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
  ...

1 files changed, 43 insertions, 29 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 5fa588e933d5..ae0f438c2ee6 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -88,7 +88,7 @@ unsigned int dirtytime_expire_interval = 12 * 60 * 60;
 
 static inline struct inode *wb_inode(struct list_head *head)
 {
-        return list_entry(head, struct inode, i_wb_list);
+        return list_entry(head, struct inode, i_io_list);
 }
 
 /*
@@ -125,22 +125,22 @@ static void wb_io_lists_depopulated(struct bdi_writeback *wb)
 }
 
 /**
- * inode_wb_list_move_locked - move an inode onto a bdi_writeback IO list
+ * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list
  * @inode: inode to be moved
  * @wb: target bdi_writeback
  * @head: one of @wb->b_{dirty|io|more_io}
  *
- * Move @inode->i_wb_list to @list of @wb and set %WB_has_dirty_io.
+ * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io.
  * Returns %true if @inode is the first occupant of the !dirty_time IO
  * lists; otherwise, %false.
  */
-static bool inode_wb_list_move_locked(struct inode *inode,
+static bool inode_io_list_move_locked(struct inode *inode,
                                       struct bdi_writeback *wb,
                                       struct list_head *head)
 {
         assert_spin_locked(&wb->list_lock);
 
-        list_move(&inode->i_wb_list, head);
+        list_move(&inode->i_io_list, head);
 
         /* dirty_time doesn't count as dirty_io until expiration */
         if (head != &wb->b_dirty_time)
@@ -151,19 +151,19 @@ static bool inode_wb_list_move_locked(struct inode *inode,
 }
 
 /**
- * inode_wb_list_del_locked - remove an inode from its bdi_writeback IO list
+ * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list
  * @inode: inode to be removed
  * @wb: bdi_writeback @inode is being removed from
  *
  * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and
  * clear %WB_has_dirty_io if all are empty afterwards.
  */
-static void inode_wb_list_del_locked(struct inode *inode,
+static void inode_io_list_del_locked(struct inode *inode,
                                      struct bdi_writeback *wb)
 {
         assert_spin_locked(&wb->list_lock);
 
-        list_del_init(&inode->i_wb_list);
+        list_del_init(&inode->i_io_list);
         wb_io_lists_depopulated(wb);
 }
 
@@ -351,7 +351,7 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
 
         /*
          * Once I_FREEING is visible under i_lock, the eviction path owns
-         * the inode and we shouldn't modify ->i_wb_list.
+         * the inode and we shouldn't modify ->i_io_list.
          */
         if (unlikely(inode->i_state & I_FREEING))
                 goto skip_switch;
@@ -390,16 +390,16 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
          * is always correct including from ->b_dirty_time.  The transfer
          * preserves @inode->dirtied_when ordering.
          */
-        if (!list_empty(&inode->i_wb_list)) {
+        if (!list_empty(&inode->i_io_list)) {
                 struct inode *pos;
 
-                inode_wb_list_del_locked(inode, old_wb);
+                inode_io_list_del_locked(inode, old_wb);
                 inode->i_wb = new_wb;
-                list_for_each_entry(pos, &new_wb->b_dirty, i_wb_list)
+                list_for_each_entry(pos, &new_wb->b_dirty, i_io_list)
                         if (time_after_eq(inode->dirtied_when,
                                           pos->dirtied_when))
                                 break;
-                inode_wb_list_move_locked(inode, new_wb, pos->i_wb_list.prev);
+                inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev);
         } else {
                 inode->i_wb = new_wb;
         }
@@ -961,12 +961,12 @@ void wb_start_background_writeback(struct bdi_writeback *wb)
 /*
  * Remove the inode from the writeback list it is on.
  */
-void inode_wb_list_del(struct inode *inode)
+void inode_io_list_del(struct inode *inode)
 {
         struct bdi_writeback *wb;
 
         wb = inode_to_wb_and_lock_list(inode);
-        inode_wb_list_del_locked(inode, wb);
+        inode_io_list_del_locked(inode, wb);
         spin_unlock(&wb->list_lock);
 }
 
@@ -988,7 +988,7 @@ static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
                 if (time_before(inode->dirtied_when, tail->dirtied_when))
                         inode->dirtied_when = jiffies;
         }
-        inode_wb_list_move_locked(inode, wb, &wb->b_dirty);
+        inode_io_list_move_locked(inode, wb, &wb->b_dirty);
 }
 
