dm: suppress endian warnings

Suppress sparse warnings about cpu_to_le32() by using __le32 types for
on-disk data etc.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 283a8328ca5b987e547848de8ff0e28edcfb9e08)

Change-Id: If4a9779681e327bd36e3600f87d0217981ce86e4
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm table: fix discard support

Remove 'discards_supported' from the dm_table structure.  The same
information can be easily discovered from the table's target(s) in
dm_table_supports_discards().

Before this fix dm_table_supports_discards() would skip checking the
individual targets' 'discards_supported' flag if any one target in the
table didn't set num_discard_requests > 0.  Now the per-target
'discards_supported' flag is effective at insuring the final DM device
advertises discard support.  But, to be clear, targets that don't
support discards (!num_discard_requests) will not receive discard
requests.

Also DMWARN if a target sets 'discards_supported' override but forgets
to set 'num_discard_requests'.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 936688d7eb0f39be96c5791be1a04994cc8d6aa0)

Change-Id: If3b15303e8c3e5b6ce1065970601d9bef982f518
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm: use vzalloc

Use vzalloc() instead of vmalloc()+memset().

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit e29e65aacbd9e628378084905cbcf62a9fa4a8cc)

Change-Id: I4701888bb6b595e403db1f99f44989d188363c29
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm table: clean dm_get_device and move exports

There is no need for __table_get_device to be factored out.
Also move the exports to the end of their respective functions.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 08649012545cfb116798260352547cf4d47064ec)

Change-Id: Ie82e8fa1daa1467d2eba7f0735f4554990ec2b34
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm: ignore merge_bvec for snapshots when safe

Add a new flag DMF_MERGE_IS_OPTIONAL to struct mapped_device to indicate
whether the device can accept bios larger than the size its merge
function returns.  When set, use this to send large bios to snapshots
which can split them if necessary.  Snapshot I/O may be significantly
fragmented and this approach seems to improve peformance.

Before the patch, dm_set_device_limits restricted bio size to page size
if the underlying device had a merge function and the target didn't
provide a merge function.  After the patch, dm_set_device_limits
restricts bio size to page size if the underlying device has a merge
function, doesn't have DMF_MERGE_IS_OPTIONAL flag and the target doesn't
provide a merge function.

The snapshot target can't provide a merge function because when the merge
function is called, it is impossible to determine where the bio will be
remapped.  Previously this led us to impose a 4k limit, which we can
now remove if the snapshot store is located on a device without a merge
function.  Together with another patch for optimizing full chunk writes,
it improves performance from 29MB/s to 40MB/s when writing to the
filesystem on snapshot store.

If the snapshot store is placed on a non-dm device with a merge function
(such as md-raid), device mapper still limits all bios to page size.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit d5b9dd04bd74b774b8e8d93ced7a0d15ad403fa9)

Change-Id: Ifa3b8f8e46f33b98c15631a47b1cf8942e0322dd
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm table: share target argument parsing functions

Move multipath target argument parsing code into dm-table so other
targets can share it.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 498f0103ea13123e007660def9072a0b7dd1c599)

Change-Id: I12e77d6f9dc51759b8edf98e6562d65fff5f2c58
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm crypt: optionally support discard requests

Add optional parameter field to dmcrypt table and support
"allow_discards" option.

Discard requests bypass crypt queue processing. Bio is simple remapped
to underlying device.

Note that discard will be never enabled by default because of security
consequences.  It is up to the administrator to enable it for encrypted
devices.

(Note that userspace cryptsetup does not understand new optional
parameters yet.  Support for this will come later.  Until then, you
should use 'dmsetup' to enable and disable this.)

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 772ae5f54d69c38a5e3c4352c5fdbdaff141af21)

Change-Id: I63e082513184a201066dff9d55be9308e08f07cd
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm table: set flush capability based on underlying devices

DM has always advertised both REQ_FLUSH and REQ_FUA flush capabilities
regardless of whether or not a given DM device's underlying devices
also advertised a need for them.

Block's flush-merge changes from 2.6.39 have proven to be more costly
for DM devices.  Performance regressions have been reported even when
DM's underlying devices do not advertise that they have a write cache.

Fix the performance regressions by configuring a DM device's flushing
capabilities based on those of the underlying devices' capabilities.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit ed8b752bccf2560e305e25125721d2f0ac759e88)

Change-Id: I46d4f2558b19f0e2f81f540905dd03899297b8f3
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
dm crypt: always disable discard_zeroes_data

If optional discard support in dm-crypt is enabled, discards requests
bypass the crypt queue and blocks of the underlying device are discarded.
For the read path, discarded blocks are handled the same as normal
ciphertext blocks, thus decrypted.

So if the underlying device announces discarded regions return zeroes,
dm-crypt must disable this flag because after decryption there is just
random noise instead of zeroes.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
(cherry picked from commit 983c7db347db8ce2d8453fd1d89b7a4bb6920d56)

Change-Id: I07563a84f0a7c46dc6b02543cda6918d68209325
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
n_tty: Fix n_tty_write crash when echoing in raw mode

The tty atomic_write_lock does not provide an exclusion guarantee for
the tty driver if the termios settings are LECHO & !OPOST.  And since
it is unexpected and not allowed to call TTY buffer helpers like
tty_insert_flip_string concurrently, this may lead to crashes when
concurrect writers call pty_write. In that case the following two
writers:
* the ECHOing from a workqueue and
* pty_write from the process
race and can overflow the corresponding TTY buffer like follows.

If we look into tty_insert_flip_string_fixed_flag, there is:
  int space = __tty_buffer_request_room(port, goal, flags);
  struct tty_buffer *tb = port->buf.tail;
  ...
  memcpy(char_buf_ptr(tb, tb->used), chars, space);
  ...
  tb->used += space;

so the race of the two can result in something like this:
              A                                B
__tty_buffer_request_room
                                  __tty_buffer_request_room
memcpy(buf(tb->used), ...)
tb->used += space;
                                  memcpy(buf(tb->used), ...) ->BOOM

B's memcpy is past the tty_buffer due to the previous A's tb->used
increment.

Since the N_TTY line discipline input processing can output
concurrently with a tty write, obtain the N_TTY ldisc output_lock to
serialize echo output with normal tty writes.  This ensures the tty
buffer helper tty_insert_flip_string is not called concurrently and
everything is fine.

Note that this is nicely reproducible by an ordinary user using
forkpty and some setup around that (raw termios + ECHO). And it is
present in kernels at least after commit
d945cb9cce20ac7143c2de8d88b187f62db99bdc (pty: Rework the pty layer to
use the normal buffering logic) in 2.6.31-rc3.

js: add more info to the commit log
js: switch to bool
js: lock unconditionally
js: lock only the tty->ops->write call

References: CVE-2014-0196
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: output_lock is a member of struct tty_struct]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

Change-Id: Ifb8bf28246556efb3c42aa5d153ef7fb4ed95cbc
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>