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Commit cf0ca9fe authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
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mm: bdi: export BDI attributes in sysfs 



Provide a place in sysfs (/sys/class/bdi) for the backing_dev_info object.
This allows us to see and set the various BDI specific variables.

In particular this properly exposes the read-ahead window for all relevant
users and /sys/block/<block>/queue/read_ahead_kb should be deprecated.

With patient help from Kay Sievers and Greg KH

[mszeredi@suse.cz]

 - split off NFS and FUSE changes into separate patches
 - document new sysfs attributes under Documentation/ABI
 - do bdi_class_init as a core_initcall, otherwise the "default" BDI
   won't be initialized
 - remove bdi_init_fmt macro, it's not used very much

[akpm@linux-foundation.org: fix ia64 warning]
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: default avatarGreg KH <greg@kroah.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent caafa432

Documentation/ABI/testing/sysfs-class-bdi

0 → 100644
+46 −0
Original line number Diff line number Diff line 
What:		/sys/class/bdi/<bdi>/

Date:		January 2008

Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>

Description:



Provide a place in sysfs for the backing_dev_info object.

This allows us to see and set the various BDI specific variables.



The <bdi> identifier can be either of the following:



MAJOR:MINOR



	Device number for block devices, or value of st_dev on

	non-block filesystems which provide their own BDI, such as NFS

	and FUSE.



default



	The default backing dev, used for non-block device backed

	filesystems which do not provide their own BDI.



Files under /sys/class/bdi/<bdi>/

---------------------------------



read_ahead_kb (read-write)



	Size of the read-ahead window in kilobytes



reclaimable_kb (read-only)



	Reclaimable (dirty or unstable) memory destined for writeback

	to this device



writeback_kb (read-only)



	Memory currently under writeback to this device



dirty_kb (read-only)



	Global threshold for reclaimable + writeback memory



bdi_dirty_kb (read-only)



	Current threshold on this BDI for reclaimable + writeback

	memory

block/genhd.c

+8 −0
Original line number Diff line number Diff line
@@ -182,11 +182,17 @@ static int exact_lock(dev_t devt, void *data) 
 */

void add_disk(struct gendisk *disk)

{

	struct backing_dev_info *bdi;



	disk->flags |= GENHD_FL_UP;

	blk_register_region(MKDEV(disk->major, disk->first_minor),

			    disk->minors, NULL, exact_match, exact_lock, disk);

	register_disk(disk);

	blk_register_queue(disk);



	bdi = &disk->queue->backing_dev_info;

	bdi_register_dev(bdi, MKDEV(disk->major, disk->first_minor));

	sysfs_create_link(&disk->dev.kobj, &bdi->dev->kobj, "bdi");

}



EXPORT_SYMBOL(add_disk);
@@ -194,6 +200,8 @@ EXPORT_SYMBOL(del_gendisk); /* in partitions/check.c */ 


void unlink_gendisk(struct gendisk *disk)

{

	sysfs_remove_link(&disk->dev.kobj, "bdi");

	bdi_unregister(&disk->queue->backing_dev_info);

	blk_unregister_queue(disk);

	blk_unregister_region(MKDEV(disk->major, disk->first_minor),

			      disk->minors);

include/linux/backing-dev.h

+9 −0
Original line number Diff line number Diff line
@@ -11,9 +11,11 @@ 
#include <linux/percpu_counter.h>

#include <linux/log2.h>

#include <linux/proportions.h>

#include <linux/kernel.h>

#include <asm/atomic.h>



struct page;

struct device;



/*

 * Bits in backing_dev_info.state
@@ -48,11 +50,18 @@ struct backing_dev_info { 


	struct prop_local_percpu completions;

	int dirty_exceeded;



	struct device *dev;

};



int bdi_init(struct backing_dev_info *bdi);

void bdi_destroy(struct backing_dev_info *bdi);



int bdi_register(struct backing_dev_info *bdi, struct device *parent,

		const char *fmt, ...);

int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);

void bdi_unregister(struct backing_dev_info *bdi);



static inline void __add_bdi_stat(struct backing_dev_info *bdi,

		enum bdi_stat_item item, s64 amount)

{

include/linux/writeback.h

+3 −0
Original line number Diff line number Diff line
@@ -114,6 +114,9 @@ struct file; 
int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,

				      void __user *, size_t *, loff_t *);



void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,

		 struct backing_dev_info *bdi);



void page_writeback_init(void);

void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,

					unsigned long nr_pages_dirtied);

lib/percpu_counter.c

+1 −0
Original line number Diff line number Diff line
@@ -102,6 +102,7 @@ void percpu_counter_destroy(struct percpu_counter *fbc) 
		return;



	free_percpu(fbc->counters);

	fbc->counters = NULL;

#ifdef CONFIG_HOTPLUG_CPU

	mutex_lock(&percpu_counters_lock);

	list_del(&fbc->list);