Merge tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull directory locking updates from Christian Brauner:
 "This contains the work to add centralized APIs for directory locking
  operations.

  This series is part of a larger effort to change directory operation
  locking to allow multiple concurrent operations in a directory. The
  ultimate goal is to lock the target dentry(s) rather than the whole
  parent directory.

  To help with changing the locking protocol, this series centralizes
  locking and lookup in new helper functions. The helpers establish a
  pattern where it is the dentry that is being locked and unlocked
  (currently the lock is held on dentry->d_parent->d_inode, but that can
  change in the future).

  This also changes vfs_mkdir() to unlock the parent on failure, as well
  as dput()ing the dentry. This allows end_creating() to only require
  the target dentry (which may be IS_ERR() after vfs_mkdir()), not the
  parent"

* tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  nfsd: fix end_creating() conversion
  VFS: introduce end_creating_keep()
  VFS: change vfs_mkdir() to unlock on failure.
  ecryptfs: use new start_creating/start_removing APIs
  Add start_renaming_two_dentries()
  VFS/ovl/smb: introduce start_renaming_dentry()
  VFS/nfsd/ovl: introduce start_renaming() and end_renaming()
  VFS: add start_creating_killable() and start_removing_killable()
  VFS: introduce start_removing_dentry()
  smb/server: use end_removing_noperm for for target of smb2_create_link()
  VFS: introduce start_creating_noperm() and start_removing_noperm()
  VFS/nfsd/cachefiles/ovl: introduce start_removing() and end_removing()
  VFS/nfsd/cachefiles/ovl: add start_creating() and end_creating()
  VFS: tidy up do_unlinkat()
  VFS: introduce start_dirop() and end_dirop()
  debugfs: rename end_creating() to debugfs_end_creating()

1 files changed, 17 insertions, 19 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 1661dcb7d983..2d6657947abd 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -2290,27 +2290,25 @@ void stashed_dentry_prune(struct dentry *dentry)
 	cmpxchg(stashed, dentry, NULL);
 }
 
-/* parent must be held exclusive */
+/**
+ * simple_start_creating - prepare to create a given name
+ * @parent: directory in which to prepare to create the name
+ * @name:   the name to be created
+ *
+ * Required lock is taken and a lookup in performed prior to creating an
+ * object in a directory.  No permission checking is performed.
+ *
+ * Returns: a negative dentry on which vfs_create() or similar may
+ *  be attempted, or an error.
+ */
 struct dentry *simple_start_creating(struct dentry *parent, const char *name)
 {
-	struct dentry *dentry;
-	struct inode *dir = d_inode(parent);
+	struct qstr qname = QSTR(name);
+	int err;
 
-	inode_lock(dir);
-	if (unlikely(IS_DEADDIR(dir))) {
-		inode_unlock(dir);
-		return ERR_PTR(-ENOENT);
-	}
-	dentry = lookup_noperm(&QSTR(name), parent);
-	if (IS_ERR(dentry)) {
-		inode_unlock(dir);
-		return dentry;
-	}
-	if (dentry->d_inode) {
-		dput(dentry);
-		inode_unlock(dir);
-		return ERR_PTR(-EEXIST);
-	}
-	return dentry;
+	err = lookup_noperm_common(&qname, parent);
+	if (err)
+		return ERR_PTR(err);
+	return start_dirop(parent, &qname, LOOKUP_CREATE | LOOKUP_EXCL);
 }
 EXPORT_SYMBOL(simple_start_creating);