Commit a88a341a authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

writeback: move bandwidth related fields from backing_dev_info into bdi_writeback 



Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear.  For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi.  To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.

This patch moves bandwidth related fields from backing_dev_info into
bdi_writeback.

* The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp,
  write_bandwidth, avg_write_bandwidth, dirty_ratelimit,
  balanced_dirty_ratelimit, completions and dirty_exceeded.

* writeback_chunk_size() and over_bground_thresh() now take @wb
  instead of @bdi.

* bdi_writeout_fraction(bdi, ...)	-> wb_writeout_fraction(wb, ...)
  bdi_dirty_limit(bdi, ...)		-> wb_dirty_limit(wb, ...)
  bdi_position_ration(bdi, ...)		-> wb_position_ratio(wb, ...)
  bdi_update_writebandwidth(bdi, ...)	-> wb_update_write_bandwidth(wb, ...)
  [__]bdi_update_bandwidth(bdi, ...)	-> [__]wb_update_bandwidth(wb, ...)
  bdi_{max|min}_pause(bdi, ...)		-> wb_{max|min}_pause(wb, ...)
  bdi_dirty_limits(bdi, ...)		-> wb_dirty_limits(wb, ...)

* Init/exits of the relocated fields are moved to bdi_wb_init/exit()
  respectively.  Note that explicit zeroing is dropped in the process
  as wb's are cleared in entirety anyway.

* As there's still only one bdi_writeback per backing_dev_info, all
  uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
  introducing no behavior changes.

v2: Typo in description fixed as suggested by Jan.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 93f78d88

fs/f2fs/node.c

+2 −2
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type) 
							PAGE_CACHE_SHIFT;

		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 2);

	} else if (type == DIRTY_DENTS) {

		if (sbi->sb->s_bdi->dirty_exceeded)

		if (sbi->sb->s_bdi->wb.dirty_exceeded)

			return false;

		mem_size = get_pages(sbi, F2FS_DIRTY_DENTS);

		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
@@ -70,7 +70,7 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type) 
				sizeof(struct extent_node)) >> PAGE_CACHE_SHIFT;

		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);

	} else {

		if (sbi->sb->s_bdi->dirty_exceeded)

		if (sbi->sb->s_bdi->wb.dirty_exceeded)

			return false;

	}

	return res;

fs/f2fs/segment.h

+1 −1
Original line number Diff line number Diff line
@@ -713,7 +713,7 @@ static inline unsigned int max_hw_blocks(struct f2fs_sb_info *sbi) 
 */

static inline int nr_pages_to_skip(struct f2fs_sb_info *sbi, int type)

{

	if (sbi->sb->s_bdi->dirty_exceeded)

	if (sbi->sb->s_bdi->wb.dirty_exceeded)

		return 0;



	if (type == DATA)

fs/fs-writeback.c

+8 −9
Original line number Diff line number Diff line
@@ -624,7 +624,7 @@ out: 
	return ret;

}



static long writeback_chunk_size(struct backing_dev_info *bdi,

static long writeback_chunk_size(struct bdi_writeback *wb,

				 struct wb_writeback_work *work)

{

	long pages;
@@ -645,7 +645,7 @@ static long writeback_chunk_size(struct backing_dev_info *bdi, 
	if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)

		pages = LONG_MAX;

	else {

		pages = min(bdi->avg_write_bandwidth / 2,

		pages = min(wb->avg_write_bandwidth / 2,

			    global_dirty_limit / DIRTY_SCOPE);

		pages = min(pages, work->nr_pages);

		pages = round_down(pages + MIN_WRITEBACK_PAGES,
@@ -743,7 +743,7 @@ static long writeback_sb_inodes(struct super_block *sb, 
		inode->i_state |= I_SYNC;

		spin_unlock(&inode->i_lock);



		write_chunk = writeback_chunk_size(wb->bdi, work);

		write_chunk = writeback_chunk_size(wb, work);

		wbc.nr_to_write = write_chunk;

		wbc.pages_skipped = 0;
@@ -830,7 +830,7 @@ static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 
	return nr_pages - work.nr_pages;

}



static bool over_bground_thresh(struct backing_dev_info *bdi)

static bool over_bground_thresh(struct bdi_writeback *wb)

{

	unsigned long background_thresh, dirty_thresh;
@@ -840,8 +840,7 @@ static bool over_bground_thresh(struct backing_dev_info *bdi) 
	    global_page_state(NR_UNSTABLE_NFS) > background_thresh)

		return true;



	if (wb_stat(&bdi->wb, WB_RECLAIMABLE) >

				bdi_dirty_limit(bdi, background_thresh))

	if (wb_stat(wb, WB_RECLAIMABLE) > wb_dirty_limit(wb, background_thresh))

		return true;



	return false;
@@ -854,7 +853,7 @@ static bool over_bground_thresh(struct backing_dev_info *bdi) 
static void wb_update_bandwidth(struct bdi_writeback *wb,

				unsigned long start_time)

{

	__bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time);

	__wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time);

}



/*
@@ -906,7 +905,7 @@ 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(wb->bdi))

		if (work->for_background && !over_bground_thresh(wb))

			break;



		/*
@@ -998,7 +997,7 @@ static unsigned long get_nr_dirty_pages(void) 


static long wb_check_background_flush(struct bdi_writeback *wb)

{

	if (over_bground_thresh(wb->bdi)) {

	if (over_bground_thresh(wb)) {



		struct wb_writeback_work work = {

			.nr_pages	= LONG_MAX,

fs/gfs2/super.c

+1 −1
Original line number Diff line number Diff line
@@ -748,7 +748,7 @@ static int gfs2_write_inode(struct inode *inode, struct writeback_control *wbc) 


	if (wbc->sync_mode == WB_SYNC_ALL)

		gfs2_log_flush(GFS2_SB(inode), ip->i_gl, NORMAL_FLUSH);

	if (bdi->dirty_exceeded)

	if (bdi->wb.dirty_exceeded)

		gfs2_ail1_flush(sdp, wbc);

	else

		filemap_fdatawrite(metamapping);

include/linux/backing-dev.h

+10 −10
Original line number Diff line number Diff line
@@ -60,16 +60,6 @@ struct bdi_writeback { 
	spinlock_t list_lock;		/* protects the b_* lists */



	struct percpu_counter stat[NR_WB_STAT_ITEMS];

};



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 long bw_time_stamp;	/* last time write bw is updated */

	unsigned long dirtied_stamp;
@@ -88,6 +78,16 @@ struct backing_dev_info { 


	struct fprop_local_percpu completions;

	int dirty_exceeded;

};



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;

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