[PATCH 5/7] readahead: remove the limit max_sectors_kb imposed on max_readahead_kb

[Fengguang Wu]

Remove the size limit max_sectors_kb imposed on max_readahead_kb.

The size restriction is unreasonable. Especially when max_sectors_kb cannot
grow larger than max_hw_sectors_kb, which can be rather small for some disk
drives.

Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx>
Acked-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
---
 block/ll_rw_blk.c |    9 ---------
 1 file changed, 9 deletions(-)

--- linux-2.6.22-rc6-mm1.orig/block/ll_rw_blk.c
+++ linux-2.6.22-rc6-mm1/block/ll_rw_blk.c
@@ -3945,7 +3945,6 @@ queue_max_sectors_store(struct request_q
 			max_hw_sectors_kb = q->max_hw_sectors >> 1,
 			page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
 	ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
-	int ra_kb;
 
 	if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
 		return -EINVAL;
@@ -3954,14 +3953,6 @@ queue_max_sectors_store(struct request_q
 	 * values synchronously:
 	 */
 	spin_lock_irq(q->queue_lock);
-	/*
-	 * Trim readahead window as well, if necessary:
-	 */
-	ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
-	if (ra_kb > max_sectors_kb)
-		q->backing_dev_info.ra_pages =
-				max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
-
 	q->max_sectors = max_sectors_kb << 1;
 	spin_unlock_irq(q->queue_lock);
 

--
-
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