
broken - the whole point of the packetized mode is that one system call
gets exactly one packet, and you cannot read a packet in pieces.

Tested-by: Michael Tokarev <mjt@tls.msk.ru>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Ian Kent <raven@themaw.net>
Cc: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
sched: Fix nohz load accounting -- again!

commit c308b56b5398779cd3da0f62ab26b0453494c3d4 upstream.

Various people reported nohz load tracking still being wrecked, but Doug
spotted the actual problem. We fold the nohz remainder in too soon,
causing us to loose samples and under-account.

So instead of playing catch-up up-front, always do a single load-fold
with whatever state we encounter and only then fold the nohz remainder
and play catch-up.

Reported-by: Doug Smythies <dsmythies@telus.net>
Reported-by: LesÅ=82aw Kope=C4=87 <leslaw.kopec@nasza-klasa.pl>
Reported-by: Aman Gupta <aman@tmm1.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-4v31etnhgg9kwd6ocgx3rxl8@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
[bwh: Backported to 3.2: change filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
fs/cifs: fix parsing of dfs referrals

commit d8f2799b105a24bb0bbd3380a0d56e6348484058 upstream.

The problem was that the first referral was parsed more than once
and so the caller tried the same referrals multiple times.

The problem was introduced partly by commit
066ce6899484d9026acd6ba3a8dbbedb33d7ae1b,
where 'ref += le16_to_cpu(ref->Size);' got lost,
but that was also wrong...

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Tested-by: Björn Jacke <bj@sernet.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
[bwh: Backport to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fix __read_seqcount_begin() to use ACCESS_ONCE for sequence value read

commit 2f624278626677bfaf73fef97f86b37981621f5c upstream.

We really need to use a ACCESS_ONCE() on the sequence value read in
__read_seqcount_begin(), because otherwise the compiler might end up
reloading the value in between the test and the return of it.  As a
result, it might end up returning an odd value (which means that a write
is in progress).

If the reader is then fast enough that that odd value is still the
current one when the read_seqcount_retry() is done, we might end up with
a "successful" read sequence, even despite the concurrent write being
active.

In practice this probably never really happens - there just isn't
anything else going on around the read of the sequence count, and the
common case is that we end up having a read barrier immediately
afterwards.

So the code sequence in which gcc might decide to reaload from memory is
small, and there's no reason to believe it would ever actually do the
reload.  But if the compiler ever were to decide to do so, it would be
incredibly annoying to debug.  Let's just make sure.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
exit_signal: simplify the "we have changed execution domain" logic

commit e636825346b36a07ccfc8e30946d52855e21f681 upstream.

exit_notify() checks "tsk->self_exec_id != tsk->parent_exec_id"
to handle the "we have changed execution domain" case.

We can change do_thread() to always set ->exit_signal = SIGCHLD
and remove this check to simplify the code.

We could change setup_new_exec() instead, this looks more logical
because it increments ->self_exec_id. But note that de_thread()
already resets ->exit_signal if it changes the leader, let's keep
both changes close to each other.

Note that we change ->exit_signal lockless, this changes the rules.
Thereafter ->exit_signal is not stable under tasklist but this is
fine, the only possible change is OLDSIG -> SIGCHLD. This can race
with eligible_child() but the race is harmless. We can race with
reparent_leader() which changes our ->exit_signal in parallel, but
it does the same change to SIGCHLD.

The noticeable user-visible change is that the execing task is not
"visible" to do_wait()->eligible_child(__WCLONE) right after exec.
To me this looks more logical, and this is consistent with mt case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
exit_signal: fix the "parent has changed security domain" logic

commit b6e238dceed36891cc633167afe7151f1f3d83c5 upstream.

exit_notify() changes ->exit_signal if the parent already did exec.
This doesn't really work, we are not going to send the signal now
if there is another live thread or the exiting task is traced. The
parent can exec before the last dies or the tracer detaches.

Move this check into do_notify_parent() which actually sends the
signal.

The user-visible change is that we do not change ->exit_signal,
and thus the exiting task is still "clone children" for
do_wait()->eligible_child(__WCLONE). Hopefully this is fine, the
current logic is racy anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
mm: nobootmem: fix sign extend problem in __free_pages_memory()

commit 6bc2e853c6b46a6041980d58200ad9b0a73a60ff upstream.

Systems with 8 TBytes of memory or greater can hit a problem where only
the the first 8 TB of memory shows up.  This is due to "int i" being
smaller than "unsigned long start_aligned", causing the high bits to be
dropped.

