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Message-ID: <Pine.LNX.4.64.0712182157480.27165@blonde.wat.veritas.com>
Date: Tue, 18 Dec 2007 21:59:22 +0000 (GMT)
From: Hugh Dickins <hugh@...itas.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: Christoph Rohland <hans-christoph.rohland@....com>,
Nick Piggin <npiggin@...e.de>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/9] tmpfs: shuffle add_to_swap_caches
add_to_swap_cache doesn't amount to much: merge it into its sole caller
read_swap_cache_async. But we'll be needing to call __add_to_swap_cache
from shmem.c, so promote it to the new add_to_swap_cache. Both were
static, so there's no interface confusion to worry about.
And lose that inappropriate "Anon pages are already on the LRU" comment
in the merging: they're not already on the LRU, as Nick Piggin noticed.
Signed-off-by: Hugh Dickins <hugh@...itas.com>
---
mm/swap_state.c | 53 ++++++++++++++++------------------------------
1 file changed, 19 insertions(+), 34 deletions(-)
--- tmpfs1/mm/swap_state.c 2007-12-05 16:42:16.000000000 +0000
+++ tmpfs2/mm/swap_state.c 2007-12-05 16:42:16.000000000 +0000
@@ -64,10 +64,10 @@ void show_swap_cache_info(void)
}
/*
- * __add_to_swap_cache resembles add_to_page_cache on swapper_space,
+ * add_to_swap_cache resembles add_to_page_cache on swapper_space,
* but sets SwapCache flag and private instead of mapping and index.
*/
-static int __add_to_swap_cache(struct page *page, swp_entry_t entry,
+static int add_to_swap_cache(struct page *page, swp_entry_t entry,
gfp_t gfp_mask)
{
int error;
@@ -94,28 +94,6 @@ static int __add_to_swap_cache(struct pa
return error;
}
-static int add_to_swap_cache(struct page *page, swp_entry_t entry,
- gfp_t gfp_mask)
-{
- int error;
-
- BUG_ON(PageLocked(page));
- if (!swap_duplicate(entry))
- return -ENOENT;
-
- SetPageLocked(page);
- error = __add_to_swap_cache(page, entry, gfp_mask & GFP_KERNEL);
- /*
- * Anon pages are already on the LRU, we don't run lru_cache_add here.
- */
- if (error) {
- ClearPageLocked(page);
- swap_free(entry);
- return error;
- }
- return 0;
-}
-
/*
* This must be called only on pages that have
* been verified to be in the swap cache.
@@ -165,7 +143,7 @@ int add_to_swap(struct page * page, gfp_
/*
* Add it to the swap cache and mark it dirty
*/
- err = __add_to_swap_cache(page, entry,
+ err = add_to_swap_cache(page, entry,
gfp_mask|__GFP_NOMEMALLOC|__GFP_NOWARN);
switch (err) {
@@ -210,7 +188,7 @@ void delete_from_swap_cache(struct page
*/
int move_to_swap_cache(struct page *page, swp_entry_t entry)
{
- int err = __add_to_swap_cache(page, entry, GFP_ATOMIC);
+ int err = add_to_swap_cache(page, entry, GFP_ATOMIC);
if (!err) {
remove_from_page_cache(page);
page_cache_release(page); /* pagecache ref */
@@ -335,16 +313,21 @@ struct page *read_swap_cache_async(swp_e
}
/*
+ * Swap entry may have been freed since our caller observed it.
+ */
+ if (!swap_duplicate(entry))
+ break;
+
+ /*
* Associate the page with swap entry in the swap cache.
- * May fail (-ENOENT) if swap entry has been freed since
- * our caller observed it. May fail (-EEXIST) if there
- * is already a page associated with this entry in the
- * swap cache: added by a racing read_swap_cache_async,
- * or by try_to_swap_out (or shmem_writepage) re-using
- * the just freed swap entry for an existing page.
+ * May fail (-EEXIST) if there is already a page associated
+ * with this entry in the swap cache: added by a racing
+ * read_swap_cache_async, or add_to_swap or shmem_writepage
+ * re-using the just freed swap entry for an existing page.
* May fail (-ENOMEM) if radix-tree node allocation failed.
*/
- err = add_to_swap_cache(new_page, entry, gfp_mask);
+ SetPageLocked(new_page);
+ err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL);
if (!err) {
/*
* Initiate read into locked page and return.
@@ -353,7 +336,9 @@ struct page *read_swap_cache_async(swp_e
swap_readpage(NULL, new_page);
return new_page;
}
- } while (err != -ENOENT && err != -ENOMEM);
+ ClearPageLocked(new_page);
+ swap_free(entry);
+ } while (err != -ENOMEM);
if (new_page)
page_cache_release(new_page);
--
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