Pull 9p updates from Dominique Martinet:
- fix a bug with O_APPEND in cached mode causing data to be written
multiple times on server
- use kvmalloc for trans_fd to avoid problems with large msize and
fragmented memory This should hopefully be used in more transports
when time allows
- convert to new mount API
- minor cleanups
* tag '9p-for-6.19-rc1' of https://github.com/martinetd/linux:
9p: fix new mount API cache option handling
9p: fix cache/debug options printing in v9fs_show_options
9p: convert to the new mount API
9p: create a v9fs_context structure to hold parsed options
net/9p: move structures and macros to header files
fs/fs_parse: add back fsparam_u32hex
fs/9p: delete unnnecessary condition
fs/9p: Don't open remote file with APPEND mode when writeback cache is used
net/9p: cleanup: change p9_trans_module->def to bool
9p: Use kvmalloc for message buffers on supported transports
After commit 4eb3117888, 9p needs to be able to accept numerical
cache= mount options as well as the string "shortcuts" because the option
is printed numerically in /proc/mounts rather than by string. This was
missed in the mount API conversion, which used an enum for the shortcuts
and therefore could not handle a numeric equivalent as an argument
to the cache option.
Fix this by removing the enum and reverting to the slightly more
open-coded option handling for Opt_cache, with the reinstated
get_cache_mode() helper.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <48cdeec9-5bb9-4c7a-a203-39bb8e0ef443@redhat.com>
Tested-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
commit 4eb3117888 changed the cache= option to accept either string
shortcuts or bitfield values. It also changed /proc/mounts to emit the
option as the hexadecimal numeric value rather than the shortcut string.
However, by printing "cache=%x" without the leading 0x, shortcuts such
as "cache=loose" will emit "cache=f" and 'f' is not a string that is
parseable by kstrtoint(), so remounting may fail if a remount with
"cache=f" is attempted.
debug=%x has had the same problem since options have been displayed in
c4fac91004 ("9p: Implement show_options")
Fix these by adding the 0x prefix to the hexadecimal value shown in
/proc/mounts.
Fixes: 4eb3117888 ("fs/9p: Rework cache modes and add new options to Documentation")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <54b93378-dcf1-4b04-922d-c8b4393da299@redhat.com>
[Dominique: use %#x at Al Viro's suggestion, also handle debug]
Tested-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Pull fs header updates from Christian Brauner:
"This contains initial work to start splitting up fs.h.
Begin the long-overdue work of splitting up the monolithic fs.h
header. The header has grown to over 3000 lines and includes types and
functions for many different subsystems, making it difficult to
navigate and causing excessive compilation dependencies.
This series introduces new focused headers for superblock-related
code:
- Rename fs_types.h to fs_dirent.h to better reflect its actual
content (directory entry types)
- Add fs/super_types.h containing superblock type definitions
- Add fs/super.h containing superblock function declarations
This is the first step in a longer effort to modularize the VFS
headers.
Cleanups:
- Inode Field Layout Optimization (Mateusz Guzik)
Move inode fields used during fast path lookup closer together to
improve cache locality during path resolution.
- current_umask() Optimization (Mateusz Guzik)
Inline current_umask() and move it to fs_struct.h. This improves
performance by avoiding function call overhead for this
frequently-used function, and places it in a more appropriate
header since it operates on fs_struct"
* tag 'vfs-6.19-rc1.fs_header' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: move inode fields used during fast path lookup closer together
fs: inline current_umask() and move it to fs_struct.h
fs: add fs/super.h header
fs: add fs/super_types.h header
fs: rename fs_types.h to fs_dirent.h
Pull writeback updates from Christian Brauner:
"Features:
- Allow file systems to increase the minimum writeback chunk size.
The relatively low minimal writeback size of 4MiB means that
written back inodes on rotational media are switched a lot. Besides
introducing additional seeks, this also can lead to extreme file
fragmentation on zoned devices when a lot of files are cached
relative to the available writeback bandwidth.
This adds a superblock field that allows the file system to
override the default size, and sets it to the zone size for zoned
XFS.
- Add logging for slow writeback when it exceeds
sysctl_hung_task_timeout_secs. This helps identify tasks waiting
for a long time and pinpoint potential issues. Recording the
starting jiffies is also useful when debugging a crashed vmcore.
- Wake up waiting tasks when finishing the writeback of a chunk
Cleanups:
- filemap_* writeback interface cleanups.
Adding filemap_fdatawrite_wbc ended up being a mistake, as all but
the original btrfs caller should be using better high level
interfaces instead.
This series removes all these low-level interfaces, switches btrfs
to a more specific interface, and cleans up other too low-level
interfaces. With this the writeback_control that is passed to the
writeback code is only initialized in three places.
