#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/random.h>
+#include <linux/iocontext.h>
#include <asm/div64.h>
#include "compat.h"
#include "ctree.h"
return NULL;
}
+static void requeue_list(struct btrfs_pending_bios *pending_bios,
+ struct bio *head, struct bio *tail)
+{
+
+ struct bio *old_head;
+
+ old_head = pending_bios->head;
+ pending_bios->head = head;
+ if (pending_bios->tail)
+ tail->bi_next = old_head;
+ else
+ pending_bios->tail = tail;
+}
+
/*
* we try to collect pending bios for a device so we don't get a large
* number of procs sending bios down to the same device. This greatly
struct bio *pending;
struct backing_dev_info *bdi;
struct btrfs_fs_info *fs_info;
+ struct btrfs_pending_bios *pending_bios;
struct bio *tail;
struct bio *cur;
int again = 0;
- unsigned long num_run = 0;
+ unsigned long num_run;
+ unsigned long num_sync_run;
unsigned long limit;
+ unsigned long last_waited = 0;
- bdi = device->bdev->bd_inode->i_mapping->backing_dev_info;
+ bdi = blk_get_backing_dev_info(device->bdev);
fs_info = device->dev_root->fs_info;
limit = btrfs_async_submit_limit(fs_info);
limit = limit * 2 / 3;
+ /* we want to make sure that every time we switch from the sync
+ * list to the normal list, we unplug
+ */
+ num_sync_run = 0;
+
loop:
spin_lock(&device->io_lock);
+ num_run = 0;
loop_lock:
+
/* take all the bios off the list at once and process them
* later on (without the lock held). But, remember the
* tail and other pointers so the bios can be properly reinserted
* into the list if we hit congestion
*/
- pending = device->pending_bios;
- tail = device->pending_bio_tail;
+ if (device->pending_sync_bios.head)
+ pending_bios = &device->pending_sync_bios;
+ else
+ pending_bios = &device->pending_bios;
+
+ pending = pending_bios->head;
+ tail = pending_bios->tail;
WARN_ON(pending && !tail);
- device->pending_bios = NULL;
- device->pending_bio_tail = NULL;
/*
* if pending was null this time around, no bios need processing
* device->running_pending is used to synchronize with the
* schedule_bio code.
*/
- if (pending) {
- again = 1;
- device->running_pending = 1;
- } else {
+ if (device->pending_sync_bios.head == NULL &&
+ device->pending_bios.head == NULL) {
again = 0;
device->running_pending = 0;
+ } else {
+ again = 1;
+ device->running_pending = 1;
}
+
+ pending_bios->head = NULL;
+ pending_bios->tail = NULL;
+
spin_unlock(&device->io_lock);
+ /*
+ * if we're doing the regular priority list, make sure we unplug
+ * for any high prio bios we've sent down
+ */
+ if (pending_bios == &device->pending_bios && num_sync_run > 0) {
+ num_sync_run = 0;
+ blk_run_backing_dev(bdi, NULL);
+ }
+
while (pending) {
+
+ rmb();
+ if (pending_bios != &device->pending_sync_bios &&
+ device->pending_sync_bios.head &&
+ num_run > 16) {
+ cond_resched();
+ spin_lock(&device->io_lock);
+ requeue_list(pending_bios, pending, tail);
+ goto loop_lock;
+ }
+
cur = pending;
pending = pending->bi_next;
cur->bi_next = NULL;
wake_up(&fs_info->async_submit_wait);
BUG_ON(atomic_read(&cur->bi_cnt) == 0);
- bio_get(cur);
submit_bio(cur->bi_rw, cur);
- bio_put(cur);
num_run++;
+ if (bio_sync(cur))
+ num_sync_run++;
+
+ if (need_resched()) {
+ if (num_sync_run) {
+ blk_run_backing_dev(bdi, NULL);
+ num_sync_run = 0;
+ }
+ cond_resched();
+ }
/*
* we made progress, there is more work to do and the bdi
*/
if (pending && bdi_write_congested(bdi) && num_run > 16 &&
fs_info->fs_devices->open_devices > 1) {
- struct bio *old_head;
+ struct io_context *ioc;
- spin_lock(&device->io_lock);
-
- old_head = device->pending_bios;
- device->pending_bios = pending;
- if (device->pending_bio_tail)
- tail->bi_next = old_head;
- else
- device->pending_bio_tail = tail;
+ ioc = current->io_context;
+ /*
+ * the main goal here is that we don't want to
+ * block if we're going to be able to submit
+ * more requests without blocking.
+ *
+ * This code does two great things, it pokes into
+ * the elevator code from a filesystem _and_
+ * it makes assumptions about how batching works.
+ */
+ if (ioc && ioc->nr_batch_requests > 0 &&
+ time_before(jiffies, ioc->last_waited + HZ/50UL) &&
+ (last_waited == 0 ||
+ ioc->last_waited == last_waited)) {
+ /*
+ * we want to go through our batch of
+ * requests and stop. So, we copy out
+ * the ioc->last_waited time and test
+ * against it before looping
+ */
+ last_waited = ioc->last_waited;
+ if (need_resched()) {
+ if (num_sync_run) {
+ blk_run_backing_dev(bdi, NULL);
+ num_sync_run = 0;
+ }
+ cond_resched();
+ }
+ continue;
+ }
+ spin_lock(&device->io_lock);
+ requeue_list(pending_bios, pending, tail);
device->running_pending = 1;
spin_unlock(&device->io_lock);
goto done;
}
}
+
+ if (num_sync_run) {
+ num_sync_run = 0;
+ blk_run_backing_dev(bdi, NULL);
+ }
+
+ cond_resched();
if (again)
goto loop;
spin_lock(&device->io_lock);
- if (device->pending_bios)
+ if (device->pending_bios.head || device->pending_sync_bios.head)
goto loop_lock;
spin_unlock(&device->io_lock);
+
+ /*
+ * IO has already been through a long path to get here. Checksumming,
+ * async helper threads, perhaps compression. We've done a pretty
+ * good job of collecting a batch of IO and should just unplug
+ * the device right away.
+ *
+ * This will help anyone who is waiting on the IO, they might have
+ * already unplugged, but managed to do so before the bio they
+ * cared about found its way down here.
+ */
+ blk_run_backing_dev(bdi, NULL);
done:
return 0;
}
max_errors = 1;
}
}
- if (multi_ret && rw == WRITE &&
+ if (multi_ret && (rw & (1 << BIO_RW)) &&
stripes_allocated < stripes_required) {
stripes_allocated = map->num_stripes;
free_extent_map(em);
int rw, struct bio *bio)
{
int should_queue = 1;
+ struct btrfs_pending_bios *pending_bios;
/* don't bother with additional async steps for reads, right now */
if (!(rw & (1 << BIO_RW))) {
bio->bi_rw |= rw;
spin_lock(&device->io_lock);
+ if (bio_sync(bio))
+ pending_bios = &device->pending_sync_bios;
+ else
+ pending_bios = &device->pending_bios;
- if (device->pending_bio_tail)
- device->pending_bio_tail->bi_next = bio;
+ if (pending_bios->tail)
+ pending_bios->tail->bi_next = bio;
- device->pending_bio_tail = bio;
- if (!device->pending_bios)
- device->pending_bios = bio;
+ pending_bios->tail = bio;
+ if (!pending_bios->head)
+ pending_bios->head = bio;
if (device->running_pending)
should_queue = 0;
projects / linux-beck.git / blobdiff