Allow the flexfiles error handling to recognise NFS level errors (as
opposed to RPC level errors) and handle them separately. The main
motivator is the NFSERR_PERM errors that get returned if the NFS client
connects to the data server through a port number that is lower than
1024. In that case, the client should disconnect and retry a READ on a
different data server, or it should retry a WRITE after reconnecting.

Reviewed-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Fixes: d67ae825a59d ("pnfs/flexfiles: Add the FlexFile Layout Driver")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

We found a few different systems hung up in writeback waiting on the same
page lock, and one task waiting on the NFS_LAYOUT_DRAIN bit in
pnfs_update_layout(), however the pnfs_layout_hdr's plh_outstanding count
was zero.

It seems most likely that this is another race between the waiter and waker
similar to commit ed0172af5d6f ("SUNRPC: Fix a race to wake a sync task").
Fix it up by applying the advised barrier.

Fixes: 880265c77ac4 ("pNFS: Avoid a live lock condition in pnfs_update_layout()")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

syzbot reported a warning below [1] following a fault injection in
nfs_fs_proc_net_init(). [0]

When nfs_fs_proc_net_init() fails, /proc/net/rpc/nfs is not removed.

Later, rpc_proc_exit() tries to remove /proc/net/rpc, and the warning
is logged as the directory is not empty.

Let's handle the error of nfs_fs_proc_net_init() properly.

[0]:
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
CPU: 1 UID: 0 PID: 6120 Comm: syz.2.27 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
  dump_stack_lvl (lib/dump_stack.c:123)
 should_fail_ex (lib/fault-inject.c:73 lib/fault-inject.c:174)
 should_failslab (mm/failslab.c:46)
 kmem_cache_alloc_noprof (mm/slub.c:4178 mm/slub.c:4204)
 __proc_create (fs/proc/generic.c:427)
 proc_create_reg (fs/proc/generic.c:554)
 proc_create_net_data (fs/proc/proc_net.c:120)
 nfs_fs_proc_net_init (fs/nfs/client.c:1409)
 nfs_net_init (fs/nfs/inode.c:2600)
 ops_init (net/core/net_namespace.c:138)
 setup_net (net/core/net_namespace.c:443)
 copy_net_ns (net/core/net_namespace.c:576)
 create_new_namespaces (kernel/nsproxy.c:110)
 unshare_nsproxy_namespaces (kernel/nsproxy.c:218 (discriminator 4))
 ksys_unshare (kernel/fork.c:3123)
 __x64_sys_unshare (kernel/fork.c:3190)
 do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
 </TASK>

[1]:
remove_proc_entry: removing non-empty directory 'net/rpc', leaking at least 'nfs'
 WARNING: CPU: 1 PID: 6120 at fs/proc/generic.c:727 remove_proc_entry+0x45e/0x530 fs/proc/generic.c:727
Modules linked in:
CPU: 1 UID: 0 PID: 6120 Comm: syz.2.27 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
 RIP: 0010:remove_proc_entry+0x45e/0x530 fs/proc/generic.c:727
Code: 3c 02 00 0f 85 85 00 00 00 48 8b 93 d8 00 00 00 4d 89 f0 4c 89 e9 48 c7 c6 40 ba a2 8b 48 c7 c7 60 b9 a2 8b e8 33 81 1d ff 90 <0f> 0b 90 90 e9 5f fe ff ff e8 04 69 5e ff 90 48 b8 00 00 00 00 00
RSP: 0018:ffffc90003637b08 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88805f534140 RCX: ffffffff817a92c8
RDX: ffff88807da99e00 RSI: ffffffff817a92d5 RDI: 0000000000000001
RBP: ffff888033431ac0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff888033431a00
R13: ffff888033431ae4 R14: ffff888033184724 R15: dffffc0000000000
FS:  0000555580328500(0000) GS:ffff888124a62000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f71733743e0 CR3: 000000007f618000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
  sunrpc_exit_net+0x46/0x90 net/sunrpc/sunrpc_syms.c:76
  ops_exit_list net/core/net_namespace.c:200 [inline]
  ops_undo_list+0x2eb/0xab0 net/core/net_namespace.c:253
  setup_net+0x2e1/0x510 net/core/net_namespace.c:457
  copy_net_ns+0x2a6/0x5f0 net/core/net_namespace.c:574
  create_new_namespaces+0x3ea/0xa90 kernel/nsproxy.c:110
  unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:218
  ksys_unshare+0x45b/0xa40 kernel/fork.c:3121
  __do_sys_unshare kernel/fork.c:3192 [inline]
  __se_sys_unshare kernel/fork.c:3190 [inline]
  __x64_sys_unshare+0x31/0x40 kernel/fork.c:3190
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa1a6b8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff3a090368 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007fa1a6db5fa0 RCX: 00007fa1a6b8e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000080
RBP: 00007fa1a6c10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa1a6db5fa0 R14: 00007fa1a6db5fa0 R15: 0000000000000001
 </TASK>