- Remove __filemap_fdatawrite, __filemap_fdatawrite_range, and
filemap_fdatawrite_wbc
- Add filemap_flush_nr helper for btrfs
- Push struct writeback_control into start_delalloc_inodes in btrfs
- Rename filemap_fdatawrite_range_kick to filemap_flush_range
- Stop opencoding filemap_fdatawrite_range in 9p, ocfs2, and mm
- Make wbc_to_tag() inline and use it in fs"
* tag 'vfs-6.19-rc1.writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: Make wbc_to_tag() inline and use it in fs.
xfs: set s_min_writeback_pages for zoned file systems
writeback: allow the file system to override MIN_WRITEBACK_PAGES
writeback: cleanup writeback_chunk_size
mm: rename filemap_fdatawrite_range_kick to filemap_flush_range
mm: remove __filemap_fdatawrite_range
mm: remove filemap_fdatawrite_wbc
mm: remove __filemap_fdatawrite
mm,btrfs: add a filemap_flush_nr helper
btrfs: push struct writeback_control into start_delalloc_inodes
btrfs: use the local tmp_inode variable in start_delalloc_inodes
ocfs2: don't opencode filemap_fdatawrite_range in ocfs2_journal_submit_inode_data_buffers
9p: don't opencode filemap_fdatawrite_range in v9fs_mmap_vm_close
mm: don't opencode filemap_fdatawrite_range in filemap_invalidate_inode
writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)
writeback: Wake up waiting tasks when finishing the writeback of a chunk.
Pull vfs inode updates from Christian Brauner:
"Features:
- Hide inode->i_state behind accessors. Open-coded accesses prevent
asserting they are done correctly. One obvious aspect is locking,
but significantly more can be checked. For example it can be
detected when the code is clearing flags which are already missing,
or is setting flags when it is illegal (e.g., I_FREEING when
->i_count > 0)
- Provide accessors for ->i_state, converts all filesystems using
coccinelle and manual conversions (btrfs, ceph, smb, f2fs, gfs2,
overlayfs, nilfs2, xfs), and makes plain ->i_state access fail to
compile
- Rework I_NEW handling to operate without fences, simplifying the
code after the accessor infrastructure is in place
Cleanups:
- Move wait_on_inode() from writeback.h to fs.h
- Spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
for clarity
- Cosmetic fixes to LRU handling
- Push list presence check into inode_io_list_del()
- Touch up predicts in __d_lookup_rcu()
- ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
- Assert on ->i_count in iput_final()
- Assert ->i_lock held in __iget()
Fixes:
- Add missing fences to I_NEW handling"
* tag 'vfs-6.19-rc1.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
dcache: touch up predicts in __d_lookup_rcu()
fs: push list presence check into inode_io_list_del()
fs: cosmetic fixes to lru handling
fs: rework I_NEW handling to operate without fences
fs: make plain ->i_state access fail to compile
xfs: use the new ->i_state accessors
nilfs2: use the new ->i_state accessors
overlayfs: use the new ->i_state accessors
gfs2: use the new ->i_state accessors
f2fs: use the new ->i_state accessors
smb: use the new ->i_state accessors
ceph: use the new ->i_state accessors
btrfs: use the new ->i_state accessors
Manual conversion to use ->i_state accessors of all places not covered by coccinelle
Coccinelle-based conversion to use ->i_state accessors
fs: provide accessors for ->i_state
fs: spell out fenced ->i_state accesses with explicit smp_wmb/smp_rmb
fs: move wait_on_inode() from writeback.h to fs.h
fs: add missing fences to I_NEW handling
ocfs2: retire ocfs2_drop_inode() and I_WILL_FREE usage
...
Convert 9p to the new mount API. This patch consolidates all parsing
into fs/9p/v9fs.c, which stores all results into a filesystem context
which can be passed to the various transports as needed.
Some of the parsing helper functions such as get_cache_mode() have been
eliminated in favor of using the new mount API's enum param type,
for simplicity.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Message-ID: <20251010214222.1347785-5-sandeen@redhat.com>
[ Dominique: handled source explicitly as per follow-up discussion ]
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
We already know that "retval" is negative, so there is no need to check
again. Also the statement is not indented far enough. Delete it.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Fixes: 43c36a56cc ("Revert "fs/9p: Refresh metadata in d_revalidate for uncached mode too"")
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Message-ID: <aPtiSJl8EwSfVvqN@stanley.mountain>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
When page cache is used, writebacks are done on a page granularity, and it
is expected that the underlying filesystem (such as v9fs) should respect
the write position. However, currently v9fs will passthrough O_APPEND to
the server even on cached mode. This causes data corruption if a sync or
fstat gets between two writes to the same file.
This patch removes the APPEND flag from the open request we send to the
server when writeback caching is involved. I believe keeping server-side
APPEND is probably fine for uncached mode (even if two fds are opened, one
without O_APPEND and one with it, this should still be fine since they
would use separate fid for the writes).
