Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs updates from Al Viro:
 "In this one:

   - d_move fixes (Eric Biederman)

   - UFS fixes (me; locking is mostly sane now, a bunch of bugs in error
     handling ought to be fixed)

   - switch of sb_writers to percpu rwsem (Oleg Nesterov)

   - superblock scalability (Josef Bacik and Dave Chinner)

   - swapon(2) race fix (Hugh Dickins)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits)
  vfs: Test for and handle paths that are unreachable from their mnt_root
  dcache: Reduce the scope of i_lock in d_splice_alias
  dcache: Handle escaped paths in prepend_path
  mm: fix potential data race in SyS_swapon
  inode: don't softlockup when evicting inodes
  inode: rename i_wb_list to i_io_list
  sync: serialise per-superblock sync operations
  inode: convert inode_sb_list_lock to per-sb
  inode: add hlist_fake to avoid the inode hash lock in evict
  writeback: plug writeback at a high level
  change sb_writers to use percpu_rw_semaphore
  shift percpu_counter_destroy() into destroy_super_work()
  percpu-rwsem: kill CONFIG_PERCPU_RWSEM
  percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()
  percpu-rwsem: introduce percpu_down_read_trylock()
  document rwsem_release() in sb_wait_write()
  fix the broken lockdep logic in __sb_start_write()
  introduce __sb_writers_{acquired,release}() helpers
  ufs_inode_get{frag,block}(): get rid of 'phys' argument
  ufs_getfrag_block(): tidy up a bit
  ...

include/linux/fs.h

@@ -1,7 +1,6 @@
 #ifndef _LINUX_FS_H
 #define _LINUX_FS_H
 
-
 #include <linux/linkage.h>
 #include <linux/wait.h>
 #include <linux/kdev_t.h>
@@ -30,6 +29,8 @@
 #include <linux/lockdep.h>
 #include <linux/percpu-rwsem.h>
 #include <linux/blk_types.h>
+#include <linux/workqueue.h>
+#include <linux/percpu-rwsem.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -636,7 +637,7 @@ struct inode {
 	unsigned long		dirtied_time_when;
 
 	struct hlist_node	i_hash;
-	struct list_head	i_wb_list;	/* backing dev IO list */
+	struct list_head	i_io_list;	/* backing dev IO list */
 #ifdef CONFIG_CGROUP_WRITEBACK
 	struct bdi_writeback	*i_wb;		/* the associated cgroup wb */
 
@@ -1281,16 +1282,9 @@ enum {
 #define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)
 
 struct sb_writers {
-	/* Counters for counting writers at each level */
-	struct percpu_counter	counter[SB_FREEZE_LEVELS];
-	wait_queue_head_t	wait;		/* queue for waiting for
-						   writers / faults to finish */
-	int			frozen;		/* Is sb frozen? */
-	wait_queue_head_t	wait_unfrozen;	/* queue for waiting for
-						   sb to be thawed */
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-	struct lockdep_map	lock_map[SB_FREEZE_LEVELS];
-#endif
+	int				frozen;		/* Is sb frozen? */
+	wait_queue_head_t		wait_unfrozen;	/* for get_super_thawed() */
+	struct percpu_rw_semaphore	rw_sem[SB_FREEZE_LEVELS];
 };
 
 struct super_block {
@@ -1316,7 +1310,6 @@ struct super_block {
 #endif
 	const struct xattr_handler **s_xattr;
 
-	struct list_head	s_inodes;	/* all inodes */
 	struct hlist_bl_head	s_anon;		/* anonymous dentries for (nfs) exporting */
 	struct list_head	s_mounts;	/* list of mounts; _not_ for fs use */
 	struct block_device	*s_bdev;
@@ -1382,11 +1375,18 @@ struct super_block {
 	struct list_lru		s_dentry_lru ____cacheline_aligned_in_smp;
 	struct list_lru		s_inode_lru ____cacheline_aligned_in_smp;
 	struct rcu_head		rcu;
+	struct work_struct	destroy_work;
+
+	struct mutex		s_sync_lock;	/* sync serialisation lock */
 
 	/*
 	 * Indicates how deep in a filesystem stack this SB is
 	 */
 	int s_stack_depth;
+
+	/* s_inode_list_lock protects s_inodes */
+	spinlock_t		s_inode_list_lock ____cacheline_aligned_in_smp;
+	struct list_head	s_inodes;	/* all inodes */
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);
@@ -1398,6 +1398,11 @@ extern struct timespec current_fs_time(struct super_block *sb);
 void __sb_end_write(struct super_block *sb, int level);
 int __sb_start_write(struct super_block *sb, int level, bool wait);
 
+#define __sb_writers_acquired(sb, lev)	\
+	percpu_rwsem_acquire(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
+#define __sb_writers_release(sb, lev)	\
+	percpu_rwsem_release(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
+
 /**
  * sb_end_write - drop write access to a superblock
  * @sb: the super we wrote to
@@ -2614,7 +2619,7 @@ static inline void insert_inode_hash(struct inode *inode)
 extern void __remove_inode_hash(struct inode *);
 static inline void remove_inode_hash(struct inode *inode)
 {
-	if (!inode_unhashed(inode))
+	if (!inode_unhashed(inode) && !hlist_fake(&inode->i_hash))
 		__remove_inode_hash(inode);
 }