Commit Graph

240 Commits

Author SHA1 Message Date
Linus Torvalds
4fc8adcfec Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull third hunk of vfs changes from Al Viro:
 "This contains the ->direct_IO() changes from Omar + saner
  generic_write_checks() + dealing with fcntl()/{read,write}() races
  (mirroring O_APPEND/O_DIRECT into iocb->ki_flags and instead of
  repeatedly looking at ->f_flags, which can be changed by fcntl(2),
  check ->ki_flags - which cannot) + infrastructure bits for dhowells'
  d_inode annotations + Christophs switch of /dev/loop to
  vfs_iter_write()"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (30 commits)
  block: loop: switch to VFS ITER_BVEC
  configfs: Fix inconsistent use of file_inode() vs file->f_path.dentry->d_inode
  VFS: Make pathwalk use d_is_reg() rather than S_ISREG()
  VFS: Fix up debugfs to use d_is_dir() in place of S_ISDIR()
  VFS: Combine inode checks with d_is_negative() and d_is_positive() in pathwalk
  NFS: Don't use d_inode as a variable name
  VFS: Impose ordering on accesses of d_inode and d_flags
  VFS: Add owner-filesystem positive/negative dentry checks
  nfs: generic_write_checks() shouldn't be done on swapout...
  ocfs2: use __generic_file_write_iter()
  mirror O_APPEND and O_DIRECT into iocb->ki_flags
  switch generic_write_checks() to iocb and iter
  ocfs2: move generic_write_checks() before the alignment checks
  ocfs2_file_write_iter: stop messing with ppos
  udf_file_write_iter: reorder and simplify
  fuse: ->direct_IO() doesn't need generic_write_checks()
  ext4_file_write_iter: move generic_write_checks() up
  xfs_file_aio_write_checks: switch to iocb/iov_iter
  generic_write_checks(): drop isblk argument
  blkdev_write_iter: expand generic_file_checks() call in there
  ...
2015-04-16 23:27:56 -04:00
Linus Torvalds
d82312c808 Merge branch 'for-4.1/core' of git://git.kernel.dk/linux-block
Pull block layer core bits from Jens Axboe:
 "This is the core pull request for 4.1.  Not a lot of stuff in here for
  this round, mostly little fixes or optimizations.  This pull request
  contains:

   - An optimization that speeds up queue runs on blk-mq, especially for
     the case where there's a large difference between nr_cpu_ids and
     the actual mapped software queues on a hardware queue.  From Chong
     Yuan.

   - Honor node local allocations for requests on legacy devices.  From
     David Rientjes.

   - Cleanup of blk_mq_rq_to_pdu() from me.

   - exit_aio() fixup from me, greatly speeding up exiting multiple IO
     contexts off exit_group().  For my particular test case, fio exit
     took ~6 seconds.  A typical case of both exposing RCU grace periods
     to user space, and serializing exit of them.

   - Make blk_mq_queue_enter() honor the gfp mask passed in, so we only
     wait if __GFP_WAIT is set.  From Keith Busch.

   - blk-mq exports and two added helpers from Mike Snitzer, which will
     be used by the dm-mq code.

   - Cleanups of blk-mq queue init from Wei Fang and Xiaoguang Wang"

* 'for-4.1/core' of git://git.kernel.dk/linux-block:
  blk-mq: reduce unnecessary software queue looping
  aio: fix serial draining in exit_aio()
  blk-mq: cleanup blk_mq_rq_to_pdu()
  blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue()
  block: remove redundant check about 'set->nr_hw_queues' in blk_mq_alloc_tag_set()
  block: allocate request memory local to request queue
  blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set
  blk-mq: export blk_mq_run_hw_queues
  blk-mq: add blk_mq_init_allocated_queue and export blk_mq_register_disk
2015-04-16 21:49:16 -04:00
Linus Torvalds
fa927894bb Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull second vfs update from Al Viro:
 "Now that net-next went in...  Here's the next big chunk - killing
  ->aio_read() and ->aio_write().

  There'll be one more pile today (direct_IO changes and
  generic_write_checks() cleanups/fixes), but I'd prefer to keep that
  one separate"

* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
  ->aio_read and ->aio_write removed
  pcm: another weird API abuse
  infinibad: weird APIs switched to ->write_iter()
  kill do_sync_read/do_sync_write
  fuse: use iov_iter_get_pages() for non-splice path
  fuse: switch to ->read_iter/->write_iter
  switch drivers/char/mem.c to ->read_iter/->write_iter
  make new_sync_{read,write}() static
  coredump: accept any write method
  switch /dev/loop to vfs_iter_write()
  serial2002: switch to __vfs_read/__vfs_write
  ashmem: use __vfs_read()
  export __vfs_read()
  autofs: switch to __vfs_write()
  new helper: __vfs_write()
  switch hugetlbfs to ->read_iter()
  coda: switch to ->read_iter/->write_iter
  ncpfs: switch to ->read_iter/->write_iter
  net/9p: remove (now-)unused helpers
  p9_client_attach(): set fid->uid correctly
  ...
2015-04-15 13:22:56 -07:00
Jens Axboe
dc48e56d76 aio: fix serial draining in exit_aio()
exit_aio() currently serializes killing io contexts. Each context
killing ends up having to do percpu_ref_kill(), which in turns has
to wait for an RCU grace period. This can take a long time, depending
on the number of contexts. And there's no point in doing them serially,
when we could be waiting for all of them in one fell swoop.

