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

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
     permission checks during path lookup and adds the
     IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
     expensive permission work.

   - Hide dentry_cache behind runtime const machinery.

   - Add German Maglione as virtiofs co-maintainer.

  Cleanups:

   - Tidy up and inline step_into() and walk_component() for improved
     code generation.

   - Re-enable IOCB_NOWAIT writes to files. This refactors file
     timestamp update logic, fixing a layering bypass in btrfs when
     updating timestamps on device files and improving FMODE_NOCMTIME
     handling in VFS now that nfsd started using it.

   - Path lookup optimizations extracting slowpaths into dedicated
     routines and adding branch prediction hints for mntput_no_expire(),
     fd_install(), lookup_slow(), and various other hot paths.

   - Enable clang's -fms-extensions flag, requiring a JFS rename to
     avoid conflicts.

   - Remove spurious exports in fs/file_attr.c.

   - Stop duplicating union pipe_index declaration. This depends on the
     shared kbuild branch that brings in -fms-extensions support which
     is merged into this branch.

   - Use MD5 library instead of crypto_shash in ecryptfs.

   - Use largest_zero_folio() in iomap_dio_zero().

   - Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
     initrd code.

   - Various typo fixes.

  Fixes:

   - Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
     call with wait == 1 to commit super blocks. The emergency sync path
     never passed this, leaving btrfs data uncommitted during emergency
     sync.

   - Use local kmap in watch_queue's post_one_notification().

   - Add hint prints in sb_set_blocksize() for LBS dependency on THP"

* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
  MAINTAINERS: add German Maglione as virtiofs co-maintainer
  fs: inline step_into() and walk_component()
  fs: tidy up step_into() & friends before inlining
  orangefs: use inode_update_timestamps directly
  btrfs: fix the comment on btrfs_update_time
  btrfs: use vfs_utimes to update file timestamps
  fs: export vfs_utimes
  fs: lift the FMODE_NOCMTIME check into file_update_time_flags
  fs: refactor file timestamp update logic
  include/linux/fs.h: trivial fix: regualr -> regular
  fs/splice.c: trivial fix: pipes -> pipe's
  fs: mark lookup_slow() as noinline
  fs: add predicts based on nd->depth
  fs: move mntput_no_expire() slowpath into a dedicated routine
  fs: remove spurious exports in fs/file_attr.c
  watch_queue: Use local kmap in post_one_notification()
  fs: touch up predicts in path lookup
  fs: move fd_install() slowpath into a dedicated routine and provide commentary
  fs: hide dentry_cache behind runtime const machinery
  fs: touch predicts in do_dentry_open()
  ...

1 files changed, 22 insertions, 16 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 4272349650b1..a7fd9682bcf9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1336,26 +1336,12 @@ static void delayed_mntput(struct work_struct *unused)
 }
 static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput);
 
-static void mntput_no_expire(struct mount *mnt)
+static void noinline mntput_no_expire_slowpath(struct mount *mnt)
 {
 	LIST_HEAD(list);
 	int count;
 
-	rcu_read_lock();
-	if (likely(READ_ONCE(mnt->mnt_ns))) {
-		/*
-		 * Since we don't do lock_mount_hash() here,
-		 * ->mnt_ns can change under us.  However, if it's
-		 * non-NULL, then there's a reference that won't
-		 * be dropped until after an RCU delay done after
-		 * turning ->mnt_ns NULL.  So if we observe it
-		 * non-NULL under rcu_read_lock(), the reference
-		 * we are dropping is not the final one.
-		 */
-		mnt_add_count(mnt, -1);
-		rcu_read_unlock();
-		return;
-	}
+	VFS_BUG_ON(mnt->mnt_ns);
 	lock_mount_hash();
 	/*
 	 * make sure that if __legitimize_mnt() has not seen us grab
@@ -1406,6 +1392,26 @@ static void mntput_no_expire(struct mount *mnt)
 	cleanup_mnt(mnt);
 }
 
+static void mntput_no_expire(struct mount *mnt)
+{
+	rcu_read_lock();
+	if (likely(READ_ONCE(mnt->mnt_ns))) {
+		/*
+		 * Since we don't do lock_mount_hash() here,
+		 * ->mnt_ns can change under us.  However, if it's
+		 * non-NULL, then there's a reference that won't
+		 * be dropped until after an RCU delay done after
+		 * turning ->mnt_ns NULL.  So if we observe it
+		 * non-NULL under rcu_read_lock(), the reference
+		 * we are dropping is not the final one.
+		 */
+		mnt_add_count(mnt, -1);
+		rcu_read_unlock();
+		return;
+	}
+	mntput_no_expire_slowpath(mnt);
+}
+
 void mntput(struct vfsmount *mnt)
 {
 	if (mnt) {