linux.git/include/linux/nfs_fs.h, branch v6.1

NFS: Cleanup to remove unused flag NFS_CONTEXT_RESEND_WRITES

2022-08-13T17:02:14+00:00

Signed-off-by: Trond Myklebust

NFS: Fix another fsync() issue after a server reboot

2022-08-13T17:02:13+00:00

Currently, when the writeback code detects a server reboot, it redirties
any pages that were not committed to disk, and it sets the flag
NFS_CONTEXT_RESEND_WRITES in the nfs_open_context of the file descriptor
that dirtied the file. While this allows the file descriptor in question
to redrive its own writes, it violates the fsync() requirement that we
should be synchronising all writes to disk.
While the problem is infrequent, we do see corner cases where an
untimely server reboot causes the fsync() call to abandon its attempt to
sync data to disk and causing data corruption issues due to missed error
conditions or similar.

In order to tighted up the client's ability to deal with this situation
without introducing livelocks, add a counter that records the number of
times pages are redirtied due to a server reboot-like condition, and use
that in fsync() to redrive the sync to disk.

Fixes: 2197e9b06c22 ("NFS: Fix up fsync() when the server rebooted")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust

NFS: don't unhash dentry during unlink/rename

2022-08-08T20:25:56+00:00

NFS unlink() (and rename over existing target) must determine if the
file is open, and must perform a "silly rename" instead of an unlink (or
before rename) if it is.  Otherwise the client might hold a file open
which has been removed on the server.

Consequently if it determines that the file isn't open, it must block
any subsequent opens until the unlink/rename has been completed on the
server.

This is currently achieved by unhashing the dentry.  This forces any
open attempt to the slow-path for lookup which will block on i_rwsem on
the directory until the unlink/rename completes.  A future patch will
change the VFS to only get a shared lock on i_rwsem for unlink, so this
will no longer work.

Instead we introduce an explicit interlock.  A special value is stored
in dentry->d_fsdata while the unlink/rename is running and
->d_revalidate blocks while that value is present.  When ->d_revalidate
unblocks, the dentry will be invalid.  This closes the race
without requiring exclusion on i_rwsem.

d_fsdata is already used in two different ways.
1/ an IS_ROOT directory dentry might have a "devname" stored in
   d_fsdata.  Such a dentry doesn't have a name and so cannot be the
   target of unlink or rename.  For safety we check if an old devname
   is still stored, and remove it if it is.
2/ a dentry with DCACHE_NFSFS_RENAMED set will have a 'struct
   nfs_unlinkdata' stored in d_fsdata.  While this is set maydelete()
   will fail, so an unlink or rename will never proceed on such
   a dentry.

Neither of these can be in effect when a dentry is the target of unlink
or rename.  So we can expect d_fsdata to be NULL, and store a special
value ((void*)1) which is given the name NFS_FSDATA_BLOCKED to indicate
that any lookup will be blocked.

The d_count() is incremented under d_lock() when a lookup finds the
dentry, so we check d_count() is low, and set NFS_FSDATA_BLOCKED under
the same lock to avoid any races.

Signed-off-by: NeilBrown 
Signed-off-by: Trond Myklebust

Merge tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-05-26T19:32:41+00:00

Pull MM updates from Andrew Morton:
"Almost all of MM here. A few things are still getting finished off,
reviewed, etc.

- Yang Shi has improved the behaviour of khugepaged collapsing of
readonly file-backed transparent hugepages.

- Johannes Weiner has arranged for zswap memory use to be tracked and
managed on a per-cgroup basis.

- Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for
runtime enablement of the recent huge page vmemmap optimization
feature.

- Baolin Wang contributes a series to fix some issues around hugetlb
pagetable invalidation.

- Zhenwei Pi has fixed some interactions between hwpoisoned pages and
virtualization.

- Tong Tiangen has enabled the use of the presently x86-only
page_table_check debugging feature on arm64 and riscv.

- David Vernet has done some fixup work on the memcg selftests.

- Peter Xu has taught userfaultfd to handle write protection faults
against shmem- and hugetlbfs-backed files.