This patches makes my fio thread offload test case exit 0.2s instead
of almost 6s.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-04-15 11:17:23 -06:00
Linus Torvalds
ca2ec32658 Merge branch 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs update from Al Viro:
 "Part one:

   - struct filename-related cleanups

   - saner iov_iter_init() replacements (and switching the syscalls to
     use of those)

   - ntfs switch to ->write_iter() (Anton)

   - aio cleanups and splitting iocb into common and async parts
     (Christoph)

   - assorted fixes (me, bfields, Andrew Elble)

  There's a lot more, including the completion of switchover to
  ->{read,write}_iter(), d_inode/d_backing_inode annotations, f_flags
  race fixes, etc, but that goes after #for-davem merge.  David has
  pulled it, and once it's in I'll send the next vfs pull request"

* 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (35 commits)
  sg_start_req(): use import_iovec()
  sg_start_req(): make sure that there's not too many elements in iovec
  blk_rq_map_user(): use import_single_range()
  sg_io(): use import_iovec()
  process_vm_access: switch to {compat_,}import_iovec()
  switch keyctl_instantiate_key_common() to iov_iter
  switch {compat_,}do_readv_writev() to {compat_,}import_iovec()
  aio_setup_vectored_rw(): switch to {compat_,}import_iovec()
  vmsplice_to_user(): switch to import_iovec()
  kill aio_setup_single_vector()
  aio: simplify arguments of aio_setup_..._rw()
  aio: lift iov_iter_init() into aio_setup_..._rw()
  lift iov_iter into {compat_,}do_readv_writev()
  NFS: fix BUG() crash in notify_change() with patch to chown_common()
  dcache: return -ESTALE not -EBUSY on distributed fs race
  NTFS: Version 2.1.32 - Update file write from aio_write to write_iter.
  VFS: Add iov_iter_fault_in_multipages_readable()
  drop bogus check in file_open_root()
  switch security_inode_getattr() to struct path *
  constify tomoyo_realpath_from_path()
  ...
2015-04-14 15:31:03 -07:00
Al Viro
2ba48ce513 mirror O_APPEND and O_DIRECT into iocb->ki_flags
... avoiding write_iter/fcntl races.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:30:22 -04:00
Al Viro
dfea934575 Merge branch 'for-linus' into for-next 2015-04-11 22:29:51 -04:00
Al Viro
8436318205 ->aio_read and ->aio_write removed
no remaining users

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:29:43 -04:00
Al Viro
47e393622b aio_run_iocb(): kill dead check
We check if ->ki_pos is positive.  However, by that point we have
already done rw_verify_area(), which would have rejected such
unless the file had been one of /dev/mem, /dev/kmem and /proc/kcore.
All of which do not have vectored rw methods, so we would've bailed
out even earlier.

This check had been introduced before rw_verify_area() had been added there
- in fact, it was a subset of checks done on sync paths by rw_verify_area()
(back then the /dev/mem exception didn't exist at all).  The rest of checks
(mandatory locking, etc.) hadn't been added until later.  Unfortunately,
by the time the call of rw_verify_area() got added, the /dev/mem exception
had already appeared, so it wasn't obvious that the older explicit check
downstream had become dead code.  It *is* a dead code, though, since the few
files for which the exception applies do not have ->aio_{read,write}() or
->{read,write}_iter() and for them we won't reach that check anyway.

What's more, even if we ever introduce vectored methods for /dev/mem
and friends, they'll have to cope with negative positions anyway, since
readv(2) and writev(2) are using the same checks as read(2) and write(2) -
i.e. rw_verify_area().

Let's bury it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:27:55 -04:00
Al Viro
08397acdd0 ioctx_alloc(): remove pointless check
Way, way back kiocb used to be picked from arrays, so ioctx_alloc()
checked for multiplication overflow when calculating the size of
such array.  By the time fs/aio.c went into the tree (in 2002) they
were already allocated one-by-one by kmem_cache_alloc(), so that
check had already become pointless.  Let's bury it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:27:54 -04:00
Al Viro
32a56afa23 aio_setup_vectored_rw(): switch to {compat_,}import_iovec()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:27:11 -04:00
Al Viro
d4fb392f4c kill aio_setup_single_vector()
identical to import_single_range()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:27:10 -04:00
Al Viro
a96114fa1a aio: simplify arguments of aio_setup_..._rw()
We don't need req in either of those.  We don't need nr_segs in caller.
We don't really need len in caller either - iov_iter_count(&iter) will do.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:26:45 -04:00
Al Viro
4c185ce06d aio: lift iov_iter_init() into aio_setup_..._rw()
the only non-trivial detail is that we do it before rw_verify_area(),
so we'd better cap the length ourselves in aio_setup_single_rw()
case (for vectored case rw_copy_check_uvector() will do that for us).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:26:45 -04:00
Al Viro
c0fec3a98b Merge branch 'iocb' into for-next 2015-04-11 22:24:41 -04:00
Al Viro
deeb8525f9 ioctx_alloc(): fix vma (and file) leak on failure
If we fail past the aio_setup_ring(), we need to destroy the
mapping.  We don't need to care about anybody having found ctx,
or added requests to it, since the last failure exit is exactly
the failure to make ctx visible to lookups.

