Commit Graph

360 Commits

Author SHA1 Message Date
Linus Torvalds a79cdfba68 Additional fixes and clean-ups for NFSD since tags/nfsd-5.13,
including a fix to grant read delegations for files open for
 writing.
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Merge tag 'nfsd-5.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

Pull more nfsd updates from Chuck Lever:
 "Additional fixes and clean-ups for NFSD since tags/nfsd-5.13,
  including a fix to grant read delegations for files open for writing"

* tag 'nfsd-5.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  SUNRPC: Fix null pointer dereference in svc_rqst_free()
  SUNRPC: fix ternary sign expansion bug in tracing
  nfsd: Fix fall-through warnings for Clang
  nfsd: grant read delegations to clients holding writes
  nfsd: reshuffle some code
  nfsd: track filehandle aliasing in nfs4_files
  nfsd: hash nfs4_files by inode number
  nfsd: ensure new clients break delegations
  nfsd: removed unused argument in nfsd_startup_generic()
  nfsd: remove unused function
  svcrdma: Pass a useful error code to the send_err tracepoint
  svcrdma: Rename goto labels in svc_rdma_sendto()
  svcrdma: Don't leak send_ctxt on Send errors
2021-05-05 13:44:19 -07:00
Linus Torvalds befbfe07e6 File locking fixes for v5.13
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Merge tag 'locks-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull file locking updates from Jeff Layton:
 "When we reworked the blocked locks into a tree structure instead of a
  flat list a few releases ago, we lost the ability to see all of the
  file locks in /proc/locks. Luo's patch fixes it to dump out all of the
  blocked locks instead, which restores the full output.

  This changes the format of /proc/locks as the blocked locks are shown
  at multiple levels of indentation now, but lslocks (the only common
  program I've ID'ed that scrapes this info) seems to be OK with that.

  Tian also contributed a small patch to remove a useless assignment"

* tag 'locks-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  fs/locks: remove useless assignment in fcntl_getlk
  fs/locks: print full locks information
2021-04-26 13:24:39 -07:00
J. Bruce Fields aba2072f45 nfsd: grant read delegations to clients holding writes
It's OK to grant a read delegation to a client that holds a write,
as long as it's the only client holding the write.

We originally tried to do this in commit 94415b06eb ("nfsd4: a
client's own opens needn't prevent delegations"), which had to be
reverted in commit 6ee65a7730 ("Revert "nfsd4: a client's own
opens needn't prevent delegations"").

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2021-04-19 16:41:36 -04:00
Tian Tao cbe6fc4e01 fs/locks: remove useless assignment in fcntl_getlk
Function parameter 'cmd' is rewritten with unused value at locks.c

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2021-04-13 07:26:38 -04:00
Luo Longjun b8da9b10e2 fs/locks: print full locks information
Commit fd7732e033 ("fs/locks: create a tree of dependent requests.")
has put blocked locks into a tree.

So, with a for loop, we can't check all locks information.

To solve this problem, we should traverse the tree.

Signed-off-by: Luo Longjun <luolongjun@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2021-03-11 07:48:11 -05:00
J. Bruce Fields 6ee65a7730 Revert "nfsd4: a client's own opens needn't prevent delegations"
This reverts commit 94415b06eb.

That commit claimed to allow a client to get a read delegation when it
was the only writer.  Actually it allowed a client to get a read
delegation when *any* client has a write open!

The main problem is that it's depending on nfs4_clnt_odstate structures
that are actually only maintained for pnfs exports.

This causes clients to miss writes performed by other clients, even when
there have been intervening closes and opens, violating close-to-open
cache consistency.

We can do this a different way, but first we should just revert this.

I've added pynfs 4.1 test DELEG19 to test for this, as I should have
done originally!

Cc: stable@vger.kernel.org
Reported-by: Timo Rothenpieler <timo@rothenpieler.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2021-03-09 10:37:34 -05:00
Linus Torvalds faf145d6f3 Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull execve updates from Eric Biederman:
 "This set of changes ultimately fixes the interaction of posix file
  lock and exec. Fundamentally most of the change is just moving where
  unshare_files is called during exec, and tweaking the users of
  files_struct so that the count of files_struct is not unnecessarily
  played with.

  Along the way fcheck and related helpers were renamed to more
  accurately reflect what they do.

  There were also many other small changes that fell out, as this is the
  first time in a long time much of this code has been touched.

  Benchmarks haven't turned up any practical issues but Al Viro has
  observed a possibility for a lot of pounding on task_lock. So I have
  some changes in progress to convert put_files_struct to always rcu
  free files_struct. That wasn't ready for the merge window so that will
  have to wait until next time"

* 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
  exec: Move io_uring_task_cancel after the point of no return
  coredump: Document coredump code exclusively used by cell spufs
  file: Remove get_files_struct
  file: Rename __close_fd_get_file close_fd_get_file
  file: Replace ksys_close with close_fd
  file: Rename __close_fd to close_fd and remove the files parameter
  file: Merge __alloc_fd into alloc_fd
  file: In f_dupfd read RLIMIT_NOFILE once.
  file: Merge __fd_install into fd_install
  proc/fd: In fdinfo seq_show don't use get_files_struct
  bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
  proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu
  file: Implement task_lookup_next_fd_rcu
  kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
  proc/fd: In tid_fd_mode use task_lookup_fd_rcu
  file: Implement task_lookup_fd_rcu
  file: Rename fcheck lookup_fd_rcu
  file: Replace fcheck_files with files_lookup_fd_rcu
  file: Factor files_lookup_fd_locked out of fcheck_files
  file: Rename __fcheck_files to files_lookup_fd_raw
  ...
2020-12-15 19:29:43 -08:00
Eric W. Biederman 120ce2b0cd file: Factor files_lookup_fd_locked out of fcheck_files
To make it easy to tell where files->file_lock protection is being
used when looking up a file create files_lookup_fd_locked.  Only allow
this function to be called with the file_lock held.

Update the callers of fcheck and fcheck_files that are called with the
files->file_lock held to call files_lookup_fd_locked instead.

