When matching DFS superblocks we can't rely on either the server's
address or tcon's UNC name from mount(2) as the existing servers and
tcons might be connected to somewhere else.  Instead, check if
superblock is dfs, and if so, match its original source pathname with
the new mount's source pathname.

For DFS connections, instead of checking server's address, match its
referral path as it could be connected to different targets.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Introduce and export two helpers for getting session and tcon during
mount(2).  Those will be used by dfs when retrieving sessions and
tcons separately while chasing referrals.  Besides, export
cifs_mount_ctx structure as it will be used by dfs code as well.

No functional changes.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

All callers from dns_resolve_server_name_to_ip() used to convert the
ip addr string back to sockaddr, so do that inside
dns_resolve_server_name_to_ip() and avoid duplicating code.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

After switching to filesystem context support, we no longer need to
handle mount options string when chasing dfs referrals.  Now, we set
the new values directly into smb3_fs_context.

Start working on a separate source file to handle most dfs related
mount functions as connect.c has already became too big.  The
remaining functions will be moved gradually in follow-up patches.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

To work around some Window servers that return
STATUS_OBJECT_NAME_INVALID on query infos under DFS namespaces that
contain non-ASCII characters, we started checking for -ENOENT on every
file open, and if so, then send additional requests to figure out
whether it is a DFS link or not.  It means that all those requests
will be sent to every non-existing file.

So, in order to reduce the number of roundtrips, check earlier whether
status code is STATUS_OBJECT_NAME_INVALID and tcon supports dfs, and
if so, then map -ENOENT to -EREMOTE so mount or automount will take
care of chasing the DFS link -- if it isn't an DFS link, then -ENOENT
will be returned appropriately.

Before patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
  SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND

After patch

  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
  SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
  SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

cifs_tcon::status wasn't correctly updated to TID_GOOD after
establishing initial IPC connection thus staying at TID_NEW as long as
it wasn't reconnected.

Cc: stable@vger.kernel.org
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

cifs_tcon::status wasn't correctly updated to TID_GOOD after initial
tree connect thus staying at TID_NEW as long as it was connected.

Cc: stable@vger.kernel.org
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

If the tlink setup failed, lost to put the connections, then
the module refcnt leak since the cifsd kthread not exit.

Also leak the fscache info, and for next mount with fsc, it will
print the follow errors:
  CIFS: Cache volume key already in use (cifs,127.0.0.1:445,TEST)

Let's check the result of tlink setup, and do some cleanup.

Fixes: 56c762eb ("cifs: Refactor out cifs_mount()")
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NZhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

`hostname` needs to be set as null-pointer after free in
`cifs_put_tcp_session` function, or when `cifsd` thread attempts
to resolve hostname and reconnect the host, the thread would deref
the invalid pointer.

Here is one of practical backtrace examples as reference:

Task 477
---------------------------
 do_mount
  path_mount
   do_new_mount
    vfs_get_tree
     smb3_get_tree
      smb3_get_tree_common
       cifs_smb3_do_mount
        cifs_mount
         mount_put_conns
          cifs_put_tcp_session
          --> kfree(server->hostname)

cifsd
---------------------------
 kthread
  cifs_demultiplex_thread
   cifs_reconnect
    reconn_set_ipaddr_from_hostname
    --> if (!server->hostname)
    --> if (server->hostname[0] == '\0')  // !! UAF fault here

