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path: root/fs/cifs/cifsglob.h
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2023-02-21cifs: get rid of dns resolve workerPaulo Alcantara1-5/+0
We already upcall to resolve hostnames during reconnect by calling reconn_set_ipaddr_from_hostname(), so there is no point in having a worker to periodically call it. Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com> Reviewed-by <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2023-02-20cifs: get rid of unneeded conditional in cifs_get_num_sgs()Paulo Alcantara1-5/+7
Just have @skip set to 0 after first iterations of the two nested loops. Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: David Howells <dhowells@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-19cifs: fix refresh of cached referralsPaulo Alcantara1-0/+3
We can't rely on cifs_tcon::ses to refresh cached referral as the server target might not respond to referrals, e.g. share is not hosted in a DFS root server. Consider the following mount //dom/dfs/link -> /root1/dfs/link -> /fs0/share where fs0 can't get a referral for "/root1/dfs/link". To simplify and fix the access of dfs root sessions, store the dfs root session pointer directly to new sessions so making it easier to select the appropriate ipc connection and use it for failover or cache refresh. Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-19cifs: share dfs connections and supersPaulo Alcantara1-5/+0
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: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-19cifs: split out ses and tcon retrieval from mount_get_conns()Paulo Alcantara1-0/+14
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: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-14cifs: Remove duplicated include in cifsglob.hYang Li1-1/+0
./fs/cifs/cifsglob.h: linux/scatterlist.h is included more than once. Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=3459 Fixes: f7f291e14dde ("cifs: fix oops during encryption") Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-12cifs: fix oops during encryptionPaulo Alcantara1-0/+68
When running xfstests against Azure the following oops occurred on an arm64 system Unable to handle kernel write to read-only memory at virtual address ffff0001221cf000 Mem abort info: ESR = 0x9600004f EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x0f: level 3 permission fault Data abort info: ISV = 0, ISS = 0x0000004f CM = 0, WnR = 1 swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000294f3000 [ffff0001221cf000] pgd=18000001ffff8003, p4d=18000001ffff8003, pud=18000001ff82e003, pmd=18000001ff71d003, pte=00600001221cf787 Internal error: Oops: 9600004f [#1] PREEMPT SMP ... pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--) pc : __memcpy+0x40/0x230 lr : scatterwalk_copychunks+0xe0/0x200 sp : ffff800014e92de0 x29: ffff800014e92de0 x28: ffff000114f9de80 x27: 0000000000000008 x26: 0000000000000008 x25: ffff800014e92e78 x24: 0000000000000008 x23: 0000000000000001 x22: 0000040000000000 x21: ffff000000000000 x20: 0000000000000001 x19: ffff0001037c4488 x18: 0000000000000014 x17: 235e1c0d6efa9661 x16: a435f9576b6edd6c x15: 0000000000000058 x14: 0000000000000001 x13: 0000000000000008 x12: ffff000114f2e590 x11: ffffffffffffffff x10: 0000040000000000 x9 : ffff8000105c3580 x8 : 2e9413b10000001a x7 : 534b4410fb86b005 x6 : 534b4410fb86b005 x5 : ffff0001221cf008 x4 : ffff0001037c4490 x3 : 0000000000000001 x2 : 0000000000000008 x1 : ffff0001037c4488 x0 : ffff0001221cf000 Call trace: __memcpy+0x40/0x230 scatterwalk_map_and_copy+0x98/0x100 crypto_ccm_encrypt+0x150/0x180 crypto_aead_encrypt+0x2c/0x40 crypt_message+0x750/0x880 smb3_init_transform_rq+0x298/0x340 smb_send_rqst.part.11+0xd8/0x180 smb_send_rqst+0x3c/0x100 compound_send_recv+0x534/0xbc0 smb2_query_info_compound+0x32c/0x440 smb2_set_ea+0x438/0x4c0 cifs_xattr_set+0x5d4/0x7c0 This is because in scatterwalk_copychunks(), we attempted to write to a buffer (@sign) that was allocated in the stack (vmalloc area) by crypt_message() and thus accessing its remaining 8 (x2) bytes ended up crossing a page boundary. To simply fix it, we could just pass @sign kmalloc'd from crypt_message() and then we're done. Luckily, we don't seem to pass any other vmalloc'd buffers in smb_rqst::rq_iov... Instead, let's map the correct pages and offsets from vmalloc buffers as well in cifs_sg_set_buf() and then avoiding such oopses. Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Cc: stable@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com>
