This is the first of 3 sets of patches which, together, allow filesystems to opt-out of having the directory inode lock held over directory operations (except readdir). - This set creates some new APIs in the VFS and makes a few changes in callers either because they are trivial (patch 08) or because they involve a flag-day change (patches 06, 07, and 09). - The second set rolls the new APIs out to all non-VFS code which invokes directory operations. - The third (which isn't yet bug-free) changes the implementation of these APIs to make the use of inode_lock() optional.
I imagine these three set landing in three different merge windows, though some of the second set could get in the same window as the first. The patches are listed below and are available at https://github.com/neilbrown/linux in branch pdirops. This first set adds and updates APIs with three particular goals: 1/ centralising all lookup and locking for directory ops. This includes a variety of dentry_lookup() calls with done_dentry_lookup(), and rename_lookup() with done_rename_lookup(). 2/ Removing the use of d_drop() during a directory operation (it is OK for d_drop to happen at the end). As the goal is for locks to be based on the dentry, a dropped dentry will no longer protect the name. The only change in this patch set is 08 which changes d_splice_alias() and d_add() to not require a preceding d_drop(), and then removes the unnecessary d_drop()s. 3/ No blocking in d_alloc_parallel() within readdir() (iterate_shared()) requests. We will need to invert the ordering between d_alloc_parallel() and inode_lock(), so blocking in d_alloc_parallel() to, e.g., prime the dcache during readdir must be avoided. The last patch introduces new interfaces that can be used instead and explains them. Patches 9 and 10 prepare for this. Please review and consider for 6.18. Thanks, NeilBrown [PATCH 01/11] VFS: discard err2 in filename_create() [PATCH 02/11] VFS: introduce dentry_lookup() and friends [PATCH 03/11] VFS: add dentry_lookup_killable() [PATCH 04/11] VFS: introduce dentry_lookup_continue() [PATCH 05/11] VFS: add rename_lookup() [PATCH 06/11] VFS: unify old_mnt_idmap and new_mnt_idmap in [PATCH 07/11] VFS: Change vfs_mkdir() to unlock on failure. [PATCH 08/11] VFS: allow d_splice_alias() and d_add() to work on [PATCH 09/11] VFS: use global wait-queue table for d_alloc_parallel() [PATCH 10/11] VFS: use d_alloc_parallel() in lookup_one_qstr_excl(). [PATCH 11/11] VFS: introduce d_alloc_noblock() and d_alloc_locked() Future patches: set 2: devtmpfs: use new dentry locking APIs audit: use new dentry locking APIs debugfs: use new dentry locking APIs. binderfs: use new dentry locking APIs. binfmt_misc: use new dentry locking APIs. kernel/bpf: use new dentry locking APIs. devpts: use new dentry locking APIs. ipc/mqueue: use new dentry locking APIs. s390/hypfs: use new dentry locking APIs. security: use new dentry locking APIs. tracefs: use new dentry locking APIs. ecryptfs: use dentry_lookup_continue() in lock_parent() ecryptfs: use rename_lookup() fs/proc: Don't look root inode when creating "self" and "thread-self" proc: use d_alloc_locked() and lock_lookup() bcachefs: use new dentry locking APIs exfat: use d_splice_alias(), don't d_drop() coda: don't d_drop() early. smb/server: use new dentry locking APIs. nfsd: use new dentry locking APIs. cachefiles: use new dentry locking APIs. btrfs: use dentry_lookup_killable() fuse: use new dentry locking APIs. sunrpc/rpc_pipe: use new dentry locking APIs. xfs: use new dentry locking APIs. ovl: use is_subdir() for testing if one thing is a subdir of another ovl: introduce ovl_upper_dentry_lookup() and use it. ovl: switch from parent_lock() to dentry_lookup_continue() except for rename. ovl: use dentry_lookup_killable() in ovl_check_whiteouts() ovl: split ovl_tempname() out from ovl_lookup_temp(). ovl: Change ovl_lookup_temp() to use ovl_upper_dentry_lookup() ovl: Change all rename code to use rename_lookup_noperm() ovl: don't dget_parent() in ovl_lookup_real_one() ovl: use new APIs in ovl_lookup_real_one() ovl: use new dir apis in ovl_cache_update() NFS: remove d_drop() from nfs_atomic_open() nfs: use d_alloc_noblock() in silly-rename afs: use d_splice_alias() in afs_vnode_new_inode() afs: use d_time instead of d_fsdata afs: don't unhash/rehash dentries during unlink/rename AFS: use new dir access APIs. set 3: VFS: make various namei.c functions static. VFS: Remove lookup_one() and lookup_noperm() VFS: Introduce S_DYING which warns that S_DEAD might follow. VFS: lift d_alloc_parallel above inode_lock VFS: provide alternative to s_vfs_rename_mutex VFS: Add ability to exclusively lock a dentry VFS: use new dentry locking for open/create/remove/rename VFS: allow a filesystem to opt out of directory locking. NFS: allow concurrent dir ops.
