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A spin lock called chan_lock was introduced recently.
But not all accesses were protected. Doing that with
this change.
To make sure that a channel is not freed when in use,
we need to introduce a ref count. But today, we don't
ever free channels.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Recent changes to multichannel required some adjustments in
the way connection states transitioned during/after reconnect.
Also some minor fixes:
1. A pending switch of GlobalMid_Lock to cifs_tcp_ses_lock
2. Relocations of the code that logs reconnect
3. Changed some code in allocate_mid to suit the new scheme
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
When a TCP connection gets reestablished by the sender in cifs_reconnect,
There is a chance for race condition with demultiplex thread waiting in
cifs_readv_from_socket on the old socket. It will now return -ECONNRESET.
This condition is handled by comparing socket pointer before and after
sock_recvmsg. If the socket pointer has changed, we should not call
cifs_reconnect again, but instead retry with new socket.
Also fixed another bug in my prev mchan commits.
We should always reestablish session (even if binding) on a channel
that needs reconnection.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
While checking/updating status for tcp ses, smb ses or tcon,
we take GlobalMid_Lock. This doesn't make any sense.
Replaced it with cifs_tcp_ses_lock.
Ideally, we should take a spin lock per struct.
But since tcp ses, smb ses and tcon objects won't add up to a lot,
I think there should not be too much contention.
Also, in few other places, these are checked without locking.
Added locking for these.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
We use the concept of "binding" when one of the secondary channel
is in the process of connecting/reconnecting to the server. Till this
binding process completes, and the channel is bound to an existing session,
we redirect traffic from other established channels on the binding channel,
effectively blocking all traffic till individual channels get reconnected.
With my last set of commits, we can get rid of this binding serialization.
We now have a bitmap of connection states for each channel. We will use
this bitmap instead for tracking channel status.
Having a bitmap also now enables us to keep the session alive, as long
as even a single channel underneath is alive.
Unfortunately, this also meant that we need to supply the tcp connection
info for the channel during all negotiate and session setup functions.
These changes have resulted in a slightly bigger code churn.
However, I expect perf and robustness improvements in the mchan scenario
after this change.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Introducing a new spin lock to protect all the channel related
fields in a cifs_ses struct. This lock should be taken
whenever dealing with the channel fields, and should be held
only for very short intervals which will not sleep.
Currently, all channel related fields in cifs_ses structure
are protected by session_mutex. However, this mutex is held for
long periods (sometimes while waiting for a reply from server).
This makes the codepath quite tricky to change.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
checkpatch complains about source files with filenames (e.g. in
these cases just below the SPDX header in comments at the top of
various files in fs/cifs). It also is helpful to change this now
so will be less confusing when the parent directory is renamed
e.g. from fs/cifs to fs/smb_client (or fs/smbfs)
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
There were three places where we were not taking the spinlock
around updates to server->tcpStatus when it was being modified.
To be consistent (also removes Coverity warning) and to remove
possibility of race best to lock all places where it is updated.
Two of the three were in initialization of the field and can't
race - but added lock around the other.
Addresses-Coverity: 1399512 ("Data race condition")
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Add SPDX license identifier and replace license boilerplate.
Corrects various checkpatch errors with the older format for
noting the LGPL license.
Signed-off-by: Steve French <stfrench@microsoft.com>
smb311_update_preauth_hash() uses the shash in server->secmech without
appropriate locking, and this can lead to sessions corrupting each
other's preauth hashes.
The following script can easily trigger the problem:
#!/bin/sh -e
NMOUNTS=10
for i in $(seq $NMOUNTS);
mkdir -p /tmp/mnt$i
umount /tmp/mnt$i 2>/dev/null || :
done
while :; do
for i in $(seq $NMOUNTS); do
mount -t cifs //192.168.0.1/test /tmp/mnt$i -o ... &
done
wait
for i in $(seq $NMOUNTS); do
umount /tmp/mnt$i
done
done
Usually within seconds this leads to one or more of the mounts failing
with the following errors, and a "Bad SMB2 signature for message" is
seen in the server logs:
CIFS: VFS: \\192.168.0.1 failed to connect to IPC (rc=-13)
CIFS: VFS: cifs_mount failed w/return code = -13
Fix it by holding the server mutex just like in the other places where
the shashes are used.
Fixes: 8bd68c6e47 ("CIFS: implement v3.11 preauth integrity")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
CC: <stable@vger.kernel.org>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
In case of interrupted syscalls, prevent sending CLOSE commands for
compound CREATE+CLOSE requests by introducing an
CIFS_CP_CREATE_CLOSE_OP flag to indicate lower layers that it should
not send a CLOSE command to the MIDs corresponding the compound
CREATE+CLOSE request.
