kernel/linux.git/fs/namei.c, branch v6.12.80

openat2: don't trigger automounts with RESOLVE_NO_XDEV

2025-10-19T14:33:51+00:00

commit 042a60680de43175eb4df0977ff04a4eba9da082 upstream. openat2 had a bug: if we pass RESOLVE_NO_XDEV, then openat2 doesn't traverse through automounts, but may still trigger them. (See the link for full bug report with reproducer.) This commit fixes this bug. Link: https://lore.kernel.org/linux-fsdevel/20250817075252.4137628-1-safinaskar@zohomail.com/ Fixes: fddb5d430ad9fa91b49b1 ("open: introduce openat2(2) syscall") Reviewed-by: Aleksa Sarai Cc: stable@vger.kernel.org Signed-off-by: Askar Safin Link: https://lore.kernel.org/20250825181233.2464822-5-safinaskar@zohomail.com Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

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

Merge tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2024-09-23T16:35:36+00:00

Pull 'struct fd' updates from Al Viro: "Just the 'struct fd' layout change, with conversion to accessor helpers" * tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: add struct fd constructors, get rid of __to_fd() struct fd: representation change introduce fd_file(), convert all accessors to it.

Merge tag 'vfs-6.12.folio' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

2024-09-16T06:54:30+00:00

Pull vfs folio updates from Christian Brauner: "This contains work to port write_begin and write_end to rely on folios for various filesystems. This converts ocfs2, vboxfs, orangefs, jffs2, hostfs, fuse, f2fs, ecryptfs, ntfs3, nilfs2, reiserfs, minixfs, qnx6, sysv, ufs, and squashfs. After this series lands a bunch of the filesystems in this list do not mention struct page anymore" * tag 'vfs-6.12.folio' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (61 commits) Squashfs: Ensure all readahead pages have been used Squashfs: Rewrite and update squashfs_readahead_fragment() to not use page->index Squashfs: Update squashfs_readpage_block() to not use page->index Squashfs: Update squashfs_readahead() to not use page->index Squashfs: Update page_actor to not use page->index jffs2: Use a folio in jffs2_garbage_collect_dnode() jffs2: Convert jffs2_do_readpage_nolock to take a folio buffer: Convert __block_write_begin() to take a folio ocfs2: Convert ocfs2_write_zero_page to use a folio fs: Convert aops->write_begin to take a folio fs: Convert aops->write_end to take a folio vboxsf: Use a folio in vboxsf_write_end() orangefs: Convert orangefs_write_begin() to use a folio orangefs: Convert orangefs_write_end() to use a folio jffs2: Convert jffs2_write_begin() to use a folio jffs2: Convert jffs2_write_end() to use a folio hostfs: Convert hostfs_write_end() to use a folio fuse: Convert fuse_write_begin() to use a folio fuse: Convert fuse_write_end() to use a folio f2fs: Convert f2fs_write_begin() to use a folio ...

fs: rearrange general fastpath check now that O_CREAT uses it

2024-08-30T06:22:35+00:00

If we find a positive dentry we can now simply try and open it. All prelimiary checks are already done with or without O_CREAT. Signed-off-by: Christian Brauner

fs: remove audit dummy context check

2024-08-30T06:22:35+00:00

Now that we audit later during lookup_open() we can remove the audit dummy context check. This simplifies things a lot. Signed-off-by: Christian Brauner

fs: pull up trailing slashes check for O_CREAT

2024-08-30T06:22:35+00:00

Perform the check for trailing slashes right in the fastpath check and don't bother with any additional work. Signed-off-by: Christian Brauner

fs: move audit parent inode

2024-08-30T06:22:35+00:00

During O_CREAT we unconditionally audit the parent inode. This makes it difficult to support a fastpath for O_CREAT when the file already exists because we have to drop out of RCU lookup needlessly. We worked around this by checking whether audit was actually active but that's also suboptimal. Instead, move the audit of the parent inode down into lookup_open() at a point where it's mostly certain that the file needs to be created. This also reduced the inconsistency that currently exists: while audit on the parent is done independent of whether or no the file already existed an audit on the file is only performed if it has been created. By moving the audit down a bit we emit the audit a little later but it will allow us to simplify the fastpath for O_CREAT significantly. Signed-off-by: Christian Brauner

fs: try an opportunistic lookup for O_CREAT opens too

2024-08-30T06:22:34+00:00

Today, when opening a file we'll typically do a fast lookup, but if O_CREAT is set, the kernel always takes the exclusive inode lock. I assume this was done with the expectation that O_CREAT means that we always expect to do the create, but that's often not the case. Many programs set O_CREAT even in scenarios where the file already exists. This patch rearranges the pathwalk-for-open code to also attempt a fast_lookup in certain O_CREAT cases. If a positive dentry is found, the inode_lock can be avoided altogether, and if auditing isn't enabled, it can stay in rcuwalk mode for the last step_into. One notable exception that is hopefully temporary: if we're doing an rcuwalk and auditing is enabled, skip the lookup_fast. Legitimizing the dentry in that case is more expensive than taking the i_rwsem for now. Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20240807-openfast-v3-1-040d132d2559@kernel.org Reviewed-by: Jan Kara Reviewed-by: Josef Bacik Signed-off-by: Christian Brauner

fs: add a kerneldoc header over lookup_fast

2024-08-30T06:22:33+00:00

The lookup_fast helper in fs/namei.c has some subtlety in how dentries are returned. Document them. Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20240802-openfast-v1-2-a1cff2a33063@kernel.org Signed-off-by: Christian Brauner