Doing writeback on lots of little files causes terrible IOPS storms
because of the per-mapping writeback plugging we do. This
essentially causes imeediate dispatch of IO for each mapping,
regardless of the context in which writeback is occurring.

IOWs, running a concurrent write-lots-of-small 4k files using fsmark
on XFS results in a huge number of IOPS being issued for data
writes.  Metadata writes are sorted and plugged at a high level by
XFS, so aggregate nicely into large IOs. However, data writeback IOs
are dispatched in individual 4k IOs, even when the blocks of two
consecutively written files are adjacent.

Test VM: 8p, 8GB RAM, 4xSSD in RAID0, 100TB sparse XFS filesystem,
metadata CRCs enabled.

Kernel: 3.10-rc5 + xfsdev + my 3.11 xfs queue (~70 patches)

Test:

$ ./fs_mark  -D  10000  -S0  -n  10000  -s  4096  -L  120  -d
/mnt/scratch/0  -d  /mnt/scratch/1  -d  /mnt/scratch/2  -d
/mnt/scratch/3  -d  /mnt/scratch/4  -d  /mnt/scratch/5  -d
/mnt/scratch/6  -d  /mnt/scratch/7

Result:

		wall	sys	create rate	Physical write IO
		time	CPU	(avg files/s)	 IOPS	Bandwidth
		-----	-----	------------	------	---------
unpatched	6m56s	15m47s	24,000+/-500	26,000	130MB/s
patched		5m06s	13m28s	32,800+/-600	 1,500	180MB/s
improvement	-26.44%	-14.68%	  +36.67%	-94.23%	+38.46%

If I use zero length files, this workload at about 500 IOPS, so
plugging drops the data IOs from roughly 25,500/s to 1000/s.
3 lines of code, 35% better throughput for 15% less CPU.

The benefits of plugging at this layer are likely to be higher for
spinning media as the IO patterns for this workload are going make a
much bigger difference on high IO latency devices.....
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Tested-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The shm implementation internally uses shmem or hugetlbfs inodes for shm
segments.  As these inodes are never directly exposed to userspace and
only accessed through the shm operations which are already hooked by
security modules, mark the inodes with the S_PRIVATE flag so that inode
security initialization and permission checking is skipped.

This was motivated by the following lockdep warning:

  ======================================================
   [ INFO: possible circular locking dependency detected ]
   4.2.0-0.rc3.git0.1.fc24.x86_64+debug #1 Tainted: G        W
  -------------------------------------------------------
   httpd/1597 is trying to acquire lock:
   (&ids->rwsem){+++++.}, at: shm_close+0x34/0x130
   but task is already holding lock:
   (&mm->mmap_sem){++++++}, at: SyS_shmdt+0x4b/0x180
   which lock already depends on the new lock.
   the existing dependency chain (in reverse order) is:
   -> #3 (&mm->mmap_sem){++++++}:
        lock_acquire+0xc7/0x270
        __might_fault+0x7a/0xa0
        filldir+0x9e/0x130
        xfs_dir2_block_getdents.isra.12+0x198/0x1c0 [xfs]
        xfs_readdir+0x1b4/0x330 [xfs]
        xfs_file_readdir+0x2b/0x30 [xfs]
        iterate_dir+0x97/0x130
        SyS_getdents+0x91/0x120
        entry_SYSCALL_64_fastpath+0x12/0x76
   -> #2 (&xfs_dir_ilock_class){++++.+}:
        lock_acquire+0xc7/0x270
        down_read_nested+0x57/0xa0
        xfs_ilock+0x167/0x350 [xfs]
        xfs_ilock_attr_map_shared+0x38/0x50 [xfs]
        xfs_attr_get+0xbd/0x190 [xfs]
        xfs_xattr_get+0x3d/0x70 [xfs]
        generic_getxattr+0x4f/0x70
        inode_doinit_with_dentry+0x162/0x670
        sb_finish_set_opts+0xd9/0x230
        selinux_set_mnt_opts+0x35c/0x660
        superblock_doinit+0x77/0xf0
        delayed_superblock_init+0x10/0x20
        iterate_supers+0xb3/0x110
        selinux_complete_init+0x2f/0x40
        security_load_policy+0x103/0x600
        sel_write_load+0xc1/0x750
        __vfs_write+0x37/0x100
        vfs_write+0xa9/0x1a0
        SyS_write+0x58/0xd0
        entry_SYSCALL_64_fastpath+0x12/0x76
  ...
Signed-off-by: NStephen Smalley <sds@tycho.nsa.gov>
Reported-by: NMorten Stevens <mstevens@fedoraproject.org>
Acked-by: NHugh Dickins <hughd@google.com>
Acked-by: NPaul Moore <paul@paul-moore.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When using a large volume, for example 9T volume with 2T already used,
frequent creation of small files with O_DIRECT when the IO is not
cluster aligned may clear sectors in the wrong place.  This will cause
filesystem corruption.

This is because p_cpos is a u32.  When calculating the corresponding
sector it should be converted to u64 first, otherwise it may overflow.
Signed-off-by: NJoseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>	[4.0+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fsnotify_clear_marks_by_group_flags() can race with
fsnotify_destroy_marks() so that when fsnotify_destroy_mark_locked()
drops mark_mutex, a mark from the list iterated by
fsnotify_clear_marks_by_group_flags() can be freed and thus the next
entry pointer we have cached may become stale and we dereference free
memory.