Reproducer (based on one by Joe Mario <jmario@redhat.com>):

void count(char *p)
{
	char s[80];
	printf("%s: ", p);
	fflush(stdout);
	sprintf(s, "/bin/cat /proc/%d/maps|/bin/fgrep -c '/[aio] (deleted)'", getpid());
	system(s);
}

int main()
{
	io_context_t *ctx;
	int created, limit, i, destroyed;
	FILE *f;

	count("before");
	if ((f = fopen("/proc/sys/fs/aio-max-nr", "r")) == NULL)
		perror("opening aio-max-nr");
	else if (fscanf(f, "%d", &limit) != 1)
		fprintf(stderr, "can't parse aio-max-nr\n");
	else if ((ctx = calloc(limit, sizeof(io_context_t))) == NULL)
		perror("allocating aio_context_t array");
	else {
		for (i = 0, created = 0; i < limit; i++) {
			if (io_setup(1000, ctx + created) == 0)
				created++;
		}
		for (i = 0, destroyed = 0; i < created; i++)
			if (io_destroy(ctx[i]) == 0)
				destroyed++;
		printf("created %d, failed %d, destroyed %d\n",
			created, limit - created, destroyed);
		count("after");
	}
}

Found-by: Joe Mario <jmario@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-06 17:57:44 -04:00
Al Viro
b2edffdd91 fix mremap() vs. ioctx_kill() race
teach ->mremap() method to return an error and have it fail for
aio mappings in process of being killed

Note that in case of ->mremap() failure we need to undo move_page_tables()
we'd already done; we could call ->mremap() first, but then the failure of
move_page_tables() would require undoing whatever _successful_ ->mremap()
has done, which would be a lot more headache in general.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-06 17:50:59 -04:00
Christoph Hellwig
04b2fa9f8f fs: split generic and aio kiocb
Most callers in the kernel want to perform synchronous file I/O, but
still have to bloat the stack with a full struct kiocb.  Split out
the parts needed in filesystem code from those in the aio code, and
only allocate those needed to pass down argument on the stack.  The
aio code embedds the generic iocb in the one it allocates and can
easily get back to it by using container_of.

Also add a ->ki_complete method to struct kiocb, this is used to call
into the aio code and thus removes the dependency on aio for filesystems
impementing asynchronous operations.  It will also allow other callers
to substitute their own completion callback.

We also add a new ->ki_flags field to work around the nasty layering
violation recently introduced in commit 5e33f6 ("usb: gadget: ffs: add
eventfd notification about ffs events").

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-13 12:10:27 -04:00
Christoph Hellwig
599bd19bdc fs: don't allow to complete sync iocbs through aio_complete
The AIO interface is fairly complex because it tries to allow
filesystems to always work async and then wakeup a synchronous
caller through aio_complete.  It turns out that basically no one
was doing this to avoid the complexity and context switches,
and we've already fixed up the remaining users and can now
get rid of this case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-13 12:10:22 -04:00
Christoph Hellwig
66ee59af63 fs: remove ki_nbytes
There is no need to pass the total request length in the kiocb, as
we already get passed in through the iov_iter argument.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-12 23:50:23 -04:00
Kinglong Mee
acd88d4e1a fs/aio.c: Remove duplicate function name in pr_debug messages
Have defined pr_fmt as below in fs/aio.c, so remove duplicate
function name in pr_debug message.

#define pr_fmt(fmt) "%s: " fmt, __func__

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-20 04:56:44 -05:00
Linus Torvalds
6bec003528 Merge branch 'for-3.20/bdi' of git://git.kernel.dk/linux-block
Pull backing device changes from Jens Axboe:
 "This contains a cleanup of how the backing device is handled, in
  preparation for a rework of the life time rules.  In this part, the
  most important change is to split the unrelated nommu mmap flags from
  it, but also removing a backing_dev_info pointer from the
  address_space (and inode), and a cleanup of other various minor bits.

