1 files changed, 103 insertions, 41 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ab38fef1c9a1..3d06ccc953aa 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -79,6 +79,11 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
         return sb->s_bdi;
 }
 
+static inline struct inode *wb_inode(struct list_head *head)
+{
+        return list_entry(head, struct inode, i_wb_list);
+}
+
 static void bdi_queue_work(struct backing_dev_info *bdi,
                 struct wb_writeback_work *work)
 {
@@ -172,11 +177,11 @@ static void redirty_tail(struct inode *inode)
         if (!list_empty(&wb->b_dirty)) {
                 struct inode *tail;
 
-                tail = list_entry(wb->b_dirty.next, struct inode, i_list);
+                tail = wb_inode(wb->b_dirty.next);
                 if (time_before(inode->dirtied_when, tail->dirtied_when))
                         inode->dirtied_when = jiffies;
         }
-        list_move(&inode->i_list, &wb->b_dirty);
+        list_move(&inode->i_wb_list, &wb->b_dirty);
 }
 
 /*
@@ -186,7 +191,7 @@ static void requeue_io(struct inode *inode)
 {
         struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
 
-        list_move(&inode->i_list, &wb->b_more_io);
+        list_move(&inode->i_wb_list, &wb->b_more_io);
 }
 
 static void inode_sync_complete(struct inode *inode)
@@ -227,14 +232,14 @@ static void move_expired_inodes(struct list_head *delaying_queue,
         int do_sb_sort = 0;
 
         while (!list_empty(delaying_queue)) {
-                inode = list_entry(delaying_queue->prev, struct inode, i_list);
+                inode = wb_inode(delaying_queue->prev);
                 if (older_than_this &&
                     inode_dirtied_after(inode, *older_than_this))
                         break;
                 if (sb && sb != inode->i_sb)
                         do_sb_sort = 1;
                 sb = inode->i_sb;
-                list_move(&inode->i_list, &tmp);
+                list_move(&inode->i_wb_list, &tmp);
         }
 
         /* just one sb in list, splice to dispatch_queue and we're done */
@@ -245,12 +250,11 @@ static void move_expired_inodes(struct list_head *delaying_queue,
 
         /* Move inodes from one superblock together */
         while (!list_empty(&tmp)) {
-                inode = list_entry(tmp.prev, struct inode, i_list);
-                sb = inode->i_sb;
+                sb = wb_inode(tmp.prev)->i_sb;
                 list_for_each_prev_safe(pos, node, &tmp) {
-                        inode = list_entry(pos, struct inode, i_list);
+                        inode = wb_inode(pos);
                         if (inode->i_sb == sb)
-                                list_move(&inode->i_list, dispatch_queue);
+                                list_move(&inode->i_wb_list, dispatch_queue);
                 }
         }
 }
@@ -408,16 +412,13 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
                          * completion.
                          */
                         redirty_tail(inode);
-                } else if (atomic_read(&inode->i_count)) {
-                        /*
-                         * The inode is clean, inuse
-                         */
-                        list_move(&inode->i_list, &inode_in_use);
                 } else {
                         /*
-                         * The inode is clean, unused
+                         * The inode is clean.  At this point we either have
+                         * a reference to the inode or it's on it's way out.
+                         * No need to add it back to the LRU.
                          */
-                        list_move(&inode->i_list, &inode_unused);
+                        list_del_init(&inode->i_wb_list);
                 }
         }
         inode_sync_complete(inode);
@@ -465,8 +466,7 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
 {
         while (!list_empty(&wb->b_io)) {
                 long pages_skipped;
-                struct inode *inode = list_entry(wb->b_io.prev,
-                                                 struct inode, i_list);
+                struct inode *inode = wb_inode(wb->b_io.prev);
 
                 if (inode->i_sb != sb) {
                         if (only_this_sb) {
@@ -487,10 +487,16 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
                         return 0;
                 }
 
-                if (inode->i_state & (I_NEW | I_WILL_FREE)) {
+                /*
+                 * Don't bother with new inodes or inodes beeing freed, first
+                 * kind does not need peridic writeout yet, and for the latter
+                 * kind writeout is handled by the freer.
+                 */
+                if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
                         requeue_io(inode);
                         continue;
                 }
+
                 /*
                  * Was this inode dirtied after sync_sb_inodes was called?
                  * This keeps sync from extra jobs and livelock.
@@ -498,7 +504,6 @@ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb,
                 if (inode_dirtied_after(inode, wbc->wb_start))
                         return 1;
 
-                BUG_ON(inode->i_state & I_FREEING);
                 __iget(inode);
                 pages_skipped = wbc->pages_skipped;
                 writeback_single_inode(inode, wbc);
@@ -536,8 +541,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
                 queue_io(wb, wbc->older_than_this);
 
         while (!list_empty(&wb->b_io)) {
-                struct inode *inode = list_entry(wb->b_io.prev,
-                                                 struct inode, i_list);
+                struct inode *inode = wb_inode(wb->b_io.prev);
                 struct super_block *sb = inode->i_sb;
 
                 if (!pin_sb_for_writeback(sb)) {
@@ -582,7 +586,7 @@ static inline bool over_bground_thresh(void)
         global_dirty_limits(&background_thresh, &dirty_thresh);
 
         return (global_page_state(NR_FILE_DIRTY) +
-                global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
+                global_page_state(NR_UNSTABLE_NFS) > background_thresh);
 }
 
