writeback: separate out include/linux/backing-dev-defs.h

With the planned cgroup writeback support, backing-dev related
declarations will be more widely used across block and cgroup;
unfortunately, including backing-dev.h from include/linux/blkdev.h
makes cyclic include dependency quite likely.

This patch separates out backing-dev-defs.h which only has the
essential definitions and updates blkdev.h to include it.  c files
which need access to more backing-dev details now include
backing-dev.h directly.  This takes backing-dev.h off the common
include dependency chain making it a lot easier to use it across block
and cgroup.

v2: fs/fat build failure fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 108 insertions, 102 deletions

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
new file mode 100644
index 000000000000..aa18c4bd43c1
--- /dev/null
+++ b/include/linux/backing-dev-defs.h
@@ -0,0 +1,106 @@
+#ifndef __LINUX_BACKING_DEV_DEFS_H
+#define __LINUX_BACKING_DEV_DEFS_H
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/percpu_counter.h>
+#include <linux/flex_proportions.h>
+#include <linux/timer.h>
+#include <linux/workqueue.h>
+
+struct page;
+struct device;
+struct dentry;
+
+/*
+ * Bits in bdi_writeback.state
+ */
+enum wb_state {
+        WB_async_congested,     /* The async (write) queue is getting full */
+        WB_sync_congested,      /* The sync queue is getting full */
+        WB_registered,          /* bdi_register() was done */
+        WB_writeback_running,   /* Writeback is in progress */
+};
+
+typedef int (congested_fn)(void *, int);
+
+enum wb_stat_item {
+        WB_RECLAIMABLE,
+        WB_WRITEBACK,
+        WB_DIRTIED,
+        WB_WRITTEN,
+        NR_WB_STAT_ITEMS
+};
+
+#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
+
+struct bdi_writeback {
+        struct backing_dev_info *bdi;   /* our parent bdi */
+
+        unsigned long state;            /* Always use atomic bitops on this */
+        unsigned long last_old_flush;   /* last old data flush */
+
+        struct list_head b_dirty;       /* dirty inodes */
+        struct list_head b_io;          /* parked for writeback */
+        struct list_head b_more_io;     /* parked for more writeback */
+        struct list_head b_dirty_time;  /* time stamps are dirty */
+        spinlock_t list_lock;           /* protects the b_* lists */
+
+        struct percpu_counter stat[NR_WB_STAT_ITEMS];
+
+        unsigned long bw_time_stamp;    /* last time write bw is updated */
+        unsigned long dirtied_stamp;
+        unsigned long written_stamp;    /* pages written at bw_time_stamp */
+        unsigned long write_bandwidth;  /* the estimated write bandwidth */
+        unsigned long avg_write_bandwidth; /* further smoothed write bw */
+
+        /*
+         * The base dirty throttle rate, re-calculated on every 200ms.
+         * All the bdi tasks' dirty rate will be curbed under it.
+         * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
+         * in small steps and is much more smooth/stable than the latter.
+         */
+        unsigned long dirty_ratelimit;
+        unsigned long balanced_dirty_ratelimit;
+
+        struct fprop_local_percpu completions;
+        int dirty_exceeded;
+
+        spinlock_t work_lock;           /* protects work_list & dwork scheduling */
+        struct list_head work_list;
+        struct delayed_work dwork;      /* work item used for writeback */
+};
+
+struct backing_dev_info {
+        struct list_head bdi_list;
+        unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
+        unsigned int capabilities; /* Device capabilities */
+        congested_fn *congested_fn; /* Function pointer if device is md/dm */
+        void *congested_data;   /* Pointer to aux data for congested func */
+
+        char *name;
+
+        unsigned int min_ratio;
+        unsigned int max_ratio, max_prop_frac;
+
+        struct bdi_writeback wb;  /* default writeback info for this bdi */
+
+        struct device *dev;
+
+        struct timer_list laptop_mode_wb_timer;
+
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *debug_dir;
+        struct dentry *debug_stats;
+#endif
+};
+
+enum {
+        BLK_RW_ASYNC    = 0,
+        BLK_RW_SYNC     = 1,
+};
+
+void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
+void set_bdi_congested(struct backing_dev_info *bdi, int sync);
+
+#endif  /* __LINUX_BACKING_DEV_DEFS_H */
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index d796f49ce87a..5e39f7a8efed 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -8,104 +8,11 @@
 #ifndef _LINUX_BACKING_DEV_H
 #define _LINUX_BACKING_DEV_H
 
