[PATCH] mm: sysfs: expose the BDI object in sysfs

From: Peter Zijlstra
Date: Fri Nov 02 2007 - 10:59:47 EST

On Fri, 2007-11-02 at 15:32 +0100, Kay Sievers wrote:
> On Fri, 2007-11-02 at 15:17 +0100, Peter Zijlstra wrote:
> > One more question,
> >
> > I currently prefix the names with "bdi-", is that needed?
>
> Not really.

Thanks.

Here is the 'pretty' patch :-)

Since it relies on the removal of the device name length limit, this
should not yet be applied.

---
Subject: mm: sysfs: expose the BDI object in sysfs

Provide a place in sysfs 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

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
block/genhd.c | 3 +
fs/fuse/inode.c | 3 -
fs/nfs/client.c | 24 +++++----
fs/nfs/internal.h | 10 ++--
fs/nfs/super.c | 10 ++--
include/linux/backing-dev.h | 19 +++++++
include/linux/writeback.h | 3 +
lib/percpu_counter.c | 1
mm/backing-dev.c | 109 ++++++++++++++++++++++++++++++++++++++++++++
mm/page-writeback.c | 2
10 files changed, 163 insertions(+), 21 deletions(-)

Index: linux-2.6-2/block/genhd.c
===================================================================
--- linux-2.6-2.orig/block/genhd.c
+++ linux-2.6-2/block/genhd.c
@@ -182,6 +182,8 @@ void add_disk(struct gendisk *disk)
disk->minors, NULL, exact_match, exact_lock, disk);
register_disk(disk);
blk_register_queue(disk);
+ bdi_register(&disk->queue->backing_dev_info, NULL,
+ "%s", disk->disk_name);
}

EXPORT_SYMBOL(add_disk);
@@ -190,6 +192,7 @@ EXPORT_SYMBOL(del_gendisk); /* in partit
void unlink_gendisk(struct gendisk *disk)
{
blk_unregister_queue(disk);
+ bdi_unregister(&disk->queue->backing_dev_info);
blk_unregister_region(MKDEV(disk->major, disk->first_minor),
disk->minors);
}
Index: linux-2.6-2/fs/fuse/inode.c
===================================================================
--- linux-2.6-2.orig/fs/fuse/inode.c
+++ linux-2.6-2/fs/fuse/inode.c
@@ -467,7 +467,8 @@ static struct fuse_conn *new_conn(void)
atomic_set(&fc->num_waiting, 0);
fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
fc->bdi.unplug_io_fn = default_unplug_io_fn;
- err = bdi_init(&fc->bdi);
+ err = bdi_init_fmt(&fc->bdi, NULL,
+ "fuse-%llu", (unsigned long long)fc->id);
if (err) {
kfree(fc);
fc = NULL;
Index: linux-2.6-2/fs/nfs/client.c
===================================================================
--- linux-2.6-2.orig/fs/nfs/client.c
+++ linux-2.6-2/fs/nfs/client.c
@@ -657,7 +657,8 @@ static void nfs_server_set_fsinfo(struct
/*
* Probe filesystem information, including the FSID on v2/v3
*/
-static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, struct nfs_fattr *fattr)
+static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh,
+ struct nfs_fattr *fattr, const char *dev_name)
{
struct nfs_fsinfo fsinfo;
struct nfs_client *clp = server->nfs_client;
@@ -678,7 +679,8 @@ static int nfs_probe_fsinfo(struct nfs_s
goto out_error;

nfs_server_set_fsinfo(server, &fsinfo);
- error = bdi_init(&server->backing_dev_info);
+ error = bdi_init_fmt(&server->backing_dev_info, NULL,
+ "nfs-%s", dev_name);
if (error)
goto out_error;

@@ -772,7 +774,7 @@ void nfs_free_server(struct nfs_server *
* - keyed on server and FSID
*/
struct nfs_server *nfs_create_server(const struct nfs_parsed_mount_data *data,
- struct nfs_fh *mntfh)
+ struct nfs_fh *mntfh, const char *dev_name)
{
struct nfs_server *server;
struct nfs_fattr fattr;
@@ -792,7 +794,7 @@ struct nfs_server *nfs_create_server(con
BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

