The patch titled
mm: introduce delete_from_page_cache()
has been added to the -mm tree. Its filename is
mm-introduce-delete_from_page_cache.patch
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------------------------------------------------------
Subject: mm: introduce delete_from_page_cache()
From: Minchan Kim <minchan.kim@xxxxxxxxx>
Presently we increase the page refcount in add_to_page_cache() but don't
decrease it in remove_from_page_cache(). Such asymmetry adds confusion,
requiring that callers notice it and a comment explaining why they release
a page reference. It's not a good API.
A long time ago, Hugh tried it (http://lkml.org/lkml/2004/10/24/140) but
gave up because reiser4's drop_page() had to unlock the page between
removing it from page cache and doing the page_cache_release(). But now
the situation is changed. I think at least things in current mainline
don't have any obstacles. The problem is for out-of-mainline filesystems
- if they have done such things as reiser4, this patch could be a problem
but they will discover this at compile time since we remove
remove_from_page_cache().
This patch:
This function works as just wrapper remove_from_page_cache(). The
difference is that it decreases page references in itself. So caller have
to make sure it has a page reference before calling.
This patch is ready for removing remove_from_page_cache().
Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Mel Gorman <mel@xxxxxxxxx>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Edward Shishkin <edward.shishkin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagemap.h | 1 +
mm/filemap.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)
diff -puN include/linux/pagemap.h~mm-introduce-delete_from_page_cache include/linux/pagemap.h
--- a/include/linux/pagemap.h~mm-introduce-delete_from_page_cache
+++ a/include/linux/pagemap.h
@@ -457,6 +457,7 @@ int add_to_page_cache_lru(struct page *p
pgoff_t index, gfp_t gfp_mask);
extern void remove_from_page_cache(struct page *page);
extern void __remove_from_page_cache(struct page *page);
+extern void delete_from_page_cache(struct page *page);
int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
/*
diff -puN mm/filemap.c~mm-introduce-delete_from_page_cache mm/filemap.c
--- a/mm/filemap.c~mm-introduce-delete_from_page_cache
+++ a/mm/filemap.c
@@ -166,6 +166,22 @@ void remove_from_page_cache(struct page
}
EXPORT_SYMBOL(remove_from_page_cache);
+/**
+ * delete_from_page_cache - delete page from page cache
+ * @page: the page which the kernel is trying to remove from page cache
+ *
+ * This must be called only on pages that have
+ * been verified to be in the page cache and locked.
+ * It will never put the page into the free list,
+ * the caller has a reference on the page.
+ */
+void delete_from_page_cache(struct page *page)
+{
+ remove_from_page_cache(page);
+ page_cache_release(page);
+}
+EXPORT_SYMBOL(delete_from_page_cache);
+
static int sync_page(void *word)
{
struct address_space *mapping;
_
Patches currently in -mm which might be from minchan.kim@xxxxxxxxx are
origin.patch
linux-next.patch
mm-vmap-area-cache.patch
mm-compaction-check-migrate_pagess-return-value-instead-of-list_empty.patch
mm-add-replace_page_cache_page-function-add-freepage-hook.patch
mm-introduce-delete_from_page_cache.patch
mm-hugetlbfs-change-remove_from_page_cache.patch
mm-shmem-change-remove_from_page_cache.patch
mm-truncate-change-remove_from_page_cache.patch
mm-good-bye-remove_from_page_cache.patch
mm-change-__remove_from_page_cache.patch
memcg-res_counter_read_u64-fix-potential-races-on-32-bit-machines.patch
memcg-soft-limit-reclaim-should-end-at-limit-not-below.patch
memcg-simplify-the-way-memory-limits-are-checked.patch
memcg-remove-unused-page-flag-bitfield-defines.patch
memcg-remove-impossible-conditional-when-committing.patch
memcg-remove-null-check-from-lookup_page_cgroup-result.patch
memcg-add-memcg-sanity-checks-at-allocating-and-freeing-pages.patch
memcg-add-memcg-sanity-checks-at-allocating-and-freeing-pages-update.patch
memcg-no-uncharged-pages-reach-page_cgroup_zoneinfo.patch
memcg-change-page_cgroup_zoneinfo-signature.patch
memcg-fold-__mem_cgroup_move_account-into-caller.patch
memcg-condense-page_cgroup-to-page-lookup-points.patch
memcg-remove-direct-page_cgroup-to-page-pointer.patch
memcg-remove-direct-page_cgroup-to-page-pointer-fix.patch
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