CIFS: VFS: cifs_mount failed w/return code = -112
mount error(112): Host is down
BUG: KASAN: use-after-free in reconn_set_ipaddr_from_hostname+0x2ba/0x310
Read of size 1 at addr ffff888108f35380 by task cifsd/480
CPU: 2 PID: 480 Comm: cifsd Not tainted 6.1.0-rc2-00106-gf705792f89dd-dirty #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x68/0x85
 print_report+0x16c/0x4a3
 kasan_report+0x95/0x190
 reconn_set_ipaddr_from_hostname+0x2ba/0x310
 __cifs_reconnect.part.0+0x241/0x800
 cifs_reconnect+0x65f/0xb60
 cifs_demultiplex_thread+0x1570/0x2570
 kthread+0x2c5/0x380
 ret_from_fork+0x22/0x30
 </TASK>
Allocated by task 477:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 __kasan_kmalloc+0x7e/0x90
 __kmalloc_node_track_caller+0x52/0x1b0
 kstrdup+0x3b/0x70
 cifs_get_tcp_session+0xbc/0x19b0
 mount_get_conns+0xa9/0x10c0
 cifs_mount+0xdf/0x1970
 cifs_smb3_do_mount+0x295/0x1660
 smb3_get_tree+0x352/0x5e0
 vfs_get_tree+0x8e/0x2e0
 path_mount+0xf8c/0x1990
 do_mount+0xee/0x110
 __x64_sys_mount+0x14b/0x1f0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Freed by task 477:
 kasan_save_stack+0x1e/0x40
 kasan_set_track+0x21/0x30
 kasan_save_free_info+0x2a/0x50
 __kasan_slab_free+0x10a/0x190
 __kmem_cache_free+0xca/0x3f0
 cifs_put_tcp_session+0x30c/0x450
 cifs_mount+0xf95/0x1970
 cifs_smb3_do_mount+0x295/0x1660
 smb3_get_tree+0x352/0x5e0
 vfs_get_tree+0x8e/0x2e0
 path_mount+0xf8c/0x1990
 do_mount+0xee/0x110
 __x64_sys_mount+0x14b/0x1f0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
The buggy address belongs to the object at ffff888108f35380
 which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
 16-byte region [ffff888108f35380, ffff888108f35390)
The buggy address belongs to the physical page:
page:00000000333f8e58 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888108f350e0 pfn:0x108f35
flags: 0x200000000000200(slab|node=0|zone=2)
raw: 0200000000000200 0000000000000000 dead000000000122 ffff8881000423c0
raw: ffff888108f350e0 000000008080007a 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
 ffff888108f35280: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
 ffff888108f35300: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
>ffff888108f35380: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
                   ^
 ffff888108f35400: fa fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888108f35480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

Fixes: 7be3248f ("cifs: To match file servers, make sure the server hostname matches")
Signed-off-by: NZeng Heng <zengheng4@huawei.com>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Improve code readability by using existing macros:

Replace hardcoded alignment computations (e.g. (len + 7) & ~0x7) by
ALIGN()/IS_ALIGNED() macros.

Also replace (DIV_ROUND_UP(len, 8) * 8) with ALIGN(len, 8), which, if
not optimized by the compiler, has the overhead of a multiplication
and a division. Do the same for roundup() by replacing it by round_up()
(division-less version, but requires the multiple to be a power of 2,
which is always the case for us).

And remove some unnecessary checks where !IS_ALIGNED() would fit, but
calling round_up() directly is fine as it's a no-op if the value is
already aligned.
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

BZ: 215375

Fixes: 76a3c92e ("cifs: remove support for NTLM and weaker authentication algorithms")
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Replace kfree with kfree_sensitive, or prepend memzero_explicit() in
other cases, when freeing sensitive material that could still be left
in memory.
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Reported-by: Nkernel test robot <oliver.sang@intel.com>
Link: https://lore.kernel.org/r/202209201529.ec633796-oliver.sang@intel.comReviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Some servers can return an empty network interface list so, unless
multichannel is requested, no need to log an error for this, and
when multichannel is requested on mount but no interfaces, log
something less confusing.  For this case change
   parse_server_interfaces: malformed interface info
to
   empty network interface list returned by server localhost

Also do not relog this error every ten minutes (only log on mount, once)

Cc: <stable@vger.kernel.org>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Needed this for debugging a failing xfstest.
Also change camel case for "treeName" to "tree_name" in tcon struct.

