linux.git/fs/ceph/file.c, branch v5.19

netfs: Fix gcc-12 warning by embedding vfs inode in netfs_i_context

2022-06-09T20:55:00+00:00

While randstruct was satisfied with using an open-coded "void *" offset
cast for the netfs_i_context <-> inode casting, __builtin_object_size() as
used by FORTIFY_SOURCE was not as easily fooled.  This was causing the
following complaint[1] from gcc v12:

  In file included from include/linux/string.h:253,
                   from include/linux/ceph/ceph_debug.h:7,
                   from fs/ceph/inode.c:2:
  In function 'fortify_memset_chk',
      inlined from 'netfs_i_context_init' at include/linux/netfs.h:326:2,
      inlined from 'ceph_alloc_inode' at fs/ceph/inode.c:463:2:
  include/linux/fortify-string.h:242:25: warning: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]
    242 |                         __write_overflow_field(p_size_field, size);
        |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by embedding a struct inode into struct netfs_i_context (which
should perhaps be renamed to struct netfs_inode).  The struct inode
vfs_inode fields are then removed from the 9p, afs, ceph and cifs inode
structs and vfs_inode is then simply changed to "netfs.inode" in those
filesystems.

Further, rename netfs_i_context to netfs_inode, get rid of the
netfs_inode() function that converted a netfs_i_context pointer to an
inode pointer (that can now be done with &ctx->inode) and rename the
netfs_i_context() function to netfs_inode() (which is now a wrapper
around container_of()).

Most of the changes were done with:

  perl -p -i -e 's/vfs_inode/netfs.inode/'g \
        `git grep -l 'vfs_inode' -- fs/{9p,afs,ceph,cifs}/*.[ch]`

Kees suggested doing it with a pair structure[2] and a special
declarator to insert that into the network filesystem's inode
wrapper[3], but I think it's cleaner to embed it - and then it doesn't
matter if struct randomisation reorders things.

Dave Chinner suggested using a filesystem-specific VFS_I() function in
each filesystem to convert that filesystem's own inode wrapper struct
into the VFS inode struct[4].

Version #2:
 - Fix a couple of missed name changes due to a disabled cifs option.
 - Rename nfs_i_context to nfs_inode
 - Use "netfs" instead of "nic" as the member name in per-fs inode wrapper
   structs.

[ This also undoes commit 507160f46c55 ("netfs: gcc-12: temporarily
  disable '-Wattribute-warning' for now") that is no longer needed ]

Fixes: bc899ee1c898 ("netfs: Add a netfs inode context")
Reported-by: Jeff Layton 
Signed-off-by: David Howells 
Reviewed-by: Jeff Layton 
Reviewed-by: Kees Cook 
Reviewed-by: Xiubo Li 
cc: Jonathan Corbet 
cc: Eric Van Hensbergen 
cc: Latchesar Ionkov 
cc: Dominique Martinet 
cc: Christian Schoenebeck 
cc: Marc Dionne 
cc: Ilya Dryomov 
cc: Steve French 
cc: William Kucharski 
cc: "Matthew Wilcox (Oracle)" 
cc: Dave Chinner 
cc: linux-doc@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-afs@lists.infradead.org
cc: ceph-devel@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: samba-technical@lists.samba.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-hardening@vger.kernel.org
Link: https://lore.kernel.org/r/d2ad3a3d7bdd794c6efb562d2f2b655fb67756b9.camel@kernel.org/ [1]
Link: https://lore.kernel.org/r/20220517210230.864239-1-keescook@chromium.org/ [2]
Link: https://lore.kernel.org/r/20220518202212.2322058-1-keescook@chromium.org/ [3]
Link: https://lore.kernel.org/r/20220524101205.GI2306852@dread.disaster.area/ [4]
Link: https://lore.kernel.org/r/165296786831.3591209.12111293034669289733.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/165305805651.4094995.7763502506786714216.stgit@warthog.procyon.org.uk # v2
Signed-off-by: Linus Torvalds

ceph: fix setting of xattrs on async created inodes

2022-05-10T07:48:31+00:00

Currently when we create a file, we spin up an xattr buffer to send
along with the create request. If we end up doing an async create
however, then we currently pass down a zero-length xattr buffer.

Fix the code to send down the xattr buffer in req->r_pagelist. If the
xattrs span more than a page, however give up and don't try to do an
async create.

