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

* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: Add a 'reason' to wb_writeback_work
  writeback: send work item to queue_io, move_expired_inodes
  writeback: trace event balance_dirty_pages
  writeback: trace event bdi_dirty_ratelimit
  writeback: fix ppc compile warnings on do_div(long long, unsigned long)
  writeback: per-bdi background threshold
  writeback: dirty position control - bdi reserve area
  writeback: control dirty pause time
  writeback: limit max dirty pause time
  writeback: IO-less balance_dirty_pages()
  writeback: per task dirty rate limit
  writeback: stabilize bdi->dirty_ratelimit
  writeback: dirty rate control
  writeback: add bg_threshold parameter to __bdi_update_bandwidth()
  writeback: dirty position control
  writeback: account per-bdi accumulated dirtied pages

7 files changed, 65 insertions, 34 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f5be06a2462..c9ee0e18bbd 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3340,7 +3340,8 @@ static int shrink_delalloc(struct btrfs_trans_handle *trans,
                 smp_mb();
                 nr_pages = min_t(unsigned long, nr_pages,
                        root->fs_info->delalloc_bytes >> PAGE_CACHE_SHIFT);
-                writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages);
+                writeback_inodes_sb_nr_if_idle(root->fs_info->sb, nr_pages,
+                                                WB_REASON_FS_FREE_SPACE);
 
                 spin_lock(&space_info->lock);
                 if (reserved > space_info->bytes_reserved)
diff --git a/fs/buffer.c b/fs/buffer.c
index 70a19745cb6..19d8eb7fdc8 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -288,7 +288,7 @@ static void free_more_memory(void)
         struct zone *zone;
         int nid;
 
-        wakeup_flusher_threads(1024);
+        wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
         yield();
 
         for_each_online_node(nid) {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cc5a6da030a..240f6e2dc7e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2372,7 +2372,7 @@ static int ext4_nonda_switch(struct super_block *sb)
          * start pushing delalloc when 1/2 of free blocks are dirty.
          */
         if (free_blocks < 2 * dirty_blocks)
-                writeback_inodes_sb_if_idle(sb);
+                writeback_inodes_sb_if_idle(sb, WB_REASON_FS_FREE_SPACE);
 
         return 0;
 }
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 04cf3b91e50..73c3992b2bb 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -41,11 +41,23 @@ struct wb_writeback_work {
         unsigned int for_kupdate:1;
         unsigned int range_cyclic:1;
         unsigned int for_background:1;
+        enum wb_reason reason;          /* why was writeback initiated? */
 
         struct list_head list;          /* pending work list */
         struct completion *done;        /* set if the caller waits */
 };
 
+const char *wb_reason_name[] = {
+        [WB_REASON_BACKGROUND]          = "background",
+        [WB_REASON_TRY_TO_FREE_PAGES]   = "try_to_free_pages",
+        [WB_REASON_SYNC]                = "sync",
+        [WB_REASON_PERIODIC]            = "periodic",
+        [WB_REASON_LAPTOP_TIMER]        = "laptop_timer",
+        [WB_REASON_FREE_MORE_MEM]       = "free_more_memory",
+        [WB_REASON_FS_FREE_SPACE]       = "fs_free_space",
+        [WB_REASON_FORKER_THREAD]       = "forker_thread"
+};
+
 /*
  * Include the creation of the trace points after defining the
  * wb_writeback_work structure so that the definition remains local to this
@@ -115,7 +127,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
 
 static void
 __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
-                      bool range_cyclic)
+                      bool range_cyclic, enum wb_reason reason)
 {
         struct wb_writeback_work *work;
 
@@ -135,6 +147,7 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
         work->sync_mode = WB_SYNC_NONE;
         work->nr_pages  = nr_pages;
         work->range_cyclic = range_cyclic;
+        work->reason    = reason;
 
         bdi_queue_work(bdi, work);
 }
@@ -150,9 +163,10 @@ __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
  *   completion. Caller need not hold sb s_umount semaphore.
  *
  */
-void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
+void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
+                        enum wb_reason reason)
 {
-        __bdi_start_writeback(bdi, nr_pages, true);
+        __bdi_start_writeback(bdi, nr_pages, true, reason);
 }
 