Hopefully this makes it easier to quickly understand what is going on.

The need for better names became apparent in the last round of
discussion of this set of changes[1].

[1] https://lkml.kernel.org/r/CAHk-=wj8BQbgJFLa+J0e=iT-1qpmCRTbPAJ8gd6MJQ=kbRPqyQ@mail.gmail.com
Link: https://lkml.kernel.org/r/20201120231441.29911-8-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2020-12-10 12:39:59 -06:00
Mauro Carvalho Chehab 529adfe8f1 locks: fix a typo at a kernel-doc markup
locks_delete_lock -> locks_delete_block

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2020-10-26 08:00:39 -04:00
Luo Meng 16238415eb locks: Fix UBSAN undefined behaviour in flock64_to_posix_lock
When the sum of fl->fl_start and l->l_len overflows,
UBSAN shows the following warning:

UBSAN: Undefined behaviour in fs/locks.c:482:29
signed integer overflow: 2 + 9223372036854775806
cannot be represented in type 'long long int'
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xe4/0x14e lib/dump_stack.c:118
 ubsan_epilogue+0xe/0x81 lib/ubsan.c:161
 handle_overflow+0x193/0x1e2 lib/ubsan.c:192
 flock64_to_posix_lock fs/locks.c:482 [inline]
 flock_to_posix_lock+0x595/0x690 fs/locks.c:515
 fcntl_setlk+0xf3/0xa90 fs/locks.c:2262
 do_fcntl+0x456/0xf60 fs/fcntl.c:387
 __do_sys_fcntl fs/fcntl.c:483 [inline]
 __se_sys_fcntl fs/fcntl.c:468 [inline]
 __x64_sys_fcntl+0x12d/0x180 fs/fcntl.c:468
 do_syscall_64+0xc8/0x5a0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix it by parenthesizing 'l->l_len - 1'.

Signed-off-by: Luo Meng <luomeng12@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2020-10-26 07:59:29 -04:00
Gustavo A. R. Silva df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Linus Torvalds 7a6b60441f Highlights:
- Support for user extended attributes on NFS (RFC 8276)
 - Further reduce unnecessary NFSv4 delegation recalls
 
 Notable fixes:
 
 - Fix recent krb5p regression
 - Address a few resource leaks and a rare NULL dereference
 
 Other:
 
 - De-duplicate RPC/RDMA error handling and other utility functions
 - Replace storage and display of kernel memory addresses by tracepoints
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Merge tag 'nfsd-5.9' of git://git.linux-nfs.org/projects/cel/cel-2.6

Pull NFS server updates from Chuck Lever:
 "Highlights:
   - Support for user extended attributes on NFS (RFC 8276)
   - Further reduce unnecessary NFSv4 delegation recalls

  Notable fixes:
   - Fix recent krb5p regression
   - Address a few resource leaks and a rare NULL dereference

  Other:
   - De-duplicate RPC/RDMA error handling and other utility functions
   - Replace storage and display of kernel memory addresses by tracepoints"

* tag 'nfsd-5.9' of git://git.linux-nfs.org/projects/cel/cel-2.6: (38 commits)
  svcrdma: CM event handler clean up
  svcrdma: Remove transport reference counting
  svcrdma: Fix another Receive buffer leak
  SUNRPC: Refresh the show_rqstp_flags() macro
  nfsd: netns.h: delete a duplicated word
  SUNRPC: Fix ("SUNRPC: Add "@len" parameter to gss_unwrap()")
  nfsd: avoid a NULL dereference in __cld_pipe_upcall()
  nfsd4: a client's own opens needn't prevent delegations
  nfsd: Use seq_putc() in two functions
  svcrdma: Display chunk completion ID when posting a rw_ctxt
  svcrdma: Record send_ctxt completion ID in trace_svcrdma_post_send()
  svcrdma: Introduce Send completion IDs
  svcrdma: Record Receive completion ID in svc_rdma_decode_rqst
  svcrdma: Introduce Receive completion IDs
  svcrdma: Introduce infrastructure to support completion IDs
  svcrdma: Add common XDR encoders for RDMA and Read segments
  svcrdma: Add common XDR decoders for RDMA and Read segments
  SUNRPC: Add helpers for decoding list discriminators symbolically
  svcrdma: Remove declarations for functions long removed
  svcrdma: Clean up trace_svcrdma_send_failed() tracepoint
  ...
2020-08-09 13:58:04 -07:00
Linus Torvalds 3208167a86 File locking fix for v5.9.
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Merge tag 'filelock-v5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

Pull file locking fix from Jeff Layton:
 "Just a single, one-line patch to fix an inefficiency in the posix
  locking code that can lead to it doing more wakeups than necessary"

* tag 'filelock-v5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: add locks_move_blocks in posix_lock_inode
2020-08-03 10:46:41 -07:00
J. Bruce Fields 94415b06eb nfsd4: a client's own opens needn't prevent delegations
We recently fixed lease breaking so that a client's actions won't break
its own delegations.

But we still have an unnecessary self-conflict when granting
delegations: a client's own write opens will prevent us from handing out
a read delegation even when no other client has the file open for write.

Fix that by turning off the checks for conflicting opens under
vfs_setlease, and instead performing those checks in the nfsd code.

We don't depend much on locks here: instead we acquire the delegation,
then check for conflicts, and drop the delegation again if we find any.

The check beforehand is an optimization of sorts, just to avoid
acquiring the delegation unnecessarily.  There's a race where the first
check could cause us to deny the delegation when we could have granted
it.  But, that's OK, delegation grants are optional (and probably not
even a good idea in that case).

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
2020-07-13 17:28:46 -04:00
Linus Torvalds c742b63473 Highlights:
- Keep nfsd clients from unnecessarily breaking their own delegations:
   Note this requires a small kthreadd addition, discussed at:
   https://lore.kernel.org/r/1588348912-24781-1-git-send-email-bfields@redhat.com
   The result is Tejun Heo's suggestion, and he was OK with this going
   through my tree.
 - Patch nfsd/clients/ to display filenames, and to fix byte-order when
   displaying stateid's.
 - fix a module loading/unloading bug, from Neil Brown.
 - A big series from Chuck Lever with RPC/RDMA and tracing improvements,
   and lay some groundwork for RPC-over-TLS.
 
