Use pr_fmt to standardize all logging for fs/cifs.

Some logging output had no CIFS: specific prefix.

Now all output has one of three prefixes:

o CIFS:
o CIFS: VFS:
o Root-CIFS:

Miscellanea:

o Convert printks to pr_<level>
o Neaten macro definitions
o Remove embedded CIFS: prefixes from formats
o Convert "illegal" to "invalid"
o Coalesce formats
o Add missing '\n' format terminations
o Consolidate multiple cifs_dbg continuations into single calls
o More consistent use of upper case first word output logging
o Multiline statement argument alignment and wrapping
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

In order to handle workloads where it is important to make sure that
a buggy app did not delete content on the drive, the new mount option
"nodelete" allows standard permission checks on the server to work,
but prevents on the client any attempts to unlink a file or delete
a directory on that mount point.  This can be helpful when running
a little understood app on a network mount that contains important
content that should not be deleted.
Signed-off-by: NSteve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>

The target iterator parameter "it" is not used in
reconn_setup_dfs_targets(), so just remove it.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

In order to support reconnect to hostnames that resolve to same ip
address, besides relying on the currently set hostname to match DFS
targets, attempt to resolve the targets and then match their addresses
with the reconnected server ip address.

For instance, if we have two hostnames "FOO" and "BAR", and both
resolve to the same ip address, we would be able to handle failover in
DFS paths like

    \\FOO\dfs\link1 -> [ \BAZ\share2 (*), \BAR\share1 ]
    \\FOO\dfs\link2 -> [ \BAZ\share2 (*), \FOO\share1 ]

so when "BAZ" is no longer accessible, link1 and link2 would get
reconnected despite having different target hostnames.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

If we mount a very specific DFS link

    \\FS0.FOO.COM\dfs\link -> \FS0\share1, \FS1\share2

where its target list contains NB names ("FS0" & "FS1") rather than
FQDN ones ("FS0.FOO.COM" & "FS1.FOO.COM"), we end up connecting to
\FOO\share1 but server->hostname will have "FOO.COM".  The reason is
because both "FS0" and "FS0.FOO.COM" resolve to same IP address and
they share same TCP server connection, but "FS0.FOO.COM" was the first
hostname set -- which is OK.

However, if the echo thread timeouts and we still have a good
connection to "FS0", in cifs_reconnect()

    rc = generic_ip_connect(server) -> success
    if (rc) {
            ...
            reconn_inval_dfs_target(server, cifs_sb, &tgt_list,
	                            &tgt_it);
            ...
     }
     ...

it successfully reconnects to "FS0" server but does not set up next
DFS target - which should be the same target server "\FS0\share1" -
and server->hostname remains set to "FS0.FOO.COM" rather than "FS0",
as reconn_inval_dfs_target() would have it set to "FS0" if called
earlier.

Finally, in __smb2_reconnect(), the reconnect of tcons would fail
because tcon->ses->server->hostname (FS0.FOO.COM) does not match DFS
target's hostname (FS0).

Fix that by calling reconn_inval_dfs_target() before
generic_ip_connect() so server->hostname will get updated correctly
prior to reconnecting its tcons in __smb2_reconnect().

With "cifs: handle hostnames that resolve to same ip in failover"
patch

    - The above problem would not occur.
    - We could save an DNS query to find out that they both resolve to
      the same ip address.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

The "nolease" mount option is only supported for SMB2+ mounts.
Fail with appropriate error message if vers=1.0 option is passed.
Signed-off-by: NKenneth D'souza <kdsouza@redhat.com>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

This disables tcon re-use for DFS shares.

tcon->dfs_path stores the path that the tcon should connect to when
doing failing over.

If that tcon is used multiple times e.g. 2 mounts using it with
different prefixpath, each will need a different dfs_path but there is
only one tcon. The other solution would be to split the tcon in 2
tcons during failover but that is much harder.

tcons could not be shared with DFS in cifs.ko because in a
DFS namespace like:

          //domain/dfsroot -> /serverA/dfsroot, /serverB/dfsroot

          //serverA/dfsroot/link -> /serverA/target1/aa/bb

          //serverA/dfsroot/link2 -> /serverA/target1/cc/dd

you can see that link and link2 are two DFS links that both resolve to
the same target share (/serverA/target1), so cifs.ko will only contain a
single tcon for both link and link2.