The fix is to change `i' to unsigned long to match start_aligned
and end_aligned.

Thanks to Jack Steiner for assistance tracking this down.

Signed-off-by: Russ Anderson <rja@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
NFSv4: Revalidate uid/gid after open

This is a shorter (and more appropriate for stable kernels) analog to
the following upstream commit:

commit 6926afd1925a54a13684ebe05987868890665e2b
Author: Trond Myklebust <Trond.Myklebust@netapp.com>
Date:   Sat Jan 7 13:22:46 2012 -0500

    NFSv4: Save the owner/group name string when doing open

    ...so that we can do the uid/gid mapping outside the asynchronous RPC
    context.
    This fixes a bug in the current NFSv4 atomic open code where the client
    isn't able to determine what the true uid/gid fields of the file are,
    (because the asynchronous nature of the OPEN call denies it the ability
    to do an upcall) and so fills them with default values, marking the
    inode as needing revalidation.
    Unfortunately, in some cases, the VFS will do some additional sanity
    checks on the file, and may override the server's decision to allow
    the open because it sees the wrong owner/group fields.

    Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Without this patch, logging into two different machines with home
directories mounted over NFS4 and then running "vim" and typing ":q"
in each reliably produces the following error on the second machine:

	E137: Viminfo file is not writable: /users/system/rtheys/.viminfo

This regression was introduced by 80e52aced138 ("NFSv4: Don't do
idmapper upcalls for asynchronous RPC calls", merged during the 2.6.32
cycle) --- after the OPEN call, .viminfo has the default values for
st_uid and st_gid (0xfffffffe) cached because we do not want to let
rpciod wait for an idmapper upcall to fill them in.

The fix used in mainline is to save the owner and group as strings and
perform the upcall in _nfs4_proc_open outside the rpciod context,
which takes about 600 lines.  For stable, we can do something similar
with a one-liner: make open check for the stale fields and make a
(synchronous) GETATTR call to fill them when needed.

Trond dictated the patch, I typed it in, and Rik tested it.

Addresses http://bugs.debian.org/659111 and
          https://bugzilla.redhat.com/789298

Reported-by: Rik Theys <Rik.Theys@esat.kuleuven.be>
Explained-by: David Flyn <davidf@rd.bbc.co.uk>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Tested-by: Rik Theys <Rik.Theys@esat.kuleuven.be>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: avoid deadlock on sync-mounted FS w/o journal

commit c1bb05a657fb3d8c6179a4ef7980261fae4521d7 upstream.

Processes hang forever on a sync-mounted ext2 file system that
is mounted with the ext4 module (default in Fedora 16).

I can reproduce this reliably by mounting an ext2 partition with
"-o sync" and opening a new file an that partition with vim. vim
will hang in "D" state forever.  The same happens on ext4 without
a journal.

I am attaching a small patch here that solves this issue for me.
In the sync mounted case without a journal,
ext4_handle_dirty_metadata() may call sync_dirty_buffer(), which
can't be called with buffer lock held.

Also move mb_cache_entry_release inside lock to avoid race
fixed previously by 8a2bfdcb ext[34]: EA block reference count racing fix
Note too that ext2 fixed this same problem in 2006 with
b2f49033 [PATCH] fix deadlock in ext2

Signed-off-by: Martin.Wilck@ts.fujitsu.com
[sandeen@redhat.com: move mb_cache_entry_release before unlock, edit commit msg]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ARM: prevent VM_GROWSDOWN mmaps extending below FIRST_USER_ADDRESS

commit 9b61a4d1b2064dbd0c9e61754305ac852170509f upstream.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fix blocking allocations called very early during bootup

commit 31a67102f4762df5544bc2dfb34a931233d2a5b2 upstream.

During early boot, when the scheduler hasn't really been fully set up,
we really can't do blocking allocations because with certain (dubious)
configurations the "might_resched()" calls can actually result in
scheduling events.

We could just make such users always use GFP_ATOMIC, but quite often the
code that does the allocation isn't really aware of the fact that the
scheduler isn't up yet, and forcing that kind of random knowledge on the
initialization code is just annoying and not good for anybody.

And we actually have a the 'gfp_allowed_mask' exactly for this reason:
it's just that the kernel init sequence happens to set it to allow
blocking allocations much too early.