Fix the problem by first moving marks to free to a special private list
and then always free the first entry in the special list.  This method
is safe even when entries from the list can disappear once we drop the
lock.
Signed-off-by: NJan Kara <jack@suse.com>
Reported-by: NAshish Sangwan <a.sangwan@samsung.com>
Reviewed-by: NAshish Sangwan <a.sangwan@samsung.com>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This function may copy the si_addr_lsb field to user mode when it hasn't
been initialized, which can leak kernel stack data to user mode.

Just checking the value of si_code is insufficient because the same
si_code value is shared between multiple signals.  This is solved by
checking the value of si_signo in addition to si_code.
Signed-off-by: NAmanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The "BUG_ON(list_empty(&osb->blocked_lock_list))" in
ocfs2_downconvert_thread_do_work can be triggered in the following case:

ocfs2dc has firstly saved osb->blocked_lock_count to local varibale
processed, and then processes the dentry lockres.  During the dentry
put, it calls iput and then deletes rw, inode and open lockres from
blocked list in ocfs2_mark_lockres_freeing.  And this causes the
variable `processed' to not reflect the number of blocked lockres to be
processed, which triggers the BUG.
Signed-off-by: NJoseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Dave Hansen reported the following;

	My laptop has been behaving strangely with 4.2-rc2.  Once I log
	in to my X session, I start getting all kinds of strange errors
	from applications and see this in my dmesg:

        	VFS: file-max limit 8192 reached

The problem is that the file-max is calculated before memory is fully
initialised and miscalculates how much memory the kernel is using.  This
patch recalculates file-max after deferred memory initialisation.  Note
that using memory hotplug infrastructure would not have avoided this
problem as the value is not recalculated after memory hot-add.

4.1:             files_stat.max_files = 6582781
4.2-rc2:         files_stat.max_files = 8192
4.2-rc2 patched: files_stat.max_files = 6562467

Small differences with the patch applied and 4.1 but not enough to matter.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NDave Hansen <dave.hansen@intel.com>
Cc: Nicolai Stange <nicstange@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Alex Ng <alexng@microsoft.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

During the change to new btrfs extent-oriented qgroup implement, due to
it doesn't use the old __qgroup_excl_accounting() for exclusive extent,
it didn't free the reserved bytes.

The bug will cause limit function go crazy as the reserved space is
never freed, increasing limit will have no effect and still cause
EQOUT.

The fix is easy, just free reserved bytes for newly created exclusive
extent as what it does before.
Reported-by: NTsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: NYang Dongsheng <yangds.fnst@cn.fujitsu.com>
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: NChris Mason <clm@fb.com>

Now that we can get there in RCU mode, we shouldn't play with
nd->path.dentry->d_inode - it's not guaranteed to be stable.
Use nd->inode instead.
Reported-by: NHugh Dickins <hughd@google.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

In RCU mode we might end up with dentry evicted just we check
that it's a directory.  In such case we should return ECHILD
rather than ENOTDIR, so that pathwalk would be retries in non-RCU
mode.

Breakage had been introduced in commit b18825a7 - prior to that
we were looking at nd->inode, which had been fetched before
verifying that ->d_seq was still valid.  That form of check
would only be satisfied if at some point the pathname prefix
would indeed have resolved to a non-directory.  The fix consists
of checking ->d_seq after we'd run into a non-directory dentry,
and failing with ECHILD in case of mismatch.

Note that all branches since 3.12 have that problem...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Currently, preprocess_stateid_op calls nfs4_check_olstateid which
verifies that the open stateid corresponds to the current filehandle in the
call by calling nfs4_check_fh.

If the stateid is a NFS4_DELEG_STID however, then no such check is done.
This could cause incorrect enforcement of permissions, because the
nfsd_permission() call in nfs4_check_file uses current the current
filehandle, but any subsequent IO operation will use the file descriptor
in the stateid.

Move the call to nfs4_check_fh into nfs4_check_file instead so that it
can be done for all stateid types.
Signed-off-by: NJeff Layton <jeff.layton@primarydata.com>
Cc: stable@vger.kernel.org
[bfields: moved fh check to avoid NULL deref in special stateid case]
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

commit e548e9b9 makes the kclient
only re-send cap flush once during MDS failover. If the kclient sends
a cap flush after MDS enters reconnect stage but before MDS recovers.
The kclient will skip re-sending the same cap flush when MDS recovers.

This causes problem for newly created inode. The MDS handles cap
flushes before replaying unsafe requests, so it's possible that MDS
find corresponding inode is missing when handling cap flush. The fix
is reverting to old behaviour: always re-send when MDS recovers
Signed-off-by: NYan, Zheng <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

posix locks should be in ctx->flc_posix list
Signed-off-by: NYan, Zheng <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>

We don't log remote attribute contents, and instead write them
synchronously before we commit the block allocation and attribute
tree update transaction. As a result we are writing to the allocated
space before the allcoation has been made permanent.

As a result, we cannot consider this allocation to be a metadata
allocation. Metadata allocation can take blocks from the free list
and so reuse them before the transaction that freed the block is
committed to disk. This behaviour is perfectly fine for journalled
metadata changes as log recovery will ensure the free operation is
replayed before the overwrite, but for remote attribute writes this
is not the case.