The problem with that is, if we (auto)mount "link" and "link2", cifs.ko
will only contain a single tcon for both DFS links so we couldn't
perform failover or refresh the DFS cache for both links because
tcon->dfs_path was set to either "link" or "link2", but not both --
which is wrong.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

We use a spinlock while we are reading and accessing the destination address for a server.
We need to also use this spinlock to protect when we are modifying this address from
reconn_set_ipaddr().
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NJeff Layton <jlayton@kernel.org>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Leaving PF_MEMALLOC set when exiting a kthread causes it to remain set
during do_exit().  That can confuse things.  For example, if BSD process
accounting is enabled and the accounting file has FS_SYNC_FL set and is
located on an ext4 filesystem without a journal, then do_exit() can end
up calling ext4_write_inode().  That triggers the
WARN_ON_ONCE(current->flags & PF_MEMALLOC) there, as it assumes
(appropriately) that inodes aren't written when allocating memory.

This was originally reported for another kernel thread, xfsaild() [1].
cifs_demultiplex_thread() also exits with PF_MEMALLOC set, so it's
potentially subject to this same class of issue -- though I haven't been
able to reproduce the WARN_ON_ONCE() via CIFS, since unlike xfsaild(),
cifs_demultiplex_thread() is sent SIGKILL before exiting, and that
interrupts the write to the BSD process accounting file.

Either way, leaving PF_MEMALLOC set is potentially problematic.  Let's
clean this up by properly saving and restoring PF_MEMALLOC.

[1] https://lore.kernel.org/r/0000000000000e7156059f751d7b@google.comSigned-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

The warning we print on mount about how to use less secure dialects
(when the user does not specify a version on mount) is useful
but is noisy to print on every default mount, and can be changed
to a warn_once.  Slightly updated the warning text as well to note
SMB3.1.1 which has been the default which is typically negotiated
(for a few years now) by most servers.

      "No dialect specified on mount. Default has changed to a more
       secure dialect, SMB2.1 or later (e.g. SMB3.1.1), from CIFS
       (SMB1). To use the less secure SMB1 dialect to access old
       servers which do not support SMB3.1.1 (or even SMB3 or SMB2.1)
       specify vers=1.0 on mount."
Signed-off-by: NSteve French <stfrench@microsoft.com>
Acked-by: NRonnie Sahlberg <lsahlber@redhat.com>

We really, really don't want people using insecure dialects
unless they realize what they are doing ...

Add mount warning if mounting with vers=1.0 (older SMB1/CIFS
dialect) instead of the default (SMB2.1 or later, typically
SMB3.1.1).
Signed-off-by: NSteve French <stfrench@microsoft.com>
Acked-by: NRonnie Sahlberg <lsahlber@redhat.com>
Acked-by: NPavel Shilovsky <pshilov@microsoft.com>

This means it's consistently called and the callers don't need to
care about it.
Signed-off-by: NStefan Metzmacher <metze@samba.org>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

For the case where we have a DFS path like below and we're currently
connected to targetA:

    //dfsroot/link -> //targetA/share/foo, //targetB/share/bar

after failover, we should make sure to update cifs_sb->prepath so the
next operations will use the new prefix path "/bar".

Besides, in order to simplify the use of different prefix paths,
enforce CIFS_MOUNT_USE_PREFIX_PATH for DFS mounts so we don't have to
revalidate the root dentry every time we set a new prefix path.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

A number of the debug statements output file or directory mode
in hex.  Change these to print using octal.
Signed-off-by: NFrank Sorenson <sorenson@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

When "backup intent" is requested on the mount (e.g. backupuid or
backupgid mount options), the corresponding flag was missing from
some of the operations.

Change all operations to use the macro cifs_create_options() to
set the backup intent flag if needed.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

RHBZ: 1760879

Fix an oops in match_prepath() by making sure that the prepath string is not
NULL before we pass it into strcmp().

This is similar to other checks we make for example in cifs_root_iget()
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

With the addition of SMB session channels, we introduced new TCP
server pointers that have no sessions or tcons associated with them.

In this case, when we started looking for TCP connections, we might
end up picking session channel rather than the master connection,
hence failing to get either a session or a tcon.

