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

Pull vfs mount updates from Al Viro:
 "Several piles this cycle, this mount-related one being the largest and
  trickiest:

   - saner handling of guards in fs/namespace.c, getting rid of
     needlessly strong locking in some of the users

   - lock_mount() calling conventions change - have it set the
     environment for attaching to given location, storing the results in
     caller-supplied object, without altering the passed struct path.

     Make unlock_mount() called as __cleanup for those objects. It's not
     exactly guard(), but similar to it

   - MNT_WRITE_HOLD done right.

     mnt_hold_writers() does *not* mess with ->mnt_flags anymore, so
     insertion of a new mount into ->s_mounts of underlying superblock
     does not, in itself, expose ->mnt_flags of that mount to concurrent
     modifications

   - getting rid of pathological cases when umount() spends quadratic
     time removing the victims from propagation graph - part of that had
     been dealt with last cycle, this should finish it

   - a bunch of stuff constified

   - assorted cleanups

* tag 'pull-mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits)
  constify {__,}mnt_is_readonly()
  WRITE_HOLD machinery: no need for to bump mount_lock seqcount
  struct mount: relocate MNT_WRITE_HOLD bit
  preparations to taking MNT_WRITE_HOLD out of ->mnt_flags
  setup_mnt(): primitive for connecting a mount to filesystem
  simplify the callers of mnt_unhold_writers()
  copy_mnt_ns(): use guards
  copy_mnt_ns(): use the regular mechanism for freeing empty mnt_ns on failure
  open_detached_copy(): separate creation of namespace into helper
  open_detached_copy(): don't bother with mount_lock_hash()
  path_has_submounts(): use guard(mount_locked_reader)
  fs/namespace.c: sanitize descriptions for {__,}lookup_mnt()
  ecryptfs: get rid of pointless mount references in ecryptfs dentries
  umount_tree(): take all victims out of propagation graph at once
  do_mount(): use __free(path_put)
  do_move_mount_old(): use __free(path_put)
  constify can_move_mount_beneath() arguments
  path_umount(): constify struct path argument
  may_copy_tree(), __do_loopback(): constify struct path argument
  path_mount(): constify struct path argument
  ...

2 files changed, 7 insertions, 6 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 75fb216b0f7a..d3c023ff1a86 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1434,6 +1434,8 @@ struct sb_writers {
 	struct percpu_rw_semaphore	rw_sem[SB_FREEZE_LEVELS];
 };
 
+struct mount;
+
 struct super_block {
 	struct list_head	s_list;		/* Keep this first */
 	dev_t			s_dev;		/* search index; _not_ kdev_t */
@@ -1468,7 +1470,7 @@ struct super_block {
 	__u16 s_encoding_flags;
 #endif
 	struct hlist_bl_head	s_roots;	/* alternate root dentries for NFS */
-	struct list_head	s_mounts;	/* list of mounts; _not_ for fs use */
+	struct mount		*s_mounts;	/* list of mounts; _not_ for fs use */
 	struct block_device	*s_bdev;	/* can go away once we use an accessor for @s_bdev_file */
 	struct file		*s_bdev_file;
 	struct backing_dev_info *s_bdi;
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 5f9c053b0897..acfe7ef86a1b 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -33,7 +33,6 @@ enum mount_flags {
 	MNT_NOSYMFOLLOW	= 0x80,
 
 	MNT_SHRINKABLE	= 0x100,
-	MNT_WRITE_HOLD	= 0x200,
 
 	MNT_INTERNAL	= 0x4000,
 
@@ -52,7 +51,7 @@ enum mount_flags {
 				  | MNT_READONLY | MNT_NOSYMFOLLOW,
 	MNT_ATIME_MASK = MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME,
 
-	MNT_INTERNAL_FLAGS = MNT_WRITE_HOLD | MNT_INTERNAL | MNT_DOOMED |
+	MNT_INTERNAL_FLAGS = MNT_INTERNAL | MNT_DOOMED |
 			     MNT_SYNC_UMOUNT | MNT_LOCKED
 };
 
@@ -77,7 +76,7 @@ extern void mntput(struct vfsmount *mnt);
 extern struct vfsmount *mntget(struct vfsmount *mnt);
 extern void mnt_make_shortterm(struct vfsmount *mnt);
 extern struct vfsmount *mnt_clone_internal(const struct path *path);
-extern bool __mnt_is_readonly(struct vfsmount *mnt);
+extern bool __mnt_is_readonly(const struct vfsmount *mnt);
 extern bool mnt_may_suid(struct vfsmount *mnt);
 
 extern struct vfsmount *clone_private_mount(const struct path *path);
@@ -104,8 +103,8 @@ extern int may_umount_tree(struct vfsmount *);
 extern int may_umount(struct vfsmount *);
 int do_mount(const char *, const char __user *,
 		     const char *, unsigned long, void *);
-extern struct path *collect_paths(const struct path *, struct path *, unsigned);
-extern void drop_collected_paths(struct path *, struct path *);
+extern const struct path *collect_paths(const struct path *, struct path *, unsigned);
+extern void drop_collected_paths(const struct path *, const struct path *);
 extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
 
 extern int cifs_root_data(char **dev, char **opts);