Hence we have to consider the remote attribute blocks to contain
data and allocate accordingly. We do this by dropping the
XFS_BMAPI_METADATA flag from the block allocation. This means the
allocation will not use blocks that are on the busy list without
first ensuring that the freeing transaction has been committed to
disk and the blocks removed from the busy list. This ensures we will
never overwrite a freed block without first ensuring that it is
really free.

cc: <stable@vger.kernel.org>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

In recent testing, a system that crashed failed log recovery on
restart with a bad symlink buffer magic number:

XFS (vda): Starting recovery (logdev: internal)
XFS (vda): Bad symlink block magic!
XFS: Assertion failed: 0, file: fs/xfs/xfs_log_recover.c, line: 2060

On examination of the log via xfs_logprint, none of the symlink
buffers in the log had a bad magic number, nor were any other types
of buffer log format headers mis-identified as symlink buffers.
Tracing was used to find the buffer the kernel was tripping over,
and xfs_db identified it's contents as:

000: 5841524d 00000000 00000346 64d82b48 8983e692 d71e4680 a5f49e2c b317576e
020: 00000000 00602038 00000000 006034ce d0020000 00000000 4d4d4d4d 4d4d4d4d
040: 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d
060: 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d 4d4d4d4d
.....

This is a remote attribute buffer, which are notable in that they
are not logged but are instead written synchronously by the remote
attribute code so that they exist on disk before the attribute
transactions are committed to the journal.

The above remote attribute block has an invalid LSN in it - cycle
0xd002000, block 0 - which means when log recovery comes along to
determine if the transaction that writes to the underlying block
should be replayed, it sees a block that has a future LSN and so
does not replay the buffer data in the transaction. Instead, it
validates the buffer magic number and attaches the buffer verifier
to it.  It is this buffer magic number check that is failing in the
above assert, indicating that we skipped replay due to the LSN of
the underlying buffer.

The problem here is that the remote attribute buffers cannot have a
valid LSN placed into them, because the transaction that contains 
the attribute tree pointer changes and the block allocation that the
attribute data is being written to hasn't yet been committed. Hence
the LSN field in the attribute block is completely unwritten,
thereby leaving the underlying contents of the block in the LSN
field. It could have any value, and hence a future overwrite of the
block by log recovery may or may not work correctly.

Fix this by always writing an invalid LSN to the remote attribute
block, as any buffer in log recovery that needs to write over the
remote attribute should occur. We are protected from having old data
written over the attribute by the fact that freeing the block before
the remote attribute is written will result in the buffer being
marked stale in the log and so all changes prior to the buffer stale
transaction will be cancelled by log recovery.

Hence it is safe to ignore the LSN in the case or synchronously
written, unlogged metadata such as remote attribute blocks, and to
ensure we do that correctly, we need to write an invalid LSN to all
remote attribute blocks to trigger immediate recovery of metadata
that is written over the top.

As a further protection for filesystems that may already have remote
attribute blocks with bad LSNs on disk, change the log recovery code
to always trigger immediate recovery of metadata over remote
attribute blocks.

cc: <stable@vger.kernel.org>
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

When modifying the patch series to handle the XFS MMAP_LOCK nesting
of page faults, I botched the conversion of the read page fault
path, and so it is only every calling through the page cache. Re-add
the necessary __dax_fault() call for such files.

Because the get_blocks callback on read faults may not set up the
mapping buffer correctly to allow unwritten extent completion to be
run, we need to allow callers of __dax_fault() to pass a null
complete_unwritten() callback. The DAX code always zeros the
unwritten page when it is read faulted so there are no stale data
exposure issues with not doing the conversion. The only downside
will be the potential for increased CPU overhead on repeated read
faults of the same page. If this proves to be a problem, then the
filesystem needs to fix it's get_block callback and provide a
convert_unwritten() callback to the read fault path.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NMatthew Wilcox <willy@linux.intel.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

An oops caused by using other thread's stack space in sunrpc ASYNC sending thread.