In order to fix that, this patch introduces a new "is_channel" field
to TCP_Server_Info structure so we can skip session channels during
lookup of connections.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Make sure that DFS referrals are sent to newly resolved root targets
as in a multi tier DFS setup.
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Link: https://lkml.kernel.org/r/05aa2995-e85e-0ff4-d003-5bb08bd17a22@canonical.com
Cc: stable@vger.kernel.org
Tested-by: NMatthew Ruffell <matthew.ruffell@canonical.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Ensure we grab an active reference in cifs superblock while doing
failover to prevent automounts (DFS links) of expiring and then
destroying the superblock pointer.

This patch fixes the following KASAN report:

[  464.301462] BUG: KASAN: use-after-free in
cifs_reconnect+0x6ab/0x1350
[  464.303052] Read of size 8 at addr ffff888155e580d0 by task
cifsd/1107

[  464.304682] CPU: 3 PID: 1107 Comm: cifsd Not tainted 5.4.0-rc4+ #13
[  464.305552] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
BIOS rel-1.12.1-0-ga5cab58-rebuilt.opensuse.org 04/01/2014
[  464.307146] Call Trace:
[  464.307875]  dump_stack+0x5b/0x90
[  464.308631]  print_address_description.constprop.0+0x16/0x200
[  464.309478]  ? cifs_reconnect+0x6ab/0x1350
[  464.310253]  ? cifs_reconnect+0x6ab/0x1350
[  464.311040]  __kasan_report.cold+0x1a/0x41
[  464.311811]  ? cifs_reconnect+0x6ab/0x1350
[  464.312563]  kasan_report+0xe/0x20
[  464.313300]  cifs_reconnect+0x6ab/0x1350
[  464.314062]  ? extract_hostname.part.0+0x90/0x90
[  464.314829]  ? printk+0xad/0xde
[  464.315525]  ? _raw_spin_lock+0x7c/0xd0
[  464.316252]  ? _raw_read_lock_irq+0x40/0x40
[  464.316961]  ? ___ratelimit+0xed/0x182
[  464.317655]  cifs_readv_from_socket+0x289/0x3b0
[  464.318386]  cifs_read_from_socket+0x98/0xd0
[  464.319078]  ? cifs_readv_from_socket+0x3b0/0x3b0
[  464.319782]  ? try_to_wake_up+0x43c/0xa90
[  464.320463]  ? cifs_small_buf_get+0x4b/0x60
[  464.321173]  ? allocate_buffers+0x98/0x1a0
[  464.321856]  cifs_demultiplex_thread+0x218/0x14a0
[  464.322558]  ? cifs_handle_standard+0x270/0x270
[  464.323237]  ? __switch_to_asm+0x40/0x70
[  464.323893]  ? __switch_to_asm+0x34/0x70
[  464.324554]  ? __switch_to_asm+0x40/0x70
[  464.325226]  ? __switch_to_asm+0x40/0x70
[  464.325863]  ? __switch_to_asm+0x34/0x70
[  464.326505]  ? __switch_to_asm+0x40/0x70
[  464.327161]  ? __switch_to_asm+0x34/0x70
[  464.327784]  ? finish_task_switch+0xa1/0x330
[  464.328414]  ? __switch_to+0x363/0x640
[  464.329044]  ? __schedule+0x575/0xaf0
[  464.329655]  ? _raw_spin_lock_irqsave+0x82/0xe0
[  464.330301]  kthread+0x1a3/0x1f0
[  464.330884]  ? cifs_handle_standard+0x270/0x270
[  464.331624]  ? kthread_create_on_node+0xd0/0xd0
[  464.332347]  ret_from_fork+0x35/0x40

[  464.333577] Allocated by task 1110:
[  464.334381]  save_stack+0x1b/0x80
[  464.335123]  __kasan_kmalloc.constprop.0+0xc2/0xd0
[  464.335848]  cifs_smb3_do_mount+0xd4/0xb00
[  464.336619]  legacy_get_tree+0x6b/0xa0
[  464.337235]  vfs_get_tree+0x41/0x110
[  464.337975]  fc_mount+0xa/0x40
[  464.338557]  vfs_kern_mount.part.0+0x6c/0x80
[  464.339227]  cifs_dfs_d_automount+0x336/0xd29
[  464.339846]  follow_managed+0x1b1/0x450
[  464.340449]  lookup_fast+0x231/0x4a0
[  464.341039]  path_openat+0x240/0x1fd0
[  464.341634]  do_filp_open+0x126/0x1c0
[  464.342277]  do_sys_open+0x1eb/0x2c0
[  464.342957]  do_syscall_64+0x5e/0x190
[  464.343555]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