  Christoph did all the work here, I just fixed an oops with pages that
  have a swap backing.  Arnd fixed a missing export, and Oleg killed the
  lustre backing_dev_info from staging.  Last patch was from Al,
  unexporting parts that are now no longer needed outside"

* 'for-3.20/bdi' of git://git.kernel.dk/linux-block:
  Make super_blocks and sb_lock static
  mtd: export new mtd_mmap_capabilities
  fs: make inode_to_bdi() handle NULL inode
  staging/lustre/llite: get rid of backing_dev_info
  fs: remove default_backing_dev_info
  fs: don't reassign dirty inodes to default_backing_dev_info
  nfs: don't call bdi_unregister
  ceph: remove call to bdi_unregister
  fs: remove mapping->backing_dev_info
  fs: export inode_to_bdi and use it in favor of mapping->backing_dev_info
  nilfs2: set up s_bdi like the generic mount_bdev code
  block_dev: get bdev inode bdi directly from the block device
  block_dev: only write bdev inode on close
  fs: introduce f_op->mmap_capabilities for nommu mmap support
  fs: kill BDI_CAP_SWAP_BACKED
  fs: deduplicate noop_backing_dev_info
2015-02-12 13:50:21 -08:00
Dave Chinner
9c9ce763b1 aio: annotate aio_read_event_ring for sleep patterns
Under CONFIG_DEBUG_ATOMIC_SLEEP=y, aio_read_event_ring() will throw
warnings like the following due to being called from wait_event
context:

 WARNING: CPU: 0 PID: 16006 at kernel/sched/core.c:7300 __might_sleep+0x7f/0x90()
 do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810d85a3>] prepare_to_wait_event+0x63/0x110
 Modules linked in:
 CPU: 0 PID: 16006 Comm: aio-dio-fcntl-r Not tainted 3.19.0-rc6-dgc+ #705
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  ffffffff821c0372 ffff88003c117cd8 ffffffff81daf2bd 000000000000d8d8
  ffff88003c117d28 ffff88003c117d18 ffffffff8109beda ffff88003c117cf8
  ffffffff821c115e 0000000000000061 0000000000000000 00007ffffe4aa300
 Call Trace:
  [<ffffffff81daf2bd>] dump_stack+0x4c/0x65
  [<ffffffff8109beda>] warn_slowpath_common+0x8a/0xc0
  [<ffffffff8109bf56>] warn_slowpath_fmt+0x46/0x50
  [<ffffffff810d85a3>] ? prepare_to_wait_event+0x63/0x110
  [<ffffffff810d85a3>] ? prepare_to_wait_event+0x63/0x110
  [<ffffffff810bdfcf>] __might_sleep+0x7f/0x90
  [<ffffffff81db8344>] mutex_lock+0x24/0x45
  [<ffffffff81216b7c>] aio_read_events+0x4c/0x290
  [<ffffffff81216fac>] read_events+0x1ec/0x220
  [<ffffffff810d8650>] ? prepare_to_wait_event+0x110/0x110
  [<ffffffff810fdb10>] ? hrtimer_get_res+0x50/0x50
  [<ffffffff8121899d>] SyS_io_getevents+0x4d/0xb0
  [<ffffffff81dba5a9>] system_call_fastpath+0x12/0x17
 ---[ end trace bde69eaf655a4fea ]---

There is not actually a bug here, so annotate the code to tell the
debug logic that everything is just fine and not to fire a false
positive.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2015-02-03 19:29:05 -05:00
Christoph Hellwig
b83ae6d421 fs: remove mapping->backing_dev_info
Now that we never use the backing_dev_info pointer in struct address_space
we can simply remove it and save 4 to 8 bytes in every inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Reviewed-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-01-20 14:03:05 -07:00
Christoph Hellwig
b4caecd480 fs: introduce f_op->mmap_capabilities for nommu mmap support
Since "BDI: Provide backing device capability information [try #3]" the
backing_dev_info structure also provides flags for the kind of mmap
operation available in a nommu environment, which is entirely unrelated
to it's original purpose.

Introduce a new nommu-only file operation to provide this information to
the nommu mmap code instead.  Splitting this from the backing_dev_info
structure allows to remove lots of backing_dev_info instance that aren't
otherwise needed, and entirely gets rid of the concept of providing a
backing_dev_info for a character device.  It also removes the need for
the mtd_inodefs filesystem.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tejun Heo <tj@kernel.org>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2015-01-20 14:02:58 -07:00
Fam Zheng
5f785de588 aio: Skip timer for io_getevents if timeout=0
In this case, it is basically a polling. Let's not involve timer at all
because that would hurt performance for application event loops.

In an arbitrary test I've done, io_getevents syscall elapsed time
reduces from 50000+ nanoseconds to a few hundereds.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-12-13 17:50:20 -05:00
Pavel Emelyanov
e4a0d3e720 aio: Make it possible to remap aio ring
There are actually two issues this patch addresses. Let me start with
the one I tried to solve in the beginning.

So, in the checkpoint-restore project (criu) we try to dump tasks'
state and restore one back exactly as it was. One of the tasks' state
bits is rings set up with io_setup() call. There's (almost) no problems
in dumping them, there's a problem restoring them -- if I dump a task
with aio ring originally mapped at address A, I want to restore one
back at exactly the same address A. Unfortunately, the io_setup() does
not allow for that -- it mmaps the ring at whatever place mm finds
appropriate (it calls do_mmap_pgoff() with zero address and without
the MAP_FIXED flag).

