...which will allow cifs to do an asynchronous read call to the server.
The caller will allocate and set up cifs_readdata for each READ_AND_X
call that should be issued on the wire. The pages passed in are added
to the pagecache, but not placed on the LRU list yet (as we need the
page->lru to keep the pages on the list in the readdata).

When cifsd identifies the mid, it will see that there is a special
receive handler for the call, and use that to receive the rest of the
frame. cifs_readv_receive will then marshal up a kvec array with
kmapped pages from the pagecache, which eliminates one copy of the
data. Once the data is received, the pages are added to the LRU list,
set uptodate, and unlocked.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

In order to handle larger SMBs for readpages and other calls, we want
to be able to read into a preallocated set of buffers. Rather than
changing all of the existing code to preallocate buffers however, we
instead add a receive callback function to the MID.

cifsd will call this function once the mid_q_entry has been identified
in order to receive the rest of the SMB. If the mid can't be identified
or the receive pointer is unset, then the standard 3rd phase receive
function will be called.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Move the entire 3rd phase of the receive codepath into a separate
function in preparation for the addition of a pluggable receive
function.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

In order to receive directly into a preallocated buffer, we need to ID
the mid earlier, before the bulk of the response is read. Call the mid
finding routine as soon as we're able to read the mid.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

We have several functions that need to access these pointers. Currently
that's done with a lot of double pointer passing. Instead, move them
into the TCP_Server_Info and simplify the handling.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Change find_cifs_mid to only return NULL if a mid could not be found.
If we got part of a multi-part T2 response, then coalesce it and still
return the mid. The caller can determine the T2 receive status from
the flags in the mid.

With this change, there is no need to pass a pointer to "length" as
well so just pass by value. If a mid is found, then we can just mark
it as malformed. If one isn't found, then the value of "length" won't
change anyway.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Begin breaking up find_cifs_mid into smaller pieces. The parts that
coalesce T2 responses don't really need to be done under the
GlobalMid_lock anyway. Create a new function that just finds the
mid on the list, and then later takes it off the list if the entire
response has been received.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Have the demultiplex thread receive just enough to get to the MID, and
then find it before receiving the rest. Later, we'll use this to swap
in a preallocated receive buffer for some calls.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Having to continually allocate a new kvec array is expensive. Allocate
one that's big enough, and only reallocate it as needed.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Eventually we'll want to allow cifsd to read data directly into the
pagecache. In order to do that we'll need a routine that can take a
kvec array and pass that directly to kernel_recvmsg.

Unfortunately though, the kernel's recvmsg routines modify the kvec
array that gets passed in, so we need to use a copy of the kvec array
and refresh that copy on each pass through the loop.
Reviewed-and-Tested-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NJeff Layton <jlayton@redhat.com>

Rename it for better clarity as to what it does and have the caller pass
in just the single type byte. Turn the if statement into a switch and
optimize it by placing the most common message type at the top. Move the
header length check back into cifs_demultiplex_thread in preparation
for adding a new receive phase and normalize the cFYI messages.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

..the length field has only 17 bits.

Cc: <stable@kernel.org>
Acked-by: NJeff Layton <jlayton@samba.org>
Signed-off-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NSteve French <smfrench@gmail.com>

Move the iovec handling entirely into read_from_socket. That simplifies
the code and gets rid of the special handling for header reads. With
this we can also get rid of the "goto incomplete_rcv" label in the main
demultiplex thread function since we can now treat header and non-header
receives the same way.

Also, make it return an int (since we'll never receive enough to worry
about the sign bit anyway), and simply make it return the amount of bytes
read or a negative error code.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

Add mount options backupuid and backugid.

It allows an authenticated user to access files with the intent to back them
up including their ACLs, who may not have access permission but has
"Backup files and directories user right" on them (by virtue of being part
of the built-in group Backup Operators.

When mount options backupuid is specified, cifs client restricts the
use of backup intents to the user whose effective user id is specified
along with the mount option.

When mount options backupgid is specified, cifs client restricts the
use of backup intents to the users whose effective user id belongs to the
group id specified along with the mount option.

If an authenticated user is not part of the built-in group Backup Operators
at the server, access to such files is denied, even if allowed by the client.
Signed-off-by: NShirish Pargaonkar <shirishpargaonkar@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

If the server stops sending data while in the middle of sending a
response then we still want to reconnect it if it doesn't come back.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

If msg_controllen is 0, then the socket layer should never touch these
fields. Thus, there's no need to continually reset them. Also, there's
no need to keep this field on the stack for the demultiplex thread, just
make it a local variable in read_from_socket.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

server->maxBuf is the maximum SMB size (including header) that the
server can handle. CIFSMaxBufSize is the maximum amount of data (sans
header) that the client can handle. Currently maxBuf is being capped at
CIFSMaxBufSize + the max headers size, and the two values are used
somewhat interchangeably in the code.

This makes little sense as these two values are not related at all.
Separate them and make sure the code uses the right values in the right
places.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

Microsoft has a bug with ntlmv2 that requires use of ntlmssp, but
we didn't get the required information on when/how to use ntlmssp to
old (but once very popular) legacy servers (various NT4 fixpacks
for example) until too late to merge for 3.1.  Will upgrade
to NTLMv2 in NTLMSSP in 3.2
Signed-off-by: NSteve French <smfrench@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>

Both these options are started with "rw" - that's why the first one
isn't switched on even if it is specified. Fix this by adding a length
check for "rw" option check.

Cc: <stable@kernel.org>
Signed-off-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

CIFS cleanup_volume_info_contents() looks like having a memory
corruption problem.
When UNCip is set to "&vol->UNC[2]" in cifs_parse_mount_options(), it
should not be kfree()-ed in cleanup_volume_info_contents().