[ 9839.007187] ------------[ cut here ]------------
[ 9839.007923] kernel BUG at fs/nfs/nfs4xdr.c:910!
[ 9839.008069] invalid opcode: 0000 [#1] SMP
[ 9839.008069] Modules linked in: blocklayoutdriver rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache snd_hda_codec_generic snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_seq snd_seq_device snd_pcm joydev iosf_mbi crct10dif_pclmul snd_timer crc32_pclmul crc32c_intel ghash_clmulni_intel snd soundcore ppdev pvpanic parport_pc i2c_piix4 serio_raw virtio_balloon parport acpi_cpufreq nfsd nfs_acl lockd grace auth_rpcgss sunrpc qxl drm_kms_helper virtio_net virtio_console virtio_blk ttm drm virtio_pci virtio_ring virtio ata_generic pata_acpi
[ 9839.008069] CPU: 0 PID: 308 Comm: kworker/0:1H Not tainted 4.0.0-0.rc4.git1.3.fc23.x86_64 #1
[ 9839.008069] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 9839.008069] Workqueue: rpciod rpc_async_schedule [sunrpc]
[ 9839.008069] task: ffff8800d8b4d8e0 ti: ffff880036678000 task.ti: ffff880036678000
[ 9839.008069] RIP: 0010:[<ffffffffa0339cc9>]  [<ffffffffa0339cc9>] reserve_space.part.73+0x9/0x10 [nfsv4]
[ 9839.008069] RSP: 0018:ffff88003667ba58  EFLAGS: 00010246
[ 9839.008069] RAX: 0000000000000000 RBX: 000000001fc15e18 RCX: ffff8800c0193800
[ 9839.008069] RDX: ffff8800e4ae3f24 RSI: 000000001fc15e2c RDI: ffff88003667bcd0
[ 9839.008069] RBP: ffff88003667ba58 R08: ffff8800d9173008 R09: 0000000000000003
[ 9839.008069] R10: ffff88003667bcd0 R11: 000000000000000c R12: 0000000000010000
[ 9839.008069] R13: ffff8800d9173350 R14: 0000000000000000 R15: ffff8800c0067b98
[ 9839.008069] FS:  0000000000000000(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000
[ 9839.008069] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9839.008069] CR2: 00007f988c9c8bb0 CR3: 00000000d99b6000 CR4: 00000000000407f0
[ 9839.008069] Stack:
[ 9839.008069]  ffff88003667bbc8 ffffffffa03412c5 00000000c6c55680 ffff880000000003
[ 9839.008069]  0000000000000088 00000010c6c55680 0001000000000002 ffffffff816e87e9
[ 9839.008069]  0000000000000000 00000000477290e2 ffff88003667bab8 ffffffff81327ba3
[ 9839.008069] Call Trace:
[ 9839.008069]  [<ffffffffa03412c5>] encode_attrs+0x435/0x530 [nfsv4]
[ 9839.008069]  [<ffffffff816e87e9>] ? inet_sendmsg+0x69/0xb0
[ 9839.008069]  [<ffffffff81327ba3>] ? selinux_socket_sendmsg+0x23/0x30
[ 9839.008069]  [<ffffffff8164c1df>] ? do_sock_sendmsg+0x9f/0xc0
[ 9839.008069]  [<ffffffff8164c278>] ? kernel_sendmsg+0x58/0x70
[ 9839.008069]  [<ffffffffa011acc0>] ? xdr_reserve_space+0x20/0x170 [sunrpc]
[ 9839.008069]  [<ffffffffa011acc0>] ? xdr_reserve_space+0x20/0x170 [sunrpc]
[ 9839.008069]  [<ffffffffa0341b40>] ? nfs4_xdr_enc_open_noattr+0x130/0x130 [nfsv4]
[ 9839.008069]  [<ffffffffa03419a5>] encode_open+0x2d5/0x340 [nfsv4]
[ 9839.008069]  [<ffffffffa0341b40>] ? nfs4_xdr_enc_open_noattr+0x130/0x130 [nfsv4]
[ 9839.008069]  [<ffffffffa011ab89>] ? xdr_encode_opaque+0x19/0x20 [sunrpc]
[ 9839.008069]  [<ffffffffa0339cfb>] ? encode_string+0x2b/0x40 [nfsv4]
[ 9839.008069]  [<ffffffffa0341bf3>] nfs4_xdr_enc_open+0xb3/0x140 [nfsv4]
[ 9839.008069]  [<ffffffffa0110a4c>] rpcauth_wrap_req+0xac/0xf0 [sunrpc]
[ 9839.008069]  [<ffffffffa01017db>] call_transmit+0x18b/0x2d0 [sunrpc]
[ 9839.008069]  [<ffffffffa0101650>] ? call_decode+0x860/0x860 [sunrpc]
[ 9839.008069]  [<ffffffffa0101650>] ? call_decode+0x860/0x860 [sunrpc]
[ 9839.008069]  [<ffffffffa010caa0>] __rpc_execute+0x90/0x460 [sunrpc]
[ 9839.008069]  [<ffffffffa010ce85>] rpc_async_schedule+0x15/0x20 [sunrpc]
[ 9839.008069]  [<ffffffff810b452b>] process_one_work+0x1bb/0x410
[ 9839.008069]  [<ffffffff810b47d3>] worker_thread+0x53/0x470
[ 9839.008069]  [<ffffffff810b4780>] ? process_one_work+0x410/0x410
[ 9839.008069]  [<ffffffff810b4780>] ? process_one_work+0x410/0x410
[ 9839.008069]  [<ffffffff810ba7b8>] kthread+0xd8/0xf0
[ 9839.008069]  [<ffffffff810ba6e0>] ? kthread_worker_fn+0x180/0x180
[ 9839.008069]  [<ffffffff81786418>] ret_from_fork+0x58/0x90
[ 9839.008069]  [<ffffffff810ba6e0>] ? kthread_worker_fn+0x180/0x180
[ 9839.008069] Code: 00 00 48 c7 c7 21 fa 37 a0 e8 94 1c d6 e0 c6 05 d2 17 05 00 01 8b 03 eb d7 66 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 e5 <0f> 0b 0f 1f 44 00 00 66 66 66 66 90 55 48 89 e5 41 54 53 89 f3
[ 9839.008069] RIP  [<ffffffffa0339cc9>] reserve_space.part.73+0x9/0x10 [nfsv4]
[ 9839.008069]  RSP <ffff88003667ba58>
[ 9839.071114] ---[ end trace cc14c03adb522e94 ]---
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

"data" is currently leaked when the prepare_layoutcommit operation
returns an error. Put the cred before taking the spinlock in that
case, take the lock and then goto out_unlock which will drop the
lock and then free "data".
Signed-off-by: NJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Handle NFS-specific llseek errors instead of letting them leak out to
userspace.
Reported-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Recoalescing does not affect whether or not we've already sent off
I/O, and doing so means that we end up sending a bunch of synchronous
for cases where we actually need to be using unstable writes.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If the function exits early, then we must put those requests that were
not processed back onto the &mirror->pg_list so they can be cleaned up
by nfs_pgio_error().