So move the 'gfp_allowed_mask' initialization from 'start_kernel()'
(which is some of the earliest init code, and runs with preemption
disabled for good reasons) into 'kernel_init()'.  kernel_init() is run
in the newly created thread that will become the 'init' process, as
opposed to the early startup code that runs within the context of what
will be the first idle thread.

So by the time we reach 'kernel_init()', we know that the scheduler must
be at least limping along, because we've already scheduled from the idle
thread into the init thread.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
vfs: make AIO use the proper rw_verify_area() area helpers

commit a70b52ec1aaeaf60f4739edb1b422827cb6f3893 upstream.

We had for some reason overlooked the AIO interface, and it didn't use
the proper rw_verify_area() helper function that checks (for example)
mandatory locking on the file, and that the size of the access doesn't
cause us to overflow the provided offset limits etc.

Instead, AIO did just the security_file_permission() thing (that
rw_verify_area() also does) directly.

This fixes it to do all the proper helper functions, which not only
means that now mandatory file locking works with AIO too, we can
actually remove lines of code.

Reported-by: Manish Honap <manish_honap_vit@yahoo.co.in>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
init: don't try mounting device as nfs root unless type fully matches

commit 377485f6244af255b04d662cf19cddbbc4ae4310 upstream.

Currently, we'll try mounting any device who's major device number is
UNNAMED_MAJOR as NFS root.  This would happen for non-NFS devices as
well (such as 9p devices) but it wouldn't cause any issues since
mounting the device as NFS would fail quickly and the code proceeded to
doing the proper mount:

       [  101.522716] VFS: Unable to mount root fs via NFS, trying floppy.
       [  101.534499] VFS: Mounted root (9p filesystem) on device 0:18.

Commit 6829a048102a ("NFS: Retry mounting NFSROOT") introduced retries
when mounting NFS root, which means that now we don't immediately fail
and instead it takes an additional 90+ seconds until we stop retrying,
which has revealed the issue this patch fixes.

This meant that it would take an additional 90 seconds to boot when
we're not using a device type which gets detected in order before NFS.

This patch modifies the NFS type check to require device type to be
'Root_NFS' instead of requiring the device to have an UNNAMED_MAJOR
major.  This makes boot process cleaner since we now won't go through
the NFS mounting code at all when the device isn't an NFS root
("/dev/nfs").

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
memcg: free spare array to avoid memory leak

commit 8c7577637ca31385e92769a77e2ab5b428e8b99c upstream.

When the last event is unregistered, there is no need to keep the spare
array anymore.  So free it to avoid memory leak.

Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext3: Fix error handling on inode bitmap corruption

commit 1415dd8705394399d59a3df1ab48d149e1e41e77 upstream.

When insert_inode_locked() fails in ext3_new_inode() it most likely
means inode bitmap got corrupted and we allocated again inode which
is already in use. Also doing unlock_new_inode() during error recovery
is wrong since inode does not have I_NEW set. Fix the problem by jumping
to fail: (instead of fail_drop:) which declares filesystem error and
does not call unlock_new_inode().

Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix error handling on inode bitmap corruption

commit acd6ad83517639e8f09a8c5525b1dccd81cd2a10 upstream.

When insert_inode_locked() fails in ext4_new_inode() it most likely means inode
bitmap got corrupted and we allocated again inode which is already in use. Also
doing unlock_new_inode() during error recovery is wrong since the inode does
not have I_NEW set. Fix the problem by jumping to fail: (instead of fail_drop:)
which declares filesystem error and does not call unlock_new_inode().

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
cifs: fix revalidation test in cifs_llseek()

commit 48a5730e5b71201e226ff06e245bf308feba5f10 upstream.

This test is always true so it means we revalidate the length every
time, which generates more network traffic.  When it is SEEK_SET or
SEEK_CUR, then we don't need to revalidate.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
block: don't mark buffers beyond end of disk as mapped

commit 080399aaaf3531f5b8761ec0ac30ff98891e8686 upstream.