2022-12-12cifs: minor cleanup of some headersSteve French1-2/+5
checkpatch showed formatting problems with extra spaces, and extra semicolon and some missing blank lines in some cifs headers. Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Germano Percossi <germano.percossi@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-15smb3: improve SMB3 change notification supportSteve French1-1/+1
Change notification is a commonly supported feature by most servers, but the current ioctl to request notification when a directory is changed does not return the information about what changed (even though it is returned by the server in the SMB3 change notify response), it simply returns when there is a change. This ioctl improves upon CIFS_IOC_NOTIFY by returning the notify information structure which includes the name of the file(s) that changed and why. See MS-SMB2 2.2.35 for details on the individual filter flags and the file_notify_information structure returned. To use this simply pass in the following (with enough space to fit at least one file_notify_information structure) struct __attribute__((__packed__)) smb3_notify { uint32_t completion_filter; bool watch_tree; uint32_t data_len; uint8_t data[]; } __packed; using CIFS_IOC_NOTIFY_INFO 0xc009cf0b or equivalently _IOWR(CIFS_IOCTL_MAGIC, 11, struct smb3_notify_info) The ioctl will block until the server detects a change to that directory or its subdirectories (if watch_tree is set). Acked-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Acked-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-13cifs: improve symlink handling for smb2+Paulo Alcantara1-10/+36
When creating inode for symlink, the client used to send below requests to fill it in: * create+query_info+close (STATUS_STOPPED_ON_SYMLINK) * create(+reparse_flag)+query_info+close (set file attrs) * create+ioctl(get_reparse)+close (query reparse tag) and then for every access to the symlink dentry, the ->link() method would send another: * create+ioctl(get_reparse)+close (parse symlink) So, in order to improve: (i) Get rid of unnecessary roundtrips and then resolve symlinks as follows: * create+query_info+close (STATUS_STOPPED_ON_SYMLINK + parse symlink + get reparse tag) * create(+reparse_flag)+query_info+close (set file attrs) (ii) Set the resolved symlink target directly in inode->i_link and use simple_get_link() for ->link() to simply return it. Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-08cifs: secmech: use shash_desc directly, remove sdescEnzo Matsumiya1-18/+8
The struct sdesc is just a wrapper around shash_desc, with exact same memory layout. Replace the hashing TFMs with shash_desc as it's what's passed to the crypto API anyway. Also remove the crypto_shash pointers as they can be accessed via shash_desc->tfm (and are actually only used in the setkey calls). Adapt cifs_{alloc,free}_hash functions to this change. Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-08smb3: rename encryption/decryption TFMsEnzo Matsumiya1-2/+2
Detach the TFM name from a specific algorithm (AES-CCM) as AES-GCM is also supported, making the name misleading. s/ccmaesencrypt/enc/ s/ccmaesdecrypt/dec/ Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-05cifs: Make tcon contain a wrapper structure cached_fids instead of cached_fidRonnie Sahlberg1-1/+1
This wrapper structure will later be expanded to contain a list of fids that are cached and not just the root fid. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-10-05smb3: add dynamic trace points for tree disconnectSteve French1-1/+1
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: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-25cifs: Add helper function to check smb1+ serverZhang Xiaoxu1-0/+5
SMB1 server's header_preamble_size is not 0, add use is_smb1 function to simplify the code, no actual functional changes. Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-25cifs: Use help macro to get the mid header sizeZhang Xiaoxu1-0/+1
It's better to use MID_HEADER_SIZE because the unfolded expression too long. No actual functional changes, minor readability improvement. Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-25cifs: Use help macro to get the header preamble sizeZhang Xiaoxu1-0/+1