[  464.344772] Freed by task 0:
[  464.345347]  save_stack+0x1b/0x80
[  464.345966]  __kasan_slab_free+0x12c/0x170
[  464.346576]  kfree+0xa6/0x270
[  464.347211]  rcu_core+0x39c/0xc80
[  464.347800]  __do_softirq+0x10d/0x3da

[  464.348919] The buggy address belongs to the object at
ffff888155e58000
                which belongs to the cache kmalloc-256 of size 256
[  464.350222] The buggy address is located 208 bytes inside of
                256-byte region [ffff888155e58000, ffff888155e58100)
[  464.351575] The buggy address belongs to the page:
[  464.352333] page:ffffea0005579600 refcount:1 mapcount:0
mapping:ffff88815a803400 index:0x0 compound_mapcount: 0
[  464.353583] flags: 0x200000000010200(slab|head)
[  464.354209] raw: 0200000000010200 ffffea0005576200 0000000400000004
ffff88815a803400
[  464.355353] raw: 0000000000000000 0000000080100010 00000001ffffffff
0000000000000000
[  464.356458] page dumped because: kasan: bad access detected

[  464.367005] Memory state around the buggy address:
[  464.367787]  ffff888155e57f80: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[  464.368877]  ffff888155e58000: fb fb fb fb fb fb fb fb fb fb fb fb
fb fb fb fb
[  464.369967] >ffff888155e58080: fb fb fb fb fb fb fb fb fb fb fb fb
fb fb fb fb
[  464.371111]                                                  ^
[  464.371775]  ffff888155e58100: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[  464.372893]  ffff888155e58180: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[  464.373983] ==================================================================
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

After doing mount() successfully we call cifs_try_adding_channels()
which will open as many channels as it can.

Channels are closed when the master session is closed.

The master connection becomes the first channel.

,-------------> global cifs_tcp_ses_list <-------------------------.
|                                                                  |
'- TCP_Server_Info  <-->  TCP_Server_Info  <-->  TCP_Server_Info <-'
      (master con)           (chan#1 con)         (chan#2 con)
      |      ^                    ^                    ^
      v      '--------------------|--------------------'
   cifs_ses                       |
   - chan_count = 3               |
   - chans[] ---------------------'
   - smb3signingkey[]
      (master signing key)

Note how channel connections don't have sessions. That's because
cifs_ses can only be part of one linked list (list_head are internal
to the elements).

For signing keys, each channel has its own signing key which must be
used only after the channel has been bound. While it's binding it must
use the master session signing key.

For encryption keys, since channel connections do not have sessions
attached we must now find matching session by looping over all sessions
in smb2_get_enc_key().

Each channel is opened like a regular server connection but at the
session setup request step it must set the
SMB2_SESSION_REQ_FLAG_BINDING flag and use the session id to bind to.

Finally, while sending in compound_send_recv() for requests that
aren't negprot, ses-setup or binding related, use a channel by cycling
through the available ones (round-robin).
Signed-off-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Currently a lot of the code to initialize a connection & session uses
the cifs_ses as input. But depending on if we are opening a new session
or a new channel we need to use different server pointers.

Add a "binding" flag in cifs_ses and a helper function that returns
the server ptr a session should use (only in the sess establishment
code path).
Signed-off-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

adds:
- [no]multichannel to enable/disable multichannel
- max_channels=N to control how many channels to create

these options are then stored in the volume struct.

- store channels and max_channels in cifs_ses
Signed-off-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

When an OPEN command is cancelled we mark a mid as
cancelled and let the demultiplex thread process it
by closing an open handle. The problem is there is
a race between a system call thread and the demultiplex
thread and there may be a situation when the mid has
been already processed before it is set as cancelled.