 Note Stephen Rothwell spotted two conflicts in linux-next.  Both should
 be straightforward:
 	include/trace/events/sunrpc.h
 		https://lore.kernel.org/r/20200529105917.50dfc40f@canb.auug.org.au
 	net/sunrpc/svcsock.c
 		https://lore.kernel.org/r/20200529131955.26c421db@canb.auug.org.au
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Merge tag 'nfsd-5.8' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Highlights:

   - Keep nfsd clients from unnecessarily breaking their own
     delegations.

     Note this requires a small kthreadd addition. The result is Tejun
     Heo's suggestion (see link), and he was OK with this going through
     my tree.

   - Patch nfsd/clients/ to display filenames, and to fix byte-order
     when displaying stateid's.

   - fix a module loading/unloading bug, from Neil Brown.

   - A big series from Chuck Lever with RPC/RDMA and tracing
     improvements, and lay some groundwork for RPC-over-TLS"

Link: https://lore.kernel.org/r/1588348912-24781-1-git-send-email-bfields@redhat.com

* tag 'nfsd-5.8' of git://linux-nfs.org/~bfields/linux: (49 commits)
  sunrpc: use kmemdup_nul() in gssp_stringify()
  nfsd: safer handling of corrupted c_type
  nfsd4: make drc_slab global, not per-net
  SUNRPC: Remove unreachable error condition in rpcb_getport_async()
  nfsd: Fix svc_xprt refcnt leak when setup callback client failed
  sunrpc: clean up properly in gss_mech_unregister()
  sunrpc: svcauth_gss_register_pseudoflavor must reject duplicate registrations.
  sunrpc: check that domain table is empty at module unload.
  NFSD: Fix improperly-formatted Doxygen comments
  NFSD: Squash an annoying compiler warning
  SUNRPC: Clean up request deferral tracepoints
  NFSD: Add tracepoints for monitoring NFSD callbacks
  NFSD: Add tracepoints to the NFSD state management code
  NFSD: Add tracepoints to NFSD's duplicate reply cache
  SUNRPC: svc_show_status() macro should have enum definitions
  SUNRPC: Restructure svc_udp_recvfrom()
  SUNRPC: Refactor svc_recvfrom()
  SUNRPC: Clean up svc_release_skb() functions
  SUNRPC: Refactor recvfrom path dealing with incomplete TCP receives
  SUNRPC: Replace dprintk() call sites in TCP receive path
  ...
2020-06-11 10:33:13 -07:00
Linus Torvalds 9ff7258575 Merge branch 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull proc updates from Eric Biederman:
 "This has four sets of changes:

   - modernize proc to support multiple private instances

   - ensure we see the exit of each process tid exactly

   - remove has_group_leader_pid

   - use pids not tasks in posix-cpu-timers lookup

  Alexey updated proc so each mount of proc uses a new superblock. This
  allows people to actually use mount options with proc with no fear of
  messing up another mount of proc. Given the kernel's internal mounts
  of proc for things like uml this was a real problem, and resulted in
  Android's hidepid mount options being ignored and introducing security
  issues.

  The rest of the changes are small cleanups and fixes that came out of
  my work to allow this change to proc. In essence it is swapping the
  pids in de_thread during exec which removes a special case the code
  had to handle. Then updating the code to stop handling that special
  case"

* 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  proc: proc_pid_ns takes super_block as an argument
  remove the no longer needed pid_alive() check in __task_pid_nr_ns()
  posix-cpu-timers: Replace __get_task_for_clock with pid_for_clock
  posix-cpu-timers: Replace cpu_timer_pid_type with clock_pid_type
  posix-cpu-timers: Extend rcu_read_lock removing task_struct references
  signal: Remove has_group_leader_pid
  exec: Remove BUG_ON(has_group_leader_pid)
  posix-cpu-timer:  Unify the now redundant code in lookup_task
  posix-cpu-timer: Tidy up group_leader logic in lookup_task
  proc: Ensure we see the exit of each process tid exactly once
  rculist: Add hlists_swap_heads_rcu
  proc: Use PIDTYPE_TGID in next_tgid
  Use proc_pid_ns() to get pid_namespace from the proc superblock
  proc: use named enums for better readability
  proc: use human-readable values for hidepid
  docs: proc: add documentation for "hidepid=4" and "subset=pid" options and new mount behavior
  proc: add option to mount only a pids subset
  proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option
  proc: allow to mount many instances of proc in one pid namespace
  proc: rename struct proc_fs_info to proc_fs_opts
2020-06-04 13:54:34 -07:00
yangerkun 5ef1596813 locks: add locks_move_blocks in posix_lock_inode
We forget to call locks_move_blocks in posix_lock_inode when try to
process same owner and different types.

Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2020-06-02 12:08:25 -04:00
Alexey Gladkov 9d78edeaec proc: proc_pid_ns takes super_block as an argument
syzbot found that

  touch /proc/testfile

causes NULL pointer dereference at tomoyo_get_local_path()
because inode of the dentry is NULL.

Before c59f415a7c, Tomoyo received pid_ns from proc's s_fs_info
directly. Since proc_pid_ns() can only work with inode, using it in
the tomoyo_get_local_path() was wrong.

To avoid creating more functions for getting proc_ns, change the
argument type of the proc_pid_ns() function. Then, Tomoyo can use
the existing super_block to get pid_ns.

Link: https://lkml.kernel.org/r/0000000000002f0c7505a5b0e04c@google.com
Link: https://lkml.kernel.org/r/20200518180738.2939611-1-gladkov.alexey@gmail.com
Reported-by: syzbot+c1af344512918c61362c@syzkaller.appspotmail.com
Fixes: c59f415a7c ("Use proc_pid_ns() to get pid_namespace from the proc superblock")
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2020-05-19 07:07:50 -05:00
J. Bruce Fields 28df3d1539 nfsd: clients don't need to break their own delegations
We currently revoke read delegations on any write open or any operation
that modifies file data or metadata (including rename, link, and
unlink).  But if the delegation in question is the only read delegation
and is held by the client performing the operation, that's not really
necessary.