It's better to use HEADER_PREAMBLE_SIZE because the unfolded expression too long. No actual functional changes, minor readability improvement. Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-18cifs: remove unused server parameter from calc_smb_size()Enzo Matsumiya1-1/+1
This parameter is unused by the called function Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-12cifs: Add constructor/destructors for tcon->cfidRonnie Sahlberg1-37/+1
and move the structure definitions into cached_dir.h Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-11cifs: Move cached-dir functions into a separate fileRonnie Sahlberg1-1/+1
Also rename crfid to cfid to have consistent naming for this variable. This commit does not change any logic. Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-11cifs: fix lock length calculationPaulo Alcantara1-2/+2
The lock length was wrongly set to 0 when fl_end == OFFSET_MAX, thus failing to lock the whole file when l_start=0 and l_len=0. This fixes test 2 from cthon04. Before patch: $ ./cthon04/lock/tlocklfs -t 2 /mnt Creating parent/child synchronization pipes. Test #1 - Test regions of an unlocked file. Parent: 1.1 - F_TEST [ 0, 1] PASSED. Parent: 1.2 - F_TEST [ 0, ENDING] PASSED. Parent: 1.3 - F_TEST [ 0,7fffffffffffffff] PASSED. Parent: 1.4 - F_TEST [ 1, 1] PASSED. Parent: 1.5 - F_TEST [ 1, ENDING] PASSED. Parent: 1.6 - F_TEST [ 1,7fffffffffffffff] PASSED. Parent: 1.7 - F_TEST [7fffffffffffffff, 1] PASSED. Parent: 1.8 - F_TEST [7fffffffffffffff, ENDING] PASSED. Parent: 1.9 - F_TEST [7fffffffffffffff,7fffffffffffffff] PASSED. Test #2 - Try to lock the whole file. Parent: 2.0 - F_TLOCK [ 0, ENDING] PASSED. Child: 2.1 - F_TEST [ 0, 1] FAILED! Child: **** Expected EACCES, returned success... Child: **** Probably implementation error. ** CHILD pass 1 results: 0/0 pass, 0/0 warn, 1/1 fail (pass/total). Parent: Child died ** PARENT pass 1 results: 10/10 pass, 0/0 warn, 0/0 fail (pass/total). After patch: $ ./cthon04/lock/tlocklfs -t 2 /mnt Creating parent/child synchronization pipes. Test #2 - Try to lock the whole file. Parent: 2.0 - F_TLOCK [ 0, ENDING] PASSED. Child: 2.1 - F_TEST [ 0, 1] PASSED. Child: 2.2 - F_TEST [ 0, ENDING] PASSED. Child: 2.3 - F_TEST [ 0,7fffffffffffffff] PASSED. Child: 2.4 - F_TEST [ 1, 1] PASSED. Child: 2.5 - F_TEST [ 1, ENDING] PASSED. Child: 2.6 - F_TEST [ 1,7fffffffffffffff] PASSED. Child: 2.7 - F_TEST [7fffffffffffffff, 1] PASSED. Child: 2.8 - F_TEST [7fffffffffffffff, ENDING] PASSED. Child: 2.9 - F_TEST [7fffffffffffffff,7fffffffffffffff] PASSED. Parent: 2.10 - F_ULOCK [ 0, ENDING] PASSED. ** PARENT pass 1 results: 2/2 pass, 0/0 warn, 0/0 fail (pass/total). ** CHILD pass 1 results: 9/9 pass, 0/0 warn, 0/0 fail (pass/total). Fixes: d80c69846ddf ("cifs: fix signed integer overflow when fl_end is OFFSET_MAX") Reported-by: Xiaoli Feng <xifeng@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-01cifs: avoid use of global locks for high contention dataShyam Prasad N1-26/+73
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: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-01cifs: remove remaining build warningsSteve French1-11/+11
Removed remaining warnings related to externs. These warnings although harmless could be distracting e.g. fs/cifs/cifsfs.c: note: in included file: fs/cifs/cifsglob.h:1968:24: warning: symbol 'sesInfoAllocCount' was not declared. Should it be static? Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-01cifs: remove minor build warningSteve French1-2/+2
The build warning: warning: symbol 'cifs_tcp_ses_lock' was not declared. Should it be static? can be distracting. Fix two of these. Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-08-01cifs: remove some camelCase and also some static build warningsSteve French1-5/+5
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: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-06-23cifs: periodically query network interfaces from serverShyam Prasad N1-0/+4
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: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-06-23cifs: change iface_list from array to sorted linked listShyam Prasad N1-1/+53