 /*
@@ -996,7 +996,7 @@ static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
  */
 static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
 {
-        inode_wb_list_move_locked(inode, wb, &wb->b_more_io);
+        inode_io_list_move_locked(inode, wb, &wb->b_more_io);
 }
 
 static void inode_sync_complete(struct inode *inode)
@@ -1055,7 +1055,7 @@ static int move_expired_inodes(struct list_head *delaying_queue,
                 if (older_than_this &&
                     inode_dirtied_after(inode, *older_than_this))
                         break;
-                list_move(&inode->i_wb_list, &tmp);
+                list_move(&inode->i_io_list, &tmp);
                 moved++;
                 if (flags & EXPIRE_DIRTY_ATIME)
                         set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state);
@@ -1078,7 +1078,7 @@ static int move_expired_inodes(struct list_head *delaying_queue,
                 list_for_each_prev_safe(pos, node, &tmp) {
                         inode = wb_inode(pos);
                         if (inode->i_sb == sb)
-                                list_move(&inode->i_wb_list, dispatch_queue);
+                                list_move(&inode->i_io_list, dispatch_queue);
                 }
         }
 out:
@@ -1232,10 +1232,10 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
                 redirty_tail(inode, wb);
         } else if (inode->i_state & I_DIRTY_TIME) {
                 inode->dirtied_when = jiffies;
-                inode_wb_list_move_locked(inode, wb, &wb->b_dirty_time);
+                inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
         } else {
                 /* The inode is clean. Remove from writeback lists. */
-                inode_wb_list_del_locked(inode, wb);
+                inode_io_list_del_locked(inode, wb);
         }
 }
 
@@ -1378,7 +1378,7 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
          * touch it. See comment above for explanation.
          */
         if (!(inode->i_state & I_DIRTY_ALL))
-                inode_wb_list_del_locked(inode, wb);
+                inode_io_list_del_locked(inode, wb);
         spin_unlock(&wb->list_lock);
         inode_sync_complete(inode);
 out:
@@ -1439,7 +1439,9 @@ static long writeback_sb_inodes(struct super_block *sb,
         unsigned long start_time = jiffies;
         long write_chunk;
         long wrote = 0;  /* count both pages and inodes */
+        struct blk_plug plug;
 
+        blk_start_plug(&plug);
         while (!list_empty(&wb->b_io)) {
                 struct inode *inode = wb_inode(wb->b_io.prev);
 
@@ -1537,6 +1539,7 @@ static long writeback_sb_inodes(struct super_block *sb,
                                 break;
                 }
         }
+        blk_finish_plug(&plug);
         return wrote;
 }
 
@@ -2088,7 +2091,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                         else
                                 dirty_list = &wb->b_dirty_time;
 
-                        wakeup_bdi = inode_wb_list_move_locked(inode, wb,
+                        wakeup_bdi = inode_io_list_move_locked(inode, wb,
                                                                dirty_list);
 
                         spin_unlock(&wb->list_lock);
@@ -2111,6 +2114,15 @@ out_unlock_inode:
 }
 EXPORT_SYMBOL(__mark_inode_dirty);
 
+/*
+ * The @s_sync_lock is used to serialise concurrent sync operations
+ * to avoid lock contention problems with concurrent wait_sb_inodes() calls.
+ * Concurrent callers will block on the s_sync_lock rather than doing contending
+ * walks. The queueing maintains sync(2) required behaviour as all the IO that
+ * has been issued up to the time this function is enter is guaranteed to be
+ * completed by the time we have gained the lock and waited for all IO that is
+ * in progress regardless of the order callers are granted the lock.
+ */
 static void wait_sb_inodes(struct super_block *sb)
 {
         struct inode *inode, *old_inode = NULL;
@@ -2121,7 +2133,8 @@ static void wait_sb_inodes(struct super_block *sb)
          */
         WARN_ON(!rwsem_is_locked(&sb->s_umount));
 
-        spin_lock(&inode_sb_list_lock);
+        mutex_lock(&sb->s_sync_lock);
+        spin_lock(&sb->s_inode_list_lock);
 
         /*
          * Data integrity sync. Must wait for all pages under writeback,
@@ -2141,14 +2154,14 @@ static void wait_sb_inodes(struct super_block *sb)
                 }
                 __iget(inode);
                 spin_unlock(&inode->i_lock);
-                spin_unlock(&inode_sb_list_lock);
+                spin_unlock(&sb->s_inode_list_lock);
 
                 /*
                  * We hold a reference to 'inode' so it couldn't have been
                  * removed from s_inodes list while we dropped the
-                 * inode_sb_list_lock.  We cannot iput the inode now as we can
+                 * s_inode_list_lock.  We cannot iput the inode now as we can
                  * be holding the last reference and we cannot iput it under
-                 * inode_sb_list_lock. So we keep the reference and iput it
+                 * s_inode_list_lock. So we keep the reference and iput it
                  * later.
                  */
                 iput(old_inode);
@@ -2158,10 +2171,11 @@ static void wait_sb_inodes(struct super_block *sb)
 
                 cond_resched();
 
-                spin_lock(&inode_sb_list_lock);
+                spin_lock(&sb->s_inode_list_lock);
         }
-        spin_unlock(&inode_sb_list_lock);
+        spin_unlock(&sb->s_inode_list_lock);
         iput(old_inode);
+        mutex_unlock(&sb->s_sync_lock);
 }
 
 static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr,