From: Daniel Phillips <phill...@google.com>
+static ctl_table dm_root_table[] = {
---
Index: linux-2.6.29-rc2/block/blk-core.c
===================================================================
--- linux-2.6.29-rc2.orig/block/blk-core.c
+++ linux-2.6.29-rc2/block/blk-core.c
@@ -1375,9 +1375,9 @@ static inline int bio_check_eod(struct b
*/
static inline void __generic_make_request(struct bio *bio)
{
- struct request_queue *q;
+ struct request_queue *q = bdev_get_queue(bio->bi_bdev);
sector_t old_sector;
- int ret, nr_sectors = bio_sectors(bio);
+ int nr_sectors = bio_sectors(bio);
dev_t old_dev;
int err = -EIO;
@@ -1386,6 +1386,13 @@ static inline void __generic_make_reques
if (bio_check_eod(bio, nr_sectors))
goto end_io;
+ if (q && q->metric && !bio->bi_queue) {
+ int need = bio->bi_max_vecs;
+ bio->bi_queue = q;
+ /* FIXME: potential race if atomic_sub is called in the middle
of condition check */
+ wait_event(q->throttle_wait, atomic_read(&q->available) >=
need);
+ atomic_sub(need, &q->available);
+ }
/*
* Resolve the mapping until finished. (drivers are
* still free to implement/resolve their own stacking
@@ -1396,10 +1403,10 @@ static inline void __generic_make_reques
*/
old_sector = -1;
old_dev = 0;
+ while (1) {
do {
char b[BDEVNAME_SIZE];
- q = bdev_get_queue(bio->bi_bdev);
if (unlikely(!q)) {
printk(KERN_ERR
"generic_make_request: Trying to access "
@@ -1449,8 +1456,10 @@ static inline void __generic_make_reques
goto end_io;
}
- ret = q->make_request_fn(q, bio);
- } while (ret);
+ if (!q->make_request_fn(q, bio))
+ return;
+ q = bdev_get_queue(bio->bi_bdev);
+ }
return;
Index: linux-2.6.29-rc2/drivers/md/dm.c
===================================================================
--- linux-2.6.29-rc2.orig/drivers/md/dm.c
+++ linux-2.6.29-rc2/drivers/md/dm.c
@@ -22,6 +22,7 @@
#include <linux/hdreg.h>
#include <linux/blktrace_api.h>
#include <trace/block.h>
+#include <linux/sysctl.h>
#define DM_MSG_PREFIX "core"
@@ -175,6 +176,45 @@ struct mapped_device {
#define MIN_IOS 256
static struct kmem_cache *_io_cache;
static struct kmem_cache *_tio_cache;
+
+static int sysctl_bio_throttle = 0;
+
+static ctl_table dm_table[] = {
+ {
+ .ctl_name = DEV_DM_BIO_THROTTLE,
+ .procname = "bio_throttle",
+ .data = &sysctl_bio_throttle,
+ .maxlen = sizeof(int),
+ .mode = S_IRUGO|S_IWUSR,
+ .proc_handler = &proc_dointvec,
+ },
+ { .ctl_name = 0 }
+};
+
+static ctl_table dm_dir_table[] = {
+ {
+ .ctl_name = DEV_DM,
+ .procname = "dm",
+ .maxlen = 0,
+ .mode = S_IRUGO|S_IXUGO,
+ .child = dm_table,
+ },
+ { .ctl_name = 0 }
+};
+
+static struct ctl_table_header *dm_table_header;
+
+static ctl_table dm_root_table[] = {
+ {
+ .ctl_name = CTL_DEV,
+ .procname = "dev",
+ .maxlen = 0,
+ .mode = 0555,
+ .child = dm_dir_table,
+ },
+ { .ctl_name = 0 }
+};
+
static struct kmem_cache *_rq_tio_cache;
static struct kmem_cache *_rq_bio_info_cache;
@@ -272,6 +312,7 @@ static int __init dm_init(void)
goto bad;
}
+ dm_table_header = register_sysctl_table(dm_root_table);
return 0;
bad:
@@ -287,6 +328,7 @@ static void __exit dm_exit(void)
while (i--)
_exits[i]();
+ unregister_sysctl_table(dm_table_header);
}
/*
@@ -915,6 +957,11 @@ out:
return max_size;
}
+static unsigned dm_metric(struct bio *bio)
+{
+ return 1;
+}
+
/*
* The request function that just remaps the bio built up by
* dm_merge_bvec.