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: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-06-09netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_contextDavid Howells1-8/+4
While randstruct was satisfied with using an open-coded "void *" offset cast for the netfs_i_context <-> inode casting, __builtin_object_size() as used by FORTIFY_SOURCE was not as easily fooled. This was causing the following complaint[1] from gcc v12: In file included from include/linux/string.h:253, from include/linux/ceph/ceph_debug.h:7, from fs/ceph/inode.c:2: In function 'fortify_memset_chk', inlined from 'netfs_i_context_init' at include/linux/netfs.h:326:2, inlined from 'ceph_alloc_inode' at fs/ceph/inode.c:463:2: include/linux/fortify-string.h:242:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning] 242 | __write_overflow_field(p_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fix this by embedding a struct inode into struct netfs_i_context (which should perhaps be renamed to struct netfs_inode). The struct inode vfs_inode fields are then removed from the 9p, afs, ceph and cifs inode structs and vfs_inode is then simply changed to "netfs.inode" in those filesystems. Further, rename netfs_i_context to netfs_inode, get rid of the netfs_inode() function that converted a netfs_i_context pointer to an inode pointer (that can now be done with &ctx->inode) and rename the netfs_i_context() function to netfs_inode() (which is now a wrapper around container_of()). Most of the changes were done with: perl -p -i -e 's/vfs_inode/netfs.inode/'g \ `git grep -l 'vfs_inode' -- fs/{9p,afs,ceph,cifs}/*.[ch]` Kees suggested doing it with a pair structure[2] and a special declarator to insert that into the network filesystem's inode wrapper[3], but I think it's cleaner to embed it - and then it doesn't matter if struct randomisation reorders things. Dave Chinner suggested using a filesystem-specific VFS_I() function in each filesystem to convert that filesystem's own inode wrapper struct into the VFS inode struct[4]. Version #2: - Fix a couple of missed name changes due to a disabled cifs option. - Rename nfs_i_context to nfs_inode - Use "netfs" instead of "nic" as the member name in per-fs inode wrapper structs. [ This also undoes commit 507160f46c55 ("netfs: gcc-12: temporarily disable '-Wattribute-warning' for now") that is no longer needed ] Fixes: bc899ee1c898 ("netfs: Add a netfs inode context") Reported-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Xiubo Li <xiubli@redhat.com> cc: Jonathan Corbet <corbet@lwn.net> cc: Eric Van Hensbergen <ericvh@gmail.com> cc: Latchesar Ionkov <lucho@ionkov.net> cc: Dominique Martinet <asmadeus@codewreck.org> cc: Christian Schoenebeck <linux_oss@crudebyte.com> cc: Marc Dionne <marc.dionne@auristor.com> cc: Ilya Dryomov <idryomov@gmail.com> cc: Steve French <smfrench@gmail.com> cc: William Kucharski <william.kucharski@oracle.com> cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> cc: Dave Chinner <david@fromorbit.com> cc: linux-doc@vger.kernel.org cc: v9fs-developer@lists.sourceforge.net cc: linux-afs@lists.infradead.org cc: ceph-devel@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: samba-technical@lists.samba.org cc: linux-fsdevel@vger.kernel.org cc: linux-hardening@vger.kernel.org Link: https://lore.kernel.org/r/d2ad3a3d7bdd794c6efb562d2f2b655fb67756b9.camel@kernel.org/ [1] Link: https://lore.kernel.org/r/20220517210230.864239-1-keescook@chromium.org/ [2] Link: https://lore.kernel.org/r/20220518202212.2322058-1-keescook@chromium.org/ [3] Link: https://lore.kernel.org/r/20220524101205.GI2306852@dread.disaster.area/ [4] Link: https://lore.kernel.org/r/165296786831.3591209.12111293034669289733.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/165305805651.4094995.7763502506786714216.stgit@warthog.procyon.org.uk # v2 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-02cifs: version operations for smb20 unneeded when legacy support disabledSteve French1-1/+3
We should not be including unused smb20 specific code when legacy support is disabled (CONFIG_CIFS_ALLOW_INSECURE_LEGACY turned off). For example smb2_operations and smb2_values aren't used in that case. Over time we can move more and more SMB1/CIFS and SMB2.0 code into the insecure legacy ifdefs Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-06-01cifs: fix potential deadlock in direct reclaimVincent Whitchurch1-1/+19