Fix this by processing cancelled requests when mids
are being destroyed which means that there is only
one thread referencing a particular mid. Also set
mids as cancelled unconditionally on their state.

Cc: Stable <stable@vger.kernel.org>
Tested-by: NFrank Sorenson <sorenson@redhat.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

There is a race between a system call processing thread
and the demultiplex thread when mid->resp_buf becomes NULL
and later is being accessed to get credits. It happens when
the 1st thread wakes up before a mid callback is called in
the 2nd one but the mid state has already been set to
MID_RESPONSE_RECEIVED. This causes NULL pointer dereference
in mid callback.

Fix this by saving credits from the response before we
update the mid state and then use this value in the mid
callback rather then accessing a response buffer.

Cc: Stable <stable@vger.kernel.org>
Fixes: ee258d79 ("CIFS: Move credit processing to mid callbacks for SMB3")
Tested-by: NFrank Sorenson <sorenson@redhat.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

When the client hits reconnect it iterates over the mid
pending queue marking entries for retry and moving them
to a temporary list to issue callbacks later without holding
GlobalMid_Lock. In the same time there is no guarantee that
mids can't be removed from the temporary list or even
freed completely by another thread. It may cause a temporary
list corruption:

[  430.454897] list_del corruption. prev->next should be ffff98d3a8f316c0, but was 2e885cb266355469
[  430.464668] ------------[ cut here ]------------
[  430.466569] kernel BUG at lib/list_debug.c:51!
[  430.468476] invalid opcode: 0000 [#1] SMP PTI
[  430.470286] CPU: 0 PID: 13267 Comm: cifsd Kdump: loaded Not tainted 5.4.0-rc3+ #19
[  430.473472] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[  430.475872] RIP: 0010:__list_del_entry_valid.cold+0x31/0x55
...
[  430.510426] Call Trace:
[  430.511500]  cifs_reconnect+0x25e/0x610 [cifs]
[  430.513350]  cifs_readv_from_socket+0x220/0x250 [cifs]
[  430.515464]  cifs_read_from_socket+0x4a/0x70 [cifs]
[  430.517452]  ? try_to_wake_up+0x212/0x650
[  430.519122]  ? cifs_small_buf_get+0x16/0x30 [cifs]
[  430.521086]  ? allocate_buffers+0x66/0x120 [cifs]
[  430.523019]  cifs_demultiplex_thread+0xdc/0xc30 [cifs]
[  430.525116]  kthread+0xfb/0x130
[  430.526421]  ? cifs_handle_standard+0x190/0x190 [cifs]
[  430.528514]  ? kthread_park+0x90/0x90
[  430.530019]  ret_from_fork+0x35/0x40

Fix this by obtaining extra references for mids being retried
and marking them as MID_DELETED which indicates that such a mid
has been dequeued from the pending list.

Also move mid cleanup logic from DeleteMidQEntry to
_cifs_mid_q_entry_release which is called when the last reference
to a particular mid is put. This allows to avoid any use-after-free
of response buffers.

The patch needs to be backported to stable kernels. A stable tag
is not mentioned below because the patch doesn't apply cleanly
to any actively maintained stable kernel.
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-and-tested-by: NDavid Wysochanski <dwysocha@redhat.com>
Signed-off-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

We only want to avoid blocking in connect when mounting SMB root
filesystems, otherwise bail out from generic_ip_connect() so cifs.ko
can perform any reconnect failover appropriately.

This fixes DFS failover/reconnection tests in upstream buildbot.

Fixes: 8eecd1c2 ("cifs: Add support for root file systems")
Signed-off-by: NPaulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Message was intended only for developer temporary build
In addition cleanup two minor warnings noticed by Coverity
and a trivial change to workaround a sparse warning
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>

Now that sparse has been fixed, it spotted a couple recent minor
endian errors (and removed one additional sparse warning).

Thanks to Luc Van Oostenryck for his help fixing sparse.
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>

Introduce a new CONFIG_CIFS_ROOT option to handle root file systems
over a SMB share.

In order to mount the root file system during the init process, make
cifs.ko perform non-blocking socket operations while mounting and
accessing it.