Fixes: d47151b79e32 ("nfs: expose /proc/net/sunrpc/nfs in net namespaces")
Reported-by: syzbot+a4cc4ac22daa4a71b87c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=a4cc4ac22daa4a71b87c
Tested-by: syzbot+a4cc4ac22daa4a71b87c@syzkaller.appspotmail.com
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Pull NFS clent updates from Anna Schumaker:
 "New Features:

   - Implement the Sunrpc rfc2203 rpcsec_gss sequence number cache

   - Add support for FALLOC_FL_ZERO_RANGE on NFS v4.2

   - Add a localio sysfs attribute

  Stable Fixes:

   - Fix double-unlock bug in nfs_return_empty_folio()

   - Don't check for OPEN feature support in v4.1

   - Always probe for LOCALIO support asynchronously

   - Prevent hang on NFS mounts with xprtsec=[m]tls

  Other Bugfixes:

   - xattr handlers should check for absent nfs filehandles

   - Fix setattr caching of TIME_[MODIFY|ACCESS]_SET when timestamps are
     delegated

   - Fix listxattr to return selinux security labels

   - Connect to NFSv3 DS using TLS if MDS connection uses TLS

   - Clear SB_RDONLY before getting a superblock, and ignore when
     remounting

   - Fix incorrect handling of NFS error codes in nfs4_do_mkdir()

   - Various nfs_localio fixes from Neil Brown that include fixing an
     rcu compilation error found by older gcc versions.

   - Update stats on flexfiles pNFS DSes when receiving NFS4ERR_DELAY

  Cleanups:

   - Add a refcount tracker for struct net in the nfs_client

   - Allow FREE_STATEID to clean up delegations

   - Always set NLINK even if the server doesn't support it

   - Cleanups to the NFS folio writeback code

   - Remove dead code from xs_tcp_tls_setup_socket()"

* tag 'nfs-for-6.16-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (30 commits)
  flexfiles/pNFS: update stats on NFS4ERR_DELAY for v4.1 DSes
  nfs_localio: change nfsd_file_put_local() to take a pointer to __rcu pointer
  nfs_localio: protect race between nfs_uuid_put() and nfs_close_local_fh()
  nfs_localio: duplicate nfs_close_local_fh()
  nfs_localio: simplify interface to nfsd for getting nfsd_file
  nfs_localio: always hold nfsd net ref with nfsd_file ref
  nfs_localio: use cmpxchg() to install new nfs_file_localio
  SUNRPC: Remove dead code from xs_tcp_tls_setup_socket()
  SUNRPC: Prevent hang on NFS mount with xprtsec=[m]tls
  nfs: fix incorrect handling of large-number NFS errors in nfs4_do_mkdir()
  nfs: ignore SB_RDONLY when remounting nfs
  nfs: clear SB_RDONLY before getting superblock
  NFS: always probe for LOCALIO support asynchronously
  pnfs/flexfiles: connect to NFSv3 DS using TLS if MDS connection uses TLS
  NFS: add localio to sysfs
  nfs: use writeback_iter directly
  nfs: refactor nfs_do_writepage
  nfs: don't return AOP_WRITEPAGE_ACTIVATE from nfs_do_writepage
  nfs: fold nfs_page_async_flush into nfs_do_writepage
  NFSv4: Always set NLINK even if the server doesn't support it
  ...

Pull netfs updates from Christian Brauner:

 - The main API document has been extensively updated/rewritten

 - Fix an oops in write-retry due to mis-resetting the I/O iterator

 - Fix the recording of transferred bytes for short DIO reads

 - Fix a request's work item to not require a reference, thereby
   avoiding the need to get rid of it in BH/IRQ context

 - Fix waiting and waking to be consistent about the waitqueue used

 - Remove NETFS_SREQ_SEEK_DATA_READ, NETFS_INVALID_WRITE,
   NETFS_ICTX_WRITETHROUGH, NETFS_READ_HOLE_CLEAR,
   NETFS_RREQ_DONT_UNLOCK_FOLIOS, and NETFS_RREQ_BLOCKED

