The patch titled
Subject: mm: add FGP_ENTRY
has been added to the -mm tree. Its filename is
mm-add-fgp_entry.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-add-fgp_entry.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-add-fgp_entry.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: add FGP_ENTRY
The functionality of find_lock_entry() and find_get_entry() can be
provided by pagecache_get_pages(), which lets us delete find_lock_entry()
and make find_get_entry() static.
Link: https://lkml.kernel.org/r/20201112212641.27837-5-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagemap.h | 1
mm/filemap.c | 44 ++++++--------------------------------
mm/internal.h | 3 --
mm/shmem.c | 3 +-
mm/swap_state.c | 3 +-
5 files changed, 13 insertions(+), 41 deletions(-)
--- a/include/linux/pagemap.h~mm-add-fgp_entry
+++ a/include/linux/pagemap.h
@@ -315,6 +315,7 @@ pgoff_t page_cache_prev_miss(struct addr
#define FGP_NOWAIT 0x00000020
#define FGP_FOR_MMAP 0x00000040
#define FGP_HEAD 0x00000080
+#define FGP_ENTRY 0x00000100
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
int fgp_flags, gfp_t cache_gfp_mask);
--- a/mm/filemap.c~mm-add-fgp_entry
+++ a/mm/filemap.c
@@ -1662,7 +1662,7 @@ pgoff_t page_cache_prev_miss(struct addr
}
EXPORT_SYMBOL(page_cache_prev_miss);
-/**
+/*
* find_get_entry - find and get a page cache entry
* @mapping: the address_space to search
* @index: The page cache index.
@@ -1675,7 +1675,7 @@ EXPORT_SYMBOL(page_cache_prev_miss);
*
* Return: The head page or shadow entry, %NULL if nothing is found.
*/
-struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
+static struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
{
XA_STATE(xas, &mapping->i_pages, index);
struct page *page;
@@ -1712,39 +1712,6 @@ out:
}
/**
- * find_lock_entry - Locate and lock a page cache entry.
- * @mapping: The address_space to search.
- * @index: The page cache index.
- *
- * Looks up the page at @mapping & @index. If there is a page in the
- * cache, the head page is returned locked and with an increased refcount.
- *
- * If the slot holds a shadow entry of a previously evicted page, or a
- * swap entry from shmem/tmpfs, it is returned.
- *
- * Context: May sleep.
- * Return: The head page or shadow entry, %NULL if nothing is found.
- */
-struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
-{
- struct page *page;
-
-repeat:
- page = find_get_entry(mapping, index);
- if (page && !xa_is_value(page)) {
- lock_page(page);
- /* Has the page been truncated? */
- if (unlikely(page->mapping != mapping)) {
- unlock_page(page);
- put_page(page);
- goto repeat;
- }
- VM_BUG_ON_PAGE(!thp_contains(page, index), page);
- }
- return page;
-}
-
-/**
* pagecache_get_page - Find and get a reference to a page.
* @mapping: The address_space to search.
* @index: The page index.
@@ -1759,6 +1726,8 @@ repeat:
* * %FGP_LOCK - The page is returned locked.
* * %FGP_HEAD - If the page is present and a THP, return the head page
* rather than the exact page specified by the index.
+ * * %FGP_ENTRY - If there is a shadow / swap / DAX entry, return it
+ * instead of allocating a new page to replace it.
* * %FGP_CREAT - If no page is present then a new page is allocated using
* @gfp_mask and added to the page cache and the VM's LRU list.
* The page is returned locked and with an increased refcount.
@@ -1783,8 +1752,11 @@ struct page *pagecache_get_page(struct a
repeat:
page = find_get_entry(mapping, index);
- if (xa_is_value(page))
+ if (xa_is_value(page)) {
+ if (fgp_flags & FGP_ENTRY)
+ return page;
page = NULL;
+ }
if (!page)
goto no_page;
--- a/mm/internal.h~mm-add-fgp_entry
+++ a/mm/internal.h
@@ -60,9 +60,6 @@ static inline void force_page_cache_read
force_page_cache_ra(&ractl, &file->f_ra, nr_to_read);
}
-struct page *find_get_entry(struct address_space *mapping, pgoff_t index);
-struct page *find_lock_entry(struct address_space *mapping, pgoff_t index);
-
/**
* page_evictable - test whether a page is evictable
* @page: the page to test
--- a/mm/shmem.c~mm-add-fgp_entry
+++ a/mm/shmem.c
@@ -1831,7 +1831,8 @@ repeat:
sbinfo = SHMEM_SB(inode->i_sb);
charge_mm = vma ? vma->vm_mm : current->mm;
- page = find_lock_entry(mapping, index);
+ page = pagecache_get_page(mapping, index,
+ FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0);
if (xa_is_value(page)) {
error = shmem_swapin_page(inode, index, &page,
sgp, gfp, vma, fault_type);
--- a/mm/swap_state.c~mm-add-fgp_entry
+++ a/mm/swap_state.c
@@ -427,7 +427,8 @@ struct page *find_get_incore_page(struct
{
swp_entry_t swp;
struct swap_info_struct *si;
- struct page *page = find_get_entry(mapping, index);
+ struct page *page = pagecache_get_page(mapping, index,
+ FGP_ENTRY | FGP_HEAD, 0);
if (!page)
return page;
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-fix-readahead_page_batch-for-retry-entries.patch
mm-fix-madvise-willneed-performance-problem.patch
mm-page-flags-fix-comment.patch
mm-page_alloc-add-__free_pages-documentation.patch
mm-make-pagecache-tagged-lookups-return-only-head-pages.patch
mm-shmem-use-pagevec_lookup-in-shmem_unlock_mapping.patch
mm-swap-optimise-get_shadow_from_swap_cache.patch
mm-add-fgp_entry.patch
mm-filemap-rename-find_get_entry-to-mapping_get_entry.patch
mm-filemap-add-helper-for-finding-pages.patch
mm-filemap-add-mapping_seek_hole_data.patch
iomap-use-mapping_seek_hole_data.patch
mm-add-and-use-find_lock_entries.patch
mm-add-an-end-parameter-to-find_get_entries.patch
mm-add-an-end-parameter-to-pagevec_lookup_entries.patch
mm-remove-nr_entries-parameter-from-pagevec_lookup_entries.patch
mm-pass-pvec-directly-to-find_get_entries.patch
mm-remove-pagevec_lookup_entries.patch
mm-truncateshmem-handle-truncates-that-split-thps.patch
mm-filemap-return-only-head-pages-from-find_get_entries.patch
mm-introduce-memfd_secret-system-call-to-create-secret-memory-areas-fix.patch