 /**
@@ -251,7 +265,7 @@ static bool inode_dirtied_after(struct inode *inode, unsigned long t)
  */
 static int move_expired_inodes(struct list_head *delaying_queue,
                                struct list_head *dispatch_queue,
-                               unsigned long *older_than_this)
+                               struct wb_writeback_work *work)
 {
         LIST_HEAD(tmp);
         struct list_head *pos, *node;
@@ -262,8 +276,8 @@ static int move_expired_inodes(struct list_head *delaying_queue,
 
         while (!list_empty(delaying_queue)) {
                 inode = wb_inode(delaying_queue->prev);
-                if (older_than_this &&
-                    inode_dirtied_after(inode, *older_than_this))
+                if (work->older_than_this &&
+                    inode_dirtied_after(inode, *work->older_than_this))
                         break;
                 if (sb && sb != inode->i_sb)
                         do_sb_sort = 1;
@@ -302,13 +316,13 @@ out:
  *                                           |
  *                                           +--> dequeue for IO
  */
-static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
+static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work)
 {
         int moved;
         assert_spin_locked(&wb->list_lock);
         list_splice_init(&wb->b_more_io, &wb->b_io);
-        moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
-        trace_writeback_queue_io(wb, older_than_this, moved);
+        moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, work);
+        trace_writeback_queue_io(wb, work, moved);
 }
 
 static int write_inode(struct inode *inode, struct writeback_control *wbc)
@@ -641,31 +655,40 @@ static long __writeback_inodes_wb(struct bdi_writeback *wb,
         return wrote;
 }
 
-long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages)
+long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
+                                enum wb_reason reason)
 {
         struct wb_writeback_work work = {
                 .nr_pages       = nr_pages,
                 .sync_mode      = WB_SYNC_NONE,
                 .range_cyclic   = 1,
+                .reason         = reason,
         };
 
         spin_lock(&wb->list_lock);
         if (list_empty(&wb->b_io))
-                queue_io(wb, NULL);
+                queue_io(wb, &work);
         __writeback_inodes_wb(wb, &work);
         spin_unlock(&wb->list_lock);
 
         return nr_pages - work.nr_pages;
 }
 
-static inline bool over_bground_thresh(void)
+static bool over_bground_thresh(struct backing_dev_info *bdi)
 {
         unsigned long background_thresh, dirty_thresh;
 
         global_dirty_limits(&background_thresh, &dirty_thresh);
 
-        return (global_page_state(NR_FILE_DIRTY) +
-                global_page_state(NR_UNSTABLE_NFS) > background_thresh);
+        if (global_page_state(NR_FILE_DIRTY) +
+            global_page_state(NR_UNSTABLE_NFS) > background_thresh)
+                return true;
+
+        if (bdi_stat(bdi, BDI_RECLAIMABLE) >
+                                bdi_dirty_limit(bdi, background_thresh))
+                return true;
+
+        return false;
 }
 
 /*
@@ -675,7 +698,7 @@ static inline bool over_bground_thresh(void)
 static void wb_update_bandwidth(struct bdi_writeback *wb,
                                 unsigned long start_time)
 {
-        __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, start_time);
+        __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time);
 }
 
 /*
@@ -727,7 +750,7 @@ static long wb_writeback(struct bdi_writeback *wb,
                  * For background writeout, stop when we are below the
                  * background dirty threshold
                  */
-                if (work->for_background && !over_bground_thresh())
+                if (work->for_background && !over_bground_thresh(wb->bdi))
                         break;
 
                 if (work->for_kupdate) {
@@ -738,7 +761,7 @@ static long wb_writeback(struct bdi_writeback *wb,
 
                 trace_writeback_start(wb->bdi, work);
                 if (list_empty(&wb->b_io))
-                        queue_io(wb, work->older_than_this);
+                        queue_io(wb, work);
                 if (work->sb)
                         progress = writeback_sb_inodes(work->sb, wb, work);
                 else
@@ -811,13 +834,14 @@ static unsigned long get_nr_dirty_pages(void)
 
 static long wb_check_background_flush(struct bdi_writeback *wb)
 {
-        if (over_bground_thresh()) {
+        if (over_bground_thresh(wb->bdi)) {
 
                 struct wb_writeback_work work = {
                         .nr_pages       = LONG_MAX,
                         .sync_mode      = WB_SYNC_NONE,
                         .for_background = 1,
                         .range_cyclic   = 1,
+                        .reason         = WB_REASON_BACKGROUND,
                 };
 
                 return wb_writeback(wb, &work);
@@ -851,6 +875,7 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
                         .sync_mode      = WB_SYNC_NONE,
                         .for_kupdate    = 1,
                         .range_cyclic   = 1,
+                        .reason         = WB_REASON_PERIODIC,
                 };
 
                 return wb_writeback(wb, &work);
@@ -969,7 +994,7 @@ int bdi_writeback_thread(void *data)
  * Start writeback of `nr_pages' pages.  If `nr_pages' is zero, write back
  * the whole world.
  */
-void wakeup_flusher_threads(long nr_pages)
+void wakeup_flusher_threads(long nr_pages, enum wb_reason reason)
 {
         struct backing_dev_info *bdi;
 