A simple reproducer:
#!/bin/bash
mount //server/share /mnt -o username=foo,password=***
tc qdisc add dev eth0 root netem delay 450ms
stat -f /mnt &>/dev/null & pid=$!
sleep 0.01
kill $pid
tc qdisc del dev eth0 root
umount /mnt
Before patch:
...
6 0.256893470 192.168.122.2 → 192.168.122.15 SMB2 402 Create Request File: ;GetInfo Request FS_INFO/FileFsFullSizeInformation;Close Request
7 0.257144491 192.168.122.15 → 192.168.122.2 SMB2 498 Create Response File: ;GetInfo Response;Close Response
9 0.260798209 192.168.122.2 → 192.168.122.15 SMB2 146 Close Request File:
10 0.260841089 192.168.122.15 → 192.168.122.2 SMB2 130 Close Response, Error: STATUS_FILE_CLOSED
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
A customer has reported that their dmesg were being flooded by
CIFS: VFS: \\server Cancelling wait for mid xxx cmd: a
CIFS: VFS: \\server Cancelling wait for mid yyy cmd: b
CIFS: VFS: \\server Cancelling wait for mid zzz cmd: c
because some processes that were performing statfs(2) on the share had
been interrupted due to their automount setup when certain users
logged in and out.
Change it to FYI as they should be mostly informative rather than
error messages.
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Introduced a new field conn_id in TCP_Server_Info structure.
This is a non-persistent unique identifier maintained by the client
for a connection to a file server. For this, a global counter named
tcpSesNextId is maintained. On allocating a new TCP_Server_Info,
this counter is incremented and assigned.
Changed the dynamic tracepoints related to reconnects and
crediting to be more informative (with conn_id printed).
Debugging a crediting issue helped me understand the
important things to print here.
Always call dynamic tracepoints outside the scope of spinlocks.
To do this, copy out the credits and in_flight fields of the
server struct before dropping the lock.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
For failure by timeout waiting for credits, changed the error
returned to the app with EBUSY, instead of ENOTSUPP. This is done
because this situation is possible even in non-buggy cases. i.e.
overloaded server can return 0 credits until done with outstanding
requests. And this feels like a better error to return to the app.
For cases of zero credits found even when there are no requests
in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
deadlock here by returning error.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
We used to share the CIFS_NEG_OP flag between negotiate and
session authentication. There was an assumption in the code that
CIFS_NEG_OP is used by negotiate only. So introcuded CIFS_SESS_OP
and used it for session setup optypes.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Currently we try to guess if a compound request is going to
succeed waiting for credits or not based on the number of
requests in flight. This approach doesn't work correctly
all the time because there may be only one request in
flight which is going to bring multiple credits satisfying
the compound request.
Change the behavior to fail a request only if there are no requests
in flight at all and proceed waiting for credits otherwise.
Cc: <stable@vger.kernel.org> # 5.1+
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Tom Talpey <tom@talpey.com>
Reviewed-by: Shyam Prasad N <nspmangalore@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
RHBZ 1848178
The original intent of returning an error in this function
in the patch:
"CIFS: Mask off signals when sending SMB packets"
was to avoid interrupting packet send in the middle of
sending the data (and thus breaking an SMB connection),
but we also don't want to fail the request for non-fatal
signals even before we have had a chance to try to
send it (the reported problem could be reproduced e.g.
by exiting a child process when the parent process was in
the midst of calling futimens to update a file's timestamps).
In addition, since the signal may remain pending when we enter the
sending loop, we may end up not sending the whole packet before
TCP buffers become full. In this case the code returns -EINTR
but what we need here is to return -ERESTARTSYS instead to
allow system calls to be restarted.
Fixes: b30c74c73c ("CIFS: Mask off signals when sending SMB packets")
Cc: stable@vger.kernel.org # v5.1+
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
There is at least one suspected bug in crediting changes in cifs.ko
which has come up a few times in the discussions and in a customer
case.
This change adds tracepoints to the code which modifies the server
credit values in any way. The goal is to be able to track the changes
to the credit values of the session to be able to catch when there is
a crediting bug.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
A customer has reported that several files in their multi-threaded app
were left with size of 0 because most of the read(2) calls returned
-EINTR and they assumed no bytes were read. Obviously, they could
have fixed it by simply retrying on -EINTR.
We noticed that most of the -EINTR on read(2) were due to real-time
signals sent by glibc to process wide credential changes (SIGRT_1),
and its signal handler had been established with SA_RESTART, in which
case those calls could have been automatically restarted by the
kernel.