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: Shyam Prasad N <nspmangalore@gmail.com> Suggested-by: Lars Persson <larper@axis.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-25cifs: fix ntlmssp on old serversPaulo Alcantara1-1/+14
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.org Reported-by: Byron Stanoszek <gandalf@winds.org> Tested-by: Byron Stanoszek <gandalf@winds.org> Fixes: 49bd49f983b5 ("cifs: send workstation name during ntlmssp session setup") Cc: stable@vger.kernel.org Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-24cifs: cache the dirents for entries in a cached directoryRonnie Sahlberg1-0/+22
This adds caching of the directory entries for a cached directory while we keep a lease on the directory. Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-24cifs: avoid parallel session setups on same channelShyam Prasad N1-0/+5
After allowing channels to reconnect in parallel, it now becomes important to take care that multiple processes do not call negotiate/session setup in parallel on the same channel. This change avoids that by marking a channel as "in_reconnect". During session setup if the channel in question has this flag set, we return immediately. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-24cifs: use new enum for ses_statusShyam Prasad N1-4/+11
ses->status today shares statusEnum with server->tcpStatus. This has been confusing, and tcon->status has deviated to use a new enum. Follow suit and use new enum for ses_status as well. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-21cifs: move definition of cifs_fattr earlier in cifsglob.hRonnie Sahlberg1-31/+31
This only moves these definitions to come earlier in the file but not change the definition itself. This is done to reduce the amount of changes in future patches. Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-05-19cifs: fix signed integer overflow when fl_end is OFFSET_MAXPaulo Alcantara1-0/+5
This fixes the following when running xfstests generic/504: [ 134.394698] CIFS: Attempting to mount \\win16.vm.test\Share [ 134.420905] CIFS: VFS: generate_smb3signingkey: dumping generated AES session keys [ 134.420911] CIFS: VFS: Session Id 05 00 00 00 00 c4 00 00 [ 134.420914] CIFS: VFS: Cipher type 1 [ 134.420917] CIFS: VFS: Session Key ea 0b d9 22 2e af 01 69 30 1b 15 74 bf 87 41 11 [ 134.420920] CIFS: VFS: Signing Key 59 28 43 5c f0 b6 b1 6f f5 7b 65 f2 9f 9e 58 7d [ 134.420923] CIFS: VFS: ServerIn Key eb aa 58 c8 95 01 9a f7 91 98 e4 fa bc d8 74 f1 [ 134.420926] CIFS: VFS: ServerOut Key 08 5b 21 e5 2e 4e 86 f6 05 c2 58 e0 af 53 83 e7 [ 134.771946] ================================================================================ [ 134.771953] UBSAN: signed-integer-overflow in fs/cifs/file.c:1706:19 [ 134.771957] 9223372036854775807 + 1 cannot be represented in type 'long long int' [ 134.771960] CPU: 4 PID: 2773 Comm: flock Not tainted 5.11.22 #1 [ 134.771964] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 134.771966] Call Trace: [ 134.771970] dump_stack+0x8d/0xb5 [ 134.771981] ubsan_epilogue+0x5/0x50 [ 134.771988] handle_overflow+0xa3/0xb0 [ 134.771997] ? lockdep_hardirqs_on_prepare+0xe8/0x1b0 [ 134.772006] cifs_setlk+0x63c/0x680 [cifs] [ 134.772085] ? _get_xid+0x5f/0xa0 [cifs] [ 134.772085] cifs_flock+0x131/0x400 [cifs] [ 134.772085] __x64_sys_flock+0xfc/0x120 [ 134.772085] do_syscall_64+0x33/0x40 [ 134.772085] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 134.772085] RIP: 0033:0x7fea4f83b3fb [ 134.772085] Code: ff 48 8b 15 8f 1a 0d 00 f7 d8 64 89 02 b8 ff ff ff ff eb da e8 16 0b 02 00 66 0f 1f 44 00 00 f3 0f 1e fa b8 49 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 5d 1a 0d 00 f7 d8 64 89 01 48 Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-04-02Merge tag '5.18-smb3-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6Linus Torvalds1-11/+13
