linux.git/fs/9p, branch v6.8

9p: Use length of data written to the server in preference to error

2024-01-04T13:15:31+00:00

In v9fs_upload_to_server(), we pass the error to netfslib to terminate the
subreq rather than the amount of data written - even if we did actually
write something.

Further, we assume that the write is always entirely done if successful -
but it might have been partially complete - as returned by
p9_client_write(), but we ignore that.

Fix this by indicating the amount written by preference and only returning
the error if we didn't write anything.

(We might want to return both in future if both are available as this
might be useful as to whether we retry or not.)

Suggested-by: Dominique Martinet 
Link: https://lore.kernel.org/r/ZZULNQAZ0n0WQv7p@codewreck.org/
Signed-off-by: David Howells 
Acked-by: Dominique Martinet 
cc: Eric Van Hensbergen 
cc: Latchesar Ionkov 
cc: Christian Schoenebeck 
cc: v9fs@lists.linux.dev
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org

9p: Do a couple of cleanups

2024-01-04T13:14:13+00:00

Do a couple of cleanups to 9p:

 (1) Remove a couple of unused variables.

 (2) Turn a BUG_ON() into a warning, consolidate with another warning and
     make the warning message include the inode number rather than
     whatever's in i_private (which will get hashed anyway).

Suggested-by: Dominique Martinet 
Link: https://lore.kernel.org/r/ZZULNQAZ0n0WQv7p@codewreck.org/
Signed-off-by: David Howells 
Acked-by: Dominique Martinet 
cc: Eric Van Hensbergen 
cc: Latchesar Ionkov 
cc: Christian Schoenebeck 
cc: v9fs@lists.linux.dev
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org

9p: Fix initialisation of netfs_inode for 9p

2024-01-03T14:53:01+00:00

The 9p filesystem is calling netfs_inode_init() in v9fs_init_inode() -
before the struct inode fields have been initialised from the obtained file
stats (ie. after v9fs_stat2inode*() has been called), but netfslib wants to
set a couple of its fields from i_size.

Reported-by: Marc Dionne 
Signed-off-by: David Howells 
Tested-by: Marc Dionne 
Tested-by: Dominique Martinet 
Acked-by: Dominique Martinet 
cc: Eric Van Hensbergen 
cc: Latchesar Ionkov 
cc: Dominique Martinet 
cc: Christian Schoenebeck 
cc: v9fs@lists.linux.dev
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org

9p: Use netfslib read/write_iter

2023-12-28T09:45:28+00:00

Use netfslib's read and write iteration helpers, allowing netfslib to take
over the management of the page cache for 9p files and to manage local disk
caching.  In particular, this eliminates write_begin, write_end, writepage
and all mentions of struct page and struct folio from 9p.

Note that netfslib now offers the possibility of write-through caching if
that is desirable for 9p: just set the NETFS_ICTX_WRITETHROUGH flag in
v9inode->netfs.flags in v9fs_set_netfs_context().

Note also this is untested as I can't get ganesha.nfsd to correctly parse
the config to turn on 9p support.

Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: Eric Van Hensbergen 
cc: Latchesar Ionkov 
cc: Dominique Martinet 
cc: Christian Schoenebeck 
cc: v9fs@lists.linux.dev
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org

netfs: Optimise away reads above the point at which there can be no data

2023-12-28T09:45:27+00:00

Track the file position above which the server is not expected to have any
data (the "zero point") and preemptively assume that we can satisfy
requests by filling them with zeroes locally rather than attempting to
download them if they're over that line - even if we've written data back
to the server.  Assume that any data that was written back above that
position is held in the local cache.  Note that we have to split requests
that straddle the line.

Make use of this to optimise away some reads from the server.  We need to
set the zero point in the following circumstances:

 (1) When we see an extant remote inode and have no cache for it, we set
     the zero_point to i_size.

 (2) On local inode creation, we set zero_point to 0.

 (3) On local truncation down, we reduce zero_point to the new i_size if
     the new i_size is lower.

 (4) On local truncation up, we don't change zero_point.

 (5) On local modification, we don't change zero_point.

 (6) On remote invalidation, we set zero_point to the new i_size.