@@ -1077,6 +1124,7 @@ out:
static struct block_device_operations dm_blk_dops;
+#define DEFAULT_THROTTLE_CAPACITY 1000
/*
* Allocate and initialise a blank device with a given minor.
*/
@@ -1118,6 +1166,13 @@ static struct mapped_device *alloc_dev(i
goto bad_queue;
md->queue->queuedata = md;
+ if (sysctl_bio_throttle == 1) {
+ md->queue->metric = dm_metric;
+ /* A dm device constructor may change the throttle capacity */
+ atomic_set(&md->queue->available, md->queue->capacity =
DEFAULT_THROTTLE_CAPACITY);
+ init_waitqueue_head(&md->queue->throttle_wait);
+ }
+
md->queue->backing_dev_info.congested_fn = dm_any_congested;
md->queue->backing_dev_info.congested_data = md;
blk_queue_make_request(md->queue, dm_request);
Index: linux-2.6.29-rc2/fs/bio.c
===================================================================
--- linux-2.6.29-rc2.orig/fs/bio.c
+++ linux-2.6.29-rc2/fs/bio.c
@@ -1379,6 +1379,13 @@ void bio_endio(struct bio *bio, int erro
else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
error = -EIO;
+ if (bio->bi_queue) {
+ struct request_queue *q = bio->bi_queue;
+ atomic_add(bio->bi_max_vecs, &q->available);
+ bio->bi_queue = NULL; /* 0xdeadbeef? */
+ wake_up(&q->throttle_wait);
+ }
+
if (bio->bi_end_io)
bio->bi_end_io(bio, error);
}
Index: linux-2.6.29-rc2/include/linux/bio.h
===================================================================
--- linux-2.6.29-rc2.orig/include/linux/bio.h
+++ linux-2.6.29-rc2/include/linux/bio.h
@@ -96,6 +96,7 @@ struct bio {
bio_end_io_t *bi_end_io;
+ struct request_queue *bi_queue; /* for throttling */
void *bi_private;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
struct bio_integrity_payload *bi_integrity; /* data integrity */
Index: linux-2.6.29-rc2/include/linux/blkdev.h
===================================================================
--- linux-2.6.29-rc2.orig/include/linux/blkdev.h
+++ linux-2.6.29-rc2/include/linux/blkdev.h
@@ -346,6 +346,10 @@ struct request_queue
struct work_struct unplug_work;
struct backing_dev_info backing_dev_info;
+ unsigned (*metric)(struct bio *bio); /* (stub) bio throttle metric */
+ wait_queue_head_t throttle_wait;
+ atomic_t available;
+ unsigned capacity;
/*
* The queue owner gets to use this for whatever they like.
Index: linux-2.6.29-rc2/include/linux/sysctl.h
===================================================================
--- linux-2.6.29-rc2.orig/include/linux/sysctl.h
+++ linux-2.6.29-rc2/include/linux/sysctl.h
@@ -858,6 +858,7 @@ enum {
DEV_MAC_HID=5,
DEV_SCSI=6,
DEV_IPMI=7,
+ DEV_DM=8
};
/* /proc/sys/dev/cdrom */
@@ -881,6 +882,11 @@ enum {
DEV_RAID_SPEED_LIMIT_MAX=2
};
+/* /proc/sys/dev/dm */
+enum {
+ DEV_DM_BIO_THROTTLE = 1
+};
+
/* /proc/sys/dev/parport/default */
enum {
DEV_PARPORT_DEFAULT_TIMESLICE=1,
Index: linux-2.6.29-rc2/kernel/sysctl_check.c
===================================================================
--- linux-2.6.29-rc2.orig/kernel/sysctl_check.c
+++ linux-2.6.29-rc2/kernel/sysctl_check.c
@@ -869,6 +869,11 @@ static const struct trans_ctl_table tran
{}
};
+static struct trans_ctl_table trans_dm_table[] = {
+ { DEV_DM_BIO_THROTTLE, "bio_throttle" },
+ {}
+};
+
static const struct trans_ctl_table trans_dev_table[] = {
{ DEV_CDROM, "cdrom", trans_cdrom_table },
/* DEV_HWMON unused */
@@ -877,6 +882,7 @@ static const struct trans_ctl_table tran
{ DEV_MAC_HID, "mac_hid", trans_mac_hid_files },
{ DEV_SCSI, "scsi", trans_scsi_table },
{ DEV_IPMI, "ipmi", trans_ipmi_table },
+ { DEV_DM, "dm", trans_dm_table },
{}
};
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