Example trace output (from "trace-cmd record -e smb3_tdis*"):
          umount-9718    [006] .....  5909.780244: smb3_tdis_enter: xid=206 sid=0xcf38894e tid=0x3d0b8cf8 path=\\localhost\test
          umount-9718    [007] .....  5909.780878: smb3_tdis_done: xid=206 sid=0xcf38894e tid=0x3d0b8cf8
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Add missing spinlock to protect updates on tcon refcount in
cifs_put_tcon().

Fixes: d7d7a66a ("cifs: avoid use of global locks for high contention data")
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

So far we were just lucky because the uninitialized members
of struct msghdr are not used by default on a SOCK_STREAM tcp
socket.

But as new things like msg_ubuf and sg_from_iter where added
recently, we should play on the safe side and avoid potention
problems in future.
Signed-off-by: NStefan Metzmacher <metze@samba.org>
Cc: stable@vger.kernel.org
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

SMB1 server's header_preamble_size is not 0, add use is_smb1 function
to simplify the code, no actual functional changes.
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NZhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

It's better to use MID_HEADER_SIZE because the unfolded expression
too long. No actual functional changes, minor readability improvement.
Signed-off-by: NZhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

It's better to use HEADER_PREAMBLE_SIZE because the unfolded expression
too long. No actual functional changes, minor readability improvement.
Signed-off-by: NZhang Xiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/Signed-off-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Deferred close can be a very useful feature for allowing
caching data for read, and for minimizing the number of
reopens needed for a file that is repeatedly opened and
close but there are workloads where its default (1 second,
similar to actimeo/acregmax) is much too small.

Allow the user to configure the amount of time we can
defer sending the final smb3 close when we have a
handle lease on the file (rather than forcing it to depend
on value of actimeo which is often unrelated, and less safe).

Adds new mount parameter "closetimeo=" which is the maximum
number of seconds we can wait before sending an SMB3
close when we have a handle lease for it.  Default value
also is set to slightly larger at 5 seconds (although some
other clients use larger default this should still help).
Suggested-by: NBharath SM <bharathsm@microsoft.com>
Reviewed-by: NBharath SM <bharathsm@microsoft.com>
Reviewed-by: NShyam Prasad N <sprasad@microsoft.com>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

DeleteMidQEntry() was just a proxy for cifs_mid_q_entry_release().

- remove DeleteMidQEntry()
- rename cifs_mid_q_entry_release() to release_mid()
- rename kref_put() callback _cifs_mid_q_entry_release to __release_mid
- rename AllocMidQEntry() to alloc_mid()
- rename cifs_delete_mid() to delete_mid()

Update callers to use new names.
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Currently much of the smb1 code is built even when
CONFIG_CIFS_ALLOW_INSECURE_LEGACY is disabled.

Move cifssmb.c to only be compiled when insecure legacy is disabled,
and move various SMB1/CIFS helper functions to that ifdef.  Some
functions that were not SMB1/CIFS specific needed to be moved out of
cifssmb.c

This shrinks cifs.ko by more than 10% which is good - but also will
help with the eventual movement of the legacy code to a distinct
module.  Follow on patches can shrink the number of ifdefs by
code restructuring where smb1 code is wedged in functions that
should be calling dialect specific helper functions instead,
and also by moving some functions from file.c/dir.c/inode.c into
smb1 specific c files.
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

It should unlock 'tcon->tc_lock' before return from cifs_tree_connect().

Fixes: fe67bd563ec2 ("cifs: avoid use of global locks for high contention data")
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

During analysis of multichannel perf, it was seen that
the global locks cifs_tcp_ses_lock and GlobalMid_Lock, which
were shared between various data structures were causing a
lot of contention points.