Cc: stable@vger.kernel.org
URL: https://bugzilla.redhat.com/show_bug.cgi?id=2063929
Fixes: 9a8d03ca2e2c ("ceph: attempt to do async create when possible")
Reported-by: John Fortin 
Reported-by: Sri Ramanujam 
Signed-off-by: Jeff Layton 
Reviewed-by: Xiubo Li 
Signed-off-by: Ilya Dryomov

fs: Pass an iocb to generic_perform_write()

2022-04-01T18:40:44+00:00

We can extract both the file pointer and the pos from the iocb.
This simplifies each caller as well as allowing generic_perform_write()
to see more of the iocb contents in the future.

Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Christian Brauner 
Reviewed-by: Al Viro 
Acked-by: Al Viro

ceph: wake waiters after failed async create

2022-03-01T17:26:36+00:00

Currently, we only wake the waiters if we got a req->r_target_inode
out of the reply. In the case where the create fails though, we may not
have one.

If there is a non-zero result from the create, then ensure that we wake
anything waiting on the inode after we shut it down.

URL: https://tracker.ceph.com/issues/54067
Signed-off-by: Jeff Layton 
Reviewed-by: Xiubo Li 
Signed-off-by: Ilya Dryomov

ceph: uninline the data on a file opened for writing

2022-03-01T17:26:36+00:00

If a ceph file is made up of inline data, uninline that in the ceph_open()
rather than in ceph_page_mkwrite(), ceph_write_iter(), ceph_fallocate() or
ceph_write_begin().

This makes it easier to convert to using the netfs library for VM write
hooks.

Should this also take the inode lock for the duration on uninlining to
prevent a race with truncation?

[ jlayton: fix up folio locking, update i_inline_version after write ]

Signed-off-by: David Howells 
Signed-off-by: Jeff Layton 
Signed-off-by: Ilya Dryomov

ceph: set pool_ns in new inode layout for async creates

2022-01-26T19:17:50+00:00

Dan reported that he was unable to write to files that had been
asynchronously created when the client's OSD caps are restricted to a
particular namespace.

The issue is that the layout for the new inode is only partially being
filled. Ensure that we populate the pool_ns_data and pool_ns_len in the
iinfo before calling ceph_fill_inode.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/54013
Fixes: 9a8d03ca2e2c ("ceph: attempt to do async create when possible")
Reported-by: Dan van der Ster 
Signed-off-by: Jeff Layton 
Reviewed-by: Ilya Dryomov 
Signed-off-by: Ilya Dryomov

ceph: properly put ceph_string reference after async create attempt

2022-01-26T19:17:50+00:00

The reference acquired by try_prep_async_create is currently leaked.
Ensure we put it.

Cc: stable@vger.kernel.org
Fixes: 9a8d03ca2e2c ("ceph: attempt to do async create when possible")
Signed-off-by: Jeff Layton 
Reviewed-by: Ilya Dryomov 
Signed-off-by: Ilya Dryomov

Merge tag 'ceph-for-5.17-rc1' of git://github.com/ceph/ceph-client

2022-01-20T11:46:20+00:00

Pull ceph updates from Ilya Dryomov:
 "The highlight is the new mount "device" string syntax implemented by
  Venky Shankar. It solves some long-standing issues with using
  different auth entities and/or mounting different CephFS filesystems
  from the same cluster, remounting and also misleading /proc/mounts
  contents. The existing syntax of course remains to be maintained.

  On top of that, there is a couple of fixes for edge cases in quota and
  a new mount option for turning on unbuffered I/O mode globally instead
  of on a per-file basis with ioctl(CEPH_IOC_SYNCIO)"

* tag 'ceph-for-5.17-rc1' of git://github.com/ceph/ceph-client:
  ceph: move CEPH_SUPER_MAGIC definition to magic.h
  ceph: remove redundant Lsx caps check
  ceph: add new "nopagecache" option
  ceph: don't check for quotas on MDS stray dirs
  ceph: drop send metrics debug message
  rbd: make const pointer spaces a static const array
  ceph: Fix incorrect statfs report for small quota
  ceph: mount syntax module parameter
  doc: document new CephFS mount device syntax
  ceph: record updated mon_addr on remount
  ceph: new device mount syntax
  libceph: rename parse_fsid() to ceph_parse_fsid() and export
  libceph: generalize addr/ip parsing based on delimiter

ceph: add new "nopagecache" option

2022-01-13T12:40:07+00:00

CephFS is a bit unlike most other filesystems in that it only
conditionally does buffered I/O based on the caps that it gets from the
MDS. In most cases, unless there is contended access for an inode the
MDS does give Fbc caps to the client, so the unbuffered codepaths are
only infrequently traveled and are difficult to test.

At one time, the "-o sync" mount option would give you this behavior,
but that was removed in commit 7ab9b3807097 ("ceph: Don't use
ceph-sync-mode for synchronous-fs.").

