kernel/linux.git/fs/ext2/namei.c, branch v7.0.10

Change inode_operations.mkdir to return struct dentry *

2025-02-27T19:00:17+00:00

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 Reviewed-by: Jan Kara Signed-off-by: NeilBrown Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de Signed-off-by: Christian Brauner

ext2: Avoid reading renamed directory if parent does not change

2023-11-25T07:53:20+00:00

The VFS will not be locking moved directory if its parent does not change. Change ext2 rename code to avoid reading renamed directory if its parent does not change. Although it is currently harmless it is a bad practice to read directory contents without inode->i_rwsem. Signed-off-by: Jan Kara Signed-off-by: Al Viro

ext2: Convert ext2_unlink() and ext2_rename() to use folios

2023-10-25T18:31:29+00:00

This involves changing ext2_find_entry(), ext2_dotdot(), ext2_inode_by_name(), ext2_set_link() and ext2_delete_entry() to take a folio. These were also the last users of ext2_get_page() and ext2_put_page(), so remove those at the same time. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Jan Kara Message-Id: <20230921200746.3303942-8-willy@infradead.org>

ext2: convert to ctime accessor functions

2023-07-13T08:28:07+00:00

In later patches, we're going to change how the inode's ctime field is used. Switch to using accessor functions instead of raw accesses of inode->i_ctime. Signed-off-by: Jeff Layton Reviewed-by: Jan Kara Message-Id: <20230705190309.579783-39-jlayton@kernel.org> Signed-off-by: Christian Brauner

ext2_find_entry()/ext2_dotdot(): callers don't need page_addr anymore

2023-05-29T09:03:31+00:00

... and that's how it should've been done in the first place Signed-off-by: Al Viro Reviewed-by: Fabio M. De Francesco Tested-by: Fabio M. De Francesco Signed-off-by: Jan Kara

ext2_{set_link,delete_entry}(): don't bother with page_addr

2023-05-29T09:03:28+00:00

ext2_set_link() simply doesn't use it anymore and ext2_delete_entry() can easily obtain it from the directory entry pointer... Signed-off-by: Al Viro Reviewed-by: Fabio M. De Francesco Tested-by: Fabio M. De Francesco Signed-off-by: Jan Kara

ext2_put_page(): accept any pointer within the page

2023-05-29T09:03:25+00:00

eliminates the need to keep the pointer to the first byte within the page if we are guaranteed to have pointers to some byte in the same page at hand. Don't backport without commit 88d7b12068b9 ("highmem: round down the address passed to kunmap_flush_on_unmap()"). Signed-off-by: Al Viro Reviewed-by: Fabio M. De Francesco Tested-by: Fabio M. De Francesco Signed-off-by: Jan Kara

ext2_rename(): set_link and delete_entry may fail

2023-05-29T09:03:06+00:00

Signed-off-by: Al Viro Reviewed-by: Fabio M. De Francesco Tested-by: Fabio M. De Francesco Signed-off-by: Jan Kara

Merge tag 'fixes_for_v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2023-02-20T20:44:08+00:00

Pull UDF and ext2 fixes from Jan Kara: - Rewrite of udf directory iteration code to address multiple syzbot reports - Fixes to udf extent handling and block mapping code to address several syzbot reports and filesystem corruption issues uncovered by fsx & fsstress - Convert udf to kmap_local() - Add sanity checks when loading udf bitmaps - Drop old VARCONV support which I've never seen used and which was broken for quite some years without anybody noticing - Finish conversion of ext2 to kmap_local() - One fix to mpage_writepages() on which other udf fixes depend * tag 'fixes_for_v6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (78 commits) udf: Avoid directory type conversion failure due to ENOMEM udf: Use unsigned variables for size calculations udf: remove reporting loc in debug output udf: Check consistency of Space Bitmap Descriptor udf: Fix file counting in LVID udf: Limit file size to 4TB udf: Don't return bh from udf_expand_dir_adinicb() udf: Convert udf_expand_file_adinicb() to avoid kmap_atomic() udf: Convert udf_adinicb_writepage() to memcpy_to_page() udf: Switch udf_adinicb_readpage() to kmap_local_page() udf: Move udf_adinicb_readpage() to inode.c udf: Mark aops implementation static udf: Switch to single address_space_operations udf: Add handling of in-ICB files to udf_bmap() udf: Convert all file types to use udf_write_end() udf: Convert in-ICB files to use udf_write_begin() udf: Convert in-ICB files to use udf_direct_IO() udf: Convert in-ICB files to use udf_writepages() udf: Unify .read_folio for normal and in-ICB files udf: Fix off-by-one error when discarding preallocation ...

fs: port ->tmpfile() to pass mnt_idmap

2023-01-19T08:24:27+00:00

Convert to struct mnt_idmap. Last cycle we merged the necessary infrastructure in 256c8aed2b42 ("fs: introduce dedicated idmap type for mounts"). This is just the conversion to struct mnt_idmap. Currently we still pass around the plain namespace that was attached to a mount. This is in general pretty convenient but it makes it easy to conflate namespaces that are relevant on the filesystem with namespaces that are relevent on the mount level. Especially for non-vfs developers without detailed knowledge in this area this can be a potential source for bugs. Once the conversion to struct mnt_idmap is done all helpers down to the really low-level helpers will take a struct mnt_idmap argument instead of two namespace arguments. This way it becomes impossible to conflate the two eliminating the possibility of any bugs. All of the vfs and all filesystems only operate on struct mnt_idmap. Acked-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner (Microsoft)