Commit cf0ca9fe authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds

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
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
......@@ -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);
......
......@@ -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)
{
......
......@@ -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);
......
......@@ -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);
......
......@@ -4,12 +4,129 @@
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/device.h>
static struct class *bdi_class;
static ssize_t read_ahead_kb_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct backing_dev_info *bdi = dev_get_drvdata(dev);
char *end;
unsigned long read_ahead_kb;
ssize_t ret = -EINVAL;
read_ahead_kb = simple_strtoul(buf, &end, 10);
if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
ret = count;
}
return ret;
}
#define K(pages) ((pages) << (PAGE_SHIFT - 10))
#define BDI_SHOW(name, expr) \
static ssize_t name##_show(struct device *dev, \
struct device_attribute *attr, char *page) \
{ \
struct backing_dev_info *bdi = dev_get_drvdata(dev); \
\
return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
}
BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))
static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
{
unsigned long thresh[3];
get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);
return thresh[i];
}
BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
static struct device_attribute bdi_dev_attrs[] = {
__ATTR_RW(read_ahead_kb),
__ATTR_RO(reclaimable_kb),
__ATTR_RO(writeback_kb),
__ATTR_RO(dirty_kb),
__ATTR_RO(bdi_dirty_kb),
__ATTR_NULL,
};
static __init int bdi_class_init(void)
{
bdi_class = class_create(THIS_MODULE, "bdi");
bdi_class->dev_attrs = bdi_dev_attrs;
return 0;
}
core_initcall(bdi_class_init);
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
char *name;
va_list args;
int ret = 0;
struct device *dev;
va_start(args, fmt);
name = kvasprintf(GFP_KERNEL, fmt, args);
va_end(args);
if (!name)
return -ENOMEM;
dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
if (IS_ERR(dev)) {
ret = PTR_ERR(dev);
goto exit;
}
bdi->dev = dev;
dev_set_drvdata(bdi->dev, bdi);
exit:
kfree(name);
return ret;
}
EXPORT_SYMBOL(bdi_register);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
{
return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
}
EXPORT_SYMBOL(bdi_register_dev);
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
device_unregister(bdi->dev);
bdi->dev = NULL;
}
}
EXPORT_SYMBOL(bdi_unregister);
int bdi_init(struct backing_dev_info *bdi)
{
int i;
int err;
bdi->dev = NULL;
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
if (err)
......@@ -33,6 +150,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
bdi_unregister(bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
......
......@@ -300,7 +300,7 @@ static unsigned long determine_dirtyable_memory(void)
return x + 1; /* Ensure that we never return 0 */
}
static void
void
get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
struct backing_dev_info *bdi)
{
......
......@@ -235,7 +235,13 @@ unsigned long max_sane_readahead(unsigned long nr)
static int __init readahead_init(void)
{
return bdi_init(&default_backing_dev_info);
int err;
err = bdi_init(&default_backing_dev_info);
if (!err)
bdi_register(&default_backing_dev_info, NULL, "default");
return err;
}
subsys_initcall(readahead_init);
......
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