Add a new mount option to tell the client to ignore Fbc caps when doing
I/O, and to use the synchronous codepaths exclusively, even on
non-O_DIRECT file descriptors. We already have an ioctl that forces this
behavior on a per-file basis, so we can just always set the CEPH_F_SYNC
flag in the file description on such mounts.

Additionally, this patch also changes the client to not request Fbc when
doing direct I/O. We aren't using the cache with O_DIRECT so we don't
have any need for those caps.

Signed-off-by: Jeff Layton 
Acked-by: Greg Farnum 
Reviewed-by: Venky Shankar 
Signed-off-by: Ilya Dryomov

Merge tag 'fscache-rewrite-20220111' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

2022-01-12T21:45:12+00:00

Pull fscache rewrite from David Howells:
"This is a set of patches that rewrites the fscache driver and the
cachefiles driver, significantly simplifying the code compared to
what's upstream, removing the complex operation scheduling and object
state machine in favour of something much smaller and simpler.

The series is structured such that the first few patches disable
fscache use by the network filesystems using it, remove the cachefiles
driver entirely and as much of the fscache driver as can be got away
with without causing build failures in the network filesystems.

The patches after that recreate fscache and then cachefiles,
attempting to add the pieces in a logical order. Finally, the
filesystems are reenabled and then the very last patch changes the
documentation.

[!] Note: I have dropped the cifs patch for the moment, leaving local
caching in cifs disabled. I've been having trouble getting that
working. I think I have it done, but it needs more testing (there
seem to be some test failures occurring with v5.16 also from
xfstests), so I propose deferring that patch to the end of the
merge window.

WHY REWRITE?
============

Fscache's operation scheduling API was intended to handle sequencing
of cache operations, which were all required (where possible) to run
asynchronously in parallel with the operations being done by the
network filesystem, whilst allowing the cache to be brought online and
offline and to interrupt service for invalidation.

With the advent of the tmpfile capacity in the VFS, however, an
opportunity arises to do invalidation much more simply, without having
to wait for I/O that's actually in progress: Cachefiles can simply
create a tmpfile, cut over the file pointer for the backing object
attached to a cookie and abandon the in-progress I/O, dismissing it
upon completion.

Future work here would involve using Omar Sandoval's vfs_link() with
AT_LINK_REPLACE[1] to allow an extant file to be displaced by a new
hard link from a tmpfile as currently I have to unlink the old file
first.

These patches can also simplify the object state handling as I/O
operations to the cache don't all have to be brought to a stop in
order to invalidate a file. To that end, and with an eye on to writing
a new backing cache model in the future, I've taken the opportunity to
simplify the indexing structure.

I've separated the index cookie concept from the file cookie concept
by C type now. The former is now called a "volume cookie" (struct
fscache_volume) and there is a container of file cookies. There are
then just the two levels. All the index cookie levels are collapsed
into a single volume cookie, and this has a single printable string as
a key. For instance, an AFS volume would have a key of something like
"afs,example.com,1000555", combining the filesystem name, cell name
and volume ID. This is freeform, but must not have '/' chars in it.

I've also eliminated all pointers back from fscache into the network
filesystem. This required the duplication of a little bit of data in
the cookie (cookie key, coherency data and file size), but it's not
actually that much. This gets rid of problems with making sure we keep
netfs data structures around so that the cache can access them.

These patches mean that most of the code that was in the drivers
before is simply gone and those drivers are now almost entirely new
code. That being the case, there doesn't seem any particular reason to
try and maintain bisectability across it. Further, there has to be a
point in the middle where things are cut over as there's a single
point everything has to go through (ie. /dev/cachefiles) and it can't
be in use by two drivers at once.

ISSUES YET OUTSTANDING
======================

There are some issues still outstanding, unaddressed by this patchset,
that will need fixing in future patchsets, but that don't stop this
series from being usable:

(1) The cachefiles driver needs to stop using the backing filesystem's
metadata to store information about what parts of the cache are
populated. This is not reliable with modern extent-based
filesystems.

Fixing this is deferred to a separate patchset as it involves
negotiation with the network filesystem and the VM as to how much
data to download to fulfil a read - which brings me on to (2)...

(2) NFS (and CIFS with the dropped patch) do not take account of how
the cache would like I/O to be structured to meet its granularity
requirements. Previously, the cache used page granularity, which
was fine as the network filesystems also dealt in page
granularity, and the backing filesystem (ext4, xfs or whatever)
did whatever it did out of sight. However, we now have folios to
deal with and the cache will now have to store its own metadata to
track its contents.