 - Reorder structs to eliminate holes

 - Remove netfs_io_request::ractl

 - Only provide proc_link field if CONFIG_PROC_FS=y

 - Remove folio_queue::marks3

 - Fix undifferentiation of DIO reads from unbuffered reads

* tag 'vfs-6.16-rc1.netfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  netfs: Fix undifferentiation of DIO reads from unbuffered reads
  netfs: Fix wait/wake to be consistent about the waitqueue used
  netfs: Fix the request's work item to not require a ref
  netfs: Fix setting of transferred bytes with short DIO reads
  netfs: Fix oops in write-retry from mis-resetting the subreq iterator
  fs/netfs: remove unused flag NETFS_RREQ_BLOCKED
  fs/netfs: remove unused flag NETFS_RREQ_DONT_UNLOCK_FOLIOS
  folio_queue: remove unused field `marks3`
  fs/netfs: declare field `proc_link` only if CONFIG_PROC_FS=y
  fs/netfs: remove `netfs_io_request.ractl`
  fs/netfs: reorder struct fields to eliminate holes
  fs/netfs: remove unused enum choice NETFS_READ_HOLE_CLEAR
  fs/netfs: remove unused flag NETFS_ICTX_WRITETHROUGH
  fs/netfs: remove unused source NETFS_INVALID_WRITE
  fs/netfs: remove unused flag NETFS_SREQ_SEEK_DATA_READ

Pull automount updates from Al Viro:
 "Automount wart removal

  A bunch of odd boilerplate gone from instances - the reason for
  those was the need to protect the yet-to-be-attched mount from
  mark_mounts_for_expiry() deciding to take it out.

  But that's easy to detect and take care of in mark_mounts_for_expiry()
  itself; no need to have every instance simulate mount being busy by
  grabbing an extra reference to it, with finish_automount() undoing
  that once it attaches that mount.

  Should've done it that way from the very beginning... This is a
  flagday change, thankfully there are very few instances.

  vfs_submount() is gone - its sole remaining user (trace_automount)
  had been switched to saner primitives"

* tag 'pull-automount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kill vfs_submount()
  saner calling conventions for ->d_automount()

On NFS4ERR_DELAY nfs slient updates its stats, but misses for
flexfiles v4.1 DSes.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Instead of calling xchg() and unrcu_pointer() before
nfsd_file_put_local(), we now pass pointer to the __rcu pointer and call
xchg() and unrcu_pointer() inside that function.

Where unrcu_pointer() is currently called the internals of "struct
nfsd_file" are not known and that causes older compilers such as gcc-8
to complain.

In some cases we have a __kernel (aka normal) pointer not an __rcu
pointer so we need to cast it to __rcu first.  This is strictly a
weakening so no information is lost.  Somewhat surprisingly, this cast
is accepted by gcc-8.

This has the pleasing result that the cmpxchg() which sets ro_file and
rw_file, and also the xchg() which clears them, are both now in the nfsd
code.

Reported-by: Pali Rohár <pali@kernel.org>
Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

The nfsd_localio_operations structure contains nfsd_file_get() to get a
reference to an nfsd_file.  This is only used in one place, where
nfsd_open_local_fh() is also used.

This patch combines the two, calling nfsd_open_local_fh() passing a
pointer to where the nfsd_file pointer might be stored.  If there is a
pointer there an nfsd_file_get() can get a reference, that reference is
returned.  If not a new nfsd_file is acquired, stored at the pointer,
and returned.  When we store a reference we also increase the refcount
on the net, as that refcount is decrements when we clear the stored
pointer.

We now get an extra reference *before* storing the new nfsd_file at the
given location.  This avoids possible races with the nfsd_file being
freed before the final reference can be taken.

This patch moves the rcu_dereference() needed after fetching from
ro_file or rw_file into the nfsd code where the 'struct nfs_file' is
fully defined.  This avoids an error reported by older versions of gcc
such as gcc-8 which complain about rcu_dereference() use in contexts
where the structure (which will supposedly be accessed) is not fully
defined.

Reported-by: Pali Rohár <pali@kernel.org>
Reported-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Having separate nfsd_file_put and nfsd_file_put_local in struct
nfsd_localio_operations doesn't make much sense.  The difference is that
nfsd_file_put doesn't drop a reference to the nfs_net which is what
keeps nfsd from shutting down.

Currently, if nfsd tries to shutdown it will invalidate the files stored
in the list from the nfs_uuid and this will drop all references to the
nfsd net that the client holds.  But the client could still hold some
references to nfsd_files for active IO.  So nfsd might think is has
completely shut down local IO, but hasn't and has no way to wait for
those active IO requests to complete.

So this patch changes nfsd_file_get to nfsd_file_get_local and has it
increase the ref count on the nfsd net and it replaces all calls to
->nfsd_put_file to ->nfsd_put_file_local.

It also changes ->nfsd_open_local_fh to return with the refcount on the
net elevated precisely when a valid nfsd_file is returned.

This means that whenever the client holds a valid nfsd_file, there will
be an associated count on the nfsd net, and so the count can only reach
zero when all nfsd_files have been returned.

nfs_local_file_put() is changed to call nfs_to_nfsd_file_put_local()
instead of replacing calls to one with calls to the other because this
will help a later patch which changes nfs_to_nfsd_file_put_local() to
take an __rcu pointer while nfs_local_file_put() doesn't.

Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client")
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>