Hi,

We have a bug report open where a squashfs image mounted on ppc64 would
exhibit errors due to trying to read beyond the end of the disk.  It can
easily be reproduced by doing the following:

[root@ibm-p750e-02-lp3 ~]# ls -l install.img
-rw-r--r-- 1 root root 142032896 Apr 30 16:46 install.img
[root@ibm-p750e-02-lp3 ~]# mount -o loop ./install.img /mnt/test
[root@ibm-p750e-02-lp3 ~]# dd if=/dev/loop0 of=/dev/null
dd: reading `/dev/loop0': Input/output error
277376+0 records in
277376+0 records out
142016512 bytes (142 MB) copied, 0.9465 s, 150 MB/s

In dmesg, you'll find the following:

squashfs: version 4.0 (2009/01/31) Phillip Lougher
[   43.106012] attempt to access beyond end of device
[   43.106029] loop0: rw=0, want=277410, limit=277408
[   43.106039] Buffer I/O error on device loop0, logical block 138704
[   43.106053] attempt to access beyond end of device
[   43.106057] loop0: rw=0, want=277412, limit=277408
[   43.106061] Buffer I/O error on device loop0, logical block 138705
[   43.106066] attempt to access beyond end of device
[   43.106070] loop0: rw=0, want=277414, limit=277408
[   43.106073] Buffer I/O error on device loop0, logical block 138706
[   43.106078] attempt to access beyond end of device
[   43.106081] loop0: rw=0, want=277416, limit=277408
[   43.106085] Buffer I/O error on device loop0, logical block 138707
[   43.106089] attempt to access beyond end of device
[   43.106093] loop0: rw=0, want=277418, limit=277408
[   43.106096] Buffer I/O error on device loop0, logical block 138708
[   43.106101] attempt to access beyond end of device
[   43.106104] loop0: rw=0, want=277420, limit=277408
[   43.106108] Buffer I/O error on device loop0, logical block 138709
[   43.106112] attempt to access beyond end of device
[   43.106116] loop0: rw=0, want=277422, limit=277408
[   43.106120] Buffer I/O error on device loop0, logical block 138710
[   43.106124] attempt to access beyond end of device
[   43.106128] loop0: rw=0, want=277424, limit=277408
[   43.106131] Buffer I/O error on device loop0, logical block 138711
[   43.106135] attempt to access beyond end of device
[   43.106139] loop0: rw=0, want=277426, limit=277408
[   43.106143] Buffer I/O error on device loop0, logical block 138712
[   43.106147] attempt to access beyond end of device
[   43.106151] loop0: rw=0, want=277428, limit=277408
[   43.106154] Buffer I/O error on device loop0, logical block 138713
[   43.106158] attempt to access beyond end of device
[   43.106162] loop0: rw=0, want=277430, limit=277408
[   43.106166] attempt to access beyond end of device
[   43.106169] loop0: rw=0, want=277432, limit=277408
...
[   43.106307] attempt to access beyond end of device
[   43.106311] loop0: rw=0, want=277470, limit=2774

Squashfs manages to read in the end block(s) of the disk during the
mount operation.  Then, when dd reads the block device, it leads to
block_read_full_page being called with buffers that are beyond end of
disk, but are marked as mapped.  Thus, it would end up submitting read
I/O against them, resulting in the errors mentioned above.  I fixed the
problem by modifying init_page_buffers to only set the buffer mapped if
it fell inside of i_size.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Nick Piggin <npiggin@kernel.dk>

--

Changes from v1->v2: re-used max_block, as suggested by Nick Piggin.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
NFS4: fix compile warnings in nfs4proc.c

commit de040beccd52bb5fcac90031505384d037b1111c upstream.

compile in nfs-for-3.3 branch shows following warnings. Fix it here.

fs/nfs/nfs4proc.c: In function ‘__nfs4_get_acl_uncached’:
fs/nfs/nfs4proc.c:3589: warning: format ‘%ld’ expects type ‘long int’, but argument 4 has type ‘size_t’
fs/nfs/nfs4proc.c:3589: warning: format ‘%ld’ expects type ‘long int’, but argument 6 has type ‘size_t’

Signed-off-by: Peng Tao <peng_tao@emc.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Avoid reading past buffer when calling GETACL

commit 5a00689930ab975fdd1b37b034475017e460cf2a upstream.

Bug noticed in commit
bf118a342f10dafe44b14451a1392c3254629a1f

When calling GETACL, if the size of the bitmap array, the length
attribute and the acl returned by the server is greater than the
allocated buffer(args.acl_len), we can Oops with a General Protection
fault at _copy_from_pages() when we attempt to read past the pages
allocated.

This patch allocates an extra PAGE for the bitmap and checks to see that
the bitmap + attribute_length + ACLs don't exceed the buffer space
allocated to it.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reported-by: Jian Li <jiali@redhat.com>
[Trond: Fixed a size_t vs unsigned int printk() warning]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>