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

Fengguang Wu
2007-07-21T04:44:00Z

[-- Attachment #1: remove-readahead-size-limit.patch --]
[-- Type: text/plain, Size: 1300 bytes --]

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@oracle.com>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
---
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);

--