Signed-off-by: Tingmao Wang <m@maowtm.org>
Fixes: 4eb3117888 ("fs/9p: Rework cache modes and add new options to Documentation")
Message-ID: <20251102235631.8724-1-m@maowtm.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
This reverts commit 290434474c.
That commit broke cache=mmap, a mode that doesn't cache metadata,
but still has writeback cache.
In commit 290434474c ("fs/9p: Refresh metadata in d_revalidate
for uncached mode too") we considered metadata cache to be enough to
not look at the server, but in writeback cache too looking at the server
size would make the vfs consider the file has been truncated before the
data has been flushed out, making the following repro fail (nothing is
ever read back, the resulting file ends up with no data written)
```
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
char buf[4096];
int main(int argc, char *argv[])
{
int ret, i;
int fdw, fdr;
if (argc < 2)
return 1;
fdw = openat(AT_FDCWD, argv[1], O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC, 0600);
if (fdw < 0) {
fprintf(stderr, "cannot open fdw\n");
return 1;
}
write(fdw, buf, sizeof(buf));
fdr = openat(AT_FDCWD, argv[1], O_RDONLY|O_CLOEXEC);
if (fdr < 0) {
fprintf(stderr, "cannot open fdr\n");
close(fdw);
return 1;
}
for (i = 0; i < 10; i++) {
ret = read(fdr, buf, sizeof(buf));
fprintf(stderr, "i: %d, read returns %d\n", i, ret);
}
close(fdr);
close(fdw);
return 0;
}
```
There is a fix for this particular reproducer but it looks like there
are other problems around metadata refresh (e.g. around file rename), so
revert this to avoid d_revalidate in uncached mode for now.
Reported-by: Song Liu <song@kernel.org>
Link: https://lkml.kernel.org/r/CAHzjS_u_SYdt5=2gYO_dxzMKXzGMt-TfdE_ueowg-Hq5tRCAiw@mail.gmail.com
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/bpf/CAEf4BzZbCE4tLoDZyUf_aASpgAGFj75QMfSXX4a4dLYixnOiLg@mail.gmail.com/
Fixes: 290434474c ("fs/9p: Refresh metadata in d_revalidate for uncached mode too")
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Pull 9p updates from Dominique Martinet:
"A bunch of unrelated fixes:
- polling fix for trans fd that ought to have been fixed otherwise
back in March, but apparently came back somewhere else...
- USB transport buffer overflow fix
- Some dentry lifetime rework to handle metadata update for currently
opened files in uncached mode, or inode type change in cached mode
- a double-put on invalid flush found by syzbot
- and finally /sys/fs/9p/caches not advancing buffer and overwriting
itself for large contents
Thanks to everyone involved!"
* tag '9p-for-6.18-rc1' of https://github.com/martinetd/linux:
9p: sysfs_init: don't hardcode error to ENOMEM
9p: fix /sys/fs/9p/caches overwriting itself
9p: clean up comment typos
9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN
net/9p: fix double req put in p9_fd_cancelled
net/9p: Fix buffer overflow in USB transport layer
fs/9p: Add p9_debug(VFS) in d_revalidate
fs/9p: Invalidate dentry if inode type change detected in cached mode
fs/9p: Refresh metadata in d_revalidate for uncached mode too
if v9fs_vfs_lookup() returns a preexisting alias, it is guaranteed to be
positive. IOW, in that case we will immediately return finish_no_open(),
leaving only the case res == NULL past that point.
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
generic_delete_inode() is rather misleading for what the routine is
doing. inode_just_drop() should be much clearer.
The new naming is inconsistent with generic_drop_inode(), so rename that
one as well with inode_ as the suffix.
No functional changes.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This is an extension of the last commit to cached mode as well. While
server-side changes when using cached mode is not expected, when it does
happen we can get things like -EOPNOTSUPP. With this change at least when
we realize the inode has updated (for example after a `touch` on the
client), we can get a new one.
Signed-off-by: Tingmao Wang <m@maowtm.org>
Message-ID: <01afd3c77d5cda181780dc931baa8f3fc54562c8.1743956147.git.m@maowtm.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Currently if another process keeps a file open, due to existing dentry in
the dcache, other processes will not see updated metadata of that file if
it is changed on the server, even in uncached mode.
This can also manifest as -ENODATA when reading a file that has shrunk on
the server (even if it's re-opened in another process), or -ENOTSUPP if
the file has changed type (e.g. regular file to directory) on the server.
We can end up in a situation where both `readdir` or `read` fails until
the file is closed by all processes using it.
This commit fixes that, and invalidates the dentry altogether if the inode
type is changed (for uncached mode).
