From: Peter Zijlstra 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//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 Signed-off-by: Peter Zijlstra CC: Kay Sievers CC: Greg KH CC: Trond Myklebust Signed-off-by: Miklos Szeredi --- Index: linux/block/genhd.c =================================================================== --- linux.orig/block/genhd.c 2008-01-29 13:02:41.000000000 +0100 +++ linux/block/genhd.c 2008-01-29 13:02:46.000000000 +0100 @@ -183,6 +183,8 @@ 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, + "blk-%s", disk->disk_name); } EXPORT_SYMBOL(add_disk); @@ -191,6 +193,7 @@ 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/include/linux/backing-dev.h =================================================================== --- linux.orig/include/linux/backing-dev.h 2008-01-29 13:02:41.000000000 +0100 +++ linux/include/linux/backing-dev.h 2008-01-29 13:02:46.000000000 +0100 @@ -11,6 +11,8 @@ #include #include #include +#include +#include #include struct page; @@ -48,11 +50,17 @@ 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); + static inline void __add_bdi_stat(struct backing_dev_info *bdi, enum bdi_stat_item item, s64 amount) { Index: linux/include/linux/writeback.h =================================================================== --- linux.orig/include/linux/writeback.h 2008-01-29 13:02:41.000000000 +0100 +++ linux/include/linux/writeback.h 2008-01-29 13:02:46.000000000 +0100 @@ -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/mm/backing-dev.c =================================================================== --- linux.orig/mm/backing-dev.c 2008-01-29 13:02:41.000000000 +0100 +++ linux/mm/backing-dev.c 2008-01-29 13:03:23.000000000 +0100 @@ -4,12 +4,118 @@ #include #include #include +#include +#include + + +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; +} + +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); + +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 +139,8 @@ 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/mm/page-writeback.c =================================================================== --- linux.orig/mm/page-writeback.c 2008-01-29 13:02:41.000000000 +0100 +++ linux/mm/page-writeback.c 2008-01-29 13:02:46.000000000 +0100 @@ -304,7 +304,7 @@ 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/lib/percpu_counter.c =================================================================== --- linux.orig/lib/percpu_counter.c 2008-01-29 13:02:41.000000000 +0100 +++ linux/lib/percpu_counter.c 2008-01-29 13:02:46.000000000 +0100 @@ -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/mm/readahead.c =================================================================== --- linux.orig/mm/readahead.c 2008-01-29 13:02:41.000000000 +0100 +++ linux/mm/readahead.c 2008-01-29 13:02:46.000000000 +0100 @@ -235,7 +235,13 @@ unsigned long max_sane_readahead(unsigne 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); Index: linux/Documentation/ABI/testing/sysfs-class-bdi =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux/Documentation/ABI/testing/sysfs-class-bdi 2008-01-29 13:02:46.000000000 +0100 @@ -0,0 +1,50 @@ +What: /sys/class/bdi// +Date: January 2008 +Contact: Peter Zijlstra +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 identifyer can take the following forms: + +blk-NAME + + Block devices, NAME is 'sda', 'loop0', etc... + +FSTYPE-MAJOR:MINOR + + Non-block device backed filesystems which provide their own + BDI, such as NFS and FUSE. MAJOR:MINOR is the value of st_dev + for files on this filesystem. + +default + + The default backing dev, used for non-block device backed + filesystems which do not provide their own BDI. + +Files under /sys/class/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 + -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/