To make restore possible I'm going to mremap() the freshly created ring
into the address A (under which it was seen before dump). The problem is
that the ring's virtual address is passed back to the user-space as the
context ID and this ID is then used as search key by all the other io_foo()
calls. Reworking this ID to be just some integer doesn't seem to work, as
this value is already used by libaio as a pointer using which this library
accesses memory for aio meta-data.

So, to make restore work we need to make sure that

a) ring is mapped at desired virtual address
b) kioctx->user_id matches this value

Having said that, the patch makes mremap() on aio region update the
kioctx's user_id and mmap_base values.

Here appears the 2nd issue I mentioned in the beginning of this mail.
If (regardless of the C/R dances I do) someone creates an io context
with io_setup(), then mremap()-s the ring and then destroys the context,
the kill_ioctx() routine will call munmap() on wrong (old) address.
This will result in a) aio ring remaining in memory and b) some other
vma get unexpectedly unmapped.

What do you think?

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-12-13 17:49:50 -05:00
Linus Torvalds
277f850fbc Merge git://git.kvack.org/~bcrl/aio-fixes
Pull aio fix from Ben LaHaise:
 "Dirty page accounting fix for aio"

* git://git.kvack.org/~bcrl/aio-fixes:
  aio: fix uncorrent dirty pages accouting when truncating AIO ring buffer
2014-11-25 18:55:44 -08:00
Gu Zheng
835f252c6d aio: fix uncorrent dirty pages accouting when truncating AIO ring buffer
https://bugzilla.kernel.org/show_bug.cgi?id=86831

Markus reported that when shutting down mysqld (with AIO support,
on a ext3 formatted Harddrive) leads to a negative number of dirty pages
(underrun to the counter). The negative number results in a drastic reduction
of the write performance because the page cache is not used, because the kernel
thinks it is still 2 ^ 32 dirty pages open.

Add a warn trace in __dec_zone_state will catch this easily:

static inline void __dec_zone_state(struct zone *zone, enum
	zone_stat_item item)
{
     atomic_long_dec(&zone->vm_stat[item]);
+    WARN_ON_ONCE(item == NR_FILE_DIRTY &&
	atomic_long_read(&zone->vm_stat[item]) < 0);
     atomic_long_dec(&vm_stat[item]);
}

[   21.341632] ------------[ cut here ]------------
[   21.346294] WARNING: CPU: 0 PID: 309 at include/linux/vmstat.h:242
cancel_dirty_page+0x164/0x224()
[   21.355296] Modules linked in: wutbox_cp sata_mv
[   21.359968] CPU: 0 PID: 309 Comm: kworker/0:1 Not tainted 3.14.21-WuT #80
[   21.366793] Workqueue: events free_ioctx
[   21.370760] [<c0016a64>] (unwind_backtrace) from [<c0012f88>]
(show_stack+0x20/0x24)
[   21.378562] [<c0012f88>] (show_stack) from [<c03f8ccc>]
(dump_stack+0x24/0x28)
[   21.385840] [<c03f8ccc>] (dump_stack) from [<c0023ae4>]
(warn_slowpath_common+0x84/0x9c)
[   21.393976] [<c0023ae4>] (warn_slowpath_common) from [<c0023bb8>]
(warn_slowpath_null+0x2c/0x34)
[   21.402800] [<c0023bb8>] (warn_slowpath_null) from [<c00c0688>]
(cancel_dirty_page+0x164/0x224)
[   21.411524] [<c00c0688>] (cancel_dirty_page) from [<c00c080c>]
(truncate_inode_page+0x8c/0x158)
[   21.420272] [<c00c080c>] (truncate_inode_page) from [<c00c0a94>]
(truncate_inode_pages_range+0x11c/0x53c)
[   21.429890] [<c00c0a94>] (truncate_inode_pages_range) from
[<c00c0f6c>] (truncate_pagecache+0x88/0xac)
[   21.439252] [<c00c0f6c>] (truncate_pagecache) from [<c00c0fec>]
(truncate_setsize+0x5c/0x74)
[   21.447731] [<c00c0fec>] (truncate_setsize) from [<c013b3a8>]
(put_aio_ring_file.isra.14+0x34/0x90)
[   21.456826] [<c013b3a8>] (put_aio_ring_file.isra.14) from
[<c013b424>] (aio_free_ring+0x20/0xcc)
[   21.465660] [<c013b424>] (aio_free_ring) from [<c013b4f4>]
(free_ioctx+0x24/0x44)
[   21.473190] [<c013b4f4>] (free_ioctx) from [<c003d8d8>]
(process_one_work+0x134/0x47c)
[   21.481132] [<c003d8d8>] (process_one_work) from [<c003e988>]
(worker_thread+0x130/0x414)
[   21.489350] [<c003e988>] (worker_thread) from [<c00448ac>]
(kthread+0xd4/0xec)
[   21.496621] [<c00448ac>] (kthread) from [<c000ec18>]
(ret_from_fork+0x14/0x20)
[   21.503884] ---[ end trace 79c4bf42c038c9a1 ]---

The cause is that we set the aio ring file pages as *DIRTY* via SetPageDirty
(bypasses the VFS dirty pages increment) when init, and aio fs uses
*default_backing_dev_info* as the backing dev, which does not disable
the dirty pages accounting capability.
So truncating aio ring file will contribute to accounting dirty pages (VFS
dirty pages decrement), then error occurs.