Pull more cifs updates from Steve French: - three fixes for big endian issues in how Persistent and Volatile file ids were stored - Various misc. fixes: including some for oops, 2 for ioctls, 1 for writeback - cleanup of how tcon (tree connection) status is tracked - Four changesets to move various duplicated protocol definitions (defined both in cifs.ko and ksmbd) into smbfs_common/smb2pdu.h - important performance improvement to use cached handles in some key compounding code paths (reduces numbers of opens/closes sent in some workloads) - fix to allow alternate DFS target to be used to retry on a failed i/o * tag '5.18-smb3-fixes-part2' of git://git.samba.org/sfrench/cifs-2.6: cifs: fix NULL ptr dereference in smb2_ioctl_query_info() cifs: prevent bad output lengths in smb2_ioctl_query_info() smb3: fix ksmbd bigendian bug in oplock break, and move its struct to smbfs_common smb3: cleanup and clarify status of tree connections smb3: move defines for query info and query fsinfo to smbfs_common smb3: move defines for ioctl protocol header and SMB2 sizes to smbfs_common [smb3] move more common protocol header definitions to smbfs_common cifs: fix incorrect use of list iterator after the loop ksmbd: store fids as opaque u64 integers cifs: fix bad fids sent over wire cifs: change smb2_query_info_compound to use a cached fid, if available cifs: convert the path to utf16 in smb2_query_info_compound cifs: writeback fix cifs: do not skip link targets when an I/O fails
2022-03-29smb3: cleanup and clarify status of tree connectionsSteve French1-5/+13
Currently the way the tid (tree connection) status is tracked is confusing. The same enum is used for structs cifs_tcon and cifs_ses and TCP_Server_info, but each of these three has different states that they transition among. The current code also unnecessarily uses camelCase. Convert from use of statusEnum to a new tid_status_enum for tree connections. The valid states for a tid are: TID_NEW = 0, TID_GOOD, TID_EXITING, TID_NEED_RECON, TID_NEED_TCON, TID_IN_TCON, TID_NEED_FILES_INVALIDATE, /* unused, considering removing in future */ TID_IN_FILES_INVALIDATE It also removes CifsNeedTcon, CifsInTcon, CifsNeedFilesInvalidate and CifsInFilesInvalidate from the statusEnum used for session and TCP_Server_Info since they are not relevant for those. A follow on patch will fix the places where we use the tcon->need_reconnect flag to be more consistent with the tid->status. Also fixes a bug that was: Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Shyam Prasad N <sprasad@microsoft.com> Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-03-27smb3: move defines for ioctl protocol header and SMB2 sizes to smbfs_commonSteve French1-6/+0
The definitions for the ioctl SMB3 request and response as well as length of various fields defined in the protocol documentation were duplicated in fs/ksmbd and fs/cifs. Move these to the common code in fs/smbfs_common/smb2pdu.h Reviewed-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-03-18netfs: Add a netfs inode contextDavid Howells1-4/+6
Add a netfs_i_context struct that should be included in the network filesystem's own inode struct wrapper, directly after the VFS's inode struct, e.g.: struct my_inode { struct { /* These must be contiguous */ struct inode vfs_inode; struct netfs_i_context netfs_ctx; }; }; The netfs_i_context struct so far contains a single field for the network filesystem to use - the cache cookie: struct netfs_i_context { ... struct fscache_cookie *cache; }; Three functions are provided to help with this: (1) void netfs_i_context_init(struct inode *inode, const struct netfs_request_ops *ops); Initialise the netfs context and set the operations. (2) struct netfs_i_context *netfs_i_context(struct inode *inode); Find the netfs context from the VFS inode. (3) struct inode *netfs_inode(struct netfs_i_context *ctx); Find the VFS inode from the netfs context. Changes ======= ver #4) - Fix netfs_is_cache_enabled() to check cookie->cache_priv to see if a cache is present[3]. - Fix netfs_skip_folio_read() to zero out all of the page, not just some of it[3]. ver #3) - Split out the bit to move ceph cap-getting on readahead into ceph_init_request()[1]. - Stick in a comment to the netfs inode structs indicating the contiguity requirements[2]. ver #2) - Adjust documentation to match. - Use "#if IS_ENABLED()" in netfs_i_cookie(), not "#ifdef". - Move the cap check from ceph_readahead() to ceph_init_request() to be called from netfslib. - Remove ceph_readahead() and use netfs_readahead() directly instead. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/8af0d47f17d89c06bbf602496dd845f2b0bf25b3.camel@kernel.org/ [1] Link: https://lore.kernel.org/r/beaf4f6a6c2575ed489adb14b257253c868f9a5c.camel@kernel.org/ [2] Link: https://lore.kernel.org/r/3536452.1647421585@warthog.procyon.org.uk/ [3] Link: https://lore.kernel.org/r/164622984545.3564931.15691742939278418580.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/164678213320.1200972.16807551936267647470.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/164692909854.2099075.9535537286264248057.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/306388.1647595110@warthog.procyon.org.uk/ # v4