It's not always possible to prevent this in the NFSv4.0 case, because
there's not always a way to determine which client an NFSv4.0 delegation
came from.  (In theory we could try to guess this from the transport
layer, e.g., by assuming all traffic on a given TCP connection comes
from the same client.  But that's not really correct.)

In the NFSv4.1 case the session layer always tells us the client.

This patch should remove such self-conflicts in all cases where we can
reliably determine the client from the compound.

To do that we need to track "who" is performing a given (possibly
lease-breaking) file operation.  We're doing that by storing the
information in the svc_rqst and using kthread_data() to map the current
task back to a svc_rqst.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2020-05-08 21:23:10 -04:00
Mauro Carvalho Chehab a02dcdf65b docs: filesystems: convert mandatory-locking.txt to ReST
- Add a SPDX header;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Use notes markups;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/aecd6259fe9f99b2c2b3440eab6a2b989125e00d.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-05-05 09:22:22 -06:00
Alexey Gladkov c59f415a7c Use proc_pid_ns() to get pid_namespace from the proc superblock
To get pid_namespace from the procfs superblock should be used a special
helper. This will avoid errors when s_fs_info will change the type.

Link: https://lore.kernel.org/lkml/20200423200316.164518-3-gladkov.alexey@gmail.com/
Link: https://lore.kernel.org/lkml/20200423112858.95820-1-gladkov.alexey@gmail.com/
Link: https://lore.kernel.org/lkml/06B50A1C-406F-4057-BFA8-3A7729EA7469@lca.pw/
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2020-04-24 16:38:30 -05:00
Linus Torvalds dcf23ac3e8 locks: reinstate locks_delete_block optimization
There is measurable performance impact in some synthetic tests due to
commit 6d390e4b5d (locks: fix a potential use-after-free problem when
wakeup a waiter). Fix the race condition instead by clearing the
fl_blocker pointer after the wake_up, using explicit acquire/release
semantics.

This does mean that we can no longer use the clearing of fl_blocker as
the wait condition, so switch the waiters over to checking whether the
fl_blocked_member list_head is empty.

Reviewed-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Fixes: 6d390e4b5d (locks: fix a potential use-after-free problem when wakeup a waiter)
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-03-18 13:03:38 -07:00
yangerkun 6d390e4b5d locks: fix a potential use-after-free problem when wakeup a waiter
'16306a61d3b7 ("fs/locks: always delete_block after waiting.")' add the
logic to check waiter->fl_blocker without blocked_lock_lock. And it will
trigger a UAF when we try to wakeup some waiter:

Thread 1 has create a write flock a on file, and now thread 2 try to
unlock and delete flock a, thread 3 try to add flock b on the same file.

Thread2                         Thread3
                                flock syscall(create flock b)
	                        ...flock_lock_inode_wait
				    flock_lock_inode(will insert
				    our fl_blocked_member list
				    to flock a's fl_blocked_requests)
				   sleep
flock syscall(unlock)
...flock_lock_inode_wait
    locks_delete_lock_ctx
    ...__locks_wake_up_blocks
        __locks_delete_blocks(
	b->fl_blocker = NULL)
	...
                                   break by a signal
				   locks_delete_block
				    b->fl_blocker == NULL &&
				    list_empty(&b->fl_blocked_requests)
	                            success, return directly
				 locks_free_lock b
	wake_up(&b->fl_waiter)
	trigger UAF

Fix it by remove this logic, and this patch may also fix CVE-2019-19769.

Cc: stable@vger.kernel.org
Fixes: 16306a61d3 ("fs/locks: always delete_block after waiting.")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2020-03-06 11:54:13 -05:00
Amir Goldstein 98ca480a8f locks: print unsigned ino in /proc/locks
An ino is unsigned, so display it as such in /proc/locks.

Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-12-29 09:00:58 -05:00
Linus Torvalds 298fb76a55 Highlights:
- add a new knfsd file cache, so that we don't have to open and
 	  close on each (NFSv2/v3) READ or WRITE.  This can speed up
 	  read and write in some cases.  It also replaces our readahead
 	  cache.
 	- Prevent silent data loss on write errors, by treating write
 	  errors like server reboots for the purposes of write caching,
 	  thus forcing clients to resend their writes.
 	- Tweak the code that allocates sessions to be more forgiving,
 	  so that NFSv4.1 mounts are less likely to hang when a server
 	  already has a lot of clients.
 	- Eliminate an arbitrary limit on NFSv4 ACL sizes; they should
 	  now be limited only by the backend filesystem and the
 	  maximum RPC size.
 	- Allow the server to enforce use of the correct kerberos
 	  credentials when a client reclaims state after a reboot.
 
 And some miscellaneous smaller bugfixes and cleanup.
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Merge tag 'nfsd-5.4' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Highlights:

   - Add a new knfsd file cache, so that we don't have to open and close
     on each (NFSv2/v3) READ or WRITE. This can speed up read and write
     in some cases. It also replaces our readahead cache.

   - Prevent silent data loss on write errors, by treating write errors
     like server reboots for the purposes of write caching, thus forcing
     clients to resend their writes.

   - Tweak the code that allocates sessions to be more forgiving, so
     that NFSv4.1 mounts are less likely to hang when a server already
     has a lot of clients.

   - Eliminate an arbitrary limit on NFSv4 ACL sizes; they should now be
     limited only by the backend filesystem and the maximum RPC size.

   - Allow the server to enforce use of the correct kerberos credentials
     when a client reclaims state after a reboot.

