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>

1 files changed, 106 insertions, 0 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 */