Let the kernel decide to whether or not restart the syscalls when
there is a signal pending in __smb_send_rqst() by returning
-ERESTARTSYS. If it can't, it will return -EINTR anyway.
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
SMB3 crediting is used for flow control, and it can be useful to
trace for problem determination how many credits were acquired
and for which operation.
Here is an example ("trace-cmd record -e *add_credits"):
cifsd-9522 [010] .... 5995.202712: smb3_add_credits:
server=localhost current_mid=0x12 credits=373 credits_to_add=10
cifsd-9522 [010] .... 5995.204040: smb3_add_credits:
server=localhost current_mid=0x15 credits=400 credits_to_add=30
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
If server returns ERRBaduid but does not reset transport connection,
we'll keep sending command with a non-valid UID for the server as long
as transport is healthy, without actually recovering. This have been
observed on the field.
This patch adds ERRBaduid handling so that we set CifsNeedReconnect.
map_and_check_smb_error() can be modified to extend use cases.
Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
The wait_event_... defines evaluate to long so we should not assign it an int as this may truncate
the value.
Reported-by: Marshall Midden <marshallmidden@gmail.com>
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Merge tag '5.8-rc-smb3-fixes-part-1' of git://git.samba.org/sfrench/cifs-2.6
Pull cifs updates from Steve French:
"22 changesets, 2 for stable.
Includes big performance improvement for large i/o when using
multichannel, also includes DFS fixes"
* tag '5.8-rc-smb3-fixes-part-1' of git://git.samba.org/sfrench/cifs-2.6: (22 commits)
cifs: update internal module version number
cifs: multichannel: try to rebind when reconnecting a channel
cifs: multichannel: use pointer for binding channel
smb3: remove static checker warning
cifs: multichannel: move channel selection above transport layer
cifs: multichannel: always zero struct cifs_io_parms
cifs: dump Security Type info in DebugData
smb3: fix incorrect number of credits when ioctl MaxOutputResponse > 64K
smb3: default to minimum of two channels when multichannel specified
cifs: multichannel: move channel selection in function
cifs: fix minor typos in comments and log messages
smb3: minor update to compression header definitions
cifs: minor fix to two debug messages
cifs: Standardize logging output
smb3: Add new parm "nodelete"
cifs: move some variables off the stack in smb2_ioctl_query_info
cifs: reduce stack use in smb2_compound_op
cifs: get rid of unused parameter in reconn_setup_dfs_targets()
cifs: handle hostnames that resolve to same ip in failover
cifs: set up next DFS target before generic_ip_connect()
...
Move the channel (TCP_Server_Info*) selection from the tranport
layer to higher in the call stack so that:
- credit handling is done with the server that will actually be used
to send.
* ->wait_mtu_credit
* ->set_credits / set_credits
* ->add_credits / add_credits
* add_credits_and_wake_if
- potential reconnection (smb2_reconnect) done when initializing a
request is checked and done with the server that will actually be
used to send.
To do this:
- remove the cifs_pick_channel() call out of compound_send_recv()
- select channel and pass it down by adding a cifs_pick_channel(ses)
call in:
- smb311_posix_mkdir
- SMB2_open
- SMB2_ioctl
- __SMB2_close
- query_info
- SMB2_change_notify
- SMB2_flush
- smb2_async_readv (if none provided in context param)
- SMB2_read (if none provided in context param)
- smb2_async_writev (if none provided in context param)
- SMB2_write (if none provided in context param)
- SMB2_query_directory
- send_set_info
- SMB2_oplock_break
- SMB311_posix_qfs_info
- SMB2_QFS_info
- SMB2_QFS_attr
- smb2_lockv
- SMB2_lease_break
- smb2_compound_op
- smb2_set_ea
- smb2_ioctl_query_info
- smb2_query_dir_first
- smb2_query_info_comound
- smb2_query_symlink
- cifs_writepages
- cifs_write_from_iter
- cifs_send_async_read
- cifs_read
- cifs_readpages
- add TCP_Server_Info *server param argument to:
- cifs_send_recv
- compound_send_recv
- SMB2_open_init
- SMB2_query_info_init
- SMB2_set_info_init
- SMB2_close_init
- SMB2_ioctl_init
- smb2_iotcl_req_init
- SMB2_query_directory_init
- SMB2_notify_init
- SMB2_flush_init
- build_qfs_info_req
- smb2_hdr_assemble
- smb2_reconnect
- fill_small_buf
- smb2_plain_req_init
- __smb2_plain_req_init
The read/write codepath is different than the rest as it is using
pages, io iterators and async calls. To deal with those we add a
server pointer in the cifs_writedata/cifs_readdata/cifs_io_parms
context struct and set it in:
- cifs_writepages (wdata)
- cifs_write_from_iter (wdata)
- cifs_readpages (rdata)
- cifs_send_async_read (rdata)
The [rw]data->server pointer is eventually copied to
cifs_io_parms->server to pass it down to SMB2_read/SMB2_write.