The original goal is keeping these pages in memory (can not be reclaimed
or swapped) in life-time via marking it dirty. But thinking more, we have
already pinned pages via elevating the page's refcount, which can already
achieve the goal, so the SetPageDirty seems unnecessary.

In order to fix the issue, using the __set_page_dirty_no_writeback instead
of the nop .set_page_dirty, and dropped the SetPageDirty (don't manually
set the dirty flags, don't disable set_page_dirty(), rely on default behaviour).

With the above change, the dirty pages accounting can work well. But as we
known, aio fs is an anonymous one, which should never cause any real write-back,
we can ignore the dirty pages (write back) accounting by disabling the dirty
pages (write back) accounting capability. So we introduce an aio private
backing dev info (disabled the ACCT_DIRTY/WRITEBACK/ACCT_WB capabilities) to
replace the default one.

Reported-by: Markus Königshaus <m.koenigshaus@wut.de>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-11-06 14:27:19 -05:00
Tejun Heo
2aad2a86f6 percpu_ref: add PERCPU_REF_INIT_* flags
With the recent addition of percpu_ref_reinit(), percpu_ref now can be
used as a persistent switch which can be turned on and off repeatedly
where turning off maps to killing the ref and waiting for it to drain;
however, there currently isn't a way to initialize a percpu_ref in its
off (killed and drained) state, which can be inconvenient for certain
persistent switch use cases.

Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic
selection of operation mode; however, currently a newly initialized
percpu_ref is always in percpu mode making it impossible to avoid the
latency overhead of switching to atomic mode.

This patch adds @flags to percpu_ref_init() and implements the
following flags.

* PERCPU_REF_INIT_ATOMIC	: start ref in atomic mode
* PERCPU_REF_INIT_DEAD		: start ref killed and drained

These flags should be able to serve the above two use cases.

v2: target_core_tpg.c conversion was missing.  Fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-09-24 13:31:50 -04:00
Tejun Heo
d06efebf0c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18
This is to receive 0a30288da1 ("blk-mq, percpu_ref: implement a
kludge for SCSI blk-mq stall during probe") which implements
__percpu_ref_kill_expedited() to work around SCSI blk-mq stall.  The
commit reverted and patches to implement proper fix will be added.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
2014-09-24 13:00:21 -04:00
Tejun Heo
a34375ef9e percpu-refcount: add @gfp to percpu_ref_init()
Percpu allocator now supports allocation mask.  Add @gfp to
percpu_ref_init() so that !GFP_KERNEL allocation masks can be used
with percpu_refs too.

This patch doesn't make any functional difference.

v2: blk-mq conversion was missing.  Updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Jens Axboe <axboe@kernel.dk>
2014-09-08 09:51:30 +09:00
Gu Zheng
6098b45b32 aio: block exit_aio() until all context requests are completed
It seems that exit_aio() also needs to wait for all iocbs to complete (like
io_destroy), but we missed the wait step in current implemention, so fix
it in the same way as we did in io_destroy.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: stable@vger.kernel.org
2014-09-04 16:54:47 -04:00
Jeff Moyer
2ff396be60 aio: add missing smp_rmb() in read_events_ring
We ran into a case on ppc64 running mariadb where io_getevents would
return zeroed out I/O events.  After adding instrumentation, it became
clear that there was some missing synchronization between reading the
tail pointer and the events themselves.  This small patch fixes the
problem in testing.

Thanks to Zach for helping to look into this, and suggesting the fix.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: stable@vger.kernel.org
2014-09-02 15:20:03 -04:00
Benjamin LaHaise
d856f32a86 aio: fix reqs_available handling
As reported by Dan Aloni, commit f8567a3845 ("aio: fix aio request
leak when events are reaped by userspace") introduces a regression when
user code attempts to perform io_submit() with more events than are
available in the ring buffer.  Reverting that commit would reintroduce a
regression when user space event reaping is used.

Fixing this bug is a bit more involved than the previous attempts to fix
this regression.  Since we do not have a single point at which we can
count events as being reaped by user space and io_getevents(), we have
to track event completion by looking at the number of events left in the
event ring.  So long as there are as many events in the ring buffer as
there have been completion events generate, we cannot call
put_reqs_available().  The code to check for this is now placed in
refill_reqs_available().

A test program from Dan and modified by me for verifying this bug is available
at http://www.kvack.org/~bcrl/20140824-aio_bug.c .