- More DAMON development from SeongJae Park - adding online tuning of
the feature and support for monitoring of fixed virtual address
ranges. Also easier discovery of which monitoring operations are
available.

- Nadav Amit has done some optimization of TLB flushing during
mprotect().

- Neil Brown continues to labor away at improving our swap-over-NFS
support.

- David Hildenbrand has some fixes to anon page COWing versus
get_user_pages().

- Peng Liu fixed some errors in the core hugetlb code.

- Joao Martins has reduced the amount of memory consumed by
device-dax's compound devmaps.

- Some cleanups of the arch-specific pagemap code from Anshuman
Khandual.

- Muchun Song has found and fixed some errors in the TLB flushing of
transparent hugepages.

- Roman Gushchin has done more work on the memcg selftests.

... and, of course, many smaller fixes and cleanups. Notably, the
customary million cleanup serieses from Miaohe Lin"

* tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (381 commits)
mm: kfence: use PAGE_ALIGNED helper
selftests: vm: add the "settings" file with timeout variable
selftests: vm: add "test_hmm.sh" to TEST_FILES
selftests: vm: check numa_available() before operating "merge_across_nodes" in ksm_tests
selftests: vm: add migration to the .gitignore
selftests/vm/pkeys: fix typo in comment
ksm: fix typo in comment
selftests: vm: add process_mrelease tests
Revert "mm/vmscan: never demote for memcg reclaim"
mm/kfence: print disabling or re-enabling message
include/trace/events/percpu.h: cleanup for "percpu: improve percpu_alloc_percpu event trace"
include/trace/events/mmflags.h: cleanup for "tracing: incorrect gfp_t conversion"
mm: fix a potential infinite loop in start_isolate_page_range()
MAINTAINERS: add Muchun as co-maintainer for HugeTLB
zram: fix Kconfig dependency warning
mm/shmem: fix shmem folio swapoff hang
cgroup: fix an error handling path in alloc_pagecache_max_30M()
mm: damon: use HPAGE_PMD_SIZE
tracing: incorrect isolate_mote_t cast in mm_vmscan_lru_isolate
nodemask.h: fix compilation error with GCC12
...

nfs: rename nfs_direct_IO and use as ->swap_rw

2022-05-10T01:20:48+00:00

The nfs_direct_IO() exists to support SWAP IO, but hasn't worked for a
while.  We now need a ->swap_rw function which behaves slightly
differently, returning zero for success rather than a byte count.

So modify nfs_direct_IO accordingly, rename it, and use it as the
->swap_rw function.

Link: https://lkml.kernel.org/r/165119301493.15698.7491285551903597618.stgit@noble.brown
Signed-off-by: NeilBrown 
Reviewed-by: Christoph Hellwig 
Tested-by: Geert Uytterhoeven  (on Renesas RSK+RZA1 with 32 MiB of SDRAM)
Cc: David Howells 
Cc: Hugh Dickins 
Cc: Mel Gorman 
Cc: Miaohe Lin 
Cc: Trond Myklebust 
Signed-off-by: Andrew Morton

nfs: Convert nfs to read_folio

2022-05-09T20:21:46+00:00

This is a "weak" conversion which converts straight back to using pages.
A full conversion should be performed at some point, hopefully by
someone familiar with the filesystem.

Signed-off-by: Matthew Wilcox (Oracle)

Merge tag 'nfs-for-5.18-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

2022-03-30T01:55:37+00:00

Pull NFS client updates from Trond Myklebust:
"Highlights include:

Features:

- Switch NFS to use readahead instead of the obsolete readpages.

- Readdir fixes to improve cacheability of large directories when
there are multiple readers and writers.

- Readdir performance improvements when doing a seekdir() immediately
after opening the directory (common when re-exporting NFS).

- NFS swap improvements from Neil Brown.

- Loosen up memory allocation to permit direct reclaim and write back
in cases where there is no danger of deadlocking the writeback code
or NFS swap.

- Avoid sillyrename when the NFSv4 server claims to support the
necessary features to recover the unlinked but open file after
reboot.