The change I'm looking at making for cachefiles is to store
content bitmaps in one or more xattrs and making a bit in the map
correspond to something like a 256KiB block. However, the size of
an xattr and the fact that they have to be read/updated in one go
means that I'm looking at covering 1GiB of data per 512-byte map
and storing each map in an xattr. Cachefiles has the potential to
grow into a fully fledged filesystem of its very own if I'm not
careful.

However, I'm also looking at changing things even more radically
and going to a different model of how the cache is arranged and
managed - one that's more akin to the way, say, openafs does
things - which brings me on to (3)...

(3) The way cachefilesd does culling is very inefficient for large
caches and it would be better to move it into the kernel if I can
as cachefilesd has to keep asking the kernel if it can cull a
file. Changing the way the backend works would allow this to be
addressed.

BITS THAT MAY BE CONTROVERSIAL
==============================

There are some bits I've added that may be controversial:

(1) I've provided a flag, S_KERNEL_FILE, that cachefiles uses to check
if a files is already being used by some other kernel service
(e.g. a duplicate cachefiles cache in the same directory) and
reject it if it is. This isn't entirely necessary, but it helps
prevent accidental data corruption.

I don't want to use S_SWAPFILE as that has other effects, but
quite possibly swapon() should set S_KERNEL_FILE too.

Note that it doesn't prevent userspace from interfering, though
perhaps it should. (I have made it prevent a marked directory from
being rmdir-able).

(2) Cachefiles wants to keep the backing file for a cookie open whilst
we might need to write to it from network filesystem writeback.
The problem is that the network filesystem unuses its cookie when
its file is closed, and so we have nothing pinning the cachefiles
file open and it will get closed automatically after a short time
to avoid EMFILE/ENFILE problems.

Reopening the cache file, however, is a problem if this is being
done due to writeback triggered by exit(). Some filesystems will
oops if we try to open a file in that context because they want to
access current->fs or suchlike.

To get around this, I added the following:

(A) An inode flag, I_PINNING_FSCACHE_WB, to be set on a network
filesystem inode to indicate that we have a usage count on the
cookie caching that inode.

(B) A flag in struct writeback_control, unpinned_fscache_wb, that
is set when __writeback_single_inode() clears the last dirty
page from i_pages - at which point it clears
I_PINNING_FSCACHE_WB and sets this flag.

This has to be done here so that clearing I_PINNING_FSCACHE_WB
can be done atomically with the check of PAGECACHE_TAG_DIRTY
that clears I_DIRTY_PAGES.

(C) A function, fscache_set_page_dirty(), which if it is not set,
sets I_PINNING_FSCACHE_WB and calls fscache_use_cookie() to
pin the cache resources.

(D) A function, fscache_unpin_writeback(), to be called by
->write_inode() to unuse the cookie.

(E) A function, fscache_clear_inode_writeback(), to be called when
the inode is evicted, before clear_inode() is called. This
cleans up any lingering I_PINNING_FSCACHE_WB.

The network filesystem can then use these tools to make sure that
fscache_write_to_cache() can write locally modified data to the
cache as well as to the server.

For the future, I'm working on write helpers for netfs lib that
should allow this facility to be removed by keeping track of the
dirty regions separately - but that's incomplete at the moment and
is also going to be affected by folios, one way or another, since
it deals with pages"

Link: https://lore.kernel.org/all/510611.1641942444@warthog.procyon.org.uk/
Tested-by: Dominique Martinet # 9p
Tested-by: kafs-testing@auristor.com # afs
Tested-by: Jeff Layton # ceph
Tested-by: Dave Wysochanski # nfs
Tested-by: Daire Byrne # nfs

* tag 'fscache-rewrite-20220111' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (67 commits)
9p, afs, ceph, nfs: Use current_is_kswapd() rather than gfpflags_allow_blocking()
fscache: Add a tracepoint for cookie use/unuse
fscache: Rewrite documentation
ceph: add fscache writeback support
ceph: conversion to new fscache API
nfs: Implement cache I/O by accessing the cache directly
nfs: Convert to new fscache volume/cookie API
9p: Copy local writes to the cache when writing to the server
9p: Use fscache indexing rewrite and reenable caching
afs: Skip truncation on the server of data we haven't written yet
afs: Copy local writes to the cache when writing to the server
afs: Convert afs to use the new fscache API
fscache, cachefiles: Display stat of culling events
fscache, cachefiles: Display stats of no-space events
cachefiles: Allow cachefiles to actually function
fscache, cachefiles: Store the volume coherency data
cachefiles: Implement the I/O routines
cachefiles: Implement cookie resize for truncate
cachefiles: Implement begin and end I/O operation
cachefiles: Implement backing file wrangling
...