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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2009-09-21 20:02:52 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 10:17:35 -0400
commit2ca4532a49be92d7b2766c3244b30fa8bfb0114d (patch)
tree1dc838cebacb10317dff78ceccd50b97e24c4f7f /mm/shmem.c
parent31a5639623a487d6db996c8138c9e53fef2e2d91 (diff)
mm: add_to_swap_cache() does not return -EEXIST
After commit 355cfa73 ("mm: modify swap_map and add SWAP_HAS_CACHE flag"), only the context which have set SWAP_HAS_CACHE flag by swapcache_prepare() or get_swap_page() would call add_to_swap_cache(). So add_to_swap_cache() doesn't return -EEXIST any more. Even though it doesn't return -EEXIST, it's not good behavior conceptually to call swapcache_prepare() in the -EEXIST case, because it means clearing SWAP_HAS_CACHE flag while the entry is on swap cache. This patch removes redundant codes and comments from callers of it, and adds VM_BUG_ON() in error path of add_to_swap_cache() and some comments. Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/shmem.c')
-rw-r--r--mm/shmem.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index bd20f8bb02a..376d8f0a8f6 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1097,6 +1097,10 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1097 shmem_swp_unmap(entry); 1097 shmem_swp_unmap(entry);
1098unlock: 1098unlock:
1099 spin_unlock(&info->lock); 1099 spin_unlock(&info->lock);
1100 /*
1101 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1102 * clear SWAP_HAS_CACHE flag.
1103 */
1100 swapcache_free(swap, NULL); 1104 swapcache_free(swap, NULL);
1101redirty: 1105redirty:
1102 set_page_dirty(page); 1106 set_page_dirty(page);