2022-01-19cifs: Support fscache indexing rewriteDavid Howells1-4/+1
Change the cifs filesystem to take account of the changes to fscache's indexing rewrite and reenable caching in cifs. The following changes have been made: (1) The fscache_netfs struct is no more, and there's no need to register the filesystem as a whole. (2) The session cookie is now an fscache_volume cookie, allocated with fscache_acquire_volume(). That takes three parameters: a string representing the "volume" in the index, a string naming the cache to use (or NULL) and a u64 that conveys coherency metadata for the volume. For cifs, I've made it render the volume name string as: "cifs,<ipaddress>,<sharename>" where the sharename has '/' characters replaced with ';'. This probably needs rethinking a bit as the total name could exceed the maximum filename component length. Further, the coherency data is currently just set to 0. It needs something else doing with it - I wonder if it would suffice simply to sum the resource_id, vol_create_time and vol_serial_number or maybe hash them. (3) The fscache_cookie_def is no more and needed information is passed directly to fscache_acquire_cookie(). The cache no longer calls back into the filesystem, but rather metadata changes are indicated at other times. fscache_acquire_cookie() is passed the same keying and coherency information as before. (4) The functions to set/reset cookies are removed and fscache_use_cookie() and fscache_unuse_cookie() are used instead. fscache_use_cookie() is passed a flag to indicate if the cookie is opened for writing. fscache_unuse_cookie() is passed updates for the metadata if we changed it (ie. if the file was opened for writing). These are called when the file is opened or closed. (5) cifs_setattr_*() are made to call fscache_resize() to change the size of the cache object. (6) The functions to read and write data are stubbed out pending a conversion to use netfslib. Changes ======= ver #8: - Abstract cache invalidation into a helper function. - Fix some checkpatch warnings[3]. ver #7: - Removed the accidentally added-back call to get the super cookie in cifs_root_iget(). - Fixed the right call to cifs_fscache_get_super_cookie() to take account of the "-o fsc" mount flag. ver #6: - Moved the change of gfpflags_allow_blocking() to current_is_kswapd() for cifs here. - Fixed one of the error paths in cifs_atomic_open() to jump around the call to use the cookie. - Fixed an additional successful return in the middle of cifs_open() to use the cookie on the way out. - Only get a volume cookie (and thus inode cookies) when "-o fsc" is supplied to mount. ver #5: - Fixed a couple of bits of cookie handling[2]: - The cookie should be released in cifs_evict_inode(), not cifsFileInfo_put_final(). The cookie needs to persist beyond file closure so that writepages will be able to write to it. - fscache_use_cookie() needs to be called in cifs_atomic_open() as it is for cifs_open(). ver #4: - Fixed the use of sizeof with memset. - tcon->vol_create_time is __le64 so doesn't need cpu_to_le64(). ver #3: - Canonicalise the cifs coherency data to make the cache portable. - Set volume coherency data. ver #2: - Use gfpflags_allow_blocking() rather than using flag directly. - Upgraded to -rc4 to allow for upstream changes[1]. - fscache_acquire_volume() now returns errors. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@kernel.org> cc: Steve French <smfrench@gmail.com> cc: Shyam Prasad N <nspmangalore@gmail.com> cc: linux-cifs@vger.kernel.org cc: linux-cachefs@redhat.com Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=23b55d673d7527b093cd97b7c217c82e70cd1af0 [1] Link: https://lore.kernel.org/r/3419813.1641592362@warthog.procyon.org.uk/ [2] Link: https://lore.kernel.org/r/CAH2r5muTanw9pJqzAHd01d9A8keeChkzGsCEH6=0rHutVLAF-A@mail.gmail.com/ [3] Link: https://lore.kernel.org/r/163819671009.215744.11230627184193298714.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906982979.143852.10672081929614953210.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967187187.1823006.247415138444991444.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021579335.640689.2681324337038770579.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/3462849.1641593783@warthog.procyon.org.uk/ # v5 Link: https://lore.kernel.org/r/1318953.1642024578@warthog.procyon.org.uk/ # v6 Signed-off-by: Steve French <stfrench@microsoft.com>