 /*
@@ -675,8 +679,7 @@ static long wb_writeback(struct bdi_writeback *wb,
                  */
                 spin_lock(&inode_lock);
                 if (!list_empty(&wb->b_more_io))  {
-                        inode = list_entry(wb->b_more_io.prev,
-                                                struct inode, i_list);
+                        inode = wb_inode(wb->b_more_io.prev);
                         trace_wbc_writeback_wait(&wbc, wb->bdi);
                         inode_wait_for_writeback(inode);
                 }
@@ -704,6 +707,17 @@ get_next_work_item(struct backing_dev_info *bdi)
         return work;
 }
 
+/*
+ * Add in the number of potentially dirty inodes, because each inode
+ * write can dirty pagecache in the underlying blockdev.
+ */
+static unsigned long get_nr_dirty_pages(void)
+{
+        return global_page_state(NR_FILE_DIRTY) +
+                global_page_state(NR_UNSTABLE_NFS) +
+                get_nr_dirty_inodes();
+}
+
 static long wb_check_old_data_flush(struct bdi_writeback *wb)
 {
         unsigned long expired;
@@ -721,9 +735,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
                 return 0;
 
         wb->last_old_flush = jiffies;
-        nr_pages = global_page_state(NR_FILE_DIRTY) +
-                        global_page_state(NR_UNSTABLE_NFS) +
-                        (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+        nr_pages = get_nr_dirty_pages();
 
         if (nr_pages) {
                 struct wb_writeback_work work = {
@@ -790,7 +802,7 @@ int bdi_writeback_thread(void *data)
         struct backing_dev_info *bdi = wb->bdi;
         long pages_written;
 
-        current->flags |= PF_FLUSHER | PF_SWAPWRITE;
+        current->flags |= PF_SWAPWRITE;
         set_freezable();
         wb->last_active = jiffies;
 
@@ -962,7 +974,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                  * dirty list.  Add blockdev inodes as well.
                  */
                 if (!S_ISBLK(inode->i_mode)) {
-                        if (hlist_unhashed(&inode->i_hash))
+                        if (inode_unhashed(inode))
                                 goto out;
                 }
                 if (inode->i_state & I_FREEING)
@@ -990,7 +1002,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                         }
 
                         inode->dirtied_when = jiffies;
-                        list_move(&inode->i_list, &bdi->wb.b_dirty);
+                        list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
                 }
         }
 out:
@@ -1069,33 +1081,42 @@ static void wait_sb_inodes(struct super_block *sb)
 }
 
 /**
- * writeback_inodes_sb  -       writeback dirty inodes from given super_block
+ * writeback_inodes_sb_nr -     writeback dirty inodes from given super_block
  * @sb: the superblock
+ * @nr: the number of pages to write
  *
  * Start writeback on some inodes on this super_block. No guarantees are made
  * on how many (if any) will be written, and this function does not wait
- * for IO completion of submitted IO. The number of pages submitted is
- * returned.
+ * for IO completion of submitted IO.
  */
-void writeback_inodes_sb(struct super_block *sb)
+void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
 {
-        unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
-        unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
         DECLARE_COMPLETION_ONSTACK(done);
         struct wb_writeback_work work = {
                 .sb             = sb,
                 .sync_mode      = WB_SYNC_NONE,
                 .done           = &done,
+                .nr_pages       = nr,
         };
 
         WARN_ON(!rwsem_is_locked(&sb->s_umount));
-
-        work.nr_pages = nr_dirty + nr_unstable +
-                        (inodes_stat.nr_inodes - inodes_stat.nr_unused);
-
         bdi_queue_work(sb->s_bdi, &work);
         wait_for_completion(&done);
 }
+EXPORT_SYMBOL(writeback_inodes_sb_nr);
+
+/**
+ * writeback_inodes_sb  -       writeback dirty inodes from given super_block
+ * @sb: the superblock
+ *
+ * Start writeback on some inodes on this super_block. No guarantees are made
+ * on how many (if any) will be written, and this function does not wait
+ * for IO completion of submitted IO.
+ */
+void writeback_inodes_sb(struct super_block *sb)
+{
+        return writeback_inodes_sb_nr(sb, get_nr_dirty_pages());
+}
 EXPORT_SYMBOL(writeback_inodes_sb);
 
 /**
@@ -1118,6 +1139,27 @@ int writeback_inodes_sb_if_idle(struct super_block *sb)
 EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
 
 /**
+ * writeback_inodes_sb_if_idle  -       start writeback if none underway
+ * @sb: the superblock
+ * @nr: the number of pages to write
+ *
+ * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Returns 1 if writeback was started, 0 if not.
+ */
+int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
+                                   unsigned long nr)
+{
+        if (!writeback_in_progress(sb->s_bdi)) {
+                down_read(&sb->s_umount);
+                writeback_inodes_sb_nr(sb, nr);
+                up_read(&sb->s_umount);
+                return 1;
+        } else
+                return 0;
+}
+EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
+
+/**
  * sync_inodes_sb       -       sync sb inode pages
  * @sb: the superblock
  *
@@ -1198,3 +1240,23 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
         return ret;
 }
 EXPORT_SYMBOL(sync_inode);
+
+/**
+ * sync_inode - write an inode to disk
+ * @inode: the inode to sync
+ * @wait: wait for I/O to complete.
+ *
+ * Write an inode to disk and adjust it's dirty state after completion.
+ *
+ * Note: only writes the actual inode, no associated data or other metadata.
+ */
+int sync_inode_metadata(struct inode *inode, int wait)
+{
+        struct writeback_control wbc = {
+                .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
+                .nr_to_write = 0, /* metadata-only */
+        };
+
+        return sync_inode(inode, &wbc);
+}
+EXPORT_SYMBOL(sync_inode_metadata);