linux.git/fs/fuse/dir.c, branch for-next

fuse: respect FOPEN_KEEP_CACHE on opendir

2025-01-04T08:58:14+00:00

The re-factoring of fuse_dir_open() missed the need to invalidate
directory inode page cache with open flag FOPEN_KEEP_CACHE.

Fixes: 7de64d521bf92 ("fuse: break up fuse_open_common()")
Reported-by: Prince Kumar 
Closes: https://lore.kernel.org/linux-fsdevel/CAEW=TRr7CYb4LtsvQPLj-zx5Y+EYBmGfM24SuzwyDoGVNoKm7w@mail.gmail.com/
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20250101130037.96680-1-amir73il@gmail.com
Reviewed-by: Bernd Schubert 
Signed-off-by: Christian Brauner

fuse: check attributes staleness on fuse_iget()

2024-11-18T11:24:13+00:00

Function fuse_direntplus_link() might call fuse_iget() to initialize a new
fuse_inode and change its attributes. If fi->attr_version is always
initialized with 0, even if the attributes returned by the FUSE_READDIR
request is staled, as the new fi->attr_version is 0, fuse_change_attributes
will still set the staled attributes to inode. This wrong behaviour may
cause file size inconsistency even when there is no changes from
server-side.

To reproduce the issue, consider the following 2 programs (A and B) are
running concurrently,

        A                                               B
----------------------------------      --------------------------------
{ /fusemnt/dir/f is a file path in a fuse mount, the size of f is 0. }

readdir(/fusemnt/dir) start
//Daemon set size 0 to f direntry
                                        fallocate(f, 1024)
                                        stat(f) // B see size 1024
                                        echo 2 > /proc/sys/vm/drop_caches
readdir(/fusemnt/dir) reply to kernel
Kernel set 0 to the I_NEW inode

                                        stat(f) // B see size 0

In the above case, only program B is modifying the file size, however, B
observes file size changing between the 2 'readonly' stat() calls. To fix
this issue, we should make sure readdirplus still follows the rule of
attr_version staleness checking even if the fi->attr_version is lost due to
inode eviction.

To identify this situation, the new fc->evict_ctr is used to record whether
the eviction of inodes occurs during the readdirplus request processing.
If it does, the result of readdirplus may be inaccurate; otherwise, the
result of readdirplus can be trusted. Although this may still lead to
incorrect invalidation, considering the relatively low frequency of
evict occurrences, it should be acceptable.

Link: https://lore.kernel.org/lkml/20230711043405.66256-2-zhangjiachen.jaycee@bytedance.com/
Link: https://lore.kernel.org/lkml/20241114070905.48901-1-zhangtianci.1997@bytedance.com/

Reported-by: Jiachen Zhang 
Suggested-by: Miklos Szeredi 
Signed-off-by: Zhang Tianci 
Signed-off-by: Miklos Szeredi

fuse: remove pages for requests and exclusively use folios

2024-11-05T13:08:35+00:00

All fuse requests use folios instead of pages for transferring data.
Remove pages from the requests and exclusively use folios.

No functional changes.

[SzM: rename back folio_descs -> descs, etc.]

Signed-off-by: Joanne Koong 
Reviewed-by: Josef Bacik 
Signed-off-by: Miklos Szeredi

fuse: convert readlink to use folios

2024-11-05T10:14:32+00:00

Convert readlink requests to use a folio instead of a page.

No functional changes.

Signed-off-by: Joanne Koong 
Reviewed-by: Josef Bacik 
Signed-off-by: Miklos Szeredi

fs/fuse: convert to use invalid_mnt_idmap

2024-09-23T09:10:26+00:00

We should convert fs/fuse code to use a newly introduced
invalid_mnt_idmap instead of passing a NULL as idmap pointer.

Suggested-by: Christian Brauner 
Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Christian Brauner 
Signed-off-by: Miklos Szeredi

fs/fuse: introduce and use fuse_simple_idmap_request() helper

2024-09-23T09:07:55+00:00

Let's convert all existing callers properly.

No functional changes intended.

Suggested-by: Christian Brauner 
Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Christian Brauner 
Signed-off-by: Miklos Szeredi

fuse: warn if fuse_access is called when idmapped mounts are allowed

2024-09-04T14:51:11+00:00

It is not possible with the current fuse code, but let's protect ourselves
from regressions in the future.

Signed-off-by: Alexander Mikhalitsyn 
Signed-off-by: Miklos Szeredi

fuse: support idmapped ->rename op

2024-09-04T14:51:11+00:00

RENAME_WHITEOUT is a special case of ->rename
and we need to take idmappings into account there.

Signed-off-by: Alexander Mikhalitsyn 
Signed-off-by: Miklos Szeredi

fuse: support idmapped ->setattr op

2024-09-04T14:51:06+00:00

Need to translate uid and gid in case of chown(2).

Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Christian Brauner 
Signed-off-by: Miklos Szeredi

fuse: support idmapped ->permission inode op

2024-09-04T14:49:58+00:00

We only cover the case when "default_permissions" flag
is used. A reason for that is that otherwise all the permission
checks are done in the userspace and we have to deal with
VFS idmapping in the userspace (which is bad), alternatively
we have to provide the userspace with idmapped req->in.h.uid/req->in.h.gid
which is also not align with VFS idmaps philosophy.

Signed-off-by: Alexander Mikhalitsyn 
Reviewed-by: Christian Brauner 
Signed-off-by: Miklos Szeredi