kernel.git/fs/udf/namei.c, branch linux-rolling-stable

Change inode_operations.mkdir to return struct dentry *

2025-02-27T19:00:17Z

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

udf: Verify inode link counts before performing rename

2024-11-26T21:54:24Z

During rename, we are updating link counts of various inodes either when rename deletes target or when moving directory across directories. Verify involved link counts are sane so that we don't trip warnings in VFS. Reported-by: syzbot+3ff7365dc04a6bcafa66@syzkaller.appspotmail.com Signed-off-by: Jan Kara

udf: Skip parent dir link count update if corrupted

2024-11-26T21:54:24Z

If the parent directory link count is too low (likely directory inode corruption), just skip updating its link count as if it goes to 0 too early it can cause unexpected issues. Signed-off-by: Jan Kara

udf: Fix bogus checksum computation in udf_rename()

2024-06-20T13:07:27Z

Syzbot reports uninitialized memory access in udf_rename() when updating checksum of '..' directory entry of a moved directory. This is indeed true as we pass on-stack diriter.fi to the udf_update_tag() and because that has only struct fileIdentDesc included in it and not the impUse or name fields, the checksumming function is going to checksum random stack contents beyond the end of the structure. This is actually harmless because the following udf_fiiter_write_fi() will recompute the checksum from on-disk buffers where everything is properly included. So all that is needed is just removing the bogus calculation. Fixes: e9109a92d2a9 ("udf: Convert udf_rename() to new directory iteration code") Link: https://lore.kernel.org/all/000000000000cf405f060d8f75a9@google.com/T/ Link: https://patch.msgid.link/20240617154201.29512-1-jack@suse.cz Reported-by: syzbot+d31185aa54170f7fc1f5@syzkaller.appspotmail.com Signed-off-by: Jan Kara

udf: Avoid GFP_NOFS allocation in udf_symlink()

2024-01-23T18:21:10Z

The GFP_NOFS allocation in udf_symlink() is called only under inode->i_rwsem and UDF_I(inode)->i_data_sem. The first is safe wrt reclaim, the second should be as well but allocating unde this lock is actually unnecessary. Move the allocation from under i_data_sem and change it to GFP_KERNEL. Signed-off-by: Jan Kara

udf: Remove GFP_NOFS from dir iteration code

2024-01-23T18:21:10Z

Directory iteration code was using GFP_NOFS allocations in two places. However the code is called only under inode->i_rwsem which is generally safe wrt reclaim. So we can do the allocations with GFP_KERNEL instead. Signed-off-by: Jan Kara

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

2024-01-12T04:23:50Z

Pull misc filesystem updates from Al Viro: "Misc cleanups (the part that hadn't been picked by individual fs trees)" * tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: apparmorfs: don't duplicate kfree_link() orangefs: saner arguments passing in readdir guts ocfs2_find_match(): there's no such thing as NULL or negative ->d_parent reiserfs_add_entry(): get rid of pointless namelen checks __ocfs2_add_entry(), ocfs2_prepare_dir_for_insert(): namelen checks ext4_add_entry(): ->d_name.len is never 0 befs: d_obtain_alias(ERR_PTR(...)) will do the right thing affs: d_obtain_alias(ERR_PTR(...)) will do the right thing /proc/sys: use d_splice_alias() calling conventions to simplify failure exits hostfs: use d_splice_alias() calling conventions to simplify failure exits udf_fiiter_add_entry(): check for zero ->d_name.len is bogus... udf: d_obtain_alias(ERR_PTR(...)) will do the right thing... udf: d_splice_alias() will do the right thing on ERR_PTR() inode nfsd: kill stale comment about simple_fill_super() requirements bfs_add_entry(): get rid of pointless ->d_name.len checks nilfs2: d_obtain_alias(ERR_PTR(...)) will do the right thing... zonefs: d_splice_alias() will do the right thing on ERR_PTR() inode

udf_fiiter_add_entry(): check for zero ->d_name.len is bogus...

2023-12-21T17:50:31Z

Acked-by: Jan Kara Signed-off-by: Al Viro

udf: d_obtain_alias(ERR_PTR(...)) will do the right thing...

2023-12-21T17:49:36Z

Acked-by: Jan Kara Signed-off-by: Al Viro

udf: d_splice_alias() will do the right thing on ERR_PTR() inode

2023-12-21T17:49:16Z

Acked-by: Jan Kara Signed-off-by: Al Viro