/* Probe the root fh to retrieve its FSID */
- error = nfs_probe_fsinfo(server, mntfh, &fattr);
+ error = nfs_probe_fsinfo(server, mntfh, &fattr, dev_name);
if (error < 0)
goto error;
if (server->nfs_client->rpc_ops->version == 3) {
@@ -949,7 +951,7 @@ static int nfs4_init_server(struct nfs_s
* - keyed on server and FSID
*/
struct nfs_server *nfs4_create_server(const struct nfs_parsed_mount_data *data,
- struct nfs_fh *mntfh)
+ struct nfs_fh *mntfh, const char *dev_name)
{
struct nfs_fattr fattr;
struct nfs_server *server;
@@ -991,7 +993,7 @@ struct nfs_server *nfs4_create_server(co
(unsigned long long) server->fsid.minor);
dprintk("Mount FH: %d\n", mntfh->size);

- error = nfs_probe_fsinfo(server, mntfh, &fattr);
+ error = nfs_probe_fsinfo(server, mntfh, &fattr, dev_name);
if (error < 0)
goto error;

@@ -1021,7 +1023,8 @@ error:
* Create an NFS4 referral server record
*/
struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
- struct nfs_fh *mntfh)
+ struct nfs_fh *mntfh,
+ const char *dev_name)
{
struct nfs_client *parent_client;
struct nfs_server *server, *parent_server;
@@ -1066,7 +1069,7 @@ struct nfs_server *nfs4_create_referral_
goto error;

/* probe the filesystem info for this server filesystem */
- error = nfs_probe_fsinfo(server, mntfh, &fattr);
+ error = nfs_probe_fsinfo(server, mntfh, &fattr, dev_name);
if (error < 0)
goto error;

@@ -1100,7 +1103,8 @@ error:
*/
struct nfs_server *nfs_clone_server(struct nfs_server *source,
struct nfs_fh *fh,
- struct nfs_fattr *fattr)
+ struct nfs_fattr *fattr,
+ const char *dev_name)
{
struct nfs_server *server;
struct nfs_fattr fattr_fsinfo;
@@ -1128,7 +1132,7 @@ struct nfs_server *nfs_clone_server(stru
nfs_init_server_aclclient(server);

/* probe the filesystem info for this server filesystem */
- error = nfs_probe_fsinfo(server, fh, &fattr_fsinfo);
+ error = nfs_probe_fsinfo(server, fh, &fattr_fsinfo, dev_name);
if (error < 0)
goto out_free_server;

Index: linux-2.6-2/include/linux/backing-dev.h
===================================================================
--- linux-2.6-2.orig/include/linux/backing-dev.h
+++ linux-2.6-2/include/linux/backing-dev.h
@@ -11,6 +11,8 @@
#include <linux/percpu_counter.h>
#include <linux/log2.h>
#include <linux/proportions.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
#include <asm/atomic.h>

struct page;
@@ -48,11 +50,28 @@ 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, ...);
+void bdi_unregister(struct backing_dev_info *bdi);
+
+#define bdi_init_fmt(bdi, parent, fmt...) \
+ ({ \
+ int ret = bdi_init(bdi); \
+ if (!ret) { \
+ ret = bdi_register(bdi, parent, ##fmt); \
+ if (ret) \
+ bdi_destroy(bdi); \
+ } \
+ ret; \
+ })
+
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
{
Index: linux-2.6-2/include/linux/writeback.h
===================================================================
--- linux-2.6-2.orig/include/linux/writeback.h
+++ linux-2.6-2/include/linux/writeback.h
@@ -113,6 +113,9 @@ 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);
Index: linux-2.6-2/mm/backing-dev.c
===================================================================
--- linux-2.6-2.orig/mm/backing-dev.c
+++ linux-2.6-2/mm/backing-dev.c
@@ -4,12 +4,119 @@
#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;
+
+ bdi->ra_pages = simple_strtoul(buf, &end, 10) >> (PAGE_SHIFT - 10);
+
+ return end - buf;
+}
+
+#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;
+}
+
+__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;
+}
+
+void bdi_unregister(struct backing_dev_info *bdi)
+{
+ if (bdi->dev) {
+ device_unregister(bdi->dev);
+ bdi->dev = NULL;
+ }
+}
+
+EXPORT_SYMBOL(bdi_register);
+EXPORT_SYMBOL(bdi_unregister);

int bdi_init(struct backing_dev_info *bdi)
{
int i, j;
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 +140,8 @@ void bdi_destroy(struct backing_dev_info
{
int i;