  And some miscellaneous smaller bugfixes and cleanup"

* tag 'nfsd-5.4' of git://linux-nfs.org/~bfields/linux: (34 commits)
  sunrpc: clean up indentation issue
  nfsd: fix nfs read eof detection
  nfsd: Make nfsd_reset_boot_verifier_locked static
  nfsd: degraded slot-count more gracefully as allocation nears exhaustion.
  nfsd: handle drc over-allocation gracefully.
  nfsd: add support for upcall version 2
  nfsd: add a "GetVersion" upcall for nfsdcld
  nfsd: Reset the boot verifier on all write I/O errors
  nfsd: Don't garbage collect files that might contain write errors
  nfsd: Support the server resetting the boot verifier
  nfsd: nfsd_file cache entries should be per net namespace
  nfsd: eliminate an unnecessary acl size limit
  Deprecate nfsd fault injection
  nfsd: remove duplicated include from filecache.c
  nfsd: Fix the documentation for svcxdr_tmpalloc()
  nfsd: Fix up some unused variable warnings
  nfsd: close cached files prior to a REMOVE or RENAME that would replace target
  nfsd: rip out the raparms cache
  nfsd: have nfsd_test_lock use the nfsd_file cache
  nfsd: hook up nfs4_preprocess_stateid_op to the nfsd_file cache
  ...
2019-09-27 17:00:27 -07:00
Wenwen Wang cfddf9f4c9 locks: fix a memory leak bug in __break_lease()
In __break_lease(), the file lock 'new_fl' is allocated in lease_alloc().
However, it is not deallocated in the following execution if
smp_load_acquire() fails, leading to a memory leak bug. To fix this issue,
free 'new_fl' before returning the error.

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-08-20 05:48:52 -04:00
Jeff Layton eb82dd3937 nfsd: convert fi_deleg_file and ls_file fields to nfsd_file
Have them keep an nfsd_file reference instead of a struct file.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-08-19 11:09:09 -04:00
Jeff Layton 18f6622ebb locks: create a new notifier chain for lease attempts
With the new file caching infrastructure in nfsd, we can end up holding
files open for an indefinite period of time, even when they are still
idle. This may prevent the kernel from handing out leases on the file,
which is something we don't want to block.

Fix this by running a SRCU notifier call chain whenever on any
lease attempt. nfsd can then purge the cache for that inode before
returning.

Since SRCU is only conditionally compiled in, we must only define the
new chain if it's enabled, and users of the chain must ensure that
SRCU is enabled.

Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-08-19 11:00:39 -04:00
Pavel Begunkov 43e4cb942e locks: Fix procfs output for file leases
Since commit 778fc546f7 ("locks: fix tracking of inprogress
lease breaks"), leases break don't change @fl_type but modifies
@fl_flags. However, procfs's part haven't been updated.

Previously, for a breaking lease the target type was printed (see
target_leasetype()), as returns fcntl(F_GETLEASE). But now it's always
"READ", as F_UNLCK no longer means "breaking". Unlike the previous
one, this behaviour don't provide a complete description of the lease.

There are /proc/pid/fdinfo/ outputs for a lease (the same for READ and
WRITE) breaked by O_WRONLY.
-- before:
lock:   1: LEASE  BREAKING  READ  2558 08:03:815793 0 EOF
-- after:
lock:   1: LEASE  BREAKING  UNLCK  2558 08:03:815793 0 EOF

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-07-25 07:49:44 -04:00
Linus Torvalds d2b6b4c832 Highlights:
- Add a new /proc/fs/nfsd/clients/ directory which exposes some
   long-requested information about NFSv4 clients (like open files) and
   allows forced revocation of client state.
 
 - Replace the global duplicate reply cache by a cache per network
   namespace; previously, a request in one network namespace could
   incorrectly match an entry from another, though we haven't seen this
   in production.  This is the last remaining container bug that I'm
   aware of; at this point you should be able to run separate nfsd's in
   each network namespace, each with their own set of exports, and
   everything should work.
 
 - Cleanup and modify lock code to show the pid of lockd as the owner of
   NLM locks.  This is the correct version of the bugfix originally
   attempted in b8eee0e90f "lockd: Show pid of lockd for remote locks".
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Merge tag 'nfsd-5.3' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "Highlights:

   - Add a new /proc/fs/nfsd/clients/ directory which exposes some
     long-requested information about NFSv4 clients (like open files)
     and allows forced revocation of client state.

   - Replace the global duplicate reply cache by a cache per network
     namespace; previously, a request in one network namespace could
     incorrectly match an entry from another, though we haven't seen
     this in production. This is the last remaining container bug that
     I'm aware of; at this point you should be able to run separate
     nfsd's in each network namespace, each with their own set of
     exports, and everything should work.

   - Cleanup and modify lock code to show the pid of lockd as the owner
     of NLM locks. This is the correct version of the bugfix originally
     attempted in b8eee0e90f ("lockd: Show pid of lockd for remote
     locks")"

* tag 'nfsd-5.3' of git://linux-nfs.org/~bfields/linux: (34 commits)
  nfsd: Make __get_nfsdfs_client() static
  nfsd: Make two functions static
  nfsd: Fix misuse of strlcpy
  sunrpc/cache: remove the exporting of cache_seq_next
  nfsd: decode implementation id
  nfsd: create xdr_netobj_dup helper
  nfsd: allow forced expiration of NFSv4 clients
  nfsd: create get_nfsdfs_clp helper
  nfsd4: show layout stateids
  nfsd: show lock and deleg stateids
  nfsd4: add file to display list of client's opens
  nfsd: add more information to client info file
  nfsd: escape high characters in binary data
  nfsd: copy client's address including port number to cl_addr
  nfsd4: add a client info file
  nfsd: make client/ directory names small ints
  nfsd: add nfsd/clients directory
  nfsd4: use reference count to free client
  nfsd: rename cl_refcount
  nfsd: persist nfsd filesystem across mounts
  ...
2019-07-10 21:22:43 -07:00
Benjamin Coddington f85d93385e locks: Cleanup lm_compare_owner and lm_owner_key
After the update to use nlm_lockowners for the NLM server, there are no
more users of lm_compare_owner and lm_owner_key.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-07-03 17:52:09 -04:00
Amir Goldstein 387e3746d0 locks: eliminate false positive conflicts for write lease
check_conflicting_open() is checking for existing fd's open for read or
for write before allowing to take a write lease.  The check that was
implemented using i_count and d_count is an approximation that has
several false positives.  For example, overlayfs since v4.19, takes an
extra reference on the dentry; An open with O_PATH takes a reference on
the dentry although the file cannot be read nor written.