Signed-off-by: Tingmao Wang <m@maowtm.org>
Message-ID: <bfac417f65cc1d6812be822f8913f0d4ba0c1052.1743956147.git.m@maowtm.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Pull mmap_prepare updates from Christian Brauner:
"Last cycle we introduce f_op->mmap_prepare() in c84bf6dd2b ("mm:
introduce new .mmap_prepare() file callback").
This is preferred to the existing f_op->mmap() hook as it does require
a VMA to be established yet, thus allowing the mmap logic to invoke
this hook far, far earlier, prior to inserting a VMA into the virtual
address space, or performing any other heavy handed operations.
This allows for much simpler unwinding on error, and for there to be a
single attempt at merging a VMA rather than having to possibly
reattempt a merge based on potentially altered VMA state.
Far more importantly, it prevents inappropriate manipulation of
incompletely initialised VMA state, which is something that has been
the cause of bugs and complexity in the past.
The intent is to gradually deprecate f_op->mmap, and in that vein this
series coverts the majority of file systems to using f_op->mmap_prepare.
Prerequisite steps are taken - firstly ensuring all checks for mmap
capabilities use the file_has_valid_mmap_hooks() helper rather than
directly checking for f_op->mmap (which is now not a valid check) and
secondly updating daxdev_mapping_supported() to not require a VMA
parameter to allow ext4 and xfs to be converted.
Commit bb666b7c27 ("mm: add mmap_prepare() compatibility layer for
nested file systems") handles the nasty edge-case of nested file
systems like overlayfs, which introduces a compatibility shim to allow
f_op->mmap_prepare() to be invoked from an f_op->mmap() callback.
This allows for nested filesystems to continue to function correctly
with all file systems regardless of which callback is used. Once we
finally convert all file systems, this shim can be removed.
As a result, ecryptfs, fuse, and overlayfs remain unaltered so they
can nest all other file systems.
We additionally do not update resctl - as this requires an update to
remap_pfn_range() (or an alternative to it) which we defer to a later
series, equally we do not update cramfs which needs a mixed mapping
insertion with the same issue, nor do we update procfs, hugetlbfs,
syfs or kernfs all of which require VMAs for internal state and hooks.
We shall return to all of these later"
* tag 'vfs-6.17-rc1.mmap_prepare' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
doc: update porting, vfs documentation to describe mmap_prepare()
fs: replace mmap hook with .mmap_prepare for simple mappings
fs: convert most other generic_file_*mmap() users to .mmap_prepare()
fs: convert simple use of generic_file_*_mmap() to .mmap_prepare()
mm/filemap: introduce generic_file_*_mmap_prepare() helpers
fs/xfs: transition from deprecated .mmap hook to .mmap_prepare
fs/ext4: transition from deprecated .mmap hook to .mmap_prepare
fs/dax: make it possible to check dev dax support without a VMA
fs: consistently use can_mmap_file() helper
mm/nommu: use file_has_valid_mmap_hooks() helper
mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare
Update nearly all generic_file_mmap() and generic_file_readonly_mmap()
callers to use generic_file_mmap_prepare() and
generic_file_readonly_mmap_prepare() respectively.
We update blkdev, 9p, afs, erofs, ext2, nfs, ntfs3, smb, ubifs and vboxsf
file systems this way.
Remaining users we cannot yet update are ecryptfs, fuse and cramfs. The
former two are nested file systems that must support any underlying file
ssytem, and cramfs inserts a mixed mapping which currently requires a VMA.
Once all file systems have been converted to mmap_prepare(), we can then
update nested file systems.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/08db85970d89b17a995d2cffae96fb4cc462377f.1750099179.git.lorenzo.stoakes@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Since commit c84bf6dd2b ("mm: introduce new .mmap_prepare() file
callback"), the f_op->mmap() hook has been deprecated in favour of
f_op->mmap_prepare().
We have provided generic .mmap_prepare() equivalents, so update all file
systems that specify these directly in their file_operations structures.
This updates 9p, adfs, affs, bfs, fat, hfs, hfsplus, hostfs, hpfs, jffs2,
jfs, minix, omfs, ramfs and ufs file systems directly.
It updates generic_ro_fops which impacts qnx4, cramfs, befs, squashfs,
frebxfs, qnx6, efs, romfs, erofs and isofs file systems.
There are remaining file systems which use generic hooks in a less direct
way which we address in a subsequent commit.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Link: https://lore.kernel.org/c7dc90e44a9e75e750939ea369290d6e441a18e6.1750099179.git.lorenzo.stoakes@oracle.com
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
... to be used instead of manually assigning to ->s_d_op.
All in-tree filesystem converted (and field itself is renamed,
so any out-of-tree ones in need of conversion will be caught
by compiler).
