Remove the unnecessary size limit on setting read_ahead_kb. Also make possible large values harmless. The stock readahead is protected by always consulting the avaiable memory before applying this number. Other readahead paths have already did so. read_ahead_kb used to be guarded by the queue's max_sectors, which can be too rigid because some devices set max_sectors to small values like 64kb. That leads to many user complains. Signed-off-by: Wu Fengguang --- block/ll_rw_blk.c | 5 ----- 1 files changed, 5 deletions(-) --- linux-2.6.17-rc6-mm1.orig/block/ll_rw_blk.c +++ linux-2.6.17-rc6-mm1/block/ll_rw_blk.c @@ -3810,12 +3810,7 @@ queue_ra_store(struct request_queue *q, unsigned long ra_kb; ssize_t ret = queue_var_store(&ra_kb, page, count); - spin_lock_irq(q->queue_lock); - if (ra_kb > (q->max_sectors >> 1)) - ra_kb = (q->max_sectors >> 1); - q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); - spin_unlock_irq(q->queue_lock); return ret; } --- linux-2.6.17-rc6-mm1.orig/mm/readahead.c +++ linux-2.6.17-rc6-mm1/mm/readahead.c @@ -156,7 +156,7 @@ EXPORT_SYMBOL_GPL(file_ra_state_init); */ static inline unsigned long get_max_readahead(struct file_ra_state *ra) { - return ra->ra_pages; + return max_sane_readahead(ra->ra_pages); } static inline unsigned long get_min_readahead(struct file_ra_state *ra) --