 (7) If stored data is discarded from the pagecache or culled from fscache,
     we must set zero_point above that if the data also got written to the
     server.

 (8) If dirty data is written back to the server, but not fscache, we must
     set zero_point above that.

 (9) If a direct I/O write is made, set zero_point above that.

Assuming the above, any read from the server at or above the zero_point
position will return all zeroes.

The zero_point value can be stored in the cache, provided the above rules
are applied to it by any code that culls part of the local cache.

Signed-off-by: David Howells 
cc: Jeff Layton 
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

netfs: Provide invalidate_folio and release_folio calls

2023-12-24T15:08:51+00:00

Provide default invalidate_folio and release_folio calls.  These will need
to interact with invalidation correctly at some point.  They will be needed
if netfslib is to make use of folio->private for its own purposes.

Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

netfs: Move pinning-for-writeback from fscache to netfs

2023-12-24T15:08:49+00:00

Move the resource pinning-for-writeback from fscache code to netfslib code.
This is used to keep a cache backing object pinned whilst we have dirty
pages on the netfs inode in the pagecache such that VM writeback will be
able to reach it.

Whilst we're at it, switch the parameters of netfs_unpin_writeback() to
match ->write_inode() so that it can be used for that directly.

Note that this mechanism could be more generically useful than that for
network filesystems.  Quite often they have to keep around other resources
(e.g. authentication tokens or network connections) until the writeback is
complete.

Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

netfs, fscache: Remove ->begin_cache_operation

2023-12-24T15:08:48+00:00

Remove ->begin_cache_operation() in favour of just calling fscache directly.

Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
cc: Christian Brauner 
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com

Merge tag '9p-for-6.7-rc1' of https://github.com/martinetd/linux

2023-11-04T19:20:04+00:00

Pull 9p updates from Dominique Martinet:
 A bunch of small fixes:

   - three W=1 warning fixes: the NULL -> "" replacement isn't trivial
     but is serialized identically by the protocol layer and has been
     tested

   - one syzbot/KCSAN datarace annotation where we don't care about
     users messing with the fd they passed to mount -t 9p

   - removing a declaration without implementation

   - yet another race fix for trans_fd around connection close: the
     'err' field is also used in potentially racy calls and this isn't
     complete, but it's better than what we had

   - and finally a theorical memory leak fix on serialization failure"

* tag '9p-for-6.7-rc1' of https://github.com/martinetd/linux:
  9p/net: fix possible memory leak in p9_check_errors()
  9p/fs: add MODULE_DESCRIPTION
  9p/net: xen: fix false positive printf format overflow warning
  9p: v9fs_listxattr: fix %s null argument warning
  9p/trans_fd: Annotate data-racy writes to file::f_flags
  fs/9p: Remove unused function declaration v9fs_inode2stat()
  9p/trans_fd: avoid sending req to a cancelled conn

Merge tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

2023-10-30T19:47:13+00:00

Pull vfs inode time accessor updates from Christian Brauner:
 "This finishes the conversion of all inode time fields to accessor
  functions as discussed on list. Changing timestamps manually as we
  used to do before is error prone. Using accessors function makes this
  robust.

  It does not contain the switch of the time fields to discrete 64 bit
  integers to replace struct timespec and free up space in struct inode.
  But after this, the switch can be trivially made and the patch should
  only affect the vfs if we decide to do it"

* tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (86 commits)
  fs: rename inode i_atime and i_mtime fields
  security: convert to new timestamp accessors
  selinux: convert to new timestamp accessors
  apparmor: convert to new timestamp accessors
  sunrpc: convert to new timestamp accessors
  mm: convert to new timestamp accessors
  bpf: convert to new timestamp accessors
  ipc: convert to new timestamp accessors
  linux: convert to new timestamp accessors
  zonefs: convert to new timestamp accessors
  xfs: convert to new timestamp accessors
  vboxsf: convert to new timestamp accessors
  ufs: convert to new timestamp accessors
  udf: convert to new timestamp accessors
  ubifs: convert to new timestamp accessors
  tracefs: convert to new timestamp accessors
  sysv: convert to new timestamp accessors
  squashfs: convert to new timestamp accessors
  server: convert to new timestamp accessors
  client: convert to new timestamp accessors
  ...