@@ -982,7 +1007,7 @@ void wakeup_flusher_threads(long nr_pages)
         list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
                 if (!bdi_has_dirty_io(bdi))
                         continue;
-                __bdi_start_writeback(bdi, nr_pages, false);
+                __bdi_start_writeback(bdi, nr_pages, false, reason);
         }
         rcu_read_unlock();
 }
@@ -1203,7 +1228,9 @@ static void wait_sb_inodes(struct super_block *sb)
  * on how many (if any) will be written, and this function does not wait
  * for IO completion of submitted IO.
  */
-void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
+void writeback_inodes_sb_nr(struct super_block *sb,
+                            unsigned long nr,
+                            enum wb_reason reason)
 {
         DECLARE_COMPLETION_ONSTACK(done);
         struct wb_writeback_work work = {
@@ -1212,6 +1239,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
                 .tagged_writepages      = 1,
                 .done                   = &done,
                 .nr_pages               = nr,
+                .reason                 = reason,
         };
 
         WARN_ON(!rwsem_is_locked(&sb->s_umount));
@@ -1228,9 +1256,9 @@ EXPORT_SYMBOL(writeback_inodes_sb_nr);
  * 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)
+void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
 {
-        return writeback_inodes_sb_nr(sb, get_nr_dirty_pages());
+        return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
 }
 EXPORT_SYMBOL(writeback_inodes_sb);
 
@@ -1241,11 +1269,11 @@ EXPORT_SYMBOL(writeback_inodes_sb);
  * Invoke writeback_inodes_sb if no writeback is currently underway.
  * Returns 1 if writeback was started, 0 if not.
  */
-int writeback_inodes_sb_if_idle(struct super_block *sb)
+int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_reason reason)
 {
         if (!writeback_in_progress(sb->s_bdi)) {
                 down_read(&sb->s_umount);
-                writeback_inodes_sb(sb);
+                writeback_inodes_sb(sb, reason);
                 up_read(&sb->s_umount);
                 return 1;
         } else
@@ -1262,11 +1290,12 @@ EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
  * Returns 1 if writeback was started, 0 if not.
  */
 int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
-                                   unsigned long nr)
+                                   unsigned long nr,
+                                   enum wb_reason reason)
 {
         if (!writeback_in_progress(sb->s_bdi)) {
                 down_read(&sb->s_umount);
-                writeback_inodes_sb_nr(sb, nr);
+                writeback_inodes_sb_nr(sb, nr, reason);
                 up_read(&sb->s_umount);
                 return 1;
         } else
@@ -1290,6 +1319,7 @@ void sync_inodes_sb(struct super_block *sb)
                 .nr_pages       = LONG_MAX,
                 .range_cyclic   = 0,
                 .done           = &done,
+                .reason         = WB_REASON_SYNC,
         };
 
         WARN_ON(!rwsem_is_locked(&sb->s_umount));
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index aae0edb95c6..35f4b0ecdeb 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -286,7 +286,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
                 /* caller already holds s_umount */
                 if (sb->s_flags & MS_RDONLY)
                         return -EROFS;
-                writeback_inodes_sb(sb);
+                writeback_inodes_sb(sb, WB_REASON_SYNC);
                 return 0;
         default:
                 return -EINVAL;
diff --git a/fs/sync.c b/fs/sync.c
index c98a7477edf..101b8ef901d 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -43,7 +43,7 @@ static int __sync_filesystem(struct super_block *sb, int wait)
         if (wait)
                 sync_inodes_sb(sb);
         else
-                writeback_inodes_sb(sb);
+                writeback_inodes_sb(sb, WB_REASON_SYNC);
 
         if (sb->s_op->sync_fs)
                 sb->s_op->sync_fs(sb, wait);
@@ -98,7 +98,7 @@ static void sync_filesystems(int wait)
  */
 SYSCALL_DEFINE0(sync)
 {
-        wakeup_flusher_threads(0);
+        wakeup_flusher_threads(0, WB_REASON_SYNC);
         sync_filesystems(0);
         sync_filesystems(1);
         if (unlikely(laptop_mode))
diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
index 315de66e52b..bc4f94b2870 100644
--- a/fs/ubifs/budget.c
+++ b/fs/ubifs/budget.c
@@ -63,7 +63,7 @@
 static void shrink_liability(struct ubifs_info *c, int nr_to_write)
 {
         down_read(&c->vfs_sb->s_umount);
-        writeback_inodes_sb(c->vfs_sb);
+        writeback_inodes_sb(c->vfs_sb, WB_REASON_FS_FREE_SPACE);
         up_read(&c->vfs_sb->s_umount);
 }