Bugfixes:

- Patch from Olga to add a mount option to control NFSv4.1 session
trunking discovery, and default it to being off.

- Fix a lockup in nfs_do_recoalesce().

- Two fixes for list iterator variables being used when pointing to
the list head.

- Fix a kernel memory scribble when reading from a non-socket
transport in /sys/kernel/sunrpc.

- Fix a race where reconnecting to a server could leave the TCP
socket stuck forever in the connecting state.

- Patch from Neil to fix a shutdown race which can leave the SUNRPC
transport timer primed after we free the struct xprt itself.

- Patch from Xin Xiong to fix reference count leaks in the NFSv4.2
copy offload.

- Sunrpc patch from Olga to avoid resending a task on an offlined
transport.

Cleanups:

- Patches from Dave Wysochanski to clean up the fscache code"

* tag 'nfs-for-5.18-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (91 commits)
NFSv4/pNFS: Fix another issue with a list iterator pointing to the head
NFS: Don't loop forever in nfs_do_recoalesce()
SUNRPC: Don't return error values in sysfs read of closed files
SUNRPC: Do not dereference non-socket transports in sysfs
NFSv4.1: don't retry BIND_CONN_TO_SESSION on session error
SUNRPC don't resend a task on an offlined transport
NFS: replace usage of found with dedicated list iterator variable
SUNRPC: avoid race between mod_timer() and del_timer_sync()
pNFS/files: Ensure pNFS allocation modes are consistent with nfsiod
pNFS/flexfiles: Ensure pNFS allocation modes are consistent with nfsiod
NFSv4/pnfs: Ensure pNFS allocation modes are consistent with nfsiod
NFS: Avoid writeback threads getting stuck in mempool_alloc()
NFS: nfsiod should not block forever in mempool_alloc()
SUNRPC: Make the rpciod and xprtiod slab allocation modes consistent
SUNRPC: Fix unx_lookup_cred() allocation
NFS: Fix memory allocation in rpc_alloc_task()
NFS: Fix memory allocation in rpc_malloc()
SUNRPC: Improve accuracy of socket ENOBUFS determination
SUNRPC: Replace internal use of SOCKWQ_ASYNC_NOSPACE
SUNRPC: Fix socket waits for write buffer space
...

NFS: nfsiod should not block forever in mempool_alloc()

2022-03-22T19:52:56+00:00

The concern is that since nfsiod is sometimes required to kick off a
commit, it can get locked up waiting forever in mempool_alloc() instead
of failing gracefully and leaving the commit until later.

Try to allocate from the slab first, with GFP_KERNEL | __GFP_NORETRY,
then fall back to a non-blocking attempt to allocate from the memory
pool.

Signed-off-by: Trond Myklebust

nfs: Convert from invalidatepage to invalidate_folio

2022-03-15T12:23:30+00:00

Print the folio index instead of the pointer, since this is more
useful.  We also don't need to use page_file_mapping() as we do not
invalidate swapcache pages.  Since this is the only caller of
nfs_wb_page_cancel(), convert it to nfs_wb_folio_cancel().

Signed-off-by: Matthew Wilcox (Oracle) 
Tested-by: Damien Le Moal 
Acked-by: Damien Le Moal 
Tested-by: Mike Marshall  # orangefs
Tested-by: David Howells  # afs

NFS: swap IO handling is slightly different for O_DIRECT IO

2022-03-13T16:59:35+00:00

1/ Taking the i_rwsem for swap IO triggers lockdep warnings regarding
   possible deadlocks with "fs_reclaim".  These deadlocks could, I believe,
   eventuate if a buffered read on the swapfile was attempted.

   We don't need coherence with the page cache for a swap file, and
   buffered writes are forbidden anyway.  There is no other need for
   i_rwsem during direct IO.  So never take it for swap_rw()

2/ generic_write_checks() explicitly forbids writes to swap, and
   performs checks that are not needed for swap.  So bypass it
   for swap_rw().

Signed-off-by: NeilBrown 
Signed-off-by: Trond Myklebust