If SMB2_read/SMB2_write is called from a different place that doesn't
set the server field it will pick a channel.
Some places do not pick a channel and just use ses->server or
cifs_ses_server(ses). All cifs_ses_server(ses) calls are in codepaths
involving negprot/sess.setup.
- SMB2_negotiate (binding channel)
- SMB2_sess_alloc_buffer (binding channel)
- SMB2_echo (uses provided one)
- SMB2_logoff (uses master)
- SMB2_tdis (uses master)
(list not exhaustive)
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit moves channel picking code in separate function.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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: Joe Perches <joe@perches.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Add a helper to directly set the TCP_CORK sockopt from kernel space
without going through a fake uaccess. Cleanup the callers to avoid
pointless wrappers now that this is a simple function call.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
When encryption is used, smb2_transform_hdr is defined on the stack and is
passed to the transport. This doesn't work with RDMA as the buffer needs to
be DMA'ed.
Fix it by using kmalloc.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve 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: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
As we get down to the transport layer, plenty of functions are passed
the session pointer and assume the transport to use is ses->server.
Instead we modify those functions to pass (ses, server) so that we
can decouple the session from the server.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
During reconnecting, the transport may have already been destroyed and is in
the process being reconnected. In this case, return -EAGAIN to not fail and
to retry this I/O.
Signed-off-by: Long Li <longli@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve 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: Frank Sorenson <sorenson@redhat.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Smatch gets confused because we sometimes refer to "server->srv_mutex" and
sometimes to "sess->server->srv_mutex". They refer to the same lock so
let's just make this consistent.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steve 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: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-and-tested-by: David Wysochanski <dwysocha@redhat.com>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Where we have a tcon available we can log \\server\share as part
of the message. Only do this for the VFS log level.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The assignment of pointer server dereferences pointer ses, however,
this dereference occurs before ses is null checked and hence we
have a potential null pointer dereference. Fix this by only
dereferencing ses after it has been null checked.
Addresses-Coverity: ("Dereference before null check")
Fixes: 2808c6639104 ("cifs: add new debugging macro cifs_server_dbg")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve 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: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Trivial cleanup. Will make future multichannel code smaller
as well.
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This header is actually where signal_pending is defined
although either would work.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
The flags were named confusingly.
CIFS_ASYNC_OP now just means that we will not block waiting for credits
to become available so we thus rename this to be CIFS_NON_BLOCKING.
Change CIFS_NO_RESP to CIFS_NO_RSP_BUF to clarify that we will actually get a
response from the server but we will not get/do not want a response buffer.
Delete CIFSSMBNotify. This is an SMB1 function that is not used.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
For SMB1 oplock breaks we would grab one credit while sending the PDU
but we would never relese the credit back since we will never receive a
response to this from the server. Eventuallt this would lead to a hang
once all credits are leaked.
Fix this by defining a new flag CIFS_NO_SRV_RSP which indicates that there
is no server response to this command and thus we need to add any credits back
immediately after sending the PDU.
CC: Stable <stable@vger.kernel.org> #v5.0+
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
To support compounding, __smb_send_rqst() now sends an array of requests to
the transport layer.
Change smbd_send() to take an array of requests, and send them in as few
packets as possible.
Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
Since we can now wait for multiple requests atomically in
wait_for_free_request() we can now greatly simplify the handling
of the credits in this function.
This fixes a potential deadlock where many concurrent compound requests
could each have reserved 1 or 2 credits each but are all blocked
waiting for the final credits they need to be able to issue the requests
to the server.
Set a default timeout of 60 seconds for compounded requests.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
To help debug credit starvation problems where we timeout
waiting for server to grant the client credits.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
A negative timeout is the same as the current behaviour, i.e. no timeout.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reserve the last MAX_COMPOUND credits for any request asking for >1 credit.
This is to prevent future compound requests from becoming starved while waiting
for potentially many requests is there is a large number of concurrent
singe-credit requests.
However, we need to protect from servers that are very slow to hand out
new credits on new sessions so we only do this IFF there are 2*MAX_COMPOUND
(arbitrary) credits already in flight.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Change wait_for_free_credits() to allow waiting for >=1 credits instead of just
a single credit.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
