kernel/linux.git/fs/fuse/dir.c, branch v6.12.80

fuse: fix race between concurrent setattrs from multiple nodes

2025-07-06T09:01:32+00:00

[ Upstream commit 69efbff69f89c9b2b72c4d82ad8b59706add768a ] When mounting a user-space filesystem on multiple clients, after concurrent ->setattr() calls from different node, stale inode attributes may be cached in some node. This is caused by fuse_setattr() racing with fuse_reverse_inval_inode(). When filesystem server receives setattr request, the client node with valid iattr cached will be required to update the fuse_inode's attr_version and invalidate the cache by fuse_reverse_inval_inode(), and at the next call to ->getattr() they will be fetched from user space. The race scenario is: 1. client-1 sends setattr (iattr-1) request to server 2. client-1 receives the reply from server 3. before client-1 updates iattr-1 to the cached attributes by fuse_change_attributes_common(), server receives another setattr (iattr-2) request from client-2 4. server requests client-1 to update the inode attr_version and invalidate the cached iattr, and iattr-1 becomes staled 5. client-2 receives the reply from server, and caches iattr-2 6. continue with step 2, client-1 invokes fuse_change_attributes_common(), and caches iattr-1 The issue has been observed from concurrent of chmod, chown, or truncate, which all invoke ->setattr() call. The solution is to use fuse_inode's attr_version to check whether the attributes have been modified during the setattr request's lifetime. If so, mark the attributes as invalid in the function fuse_change_attributes_common(). Signed-off-by: Guang Yuan Wu Reviewed-by: Bernd Schubert Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

fuse: Return EPERM rather than ENOSYS from link()

2025-05-29T09:02:03+00:00

[ Upstream commit 8344213571b2ac8caf013cfd3b37bc3467c3a893 ] link() is documented to return EPERM when a filesystem doesn't support the operation, return that instead. Link: https://github.com/libfuse/libfuse/issues/925 Signed-off-by: Matt Johnston Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

fuse: fix dax truncate/punch_hole fault path

2025-04-10T12:39:25+00:00

[ Upstream commit 7851bf649d423edd7286b292739f2eefded3d35c ] Patch series "fs/dax: Fix ZONE_DEVICE page reference counts", v9. Device and FS DAX pages have always maintained their own page reference counts without following the normal rules for page reference counting. In particular pages are considered free when the refcount hits one rather than zero and refcounts are not added when mapping the page. Tracking this requires special PTE bits (PTE_DEVMAP) and a secondary mechanism for allowing GUP to hold references on the page (see get_dev_pagemap). However there doesn't seem to be any reason why FS DAX pages need their own reference counting scheme. By treating the refcounts on these pages the same way as normal pages we can remove a lot of special checks. In particular pXd_trans_huge() becomes the same as pXd_leaf(), although I haven't made that change here. It also frees up a valuable SW define PTE bit on architectures that have devmap PTE bits defined. It also almost certainly allows further clean-up of the devmap managed functions, but I have left that as a future improvment. It also enables support for compound ZONE_DEVICE pages which is one of my primary motivators for doing this work. This patch (of 20): FS DAX requires file systems to call into the DAX layout prior to unlinking inodes to ensure there is no ongoing DMA or other remote access to the direct mapped page. The fuse file system implements fuse_dax_break_layouts() to do this which includes a comment indicating that passing dmap_end == 0 leads to unmapping of the whole file. However this is not true - passing dmap_end == 0 will not unmap anything before dmap_start, and further more dax_layout_busy_page_range() will not scan any of the range to see if there maybe ongoing DMA access to the range. Fix this by passing -1 for dmap_end to fuse_dax_break_layouts() which will invalidate the entire file range to dax_layout_busy_page_range(). Link: https://lkml.kernel.org/r/cover.8068ad144a7eea4a813670301f4d2a86a8e68ec4.1740713401.git-series.apopple@nvidia.com Link: https://lkml.kernel.org/r/f09a34b6c40032022e4ddee6fadb7cc676f08867.1740713401.git-series.apopple@nvidia.com Fixes: 6ae330cad6ef ("virtiofs: serialize truncate/punch_hole and dax fault path") Signed-off-by: Alistair Popple Co-developed-by: Dan Williams Signed-off-by: Dan Williams Reviewed-by: Balbir Singh Tested-by: Alison Schofield Cc: Vivek Goyal Cc: Alexander Gordeev Cc: Asahi Lina Cc: Bjorn Helgaas Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christoph Hellwig Cc: Chunyan Zhang Cc: "Darrick J. Wong" Cc: Dave Chinner Cc: Dave Hansen Cc: Dave Jiang Cc: David Hildenbrand Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huacai Chen Cc: Ira Weiny Cc: Jan Kara Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: John Hubbard Cc: linmiaohe Cc: Logan Gunthorpe Cc: Matthew Wilcow (Oracle) Cc: Michael "Camp Drill Sergeant" Ellerman Cc: Nicholas Piggin Cc: Peter Xu Cc: Sven Schnelle Cc: Ted Ts'o Cc: Vasily Gorbik Cc: Vishal Verma Cc: WANG Xuerui Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

fuse: don't truncate cached, mutated symlink

2025-03-22T19:54:20+00:00

[ Upstream commit b4c173dfbb6c78568578ff18f9e8822d7bd0e31b ] Fuse allows the value of a symlink to change and this property is exploited by some filesystems (e.g. CVMFS). It has been observed, that sometimes after changing the symlink contents, the value is truncated to the old size. This is caused by fuse_getattr() racing with fuse_reverse_inval_inode(). fuse_reverse_inval_inode() updates the fuse_inode's attr_version, which results in fuse_change_attributes() exiting before updating the cached attributes This is okay, as the cached attributes remain invalid and the next call to fuse_change_attributes() will likely update the inode with the correct values. The reason this causes problems is that cached symlinks will be returned through page_get_link(), which truncates the symlink to inode->i_size. This is correct for filesystems that don't mutate symlinks, but in this case it causes bad behavior. The solution is to just remove this truncation. This can cause a regression in a filesystem that relies on supplying a symlink larger than the file size, but this is unlikely. If that happens we'd need to make this behavior conditional. Reported-by: Laura Promberger Tested-by: Sam Lewis Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20250220100258.793363-1-mszeredi@redhat.com Reviewed-by: Bernd Schubert Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

fuse: respect FOPEN_KEEP_CACHE on opendir

2025-01-17T12:40:36+00:00

[ Upstream commit 03f275adb8fbd7b4ebe96a1ad5044d8e602692dc ] 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 Signed-off-by: Sasha Levin

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