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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
When the netfs_io_request struct's work item is queued, it must be supplied
with a ref to the work item struct to prevent it being deallocated whilst
on the queue or whilst it is being processed. This is tricky to manage as
we have to get a ref before we try and queue it and then we may find it's
already queued and is thus already holding a ref - in which case we have to
try and get rid of the ref again.
The problem comes if we're in BH or IRQ context and need to drop the ref:
if netfs_put_request() reduces the count to 0, we have to do the cleanup -
but the cleanup may need to wait.
Fix this by adding a new work item to the request, ->cleanup_work, and
dispatching that when the refcount hits zero. That can then synchronously
cancel any outstanding work on the main work item before doing the cleanup.
Adding a new work item also deals with another problem upstream where it's
sometimes changing the work func in the put function and requeuing it -
which has occasionally in the past caused the cleanup to happen
incorrectly.
As a bonus, this allows us to get rid of the 'was_async' parameter from a
bunch of functions. This indicated whether the put function might not be
permitted to sleep.
Fixes: 3d3c950467 ("netfs: Provide readahead and readpage netfs helpers")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/20250519090707.2848510-4-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Steve French <stfrench@microsoft.com>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull 9p updates from Dominique Martinet:
- fix handling of bogus (negative/too long) replies
- fix crash on mkdir with ACLs (... looks like nobody is using ACLs
with semi-recent kernels...)
- ipv6 support for trans=tcp
- minor concurrency fix to make syzbot happy
- minor cleanup
* tag '9p-for-6.15-rc1' of https://github.com/martinetd/linux:
docs: fs/9p: Add missing "not" in cache documentation
9p: Use hashtable.h for hash_errmap
Documentation/fs/9p: fix broken link
9p/trans_fd: mark concurrent read and writes to p9_conn->err
9p/net: return error on bogus (longer than requested) replies
9p/net: fix improper handling of bogus negative read/write replies
fs/9p: fix NULL pointer dereference on mkdir
net/9p/fd: support ipv6 for trans=tcp
Some filesystems, such as NFS, cifs, ceph, and fuse, do not have
complete control of sequencing on the actual filesystem (e.g. on a
different server) and may find that the inode created for a mkdir
request already exists in the icache and dcache by the time the mkdir
request returns. For example, if the filesystem is mounted twice the
directory could be visible on the other mount before it is on the
original mount, and a pair of name_to_handle_at(), open_by_handle_at()
calls could instantiate the directory inode with an IS_ROOT() dentry
before the first mkdir returns.
This means that the dentry passed to ->mkdir() may not be the one that
is associated with the inode after the ->mkdir() completes. Some
callers need to interact with the inode after the ->mkdir completes and
they currently need to perform a lookup in the (rare) case that the
dentry is no longer hashed.
This lookup-after-mkdir requires that the directory remains locked to
avoid races. Planned future patches to lock the dentry rather than the
directory will mean that this lookup cannot be performed atomically with
the mkdir.
To remove this barrier, this patch changes ->mkdir to return the
resulting dentry if it is different from the one passed in.
Possible returns are:
NULL - the directory was created and no other dentry was used
ERR_PTR() - an error occurred
non-NULL - this other dentry was spliced in
This patch only changes file-systems to return "ERR_PTR(err)" instead of
"err" or equivalent transformations. Subsequent patches will make
further changes to some file-systems to return a correct dentry.
Not all filesystems reliably result in a positive hashed dentry:
- NFS, cifs, hostfs will sometimes need to perform a lookup of
the name to get inode information. Races could result in this
returning something different. Note that this lookup is
non-atomic which is what we are trying to avoid. Placing the
lookup in filesystem code means it only happens when the filesystem
has no other option.
- kernfs and tracefs leave the dentry negative and the ->revalidate
operation ensures that lookup will be called to correctly populate
the dentry. This could be fixed but I don't think it is important
to any of the users of vfs_mkdir() which look at the dentry.
The recommendation to use
d_drop();d_splice_alias()
is ugly but fits with current practice. A planned future patch will
change this.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull vfs d_revalidate updates from Al Viro:
"Provide stable parent and name to ->d_revalidate() instances
Most of the filesystem methods where we care about dentry name and
parent have their stability guaranteed by the callers;
->d_revalidate() is the major exception.