Cc: Steve French <smfrench@gmail.com>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NPaulo Alcantara (SUSE) <paulo@paulo.ac>
Signed-off-by: NSteve French <stfrench@microsoft.com>

In some cases to work around server bugs or performance
problems it can be helpful to be able to disable requesting
SMB2.1/SMB3 leases on a particular mount (not to all servers
and all shares we are mounted to). Add new mount parm
"nolease" which turns off requesting leases on directory
or file opens.  Currently the only way to disable leases is
globally through a module load parameter. This is more
granular.
Suggested-by: NPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>

Displayed in /proc/fs/cifs/Stats once for each
socket we are connected to.

This allows us to find out what the maximum number of
requests that had been in flight (at any one time). Note that
/proc/fs/cifs/Stats can be reset if you want to look for
maximum over a small period of time.

Sample output (immediately after mount):

Resources in use
CIFS Session: 1
Share (unique mount targets): 2
SMB Request/Response Buffer: 1 Pool size: 5
SMB Small Req/Resp Buffer: 1 Pool size: 30
Operations (MIDs): 0

0 session 0 share reconnects
Total vfs operations: 5 maximum at one time: 2

Max requests in flight: 2
1) \\localhost\scratch
SMBs: 18
Bytes read: 0  Bytes written: 0
...
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NPavel Shilovsky <pshilov@microsoft.com>

Disable offload of the decryption of encrypted read responses
by default (equivalent to setting this new mount option "esize=0").

Allow setting the minimum encrypted read response size that we
will choose to offload to a worker thread - it is now configurable
via on a new mount option "esize="

Depending on which encryption mechanism (GCM vs. CCM) and
the number of reads that will be issued in parallel and the
performance of the network and CPU on the client, it may make
sense to enable this since it can provide substantial benefit when
multiple large reads are in flight at the same time.
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>

Add new mount option "signloosely" which enables signing but skips the
sometimes expensive signing checks in the responses (signatures are
calculated and sent correctly in the SMB2/SMB3 requests even with this
mount option but skipped in the responses).  Although weaker for security
(and also data integrity in case a packet were corrupted), this can provide
enough of a performance benefit (calculating the signature to verify a
packet can be expensive especially for large packets) to be useful in
some cases.
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>

If the server config (e.g. Samba smb.conf "csc policy = disable)
for the share indicates that the share should not be cached, log
a warning message if forced client side caching ("cache=ro" or
"cache=singleclient") is requested on mount.
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>

If a share is known to be only to be accessed by one client, we
can aggressively cache writes not just reads to it.

Add "cache=" option (cache=singleclient) for mounting read write shares
(that will not be read or written to from other clients while we have
it mounted) in order to improve performance.
Signed-off-by: NSteve French <stfrench@microsoft.com>

Add some additional logging so the user can see if the share they
mounted with cache=ro is considered read only by the server

CIFS: Attempting to mount //localhost/test
CIFS VFS: mounting share with read only caching. Ensure that the share will not be modified while in use.
CIFS VFS: read only mount of RW share

CIFS: Attempting to mount //localhost/test-ro
CIFS VFS: mounting share with read only caching. Ensure that the share will not be modified while in use.
CIFS VFS: mounted to read only share
Signed-off-by: NSteve French <stfrench@microsoft.com>
Reviewed-by: NRonnie Sahlberg <lsahlber@redhat.com>

If a share is immutable (at least for the period that it will
be mounted) it would be helpful to not have to revalidate
dentries repeatedly that we know can not be changed remotely.

Add "cache=" option (cache=ro) for mounting read only shares
in order to improve performance in cases in which we know that
the share will not be changing while it is in use.
Signed-off-by: NSteve French <stfrench@microsoft.com>

which can be used from contexts where we have a TCP_Server_Info *server.
This new macro will prepend the debugging string with "Server:<servername> "
which will help when debugging issues on hosts with many cifs connections
to several different servers.

Convert a bunch of cifs_dbg(VFS) calls to cifs_server_dbg(VFS)
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Clarify a trivial comment
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

Using strscpy is cleaner, and avoids some problems with
handling maximum length strings.  Linus noticed the
original problem and Aurelien pointed out some additional
problems. Fortunately most of this is SMB1 code (and
in particular the ASCII string handling older, which
is less common).
Reported-by: NLinus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: NAurelien Aptel <aaptel@suse.com>
Signed-off-by: NRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>