Change the implementation to use i_readcount and i_writecount to
eliminate the false positive conflicts and allow a write lease to be
taken on an overlayfs file.

The change of behavior with existing fd's open with O_PATH is symmetric
w.r.t. current behavior of lease breakers - an open with O_PATH currently
does not break a write lease.

This increases the size of struct inode by 4 bytes on 32bit archs when
CONFIG_FILE_LOCKING is defined and CONFIG_IMA was not already
defined.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-06-19 08:49:38 -04:00
Ira Weiny d51f527f44 locks: Add trace_leases_conflict
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-06-19 08:49:37 -04:00
Thomas Gleixner 457c899653 treewide: Add SPDX license identifier for missed files
Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:45 +02:00
Linus Torvalds 700a800a94 This pull consists mostly of nfsd container work:
Scott Mayhew revived an old api that communicates with a userspace
 daemon to manage some on-disk state that's used to track clients across
 server reboots.  We've been using a usermode_helper upcall for that, but
 it's tough to run those with the right namespaces, so a daemon is much
 friendlier to container use cases.
 
 Trond fixed nfsd's handling of user credentials in user namespaces.  He
 also contributed patches that allow containers to support different sets
 of NFS protocol versions.
 
 The only remaining container bug I'm aware of is that the NFS reply
 cache is shared between all containers.  If anyone's aware of other gaps
 in our container support, let me know.
 
 The rest of this is miscellaneous bugfixes.
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Merge tag 'nfsd-5.2' of git://linux-nfs.org/~bfields/linux

Pull nfsd updates from Bruce Fields:
 "This consists mostly of nfsd container work:

  Scott Mayhew revived an old api that communicates with a userspace
  daemon to manage some on-disk state that's used to track clients
  across server reboots. We've been using a usermode_helper upcall for
  that, but it's tough to run those with the right namespaces, so a
  daemon is much friendlier to container use cases.

  Trond fixed nfsd's handling of user credentials in user namespaces. He
  also contributed patches that allow containers to support different
  sets of NFS protocol versions.

  The only remaining container bug I'm aware of is that the NFS reply
  cache is shared between all containers. If anyone's aware of other
  gaps in our container support, let me know.

  The rest of this is miscellaneous bugfixes"

* tag 'nfsd-5.2' of git://linux-nfs.org/~bfields/linux: (23 commits)
  nfsd: update callback done processing
  locks: move checks from locks_free_lock() to locks_release_private()
  nfsd: fh_drop_write in nfsd_unlink
  nfsd: allow fh_want_write to be called twice
  nfsd: knfsd must use the container user namespace
  SUNRPC: rsi_parse() should use the current user namespace
  SUNRPC: Fix the server AUTH_UNIX userspace mappings
  lockd: Pass the user cred from knfsd when starting the lockd server
  SUNRPC: Temporary sockets should inherit the cred from their parent
  SUNRPC: Cache the process user cred in the RPC server listener
  nfsd: Allow containers to set supported nfs versions
  nfsd: Add custom rpcbind callbacks for knfsd
  SUNRPC: Allow further customisation of RPC program registration
  SUNRPC: Clean up generic dispatcher code
  SUNRPC: Add a callback to initialise server requests
  SUNRPC/nfs: Fix return value for nfs4_callback_compound()
  nfsd: handle legacy client tracking records sent by nfsdcld
  nfsd: re-order client tracking method selection
  nfsd: keep a tally of RECLAIM_COMPLETE operations when using nfsdcld
  nfsd: un-deprecate nfsdcld
  ...
2019-05-15 18:21:43 -07:00
Linus Torvalds b4b52b881c Wimplicit-fallthrough patches for 5.2-rc1
Hi Linus,
 
 This is my very first pull-request.  I've been working full-time as
 a kernel developer for more than two years now. During this time I've
 been fixing bugs reported by Coverity all over the tree and, as part
 of my work, I'm also contributing to the KSPP. My work in the kernel
 community has been supervised by Greg KH and Kees Cook.
 
 OK. So, after the quick introduction above, please, pull the following
 patches that mark switch cases where we are expecting to fall through.
 These patches are part of the ongoing efforts to enable -Wimplicit-fallthrough.
 They have been ignored for a long time (most of them more than 3 months,
 even after pinging multiple times), which is the reason why I've created
 this tree. Most of them have been baking in linux-next for a whole development
 cycle. And with Stephen Rothwell's help, we've had linux-next nag-emails
 going out for newly introduced code that triggers -Wimplicit-fallthrough
 to avoid gaining more of these cases while we work to remove the ones
 that are already present.
 
 I'm happy to let you know that we are getting close to completing this
 work.  Currently, there are only 32 of 2311 of these cases left to be
 addressed in linux-next.  I'm auditing every case; I take a look into
 the code and analyze it in order to determine if I'm dealing with an
 actual bug or a false positive, as explained here:
 
 https://lore.kernel.org/lkml/c2fad584-1705-a5f2-d63c-824e9b96cf50@embeddedor.com/
 
 While working on this, I've found and fixed the following missing
 break/return bugs, some of them introduced more than 5 years ago:
 
 84242b82d8
 7850b51b6c
 5e420fe635
 09186e5034
 b5be853181
 7264235ee7
 cc5034a5d2
 479826cc86
 5340f23df8
 df997abeeb
 2f10d82373
 307b00c5e6
 5d25ff7a54
 a7ed5b3e7d
 c24bfa8f21
 ad0eaee619
 9ba8376ce1
 dc586a60a1
 a8e9b186f1
 4e57562b48
 60747828ea
 c5b974bee9
 cc44ba9116
 2c930e3d0a
 
 Once this work is finish, we'll be able to universally enable
 "-Wimplicit-fallthrough" to avoid any of these kinds of bugs from
 entering the kernel again.
 