-#include <linux/percpu_counter.h>
-#include <linux/log2.h>
-#include <linux/flex_proportions.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
-#include <linux/timer.h>
 #include <linux/writeback.h>
-#include <linux/atomic.h>
-#include <linux/sysctl.h>
-#include <linux/workqueue.h>
-
-struct page;
-struct device;
-struct dentry;
-
-/*
- * Bits in bdi_writeback.state
- */
-enum wb_state {
-        WB_async_congested,     /* The async (write) queue is getting full */
-        WB_sync_congested,      /* The sync queue is getting full */
-        WB_registered,          /* bdi_register() was done */
-        WB_writeback_running,   /* Writeback is in progress */
-};
-
-typedef int (congested_fn)(void *, int);
-
-enum wb_stat_item {
-        WB_RECLAIMABLE,
-        WB_WRITEBACK,
-        WB_DIRTIED,
-        WB_WRITTEN,
-        NR_WB_STAT_ITEMS
-};
-
-#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
-
-struct bdi_writeback {
-        struct backing_dev_info *bdi;   /* our parent bdi */
-
-        unsigned long state;            /* Always use atomic bitops on this */
-        unsigned long last_old_flush;   /* last old data flush */
-
-        struct list_head b_dirty;       /* dirty inodes */
-        struct list_head b_io;          /* parked for writeback */
-        struct list_head b_more_io;     /* parked for more writeback */
-        struct list_head b_dirty_time;  /* time stamps are dirty */
-        spinlock_t list_lock;           /* protects the b_* lists */
-
-        struct percpu_counter stat[NR_WB_STAT_ITEMS];
-
-        unsigned long bw_time_stamp;    /* last time write bw is updated */
-        unsigned long dirtied_stamp;
-        unsigned long written_stamp;    /* pages written at bw_time_stamp */
-        unsigned long write_bandwidth;  /* the estimated write bandwidth */
-        unsigned long avg_write_bandwidth; /* further smoothed write bw */
-
-        /*
-         * The base dirty throttle rate, re-calculated on every 200ms.
-         * All the bdi tasks' dirty rate will be curbed under it.
-         * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
-         * in small steps and is much more smooth/stable than the latter.
-         */
-        unsigned long dirty_ratelimit;
-        unsigned long balanced_dirty_ratelimit;
-
-        struct fprop_local_percpu completions;
-        int dirty_exceeded;
-
-        spinlock_t work_lock;           /* protects work_list & dwork scheduling */
-        struct list_head work_list;
-        struct delayed_work dwork;      /* work item used for writeback */
-};
-
-struct backing_dev_info {
-        struct list_head bdi_list;
-        unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
-        unsigned int capabilities; /* Device capabilities */
-        congested_fn *congested_fn; /* Function pointer if device is md/dm */
-        void *congested_data;   /* Pointer to aux data for congested func */
-
-        char *name;
-
-        unsigned int min_ratio;
-        unsigned int max_ratio, max_prop_frac;
-
-        struct bdi_writeback wb;  /* default writeback info for this bdi */
-
-        struct device *dev;
-
-        struct timer_list laptop_mode_wb_timer;
-
-#ifdef CONFIG_DEBUG_FS
-        struct dentry *debug_dir;
-        struct dentry *debug_stats;
-#endif
-};
+#include <linux/backing-dev-defs.h>
 
 struct backing_dev_info *inode_to_bdi(struct inode *inode);
 
@@ -265,13 +172,6 @@ static inline int bdi_rw_congested(struct backing_dev_info *bdi)
                                   (1 << WB_async_congested));
 }
 
-enum {
-        BLK_RW_ASYNC    = 0,
-        BLK_RW_SYNC     = 1,
-};
-
-void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
-void set_bdi_congested(struct backing_dev_info *bdi, int sync);
 long congestion_wait(int sync, long timeout);
 long wait_iff_congested(struct zone *zone, int sync, long timeout);
 int pdflush_proc_obsolete(struct ctl_table *table, int write,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ccaa9aecd593..60d2726a6b62 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -12,7 +12,7 @@
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 #include <linux/pagemap.h>
-#include <linux/backing-dev.h>
+#include <linux/backing-dev-defs.h>
 #include <linux/wait.h>
 #include <linux/mempool.h>
 #include <linux/bio.h>