Introduced in commit b946845aSigned-off-by: NJ.R. Okajima <hooanon05@yahoo.co.jp>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
CC: Stable <stable@kernel.org>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Reviewed-and-Tested-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Reviewed-and-Tested-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Reviewed-and-Tested-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Move reading to separate function and remove csocket variable.

Also change semantic in a little: goto incomplete_rcv only when
we get -EAGAIN (or a familiar error) while reading rfc1002 header.
In this case we don't check for echo timeout when we don't get whole
header at once, as it was before.
Reviewed-and-Tested-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Reviewed-and-Tested-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

...and remove some obsolete comments.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

... and get rid of a bogus typecast, while we are at it; it's not
just that we want a function returning int and not void, but cast
to pointer to function taking void * and returning void would be
(void (*)(void *)) and not (void *)(void *), TYVM...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

In 34c87901 "Shrink stack space usage in cifs_construct_tcon" we
change the size of the username name buffer from MAX_USERNAME_SIZE
(256) to 28.  This call to snprintf() needs to be updated as well.
Reported by Dan Carpenter.
Reviewed-by: NDan Carpenter <error27@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

...as that function can sleep.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Regression introduced in commit 724d9f1c.

Prior to that, expand_dfs_referral would regenerate the mount data string
and then call cifs_parse_mount_options to re-parse it (klunky, but it
worked). The above commit moved cifs_parse_mount_options out of cifs_mount,
so the re-parsing of the new mount options no longer occurred. Fix it by
making expand_dfs_referral re-parse the mount options.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

This needs to be done regardless of whether that KConfig option is set
or not.
Reported-by: NSven-Haegar Koch <haegar@sdinet.de>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

...as that makes for a cumbersome interface. Make it take a regular
smb_vol pointer and rely on the caller to zero it out if needed.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Regression introduced by commit f87d39d9.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

This call to cifs_cleanup_volume_info is clearly wrong. As soon as it's
called the following call to cifs_get_tcp_session will oops as the
volume_info pointer will then be NULL.

The caller of cifs_mount should clean up this data since it passed it
in. There's no need for us to call this here.

Regression introduced by commit 724d9f1c.
Reported-by: NAdam Williamson <awilliam@redhat.com>
Cc: Pavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

Benjamin S. reported that he was unable to suspend his machine while
it had a cifs share mounted. The freezer caused this to spew when he
tried it:

-----------------------[snip]------------------
PM: Syncing filesystems ... done.
Freezing user space processes ... (elapsed 0.01 seconds) done.
Freezing remaining freezable tasks ...
Freezing of tasks failed after 20.01 seconds (1 tasks refusing to freeze, wq_busy=0):
cifsd         S ffff880127f7b1b0     0  1821      2 0x00800000
 ffff880127f7b1b0 0000000000000046 ffff88005fe008a8 ffff8800ffffffff
 ffff880127cee6b0 0000000000011100 ffff880127737fd8 0000000000004000
 ffff880127737fd8 0000000000011100 ffff880127f7b1b0 ffff880127736010
Call Trace:
 [<ffffffff811e85dd>] ? sk_reset_timer+0xf/0x19
 [<ffffffff8122cf3f>] ? tcp_connect+0x43c/0x445
 [<ffffffff8123374e>] ? tcp_v4_connect+0x40d/0x47f
 [<ffffffff8126ce41>] ? schedule_timeout+0x21/0x1ad
 [<ffffffff8126e358>] ? _raw_spin_lock_bh+0x9/0x1f
 [<ffffffff811e81c7>] ? release_sock+0x19/0xef
 [<ffffffff8123e8be>] ? inet_stream_connect+0x14c/0x24a
 [<ffffffff8104485b>] ? autoremove_wake_function+0x0/0x2a
 [<ffffffffa02ccfe2>] ? ipv4_connect+0x39c/0x3b5 [cifs]
 [<ffffffffa02cd7b7>] ? cifs_reconnect+0x1fc/0x28a [cifs]
 [<ffffffffa02cdbdc>] ? cifs_demultiplex_thread+0x397/0xb9f [cifs]
 [<ffffffff81076afc>] ? perf_event_exit_task+0xb9/0x1bf
 [<ffffffffa02cd845>] ? cifs_demultiplex_thread+0x0/0xb9f [cifs]
 [<ffffffffa02cd845>] ? cifs_demultiplex_thread+0x0/0xb9f [cifs]
 [<ffffffff810444a1>] ? kthread+0x7a/0x82
 [<ffffffff81002d14>] ? kernel_thread_helper+0x4/0x10
 [<ffffffff81044427>] ? kthread+0x0/0x82
 [<ffffffff81002d10>] ? kernel_thread_helper+0x0/0x10

Restarting tasks ... done.
-----------------------[snip]------------------

We do attempt to perform a try_to_freeze in cifs_reconnect, but the
connection attempt itself seems to be taking longer than 20s to time
out. The connect timeout is governed by the socket send and receive
timeouts, so we can shorten that period by setting those timeouts
before attempting the connect instead of after.

Adam Williamson tested the patch and said that it seems to have fixed
suspending on his laptop when a cifs share is mounted.
Reported-by: NBenjamin S <da_joind@gmx.net>
Tested-by: NAdam Williamson <awilliam@redhat.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

all callers of cifs_umount() proceed to do the same thing; pull it into
cifs_umount() itself.
Acked-by: NPavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

a) superblock argument is unused
b) it always returns 0
Acked-by: NPavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

no need to wait until cifs_read_super() and we need it done
by the time cifs_mount() will be called.
Acked-by: NPavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>