[PATCH] Remove most of the blk_run_queues() calls

We don't need these with self-unplugging queues.

The patch also contains a couple of microopts suggested by Andrea: we
don't need to run sync_page() if the page just came unlocked.

fs/buffer.c

@@ -127,9 +127,10 @@ void __wait_on_buffer(struct buffer_head * bh)
 	get_bh(bh);
 	do {
 		prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
+		if (buffer_locked(bh)) {
 			blk_run_queues();
-		if (buffer_locked(bh))
 			io_schedule();
+		}
 	} while (buffer_locked(bh));
 	put_bh(bh);
 	finish_wait(wqh, &wait);
@@ -959,8 +960,6 @@ create_buffers(struct page * page, unsigned long size, int retry)
 	 * the reserve list is empty, we're sure there are 
 	 * async buffer heads in use.
 	 */
-	blk_run_queues();
-
 	free_more_memory();
 	goto try_again;
 }

fs/fs-writeback.c

@@ -334,7 +334,6 @@ writeback_inodes(struct writeback_control *wbc)
 	}
 	spin_unlock(&sb_lock);
 	spin_unlock(&inode_lock);
-	blk_run_queues();
 }
 
 /*

fs/mpage.c

@@ -618,7 +618,6 @@ mpage_writepages(struct address_space *mapping,
 	int (*writepage)(struct page *page, struct writeback_control *wbc);
 
 	if (wbc->nonblocking && bdi_write_congested(bdi)) {
-		blk_run_queues();
 		wbc->encountered_congestion = 1;
 		return 0;
 	}
@@ -673,7 +672,6 @@ mpage_writepages(struct address_space *mapping,
 			if (ret || (--(wbc->nr_to_write) <= 0))
 				done = 1;
 			if (wbc->nonblocking && bdi_write_congested(bdi)) {
-				blk_run_queues();
 				wbc->encountered_congestion = 1;
 				done = 1;
 			}

mm/filemap.c

@@ -259,9 +259,10 @@ void wait_on_page_bit(struct page *page, int bit_nr)
 
 	do {
 		prepare_to_wait(waitqueue, &wait, TASK_UNINTERRUPTIBLE);
+		if (test_bit(bit_nr, &page->flags)) {
 			sync_page(page);
-		if (test_bit(bit_nr, &page->flags))
 			io_schedule();
+		}
 	} while (test_bit(bit_nr, &page->flags));
 	finish_wait(waitqueue, &wait);
 }
@@ -326,10 +327,11 @@ void __lock_page(struct page *page)
 
 	while (TestSetPageLocked(page)) {
 		prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
+		if (PageLocked(page)) {
 			sync_page(page);
-		if (PageLocked(page))
 			io_schedule();
 		}
+	}
 	finish_wait(wqh, &wait);
 }
 EXPORT_SYMBOL(__lock_page);

mm/page-writeback.c

@@ -237,7 +237,6 @@ static void background_writeout(unsigned long _min_pages)
 				break;
 		}
 	}
-	blk_run_queues();
 }
 
 /*
@@ -308,7 +307,6 @@ static void wb_kupdate(unsigned long arg)
 		}
 		nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
 	}
-	blk_run_queues();
 	if (time_before(next_jif, jiffies + HZ))
 		next_jif = jiffies + HZ;
 	mod_timer(&wb_timer, next_jif);

mm/readahead.c

@@ -236,10 +236,8 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
 	 * uptodate then the caller will launch readpage again, and
 	 * will then handle the error.
 	 */
-	if (ret) {
+	if (ret)
 		read_pages(mapping, filp, &page_pool, ret);
-		blk_run_queues();
-	}
 	BUG_ON(!list_empty(&page_pool));
 out:
 	return ret;

mm/vmscan.c

@@ -957,7 +957,6 @@ int kswapd(void *p)
 		finish_wait(&pgdat->kswapd_wait, &wait);
 		get_page_state(&ps);
 		balance_pgdat(pgdat, 0, &ps);
-		blk_run_queues();
 	}
 }