It's easy enough for callers to supply stable values for expected name
and expected parent of the dentry being validated. That kills quite a
bit of boilerplate in ->d_revalidate() instances, along with a bunch
of races where they used to access ->d_name without sufficient
precautions"
* tag 'pull-revalidate' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
9p: fix ->rename_sem exclusion
orangefs_d_revalidate(): use stable parent inode and name passed by caller
ocfs2_dentry_revalidate(): use stable parent inode and name passed by caller
nfs: fix ->d_revalidate() UAF on ->d_name accesses
nfs{,4}_lookup_validate(): use stable parent inode passed by caller
gfs2_drevalidate(): use stable parent inode and name passed by caller
fuse_dentry_revalidate(): use stable parent inode and name passed by caller
vfat_revalidate{,_ci}(): use stable parent inode passed by caller
exfat_d_revalidate(): use stable parent inode passed by caller
fscrypt_d_revalidate(): use stable parent inode passed by caller
ceph_d_revalidate(): propagate stable name down into request encoding
ceph_d_revalidate(): use stable parent inode passed by caller
afs_d_revalidate(): use stable name and parent inode passed by caller
Pass parent directory inode and expected name to ->d_revalidate()
generic_ci_d_compare(): use shortname_storage
ext4 fast_commit: make use of name_snapshot primitives
dissolve external_name.u into separate members
make take_dentry_name_snapshot() lockless
dcache: back inline names with a struct-wrapped array of unsigned long
make sure that DNAME_INLINE_LEN is a multiple of word size
9p wants to be able to build a path from given dentry to fs root and keep
it valid over a blocking operation.
->s_vfs_rename_mutex would be a natural candidate, but there are places
where we need that and where we have no way to tell if ->s_vfs_rename_mutex
is already held deeper in callchain. Moreover, it's only held for
cross-directory renames; name changes within the same directory happen
without it.
Solution:
* have d_move() done in ->rename() rather than in its caller
* maintain a 9p-private rwsem (per-filesystem)
* hold it exclusive over the relevant part of ->rename()
* hold it shared over the places where we want the path.
That almost works. FS_RENAME_DOES_D_MOVE is enough to put all d_move()
and d_exchange() calls under filesystem's control. However, there's
also __d_unalias(), which isn't covered by any of that.
If ->lookup() hits a directory inode with preexisting dentry elsewhere
(due to e.g. rename done on server behind our back), d_splice_alias()
called by ->lookup() will move/rename that alias.
Add a couple of optional methods, so that __d_unalias() would do
if alias->d_op->d_unalias_trylock != NULL
if (!alias->d_op->d_unalias_trylock(alias))
fail (resulting in -ESTALE from lookup)
__d_move(...)
if alias->d_op->d_unalias_unlock != NULL
alias->d_unalias_unlock(alias)
where it currently does __d_move(). 9p instances do down_write_trylock()
and up_write() of ->rename_mutex.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
->d_revalidate() often needs to access dentry parent and name; that has
to be done carefully, since the locking environment varies from caller
to caller. We are not guaranteed that dentry in question will not be
moved right under us - not unless the filesystem is such that nothing
on it ever gets renamed.
It can be dealt with, but that results in boilerplate code that isn't
even needed - the callers normally have just found the dentry via dcache
lookup and want to verify that it's in the right place; they already
have the values of ->d_parent and ->d_name stable. There is a couple
of exceptions (overlayfs and, to less extent, ecryptfs), but for the
majority of calls that song and dance is not needed at all.
It's easier to make ecryptfs and overlayfs find and pass those values if
there's a ->d_revalidate() instance to be called, rather than doing that
in the instances.
This commit only changes the calling conventions; making use of supplied
values is left to followups.
NOTE: some instances need more than just the parent - things like CIFS
may need to build an entire path from filesystem root, so they need
more precautions than the usual boilerplate. This series doesn't
do anything to that need - these filesystems have to keep their locking
mechanisms (rename_lock loops, use of dentry_path_raw(), private rwsem
a-la v9fs).
One thing to keep in mind when using name is that name->name will normally
point into the pathname being resolved; the filename in question occupies
name->len bytes starting at name->name, and there is NUL somewhere after it,
but it the next byte might very well be '/' rather than '\0'. Do not
ignore name->len.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gabriel Krisman Bertazi <gabriel@krisman.be>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Change the way netfslib collects read results to do all the collection for
a particular read request using a single work item that walks along the
subrequest queue as subrequests make progress or complete, unlocking folios
progressively rather than doing the unlock in parallel as parallel requests
come in.
The code is remodelled to be more like the write-side code, though only
using a single stream. This makes it more directly comparable and thus
easier to duplicate fixes between the two sides.
This has a number of advantages:
(1) It's simpler. There doesn't need to be a complex donation mechanism
to handle mismatches between the size and alignment of subrequests and
folios. The collector unlocks folios as the subrequests covering each
complete.
(2) It should cause less scheduler overhead as there's a single work item
in play unlocking pages in parallel when a read gets split up into a
lot of subrequests instead of one per subrequest.
Whilst the parallellism is nice in theory, in practice, the vast
majority of loads are sequential reads of the whole file, so
committing a bunch of threads to unlocking folios out of order doesn't
help in those cases.
(3) It should make it easier to implement content decryption. A folio
cannot be decrypted until all the requests that contribute to it have
completed - and, again, most loads are sequential and so, most of the
time, we want to begin decryption sequentially (though it's great if
the decryption can happen in parallel).