Fixes: a7d42ddb ("nfs: add mirroring support to pgio layer")
Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

The cgroup attaches inode->i_wb via mark_inode_dirty and when set_page_writeback
is called, __inc_wb_stat() updates i_wb's stat.

So, we need to explicitly call set_page_dirty->__mark_inode_dirty in prior to
any writebacking pages.

This patch should resolve the following kernel panic reported by Andreas Reis.

https://bugzilla.kernel.org/show_bug.cgi?id=101801

--- Comment #2 from Andreas Reis <andreas.reis@gmail.com> ---
BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8
IP: [<ffffffff8149deea>] __percpu_counter_add+0x1a/0x90
PGD 2951ff067 PUD 2df43f067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
Modules linked in:
CPU: 7 PID: 10356 Comm: gcc Tainted: G        W       4.2.0-1-cu #1
Hardware name: Gigabyte Technology Co., Ltd. G1.Sniper M5/G1.Sniper M5, BIOS
T01 02/03/2015
task: ffff880295044f80 ti: ffff880295140000 task.ti: ffff880295140000
RIP: 0010:[<ffffffff8149deea>]  [<ffffffff8149deea>]
__percpu_counter_add+0x1a/0x90
RSP: 0018:ffff880295143ac8  EFLAGS: 00010082
RAX: 0000000000000003 RBX: ffffea000a526d40 RCX: 0000000000000001
RDX: 0000000000000020 RSI: 0000000000000001 RDI: 0000000000000088
RBP: ffff880295143ae8 R08: 0000000000000000 R09: ffff88008f69bb30
R10: 00000000fffffffa R11: 0000000000000000 R12: 0000000000000088
R13: 0000000000000001 R14: ffff88041d099000 R15: ffff880084a205d0
FS:  00007f8549374700(0000) GS:ffff88042f3c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000a8 CR3: 000000033e1d5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000 ffffea000a526d40 ffff880084a20738 ffff880084a20750
 ffff880295143b48 ffffffff811cc91e ffff880000000000 0000000000000296
 0000000000000000 ffff880417090198 0000000000000000 ffffea000a526d40
Call Trace:
 [<ffffffff811cc91e>] __test_set_page_writeback+0xde/0x1d0
 [<ffffffff813fee87>] do_write_data_page+0xe7/0x3a0
 [<ffffffff813faeea>] gc_data_segment+0x5aa/0x640
 [<ffffffff813fb0b8>] do_garbage_collect+0x138/0x150
 [<ffffffff813fb3fe>] f2fs_gc+0x1be/0x3e0
 [<ffffffff81405541>] f2fs_balance_fs+0x81/0x90
 [<ffffffff813ee357>] f2fs_unlink+0x47/0x1d0
 [<ffffffff81239329>] vfs_unlink+0x109/0x1b0
 [<ffffffff8123e3d7>] do_unlinkat+0x287/0x2c0
 [<ffffffff8123ebc6>] SyS_unlink+0x16/0x20
 [<ffffffff81942e2e>] entry_SYSCALL_64_fastpath+0x12/0x71
Code: 41 5e 5d c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 41 55 49
89 f5 41 54 49 89 fc 53 48 83 ec 08 65 ff 05 e6 d9 b6 7e <48> 8b 47 20 48 63 ca
65 8b 18 48 63 db 48 01 f3 48 39 cb 7d 0a
RIP  [<ffffffff8149deea>] __percpu_counter_add+0x1a/0x90
 RSP <ffff880295143ac8>
CR2: 00000000000000a8
---[ end trace 5132449a58ed93a3 ]---
note: gcc[10356] exited with preempt_count 2
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

This patch fixes some missing error handlers.
Reviewed-by: NChao Yu <chao2.yu@samsung.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

bio_associate_blkcg(), bio_associate_current() and wbc_account_io()
are used to implement cgroup writeback support for filesystems and
thus need to be exported.  Export them.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJens Axboe <axboe@fb.com>

The handling of in detach_mounts of unmounted but connected mounts is
buggy and can lead to an infinite loop.

Correct the handling of unmounted mounts in detach_mount.  When the
mountpoint of an unmounted but connected mount is connected to a
dentry, and that dentry is deleted we need to disconnect that mount
from the parent mount and the deleted dentry.

Nothing changes for the unmounted and connected children.  They can be
safely ignored.

Cc: stable@vger.kernel.org
Fixes: ce07d891 mnt: Honor MNT_LOCKED when detaching mounts
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

rmdir mntpoint will result in an infinite loop when there is
a mount locked on the mountpoint in another mount namespace.

This is because the logic to test to see if a mount should
be disconnected in umount_tree is buggy.

Move the logic to decide if a mount should remain connected to
it's mountpoint into it's own function disconnect_mount so that
clarity of expression instead of terseness of expression becomes
a virtue.

When the conditions where it is invalid to leave a mount connected
are first ruled out, the logic for deciding if a mount should
be disconnected becomes much clearer and simpler.