 Thanks
 
 Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
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Merge tag 'Wimplicit-fallthrough-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull Wimplicit-fallthrough updates from Gustavo A. R. Silva:
 "Mark switch cases where we are expecting to fall through.

  This is part of the ongoing efforts to enable -Wimplicit-fallthrough.

  Most of them have been baking in linux-next for a whole development
  cycle. And with Stephen Rothwell's help, we've had linux-next
  nag-emails going out for newly introduced code that triggers
  -Wimplicit-fallthrough to avoid gaining more of these cases while we
  work to remove the ones that are already present.

  We are getting close to completing this work. Currently, there are
  only 32 of 2311 of these cases left to be addressed in linux-next. I'm
  auditing every case; I take a look into the code and analyze it in
  order to determine if I'm dealing with an actual bug or a false
  positive, as explained here:

      https://lore.kernel.org/lkml/c2fad584-1705-a5f2-d63c-824e9b96cf50@embeddedor.com/

  While working on this, I've found and fixed the several missing
  break/return bugs, some of them introduced more than 5 years ago.

  Once this work is finished, we'll be able to universally enable
  "-Wimplicit-fallthrough" to avoid any of these kinds of bugs from
  entering the kernel again"

* tag 'Wimplicit-fallthrough-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (27 commits)
  memstick: mark expected switch fall-throughs
  drm/nouveau/nvkm: mark expected switch fall-throughs
  NFC: st21nfca: Fix fall-through warnings
  NFC: pn533: mark expected switch fall-throughs
  block: Mark expected switch fall-throughs
  ASN.1: mark expected switch fall-through
  lib/cmdline.c: mark expected switch fall-throughs
  lib: zstd: Mark expected switch fall-throughs
  scsi: sym53c8xx_2: sym_nvram: Mark expected switch fall-through
  scsi: sym53c8xx_2: sym_hipd: mark expected switch fall-throughs
  scsi: ppa: mark expected switch fall-through
  scsi: osst: mark expected switch fall-throughs
  scsi: lpfc: lpfc_scsi: Mark expected switch fall-throughs
  scsi: lpfc: lpfc_nvme: Mark expected switch fall-through
  scsi: lpfc: lpfc_nportdisc: Mark expected switch fall-through
  scsi: lpfc: lpfc_hbadisc: Mark expected switch fall-throughs
  scsi: lpfc: lpfc_els: Mark expected switch fall-throughs
  scsi: lpfc: lpfc_ct: Mark expected switch fall-throughs
  scsi: imm: mark expected switch fall-throughs
  scsi: csiostor: csio_wr: mark expected switch fall-through
  ...
2019-05-07 12:48:10 -07:00
NeilBrown 5926459e7c locks: move checks from locks_free_lock() to locks_release_private()
Code that allocates locks using locks_alloc_lock() will free it
using locks_free_lock(), and will benefit from the BUG_ON()
consistency checks therein.

However some code (nfsd and lockd) allocate a lock embedded in
some other data structure, and so free the lock themselves after
calling locks_release_private().  This path does not benefit from
the consistency checks.

To help catch future errors, move the BUG_ON() checks to
locks_release_private() - which locks_free_lock() already calls.
This ensures that all users for locks will find out if the lock
isn't detached properly before being free.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2019-04-24 09:51:48 -04:00
Gustavo A. R. Silva 0a4c92657f fs: mark expected switch fall-throughs
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

This patch fixes the following warnings:

fs/affs/affs.h:124:38: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1692:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1694:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ceph/file.c:249:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:233:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:246:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1237:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1244:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1182:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1188:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1432:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1440:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:618:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:620:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/btrfs/ref-verify.c:522:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:711:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:722:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/jffs2/fs.c:339:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/nfsd/nfs4proc.c:429:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:62:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:43:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/fcntl.c:770:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/seq_file.c:319:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:148:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:150:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/signalfd.c:178:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/locks.c:1473:16: warning: this statement may fall through [-Wimplicit-fallthrough=]

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling
-Wimplicit-fallthrough.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
2019-04-08 18:21:02 -05:00
Jeff Layton 945ab8f6de locks: wake any locks blocked on request before deadlock check
Andreas reported that he was seeing the tdbtorture test fail in some
cases with -EDEADLCK when it wasn't before. Some debugging showed that
deadlock detection was sometimes discovering the caller's lock request
itself in a dependency chain.

While we remove the request from the blocked_lock_hash prior to
reattempting to acquire it, any locks that are blocked on that request
will still be present in the hash and will still have their fl_blocker
pointer set to the current request.

This causes posix_locks_deadlock to find a deadlock dependency chain
when it shouldn't, as a lock request cannot block itself.

We are going to end up waking all of those blocked locks anyway when we
go to reinsert the request back into the blocked_lock_hash, so just do
it prior to checking for deadlocks. This ensures that any lock blocked
on the current request will no longer be part of any blocked request
chain.

URL: https://bugzilla.kernel.org/show_bug.cgi?id=202975
Fixes: 5946c4319e ("fs/locks: allow a lock request to block other requests.")
Cc: stable@vger.kernel.org
Reported-by: Andreas Schneider <asn@redhat.com>
Signed-off-by: Neil Brown <neilb@suse.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-03-25 08:36:24 -04:00
Peter Zijlstra 02e525b2af locking/percpu-rwsem: Remove preempt_disable variants
Effective revert commit:

  87709e28dc ("fs/locks: Use percpu_down_read_preempt_disable()")

This is causing major pain for PREEMPT_RT.

Sebastian did a lot of lockperf runs on 2 and 4 node machines with all
preemption modes (PREEMPT=n should be an obvious NOP for this patch
and thus serves as a good control) and no results showed significance
over 2-sigma (the PREEMPT=n results were almost empty at 1-sigma).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-28 07:55:37 +01:00
NeilBrown bf77ae4c98 locks: fix error in locks_move_blocks()
After moving all requests from
   fl->fl_blocked_requests
to
   new->fl_blocked_requests

it is nonsensical to do anything to all the remaining elements, there
aren't any.  This should do something to all the requests that have been
moved. For simplicity, it does it to all requests in the target list.