With this change, we're breaking down the use of these locks
by introducing new locks at more granular levels. i.e.
server->srv_lock, ses->ses_lock and tcon->tc_lock to protect
the unprotected fields of server, session and tcon structs;
and server->mid_lock to protect mid related lists and entries
at server level.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Replace list_for_each() by list_for_each_entr() where appropriate.
Remove no longer used list_head stack variables.
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NSteve French <stfrench@microsoft.com>

If the command is SMB2_IOCTL, OutputLength and OutputContext are
optional and can be zero, so return early and skip calculated length
check.

Move the mismatched length message to the end of the check, to avoid
unnecessary logs when the check was not a real miscalculation.

Also change the pr_warn_once() to a pr_warn() so we're sure to get a
log for the real mismatches.
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Remove warnings for five global variables. For example:
  fs/cifs/cifsglob.h:1984:24: warning: symbol 'midCount' was not declared. Should it be static?

Also change them from camelCase (e.g. "midCount" to "mid_count")
Reviewed-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

remove unnecessary void* type castings.
Signed-off-by: NYu Zhe <yuzhe@nfschina.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

In cifs_put_smb_ses, when we're freeing the last ref count to
the session, we need to free up each channel. At this point,
it is unnecessary to take chan_lock, since we have the last
reference to the ses.

Picking up this lock also introduced a deadlock because it calls
cifs_put_tcp_ses, which locks cifs_tcp_ses_lock.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Acked-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NSteve French <stfrench@microsoft.com>

cifs_ses::ip_addr wasn't being updated in cifs_session_setup() when
reconnecting SMB sessions thus returning wrong value in
/proc/fs/cifs/DebugData.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Cc: stable@kernel.org
Signed-off-by: NSteve French <stfrench@microsoft.com>

We use cifs_tcp_ses_lock to protect a lot of things.
Not only does it protect the lists of connections, sessions,
tree connects, open file lists, etc., we also use it to
protect some fields in each of it's entries.

In this case, cifs_mark_ses_for_reconnect takes the
cifs_tcp_ses_lock to traverse the lists, and then calls
cifs_update_iface. However, that can end up calling
cifs_put_tcp_session, which picks up the same lock again.

Avoid this by taking a ref for the session, drop the lock,
and then call update iface.

Also, in cifs_update_iface, avoid nested locking of iface_lock
and chan_lock, as much as possible. When unavoidable, we need
to pick iface_lock first.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Currently, we only query the server for network interfaces
information at the time of mount, and never afterwards.
This can be a problem, especially for services like Azure,
where the IP address of the channel endpoints can change
over time.

With this change, we schedule a 600s polling of this info
from the server for each tree connect.

An alternative for periodic polling was to do this only at
the time of reconnect. But this could delay the reconnect
time slightly. Also, there are some challenges w.r.t how
we have cifs_reconnect implemented today.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Going forward, the plan is to periodically query the server
for it's interfaces (when multichannel is enabled).

This change allows checking for inactive interfaces during
reconnect, and reconnect to a new interface if necessary.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

A server's published interface list can change over time, and needs
to be updated. We've storing iface_list as a simple array, which
makes it difficult to manipulate an existing list.

With this change, iface_list is modified into a linked list of
interfaces, which is kept sorted by speed.

Also added a reference counter for an iface entry, so that each
channel can maintain a backpointer to the iface and drop it
easily when needed.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Currently, the secondary channels of a multichannel session
also get hostname populated based on the info in primary channel.
However, this will end up with a wrong resolution of hostname to
IP address during reconnect.

This change fixes this by not populating hostname info for all
secondary channels.

