From 7992fde72ce06c73280a1939b7a1e903bc95ef85 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Tue, 6 Jan 2009 14:39:53 -0800 Subject: swapfile: swap allocation use discard When scan_swap_map() finds a free cluster of swap pages to allocate, discard the old contents of the cluster if the device supports discard. But don't bother when swap is so fragmented that we allocate single pages. Be careful about racing allocations made while we're scanning for a cluster; and hold up allocations made while we're discarding. Signed-off-by: Hugh Dickins Cc: KAMEZAWA Hiroyuki Cc: Nick Piggin Cc: David Woodhouse Cc: Jens Axboe Cc: Matthew Wilcox Cc: Joern Engel Cc: James Bottomley Cc: Donjun Shin Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/swap.h b/include/linux/swap.h index 0b9210ea96c7..fe79f44c858e 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -121,6 +121,7 @@ enum { SWP_USED = (1 << 0), /* is slot in swap_info[] used? */ SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */ SWP_DISCARDABLE = (1 << 2), /* blkdev supports discard */ + SWP_DISCARDING = (1 << 3), /* now discarding a free cluster */ /* add others here before... */ SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */ }; @@ -144,6 +145,8 @@ struct swap_info_struct { unsigned short *swap_map; unsigned int lowest_bit; unsigned int highest_bit; + unsigned int lowest_alloc; /* while preparing discard cluster */ + unsigned int highest_alloc; /* while preparing discard cluster */ unsigned int cluster_next; unsigned int cluster_nr; unsigned int pages; -- cgit v1.2.3