Commit 44835d20 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

mm: add FGP_ENTRY 

The functionality of find_lock_entry() and find_get_entry() can be
provided by pagecache_get_page(), which lets us delete find_lock_entry()
and make find_get_entry() static.

Link: https://lkml.kernel.org/r/20201112212641.27837-5-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8c647dd1

include/linux/pagemap.h

+1 −0
Original line number Diff line number Diff line
@@ -315,6 +315,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping, 
#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);

mm/filemap.c

+8 −36
Original line number Diff line number Diff line
@@ -1658,7 +1658,7 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping, 
}

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.
@@ -1671,7 +1671,7 @@ 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;
@@ -1707,39 +1707,6 @@ struct page *find_get_entry(struct address_space *mapping, pgoff_t index) 
	return page;

}



/**

 * 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.
@@ -1755,6 +1722,8 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t index) 
 * * %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.
@@ -1779,8 +1748,11 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, 


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;

mm/internal.h

+0 −3
Original line number Diff line number Diff line
@@ -60,9 +60,6 @@ static inline void force_page_cache_readahead(struct address_space *mapping, 
	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

mm/shmem.c

+2 −1
Original line number Diff line number Diff line
@@ -1812,7 +1812,8 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, 
	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);

mm/swap_state.c

+2 −1
Original line number Diff line number Diff line
@@ -403,7 +403,8 @@ struct page *find_get_incore_page(struct address_space *mapping, pgoff_t index) 
{

	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;