Setting "f->fl_blocker = new" to all members of new->fl_blocked_requests
is "obviously correct" as it preserves the invariant of the linkage
among requests.

Reported-by: syzbot+239d99847eb49ecb3899@syzkaller.appspotmail.com
Fixes: 5946c4319e ("fs/locks: allow a lock request to block other requests.")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2019-01-02 20:14:50 -05:00
Nikolay Borisov 052b8cfa40 locks: Use inode_is_open_for_write
Use the aptly named function rather than open coding it. No functional
changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-17 07:19:46 -05:00
NeilBrown 7bbd1fc0e9 fs/locks: remove unnecessary white space.
- spaces before tabs,
 - spaces at the end of lines,
 - multiple blank lines,
 - blank lines before EXPORT_SYMBOL,
can all go.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-07 06:51:00 -05:00
NeilBrown cb03f94ffb fs/locks: merge posix_unblock_lock() and locks_delete_block()
posix_unblock_lock() is not specific to posix locks, and behaves
nearly identically to locks_delete_block() - the former returning a
status while the later doesn't.

So discard posix_unblock_lock() and use locks_delete_block() instead,
after giving that function an appropriate return value.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-07 06:50:56 -05:00
NeilBrown fd7732e033 fs/locks: create a tree of dependent requests.
When we find an existing lock which conflicts with a request,
and the request wants to wait, we currently add the request
to a list.  When the lock is removed, the whole list is woken.
This can cause the thundering-herd problem.
To reduce the problem, we make use of the (new) fact that
a pending request can itself have a list of blocked requests.
When we find a conflict, we look through the existing blocked requests.
If any one of them blocks the new request, the new request is attached
below that request, otherwise it is added to the list of blocked
requests, which are now known to be mutually non-conflicting.

This way, when the lock is released, only a set of non-conflicting
locks will be woken, the rest can stay asleep.
If the lock request cannot be granted and the request needs to be
requeued, all the other requests it blocks will then be woken

To make this more concrete:

  If you have a many-core machine, and have many threads all wanting to
  briefly lock a give file (udev is known to do this), you can get quite
  poor performance.

  When one thread releases a lock, it wakes up all other threads that
  are waiting (classic thundering-herd) - one will get the lock and the
  others go to sleep.
  When you have few cores, this is not very noticeable: by the time the
  4th or 5th thread gets enough CPU time to try to claim the lock, the
  earlier threads have claimed it, done what was needed, and released.
  So with few cores, many of the threads don't end up contending.
  With 50+ cores, lost of threads can get the CPU at the same time,
  and the contention can easily be measured.

  This patchset creates a tree of pending lock requests in which siblings
  don't conflict and each lock request does conflict with its parent.
  When a lock is released, only requests which don't conflict with each
  other a woken.

  Testing shows that lock-acquisitions-per-second is now fairly stable
  even as the number of contending process goes to 1000.  Without this
  patch, locks-per-second drops off steeply after a few 10s of
  processes.

  There is a small cost to this extra complexity.
  At 20 processes running a particular test on 72 cores, the lock
  acquisitions per second drops from 1.8 million to 1.4 million with
  this patch.  For 100 processes, this patch still provides 1.4 million
  while without this patch there are about 700,000.

Reported-and-tested-by: Martin Wilck <mwilck@suse.de>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-07 06:49:24 -05:00
NeilBrown c0e1590897 fs/locks: change all *_conflict() functions to return bool.
posix_locks_conflict() and flock_locks_conflict() both return int.
leases_conflict() returns bool.

This inconsistency will cause problems for the next patch if not
fixed.

So change posix_locks_conflict() and flock_locks_conflict() to return
bool.
Also change the locks_conflict() helper.

And convert some
   return (foo);
to
   return foo;

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-07 06:49:24 -05:00
NeilBrown 16306a61d3 fs/locks: always delete_block after waiting.
Now that requests can block other requests, we
need to be careful to always clean up those blocked
requests.
Any time that we wait for a request, we might have
other requests attached, and when we stop waiting,
we must clean them up.
If the lock was granted, the requests might have been
moved to the new lock, though when merged with a
pre-exiting lock, this might not happen.
In all cases we don't want blocked locks to remain
attached, so we remove them to be safe.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Tested-by: syzbot+a4a3d526b4157113ec6a@syzkaller.appspotmail.com
Tested-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-12-07 06:49:17 -05:00
NeilBrown 5946c4319e fs/locks: allow a lock request to block other requests.
Currently, a lock can block pending requests, but all pending
requests are equal.  If lots of pending requests are
mutually exclusive, this means they will all be woken up
and all but one will fail.  This can hurt performance.

So we will allow pending requests to block other requests.
Only the first request will be woken, and it will wake the others.

This patch doesn't implement this fully, but prepares the way.

- It acknowledges that a request might be blocking other requests,
  and when the request is converted to a lock, those blocked
  requests are moved across.
- When a request is requeued or discarded, all blocked requests are
  woken.
- When deadlock-detection looks for the lock which blocks a
  given request, we follow the chain of ->fl_blocker all
  the way to the top.

Tested-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-11-30 11:26:12 -05:00
NeilBrown d6367d6241 fs/locks: use properly initialized file_lock when unlocking.
Both locks_remove_posix() and locks_remove_flock() use a
struct file_lock without calling locks_init_lock() on it.
This means the various list_heads are not initialized, which
will become a problem with a later patch.

So change them both to initialize properly.  For flock locks,
this involves using flock_make_lock(), and changing it to
allow a file_lock to be passed in, so memory allocation isn't
always needed.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-11-30 11:26:12 -05:00
NeilBrown ad6bbd8b18 fs/locks: split out __locks_wake_up_blocks().
This functionality will be useful in future patches, so
split it out from locks_wake_up_blocks().

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
2018-11-30 11:26:12 -05:00