There is a disadvantage in that we're losing the ability to decrypt and
unlock things on an as-things-arrive basis which may affect some
applications.
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-28-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
syzkaller reported recursion with a loop of three calls (netfs_rreq_assess,
netfs_retry_reads and netfs_rreq_terminated) hitting the limit of the stack
during an unbuffered or direct I/O read.
There are a number of issues:
(1) There is no limit on the number of retries.
(2) A subrequest is supposed to be abandoned if it does not transfer
anything (NETFS_SREQ_NO_PROGRESS), but that isn't checked under all
circumstances.
(3) The actual root cause, which is this:
if (atomic_dec_and_test(&rreq->nr_outstanding))
netfs_rreq_terminated(rreq, ...);
When we do a retry, we bump the rreq->nr_outstanding counter to
prevent the final cleanup phase running before we've finished
dispatching the retries. The problem is if we hit 0, we have to do
the cleanup phase - but we're in the cleanup phase and end up
repeating the retry cycle, hence the recursion.
Work around the problem by limiting the number of retries. This is based
on Lizhi Xu's patch[1], and makes the following changes:
(1) Replace NETFS_SREQ_NO_PROGRESS with NETFS_SREQ_MADE_PROGRESS and make
the filesystem set it if it managed to read or write at least one byte
of data. Clear this bit before issuing a subrequest.
(2) Add a ->retry_count member to the subrequest and increment it any time
we do a retry.
(3) Remove the NETFS_SREQ_RETRYING flag as it is superfluous with
->retry_count. If the latter is non-zero, we're doing a retry.
(4) Abandon a subrequest if retry_count is non-zero and we made no
progress.
(5) Use ->retry_count in both the write-side and the read-size.
[?] Question: Should I set a hard limit on retry_count in both read and
write? Say it hits 50, we always abandon it. The problem is that
these changes only mitigate the issue. As long as it made at least one
byte of progress, the recursion is still an issue. This patch
mitigates the problem, but does not fix the underlying cause. I have
patches that will do that, but it's an intrusive fix that's currently
pending for the next merge window.
The oops generated by KASAN looks something like:
BUG: TASK stack guard page was hit at ffffc9000482ff48 (stack is ffffc90004830000..ffffc90004838000)
Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN NOPTI
...
RIP: 0010:mark_lock+0x25/0xc60 kernel/locking/lockdep.c:4686
...
mark_usage kernel/locking/lockdep.c:4646 [inline]
__lock_acquire+0x906/0x3ce0 kernel/locking/lockdep.c:5156
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
___slab_alloc+0x123/0x1880 mm/slub.c:3695
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3908
__slab_alloc_node mm/slub.c:3961 [inline]
slab_alloc_node mm/slub.c:4122 [inline]
kmem_cache_alloc_noprof+0x2a7/0x2f0 mm/slub.c:4141
radix_tree_node_alloc.constprop.0+0x1e8/0x350 lib/radix-tree.c:253
idr_get_free+0x528/0xa40 lib/radix-tree.c:1506
idr_alloc_u32+0x191/0x2f0 lib/idr.c:46
idr_alloc+0xc1/0x130 lib/idr.c:87
p9_tag_alloc+0x394/0x870 net/9p/client.c:321
p9_client_prepare_req+0x19f/0x4d0 net/9p/client.c:644
p9_client_zc_rpc.constprop.0+0x105/0x880 net/9p/client.c:793
p9_client_read_once+0x443/0x820 net/9p/client.c:1570
p9_client_read+0x13f/0x1b0 net/9p/client.c:1534
v9fs_issue_read+0x115/0x310 fs/9p/vfs_addr.c:74
netfs_retry_read_subrequests fs/netfs/read_retry.c:60 [inline]
netfs_retry_reads+0x153a/0x1d00 fs/netfs/read_retry.c:232
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
...