Fixes: e0c9c0af mnt: Update detach_mounts to leave mounts connected
Fixes: ce07d891 mnt: Honor MNT_LOCKED when detaching mounts
Cc: stable@vger.kernel.org
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Omar reported that after commit 4fbcdf66 ("Btrfs: fix -ENOSPC when
finishing block group creation"), introduced in 4.2-rc1, the following
test was failing due to exhaustion of the system array in the superblock:

  #!/bin/bash

  truncate -s 100T big.img
  mkfs.btrfs big.img
  mount -o loop big.img /mnt/loop

  num=5
  sz=10T
  for ((i = 0; i < $num; i++)); do
      echo fallocate $i $sz
      fallocate -l $sz /mnt/loop/testfile$i
  done
  btrfs filesystem sync /mnt/loop

  for ((i = 0; i < $num; i++)); do
        echo rm $i
        rm /mnt/loop/testfile$i
        btrfs filesystem sync /mnt/loop
  done
  umount /mnt/loop

This made btrfs_add_system_chunk() fail with -EFBIG due to excessive
allocation of system block groups. This happened because the test creates
a large number of data block groups per transaction and when committing
the transaction we start the writeout of the block group caches for all
the new new (dirty) block groups, which results in pre-allocating space
for each block group's free space cache using the same transaction handle.
That in turn often leads to creation of more block groups, and all get
attached to the new_bgs list of the same transaction handle to the point
of getting a list with over 1500 elements, and creation of new block groups
leads to the need of reserving space in the chunk block reserve and often
creating a new system block group too.

So that made us quickly exhaust the chunk block reserve/system space info,
because as of the commit mentioned before, we do reserve space for each
new block group in the chunk block reserve, unlike before where we would
not and would at most allocate one new system block group and therefore
would only ensure that there was enough space in the system space info to
allocate 1 new block group even if we ended up allocating thousands of
new block groups using the same transaction handle. That worked most of
the time because the computed required space at check_system_chunk() is
very pessimistic (assumes a chunk tree height of BTRFS_MAX_LEVEL/8 and
that all nodes/leafs in a path will be COWed and split) and since the
updates to the chunk tree all happen at btrfs_create_pending_block_groups
it is unlikely that a path needs to be COWed more than once (unless
writepages() for the btree inode is called by mm in between) and that
compensated for the need of creating any new nodes/leads in the chunk
tree.

So fix this by ensuring we don't accumulate a too large list of new block
groups in a transaction's handles new_bgs list, inserting/updating the
chunk tree for all accumulated new block groups and releasing the unused
space from the chunk block reserve whenever the list becomes sufficiently
large. This is a generic solution even though the problem currently can
only happen when starting the writeout of the free space caches for all
dirty block groups (btrfs_start_dirty_block_groups()).
Reported-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Tested-by: NOmar Sandoval <osandov@fb.com>
Signed-off-by: NChris Mason <clm@fb.com>

sorry I indented to use btrfs_err() and I have no idea
how btrfs_error() got there.
infact I was thinking about these kind of oversights
since these two func are too closely named.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NChris Mason <clm@fb.com>

When read_tree_block() failed, we can see following dmesg:
 [  134.371389] BUG: unable to handle kernel NULL pointer dereference at 0000000000000063
 [  134.372236] IP: [<ffffffff813a4a51>] free_extent_buffer+0x21/0x90
 [  134.372236] PGD 0
 [  134.372236] Oops: 0000 [#1] SMP
 [  134.372236] Modules linked in:
 [  134.372236] CPU: 0 PID: 2289 Comm: mount Not tainted 4.2.0-rc1_HEAD_c65b99f0_+ #115
 [  134.372236] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
 [  134.372236] task: ffff88003b6e1a00 ti: ffff880011e60000 task.ti: ffff880011e60000
 [  134.372236] RIP: 0010:[<ffffffff813a4a51>]  [<ffffffff813a4a51>] free_extent_buffer+0x21/0x90
 ...
 [  134.372236] Call Trace:
 [  134.372236]  [<ffffffff81379aa1>] free_root_extent_buffers+0x91/0xb0
 [  134.372236]  [<ffffffff81379c3d>] free_root_pointers+0x17d/0x190
 [  134.372236]  [<ffffffff813801b0>] open_ctree+0x1ca0/0x25b0
 [  134.372236]  [<ffffffff8144d017>] ? disk_name+0x97/0xb0
 [  134.372236]  [<ffffffff813558aa>] btrfs_mount+0x8fa/0xab0
 ...

Reason:
 read_tree_block() changed to return error number on fail,
 and this value(not NULL) is set to tree_root->node, then subsequent
 code will run to:
  free_root_pointers()
  ->free_root_extent_buffers()
  ->free_extent_buffer()
  ->atomic_read((extent_buffer *)(-E_XXX)->refs);
 and trigger above error.

Fix:
 Set tree_root->node to NULL on fail to make error_handle code
 happy.
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: NChris Mason <clm@fb.com>

Liu Bo <bo.li.liu@oracle.com> reported a lockdep warning of
delayed_iput_sem in xfstests generic/241:
  [ 2061.345955] =============================================
  [ 2061.346027] [ INFO: possible recursive locking detected ]
  [ 2061.346027] 4.1.0+ #268 Tainted: G        W
  [ 2061.346027] ---------------------------------------------
  [ 2061.346027] btrfs-cleaner/3045 is trying to acquire lock:
  [ 2061.346027]  (&fs_info->delayed_iput_sem){++++..}, at:
  [<ffffffff814063ab>] btrfs_run_delayed_iputs+0x6b/0x100
  [ 2061.346027] but task is already holding lock:
  [ 2061.346027]  (&fs_info->delayed_iput_sem){++++..}, at: [<ffffffff814063ab>] btrfs_run_delayed_iputs+0x6b/0x100
  [ 2061.346027] other info that might help us debug this:
  [ 2061.346027]  Possible unsafe locking scenario:

  [ 2061.346027]        CPU0
  [ 2061.346027]        ----
  [ 2061.346027]   lock(&fs_info->delayed_iput_sem);
  [ 2061.346027]   lock(&fs_info->delayed_iput_sem);
  [ 2061.346027]
   *** DEADLOCK ***
It is rarely happened, about 1/400 in my test env.