Fixes: 5112d80c ("cifs: populate server_hostname for extra channels")
Cc: stable@vger.kernel.org
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

The srv_mutex is used during writeback so cifs should ensure that
allocations done when that mutex is held are done with GFP_NOFS, to
avoid having direct reclaim ending up waiting for the same mutex and
causing a deadlock.  This is detected by lockdep with the splat below:

 ======================================================
 WARNING: possible circular locking dependency detected
 5.18.0 #70 Not tainted
 ------------------------------------------------------
 kswapd0/49 is trying to acquire lock:
 ffff8880195782e0 (&tcp_ses->srv_mutex){+.+.}-{3:3}, at: compound_send_recv

 but task is already holding lock:
 ffffffffa98e66c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #1 (fs_reclaim){+.+.}-{0:0}:
        fs_reclaim_acquire
        kmem_cache_alloc_trace
        __request_module
        crypto_alg_mod_lookup
        crypto_alloc_tfm_node
        crypto_alloc_shash
        cifs_alloc_hash
        smb311_crypto_shash_allocate
        smb311_update_preauth_hash
        compound_send_recv
        cifs_send_recv
        SMB2_negotiate
        smb2_negotiate
        cifs_negotiate_protocol
        cifs_get_smb_ses
        cifs_mount
        cifs_smb3_do_mount
        smb3_get_tree
        vfs_get_tree
        path_mount
        __x64_sys_mount
        do_syscall_64
        entry_SYSCALL_64_after_hwframe

 -> #0 (&tcp_ses->srv_mutex){+.+.}-{3:3}:
        __lock_acquire
        lock_acquire
        __mutex_lock
        mutex_lock_nested
        compound_send_recv
        cifs_send_recv
        SMB2_write
        smb2_sync_write
        cifs_write
        cifs_writepage_locked
        cifs_writepage
        shrink_page_list
        shrink_lruvec
        shrink_node
        balance_pgdat
        kswapd
        kthread
        ret_from_fork

 other info that might help us debug this:

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(fs_reclaim);
                                lock(&tcp_ses->srv_mutex);
                                lock(fs_reclaim);
   lock(&tcp_ses->srv_mutex);

  *** DEADLOCK ***

 1 lock held by kswapd0/49:
  #0: ffffffffa98e66c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat

 stack backtrace:
 CPU: 2 PID: 49 Comm: kswapd0 Not tainted 5.18.0 #70
 Call Trace:
  <TASK>
  dump_stack_lvl
  dump_stack
  print_circular_bug.cold
  check_noncircular
  __lock_acquire
  lock_acquire
  __mutex_lock
  mutex_lock_nested
  compound_send_recv
  cifs_send_recv
  SMB2_write
  smb2_sync_write
  cifs_write
  cifs_writepage_locked
  cifs_writepage
  shrink_page_list
  shrink_lruvec
  shrink_node
  balance_pgdat
  kswapd
  kthread
  ret_from_fork
  </TASK>

Fix this by using the memalloc_nofs_save/restore APIs around the places
where the srv_mutex is held.  Do this in a wrapper function for the
lock/unlock of the srv_mutex, and rename the srv_mutex to avoid missing
call sites in the conversion.

Note that there is another lockdep warning involving internal crypto
locks, which was masked by this problem and is visible after this fix,
see the discussion in this thread:

 https://lore.kernel.org/all/20220523123755.GA13668@axis.com/

Link: https://lore.kernel.org/r/CANT5p=rqcYfYMVHirqvdnnca4Mo+JQSw5Qu12v=kPfpk5yhhmg@mail.gmail.com/Reported-by: NShyam Prasad N <nspmangalore@gmail.com>
Suggested-by: NLars Persson <larper@axis.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NVincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Similar message is printed a few lines later in the same function
Signed-off-by: NEnzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Some older servers seem to require the workstation name during ntlmssp
to be at most 15 chars (RFC1001 name length), so truncate it before
sending when using insecure dialects.

Link: https://lore.kernel.org/r/e6837098-15d9-acb6-7e34-1923cf8c6fe1@winds.orgReported-by: NByron Stanoszek <gandalf@winds.org>
Tested-by: NByron Stanoszek <gandalf@winds.org>
Fixes: 49bd49f9 ("cifs: send workstation name during ntlmssp session setup")
Cc: stable@vger.kernel.org
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>