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_retry_reads+0x155e/0x1d00 fs/netfs/read_retry.c:235
netfs_rreq_assess+0x5d3/0x870 fs/netfs/read_collect.c:371
netfs_rreq_terminated+0xe5/0x110 fs/netfs/read_collect.c:407
netfs_dispatch_unbuffered_reads fs/netfs/direct_read.c:103 [inline]
netfs_unbuffered_read fs/netfs/direct_read.c:127 [inline]
netfs_unbuffered_read_iter_locked+0x12f6/0x19b0 fs/netfs/direct_read.c:221
netfs_unbuffered_read_iter+0xc5/0x100 fs/netfs/direct_read.c:256
v9fs_file_read_iter+0xbf/0x100 fs/9p/vfs_file.c:361
do_iter_readv_writev+0x614/0x7f0 fs/read_write.c:832
vfs_readv+0x4cf/0x890 fs/read_write.c:1025
do_preadv fs/read_write.c:1142 [inline]
__do_sys_preadv fs/read_write.c:1192 [inline]
__se_sys_preadv fs/read_write.c:1187 [inline]
__x64_sys_preadv+0x22d/0x310 fs/read_write.c:1187
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
Fixes: ee4cdf7ba8 ("netfs: Speed up buffered reading")
Closes: https://syzkaller.appspot.com/bug?extid=1fc6f64c40a9d143cfb6
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241108034020.3695718-1-lizhi.xu@windriver.com/ [1]
Link: https://lore.kernel.org/r/20241213135013.2964079-9-dhowells@redhat.com
Tested-by: syzbot+885c03ad650731743489@syzkaller.appspotmail.com
Suggested-by: Lizhi Xu <lizhi.xu@windriver.com>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: v9fs@lists.linux.dev
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Reported-by: syzbot+885c03ad650731743489@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
The helper functions v9fs_cache_register and v9fs_cache_unregister are
trivial helper functions that don't offer any extra functionality and
are unncessary. Replace them with direct calls to v9fs_init_inode_cache
and v9fs_destroy_inode_cache respectively to simplify the code.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Message-ID: <20241107095756.10261-1-colin.i.king@gmail.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Pull more 9p reverts from Dominique Martinet:
"Revert patches causing inode collision problems.
The code simplification introduced significant regressions on servers
that do not remap inode numbers when exporting multiple underlying
filesystems with colliding inodes. See the top-most revert (commit
be2ca38253) for details.
This problem had been ignored for too long and the reverts will also
head to stable (6.9+).
I'm confident this set of patches gets us back to previous behaviour
(another related patch had already been reverted back in April and
we're almost back to square 1, and the rest didn't touch inode
lifecycle)"
* tag '9p-for-6.12-rc5' of https://github.com/martinetd/linux:
Revert "fs/9p: simplify iget to remove unnecessary paths"
Revert "fs/9p: fix uaf in in v9fs_stat2inode_dotl"
Revert "fs/9p: remove redundant pointer v9ses"
Revert " fs/9p: mitigate inode collisions"
This reverts commit 724a08450f.
This code simplification introduced significant regressions on servers
that do not remap inode numbers when exporting multiple underlying
filesystems with colliding inodes, as can be illustrated with simple
tmpfs exports in qemu with remapping disabled:
```
# host side
cd /tmp/linux-test
mkdir m1 m2
mount -t tmpfs tmpfs m1
mount -t tmpfs tmpfs m2
mkdir m1/dir m2/dir
echo foo > m1/dir/foo
echo bar > m2/dir/bar
# guest side
# started with -virtfs local,path=/tmp/linux-test,mount_tag=tmp,security_model=mapped-file
mount -t 9p -o trans=virtio,debug=1 tmp /mnt/t
ls /mnt/t/m1/dir
# foo
ls /mnt/t/m2/dir
# bar (works ok if directry isn't open)
# cd to keep first dir's inode alive
cd /mnt/t/m1/dir
ls /mnt/t/m2/dir
# foo (should be bar)
```
Other examples can be crafted with regular files with fscache enabled,
in which case I/Os just happen to the wrong file leading to
corruptions, or guest failing to boot with:
| VFS: Lookup of 'com.android.runtime' in 9p 9p would have caused loop
In theory, we'd want the servers to be smart enough and ensure they
never send us two different files with the same 'qid.path', but while
qemu has an option to remap that is recommended (and qemu prints a
warning if this case happens), there are many other servers which do
not (kvmtool, nfs-ganesha, probably diod...), we should at least ensure
we don't cause regressions on this:
- assume servers can't be trusted and operations that should get a 'new'
inode properly do so. commit d05dcfdf5e (" fs/9p: mitigate inode
collisions") attempted to do this, but v9fs_fid_iget_dotl() was not
called so some higher level of caching got in the way; this needs to be
fixed properly before we can re-apply the patches.
- if we ever want to really simplify this code, we will need to add some
negotiation with the server at mount time where the server could claim
they handle this properly, at which point we could optimize this out.
(but that might not be needed at all if we properly handle the 'new'
check?)
Fixes: 724a08450f ("fs/9p: simplify iget to remove unnecessary paths")
Reported-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/all/20240408141436.GA17022@redhat.com/
Link: https://lkml.kernel.org/r/20240923100508.GA32066@willie-the-truck
Cc: stable@vger.kernel.org # v6.9+
Message-ID: <20241024-revert_iget-v1-4-4cac63d25f72@codewreck.org>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
This reverts commit 1325e4a91a.
using multipage folios apparently break some madvise operations like
MADV_PAGEOUT which do not reliably unload the specified page anymore,
Revert the patch until that is figured out.
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Fixes: 1325e4a91a ("9p: Enable multipage folios")
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