The reason is recursion of btrfs_run_delayed_iputs():
  cleaner_kthread
  -> btrfs_run_delayed_iputs() *1
  -> get delayed_iput_sem lock *2
  -> iput()
  -> ...
  -> btrfs_commit_transaction()
  -> btrfs_run_delayed_iputs() *1
  -> get delayed_iput_sem lock (dead lock) *2
  *1: recursion of btrfs_run_delayed_iputs()
  *2: warning of lockdep about delayed_iput_sem

When fs is in high stress, new iputs may added into fs_info->delayed_iputs
list when btrfs_run_delayed_iputs() is running, which cause
second btrfs_run_delayed_iputs() run into down_read(&fs_info->delayed_iput_sem)
again, and cause above lockdep warning.

Actually, it will not cause real problem because both locks are read lock,
but to avoid lockdep warning, we can do a fix.

Fix:
  Don't do btrfs_run_delayed_iputs() in btrfs_commit_transaction() for
  cleaner_kthread thread to break above recursion path.
  cleaner_kthread is calling btrfs_run_delayed_iputs() explicitly in code,
  and don't need to call btrfs_run_delayed_iputs() again in
  btrfs_commit_transaction(), it also give us a bonus to avoid stack overflow.

Test:
  No above lockdep warning after patch in 1200 generic/241 tests.
Reported-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NChris Mason <clm@fb.com>

Setting the change attribute has been mandatory for all NFS versions, since
commit 3a1556e8 ("NFSv2/v3: Simulate the change attribute"). We should
therefore not have anything be conditional on it being set/unset.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

We can't allow caching of data until the change attribute has been
initialised correctly.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

If we've ensured that the size and the change attribute are both correct,
then there is no point in marking those attributes as needing revalidation
again. Only do so if we know the size is incorrect and was not updated.

Fixes: f2467b6f ("NFS: Clear NFS_INO_REVAL_PAGECACHE when...")
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

pNFS writes don't return attributes, however that doesn't mean that we
should ignore the fact that they may be extending the file. This patch
ensures that if a write is seen to extend the file, then we always set
an attribute barrier, and update the cached file size.
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

Otherwise, nfs4_select_rw_stateid() will always return the zero stateid
instead of the correct open stateid.

Fixes: f95549cf ("NFSv4: More CLOSE/OPEN races")
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

This reverts commit a2673b6e.

Kinglong Mee reports a memory leak with that patch, and Jan Kara confirms:

 "Thanks for report! You are right that my patch introduces a race
  between fsnotify kthread and fsnotify_destroy_group() which can result
  in leaking inotify event on group destruction.

  I haven't yet decided whether the right fix is not to queue events for
  dying notification group (as that is pointless anyway) or whether we
  should just fix the original problem differently...  Whenever I look
  at fsnotify code mark handling I get lost in the maze of locks, lists,
  and subtle differences between how different notification systems
  handle notification marks :( I'll think about it over night"

and after thinking about it, Jan says:

 "OK, I have looked into the code some more and I found another
  relatively simple way of fixing the original oops.  It will be IMHO
  better than trying to fixup this issue which has more potential for
  breakage.  I'll ask Linus to revert the fsnotify fix he already merged
  and send a new fix"
Reported-by: NKinglong Mee <kinglongmee@gmail.com>
Requested-by: NJan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If nfsd4_layout_setlease fails, nfsd will not put ls->ls_file.

Fix commit c5c707f9 "nfsd: implement pNFS layout recalls".
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

On an absent filesystem (one served by another server), we need to be
able to handle requests for certain attributest (like fs_locations, so
the client can find out which server does have the filesystem), but
others we can't.

We forgot to take that into account when adding another attribute
bitmask work for the SECURITY_LABEL attribute.

There an export entry with the "refer" option can result in:

[   88.414272] kernel BUG at fs/nfsd/nfs4xdr.c:2249!
[   88.414828] invalid opcode: 0000 [#1] SMP
[   88.415368] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache nfsd xfs libcrc32c iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi iosf_mbi ppdev btrfs coretemp crct10dif_pclmul crc32_pclmul crc32c_intel xor ghash_clmulni_intel raid6_pq vmw_balloon parport_pc parport i2c_piix4 shpchp vmw_vmci acpi_cpufreq auth_rpcgss nfs_acl lockd grace sunrpc vmwgfx drm_kms_helper ttm drm mptspi mptscsih serio_raw mptbase e1000 scsi_transport_spi ata_generic pata_acpi [last unloaded: nfsd]
[   88.417827] CPU: 0 PID: 2116 Comm: nfsd Not tainted 4.0.7-300.fc22.x86_64 #1
[   88.418448] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/20/2014
[   88.419093] task: ffff880079146d50 ti: ffff8800785d8000 task.ti: ffff8800785d8000
[   88.419729] RIP: 0010:[<ffffffffa04b3c10>]  [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd]
[   88.420376] RSP: 0000:ffff8800785db998  EFLAGS: 00010206
[   88.421027] RAX: 0000000000000001 RBX: 000000000018091a RCX: ffff88006668b980
[   88.421676] RDX: 00000000fffef7fc RSI: 0000000000000000 RDI: ffff880078d05000
[   88.422315] RBP: ffff8800785dbb58 R08: ffff880078d043f8 R09: ffff880078d4a000
[   88.422968] R10: 0000000000010000 R11: 0000000000000002 R12: 0000000000b0a23a
[   88.423612] R13: ffff880078d05000 R14: ffff880078683100 R15: ffff88006668b980
[   88.424295] FS:  0000000000000000(0000) GS:ffff88007c600000(0000) knlGS:0000000000000000
[   88.424944] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   88.425597] CR2: 00007f40bc370f90 CR3: 0000000035af5000 CR4: 00000000001407f0
[   88.426285] Stack:
[   88.426921]  ffff8800785dbaa8 ffffffffa049e4af ffff8800785dba08 ffffffff813298f0
[   88.427585]  ffff880078683300 ffff8800769b0de8 0000089d00000001 0000000087f805e0
[   88.428228]  ffff880000000000 ffff880079434a00 0000000000000000 ffff88006668b980
[   88.428877] Call Trace:
[   88.429527]  [<ffffffffa049e4af>] ? exp_get_by_name+0x7f/0xb0 [nfsd]
[   88.430168]  [<ffffffff813298f0>] ? inode_doinit_with_dentry+0x210/0x6a0
[   88.430807]  [<ffffffff8123833e>] ? d_lookup+0x2e/0x60
[   88.431449]  [<ffffffff81236133>] ? dput+0x33/0x230
[   88.432097]  [<ffffffff8123f214>] ? mntput+0x24/0x40
[   88.432719]  [<ffffffff812272b2>] ? path_put+0x22/0x30
[   88.433340]  [<ffffffffa049ac87>] ? nfsd_cross_mnt+0xb7/0x1c0 [nfsd]
[   88.433954]  [<ffffffffa04b54e0>] nfsd4_encode_dirent+0x1b0/0x3d0 [nfsd]
[   88.434601]  [<ffffffffa04b5330>] ? nfsd4_encode_getattr+0x40/0x40 [nfsd]
[   88.435172]  [<ffffffffa049c991>] nfsd_readdir+0x1c1/0x2a0 [nfsd]
[   88.435710]  [<ffffffffa049a530>] ? nfsd_direct_splice_actor+0x20/0x20 [nfsd]
[   88.436447]  [<ffffffffa04abf30>] nfsd4_encode_readdir+0x120/0x220 [nfsd]
[   88.437011]  [<ffffffffa04b58cd>] nfsd4_encode_operation+0x7d/0x190 [nfsd]
[   88.437566]  [<ffffffffa04aa6dd>] nfsd4_proc_compound+0x24d/0x6f0 [nfsd]
[   88.438157]  [<ffffffffa0496103>] nfsd_dispatch+0xc3/0x220 [nfsd]
[   88.438680]  [<ffffffffa006f0cb>] svc_process_common+0x43b/0x690 [sunrpc]
[   88.439192]  [<ffffffffa0070493>] svc_process+0x103/0x1b0 [sunrpc]
[   88.439694]  [<ffffffffa0495a57>] nfsd+0x117/0x190 [nfsd]
[   88.440194]  [<ffffffffa0495940>] ? nfsd_destroy+0x90/0x90 [nfsd]
[   88.440697]  [<ffffffff810bb728>] kthread+0xd8/0xf0
[   88.441260]  [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180
[   88.441762]  [<ffffffff81789e58>] ret_from_fork+0x58/0x90
[   88.442322]  [<ffffffff810bb650>] ? kthread_worker_fn+0x180/0x180
[   88.442879] Code: 0f 84 93 05 00 00 83 f8 ea c7 85 a0 fe ff ff 00 00 27 30 0f 84 ba fe ff ff 85 c0 0f 85 a5 fe ff ff e9 e3 f9 ff ff 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00 00 be 04 00 00 00 4c 89 ef 4c 89 8d 68 fe
[   88.444052] RIP  [<ffffffffa04b3c10>] nfsd4_encode_fattr+0x820/0x1f00 [nfsd]
[   88.444658]  RSP <ffff8800785db998>
[   88.445232] ---[ end trace 6cb9d0487d94a29f ]---
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

Don't burden architectures without dynamic task_struct sizing
with the overhead of dynamic sizing.

Also optimize the x86 code a bit by caching task_struct_size.
Acked-and-Tested-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437128892-9831-3-git-send-email-mingo@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The FPU rewrite removed the dynamic allocations of 'struct fpu'.
But, this potentially wastes massive amounts of memory (2k per
task on systems that do not have AVX-512 for instance).

Instead of having a separate slab, this patch just appends the
space that we need to the 'task_struct' which we dynamically
allocate already.  This saves from doing an extra slab
allocation at fork().

The only real downside here is that we have to stick everything
and the end of the task_struct.  But, I think the
BUILD_BUG_ON()s I stuck in there should keep that from being too
fragile.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437128892-9831-2-git-send-email-mingo@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>