+ bdi_unregister(bdi);
+
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);

Index: linux-2.6-2/mm/page-writeback.c
===================================================================
--- linux-2.6-2.orig/mm/page-writeback.c
+++ linux-2.6-2/mm/page-writeback.c
@@ -291,7 +291,7 @@ static unsigned long determine_dirtyable
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)
{
Index: linux-2.6-2/lib/percpu_counter.c
===================================================================
--- linux-2.6-2.orig/lib/percpu_counter.c
+++ linux-2.6-2/lib/percpu_counter.c
@@ -102,6 +102,7 @@ void percpu_counter_destroy(struct percp
return;

free_percpu(fbc->counters);
+ fbc->counters = NULL;
#ifdef CONFIG_HOTPLUG_CPU
mutex_lock(&percpu_counters_lock);
list_del(&fbc->list);
Index: linux-2.6-2/fs/nfs/internal.h
===================================================================
--- linux-2.6-2.orig/fs/nfs/internal.h
+++ linux-2.6-2/fs/nfs/internal.h
@@ -65,16 +65,18 @@ extern void nfs_put_client(struct nfs_cl
extern struct nfs_client *nfs_find_client(const struct sockaddr_in *, int);
extern struct nfs_server *nfs_create_server(
const struct nfs_parsed_mount_data *,
- struct nfs_fh *);
+ struct nfs_fh *, const char *);
extern struct nfs_server *nfs4_create_server(
const struct nfs_parsed_mount_data *,
- struct nfs_fh *);
+ struct nfs_fh *, const char *);
extern struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *,
- struct nfs_fh *);
+ struct nfs_fh *,
+ const char *);
extern void nfs_free_server(struct nfs_server *server);
extern struct nfs_server *nfs_clone_server(struct nfs_server *,
struct nfs_fh *,
- struct nfs_fattr *);
+ struct nfs_fattr *,
+ const char *);
#ifdef CONFIG_PROC_FS
extern int __init nfs_fs_proc_init(void);
extern void nfs_fs_proc_exit(void);
Index: linux-2.6-2/fs/nfs/super.c
===================================================================
--- linux-2.6-2.orig/fs/nfs/super.c
+++ linux-2.6-2/fs/nfs/super.c
@@ -1359,7 +1359,7 @@ static int nfs_get_sb(struct file_system
goto out;

/* Get a volume representation */
- server = nfs_create_server(&data, &mntfh);
+ server = nfs_create_server(&data, &mntfh, dev_name);
if (IS_ERR(server)) {
error = PTR_ERR(server);
goto out;
@@ -1442,7 +1442,7 @@ static int nfs_xdev_get_sb(struct file_s
dprintk("--> nfs_xdev_get_sb()\n");

/* create a new volume representation */
- server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
+ server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr, dev_name);
if (IS_ERR(server)) {
error = PTR_ERR(server);
goto out_err_noserver;
@@ -1702,7 +1702,7 @@ static int nfs4_get_sb(struct file_syste
goto out;

/* Get a volume representation */
- server = nfs4_create_server(&data, &mntfh);
+ server = nfs4_create_server(&data, &mntfh, dev_name);
if (IS_ERR(server)) {
error = PTR_ERR(server);
goto out;
@@ -1787,7 +1787,7 @@ static int nfs4_xdev_get_sb(struct file_
dprintk("--> nfs4_xdev_get_sb()\n");

/* create a new volume representation */
- server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
+ server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr, dev_name);
if (IS_ERR(server)) {
error = PTR_ERR(server);
goto out_err_noserver;
@@ -1861,7 +1861,7 @@ static int nfs4_referral_get_sb(struct f
dprintk("--> nfs4_referral_get_sb()\n");

/* create a new volume representation */
- server = nfs4_create_referral_server(data, &mntfh);
+ server = nfs4_create_referral_server(data, &mntfh, dev_name);
if (IS_ERR(server)) {
error = PTR_ERR(server);
goto out_err_noserver;


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/