Reported-by: Dan Aloni <dan@kernelim.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Acked-by: Dan Aloni <dan@kernelim.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: stable@vger.kernel.org      # v3.16 and anything that f8567a3845 was backported to
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-24 15:47:27 -07:00
Linus Torvalds
da06df548e Merge git://git.kvack.org/~bcrl/aio-next
Pull aio updates from Ben LaHaise.

* git://git.kvack.org/~bcrl/aio-next:
  aio: use iovec array rather than the single one
  aio: fix some comments
  aio: use the macro rather than the inline magic number
  aio: remove the needless registration of ring file's private_data
  aio: remove no longer needed preempt_disable()
  aio: kill the misleading rcu read locks in ioctx_add_table() and kill_ioctx()
  aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()
2014-08-16 08:56:27 -06:00
Linus Torvalds
f2a84170ed Merge branch 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
Pull percpu updates from Tejun Heo:

 - Major reorganization of percpu header files which I think makes
   things a lot more readable and logical than before.

 - percpu-refcount is updated so that it requires explicit destruction
   and can be reinitialized if necessary.  This was pulled into the
   block tree to replace the custom percpu refcnting implemented in
   blk-mq.

 - In the process, percpu and percpu-refcount got cleaned up a bit

* 'for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (21 commits)
  percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero()
  percpu-refcount: require percpu_ref to be exited explicitly
  percpu-refcount: use unsigned long for pcpu_count pointer
  percpu-refcount: add helpers for ->percpu_count accesses
  percpu-refcount: one bit is enough for REF_STATUS
  percpu-refcount, aio: use percpu_ref_cancel_init() in ioctx_alloc()
  workqueue: stronger test in process_one_work()
  workqueue: clear POOL_DISASSOCIATED in rebind_workers()
  percpu: Use ALIGN macro instead of hand coding alignment calculation
  percpu: invoke __verify_pcpu_ptr() from the generic part of accessors and operations
  percpu: preffity percpu header files
  percpu: use raw_cpu_*() to define __this_cpu_*()
  percpu: reorder macros in percpu header files
  percpu: move {raw|this}_cpu_*() definitions to include/linux/percpu-defs.h
  percpu: move generic {raw|this}_cpu_*_N() definitions to include/asm-generic/percpu.h
  percpu: only allow sized arch overrides for {raw|this}_cpu_*() ops
  percpu: reorganize include/linux/percpu-defs.h
  percpu: move accessors from include/linux/percpu.h to percpu-defs.h
  percpu: include/asm-generic/percpu.h should contain only arch-overridable parts
  percpu: introduce arch_raw_cpu_ptr()
  ...
2014-08-04 10:09:27 -07:00
Gu Zheng
00fefb9cf2 aio: use iovec array rather than the single one
Previously, we only offer a single iovec to handle all the read/write cases, so
the PREADV/PWRITEV request always need to alloc more iovec buffer when copying
user vectors.
If we use a tmp iovec array rather than the single one, some small PREADV/PWRITEV
workloads(vector size small than the tmp buffer) will not need to alloc more
iovec buffer when copying user vectors.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-07-24 10:59:40 -04:00
Gu Zheng
2be4e7deec aio: fix some comments
The function comments of aio_run_iocb and aio_read_events are out of date, so
fix them here.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-07-24 10:59:40 -04:00
Gu Zheng
8dc4379e17 aio: use the macro rather than the inline magic number
Replace the inline magic number with the ready-made macro(AIO_RING_MAGIC),
just clean up.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-07-24 10:59:40 -04:00
Gu Zheng
b53f1f82fb aio: remove the needless registration of ring file's private_data
Remove the registration of ring file's private_data, we do not use
it.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-07-24 10:59:40 -04:00
Benjamin LaHaise
be6fb451a2 aio: remove no longer needed preempt_disable()
Based on feedback from Jens Axboe on 263782c1c9,
clean up get/put_reqs_available() to remove the no longer needed preempt_disable()
and preempt_enable() pair.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Jens Axboe <axboe@kernel.dk>
2014-07-22 09:56:56 -04:00
Benjamin LaHaise
6e830d5371 Merge ../aio-fixes 2014-07-14 13:14:27 -04:00
Benjamin LaHaise
263782c1c9 aio: protect reqs_available updates from changes in interrupt handlers
As of commit f8567a3845 it is now possible to
have put_reqs_available() called from irq context.  While put_reqs_available()
is per cpu, it did not protect itself from interrupts on the same CPU.  This
lead to aio_complete() corrupting the available io requests count when run
under a heavy O_DIRECT workloads as reported by Robert Elliott.  Fix this by
disabling irq updates around the per cpu batch updates of reqs_available.

Many thanks to Robert and folks for testing and tracking this down.

Reported-by: Robert Elliot <Elliott@hp.com>
Tested-by: Robert Elliot <Elliott@hp.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@infradead.org>
Cc: stable@vger.kenel.org
2014-07-14 13:05:26 -04:00
Tejun Heo
9a1049da9b percpu-refcount: require percpu_ref to be exited explicitly
Currently, a percpu_ref undoes percpu_ref_init() automatically by
freeing the allocated percpu area when the percpu_ref is killed.
While seemingly convenient, this has the following niggles.