2022-01-19cifs: check reconnects for channels of active tcons tooShyam Prasad N1-0/+2
With the new multichannel logic, when a channel needs reconnection, the tree connect and other channels can still be active. This fix will handle cases of checking for channel reconnect, when the tcon does not need reconnect. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-01-15cifs: move superblock magic defitions to magic.hJeff Layton1-2/+0
Help userland apps to identify cifs and smb2 mounts. Signed-off-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-01-08cifs: maintain a state machine for tcp/smb/tcon sessionsShyam Prasad N1-1/+7
If functions like cifs_negotiate_protocol, cifs_setup_session, cifs_tree_connect are called in parallel on different channels, each of these will be execute the requests. This maybe unnecessary in some cases, and only the first caller may need to do the work. This is achieved by having more states for the tcp/smb/tcon session status fields. And tracking the state of reconnection based on the state machine. For example: for tcp connections: CifsNew/CifsNeedReconnect -> CifsNeedNegotiate -> CifsInNegotiate -> CifsNeedSessSetup -> CifsInSessSetup -> CifsGood for smb sessions: CifsNew/CifsNeedReconnect -> CifsGood for tcon: CifsNew/CifsNeedReconnect -> CifsInFilesInvalidate -> CifsNeedTcon -> CifsInTcon -> CifsGood If any channel reconnect sees that it's in the middle of transition to CifsGood, then they can skip the function. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-01-08cifs: take cifs_tcp_ses_lock for status checksShyam Prasad N1-2/+2
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>
2022-01-03cifs: reconnect only the connection and not smb session where possibleShyam Prasad N1-0/+2
With the new per-channel bitmask for reconnect, we have an option to reconnect the tcp session associated with the channel without reconnecting the smb session. i.e. if there are still channels to operate on, we can continue to use the smb session and tcon. However, there are cases where it makes sense to reconnect the smb session even when there are active channels underneath. For example for SMB session expiry. With this patch, we'll have an option to do either, and use the correct option for specific cases. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2022-01-03cifs: use the chans_need_reconnect bitmap for reconnect statusShyam Prasad N1-37/+11
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>
2022-01-03cifs: track individual channel status using chans_need_reconnectShyam Prasad N1-1/+14
We needed a way to identify the channels under the smb session which are in reconnect, so that the traffic to other channels can continue. So I replaced the bool need_reconnect with a bitmask identifying all the channels that need reconnection (named chans_need_reconnect). When a channel needs reconnection, the bit corresponding to the index of the server in ses->chans is used to set this bitmask. Checking if no channels or all the channels need reconnect then becomes very easy. Also wrote some helper macros for checking and setting the bits. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2021-11-13cifs: connect individual channel servers to primary channel serverShyam Prasad N1-1/+9
Today, we don't have any way to get the smb session for any of the secondary channels. Introducing a pointer to the primary server from server struct of any secondary channel. The value will be NULL for the server of the primary channel. This will enable us to get the smb session for any channel. This will be needed for some of the changes that I'm planning to make soon. Signed-off-by: Shyam Prasad N <sprasad@microsoft.com> Signed-off-by: Steve French <stfrench@microsoft.com>
2021-11-13cifs: protect session channel fields with chan_lockShyam Prasad N1-0/+5
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>