* It's impossible to re-init a released reference counter without
  going through re-allocation.

* In the similar vein, it's impossible to initialize a percpu_ref
  count with static percpu variables.

* We need and have an explicit destructor anyway for failure paths -
  percpu_ref_cancel_init().

This patch removes the automatic percpu counter freeing in
percpu_ref_kill_rcu() and repurposes percpu_ref_cancel_init() into a
generic destructor now named percpu_ref_exit().  percpu_ref_destroy()
is considered but it gets confusing with percpu_ref_kill() while
"exit" clearly indicates that it's the counterpart of
percpu_ref_init().

All percpu_ref_cancel_init() users are updated to invoke
percpu_ref_exit() instead and explicit percpu_ref_exit() calls are
added to the destruction path of all percpu_ref users.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Li Zefan <lizefan@huawei.com>
2014-06-28 08:10:14 -04:00
Tejun Heo
55c6c814ae percpu-refcount, aio: use percpu_ref_cancel_init() in ioctx_alloc()
ioctx_alloc() reaches inside percpu_ref and directly frees
->pcpu_count in its failure path, which is quite gross.  percpu_ref
has been providing a proper interface to do this,
percpu_ref_cancel_init(), for quite some time now.  Let's use that
instead.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Kent Overstreet <kmo@daterainc.com>
2014-06-28 08:10:12 -04:00
Oleg Nesterov
855ef0dec7 aio: kill the misleading rcu read locks in ioctx_add_table() and kill_ioctx()
ioctx_add_table() is the writer, it does not need rcu_read_lock() to
protect ->ioctx_table. It relies on mm->ioctx_lock and rcu locks just
add the confusion.

And it doesn't need rcu_dereference() by the same reason, it must see
any updates previously done under the same ->ioctx_lock. We could use
rcu_dereference_protected() but the patch uses rcu_dereference_raw(),
the function is simple enough.

The same for kill_ioctx(), although it does not update the pointer.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-06-24 18:10:25 -04:00
Oleg Nesterov
4b70ac5fd9 aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()
On 04/30, Benjamin LaHaise wrote:
>
> > -		ctx->mmap_size = 0;
> > -
> > -		kill_ioctx(mm, ctx, NULL);
> > +		if (ctx) {
> > +			ctx->mmap_size = 0;
> > +			kill_ioctx(mm, ctx, NULL);
> > +		}
>
> Rather than indenting and moving the two lines changing mmap_size and the
> kill_ioctx() call, why not just do "if (!ctx) ... continue;"?  That reduces
> the number of lines changed and avoid excessive indentation.

OK. To me the code looks better/simpler with "if (ctx)", but this is subjective
of course, I won't argue.

The patch still removes the empty line between mmap_size = 0 and kill_ioctx(),
we reset mmap_size only for kill_ioctx(). But feel free to remove this change.

-------------------------------------------------------------------------------
Subject: [PATCH v3 1/2] aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()

1. We can read ->ioctx_table only once and we do not read rcu_read_lock()
   or even rcu_dereference().

   This mm has no users, nobody else can play with ->ioctx_table. Otherwise
   the code is buggy anyway, if we need rcu_read_lock() in a loop because
   ->ioctx_table can be updated then kfree(table) is obviously wrong.

2. Update the comment. "exit_mmap(mm) is coming" is the good reason to avoid
   munmap(), but another reason is that we simply can't do vm_munmap() unless
   current->mm == mm and this is not true in general, the caller is mmput().

3. We do not really need to nullify mm->ioctx_table before return, probably
   the current code does this to catch the potential problems. But in this
   case RCU_INIT_POINTER(NULL) looks better.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
2014-06-24 18:10:24 -04:00
Benjamin LaHaise
edfbbf388f aio: fix kernel memory disclosure in io_getevents() introduced in v3.10
A kernel memory disclosure was introduced in aio_read_events_ring() in v3.10
by commit a31ad380be.  The changes made to
aio_read_events_ring() failed to correctly limit the index into
ctx->ring_pages[], allowing an attacked to cause the subsequent kmap() of
an arbitrary page with a copy_to_user() to copy the contents into userspace.
This vulnerability has been assigned CVE-2014-0206.  Thanks to Mateusz and
Petr for disclosing this issue.

This patch applies to v3.12+.  A separate backport is needed for 3.10/3.11.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: stable@vger.kernel.org
2014-06-24 13:46:01 -04:00
Benjamin LaHaise
f8567a3845 aio: fix aio request leak when events are reaped by userspace
The aio cleanups and optimizations by kmo that were merged into the 3.10
tree added a regression for userspace event reaping.  Specifically, the
reference counts are not decremented if the event is reaped in userspace,
leading to the application being unable to submit further aio requests.
This patch applies to 3.12+.  A separate backport is required for 3.10/3.11.
This issue was uncovered as part of CVE-2014-0206.

Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: stable@vger.kernel.org
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>
2014-06-24 13:32:27 -04:00