Commit 539a3322 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

filemap: Add read_cache_folio and read_mapping_folio 



Reimplement read_cache_page() as a wrapper around read_cache_folio().
Saves over 400 bytes of text from do_read_cache_folio() which more
than makes up for the extra 100 bytes of text added to the various
wrapper functions.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
parent e292e6d6

include/linux/pagemap.h

+10 −2
Original line number Diff line number Diff line
@@ -629,8 +629,10 @@ static inline struct page *grab_cache_page(struct address_space *mapping, 
	return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));

}



extern struct page * read_cache_page(struct address_space *mapping,

				pgoff_t index, filler_t *filler, void *data);

struct folio *read_cache_folio(struct address_space *, pgoff_t index,

		filler_t *filler, void *data);

struct page *read_cache_page(struct address_space *, pgoff_t index,

		filler_t *filler, void *data);

extern struct page * read_cache_page_gfp(struct address_space *mapping,

				pgoff_t index, gfp_t gfp_mask);

extern int read_cache_pages(struct address_space *mapping,
@@ -642,6 +644,12 @@ static inline struct page *read_mapping_page(struct address_space *mapping, 
	return read_cache_page(mapping, index, NULL, data);

}



static inline struct folio *read_mapping_folio(struct address_space *mapping,

				pgoff_t index, void *data)

{

	return read_cache_folio(mapping, index, NULL, data);

}



/*

 * Get index of the page within radix-tree (but not for hugetlb pages).

 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)

mm/filemap.c

+51 −46
Original line number Diff line number Diff line
@@ -3418,35 +3418,20 @@ EXPORT_SYMBOL(filemap_page_mkwrite); 
EXPORT_SYMBOL(generic_file_mmap);

EXPORT_SYMBOL(generic_file_readonly_mmap);



static struct page *wait_on_page_read(struct page *page)

static struct folio *do_read_cache_folio(struct address_space *mapping,

		pgoff_t index, filler_t filler, void *data, gfp_t gfp)

{

	if (!IS_ERR(page)) {

		wait_on_page_locked(page);

		if (!PageUptodate(page)) {

			put_page(page);

			page = ERR_PTR(-EIO);

		}

	}

	return page;

}



static struct page *do_read_cache_page(struct address_space *mapping,

				pgoff_t index,

				int (*filler)(void *, struct page *),

				void *data,

				gfp_t gfp)

{

	struct page *page;

	struct folio *folio;

	int err;

repeat:

	page = find_get_page(mapping, index);

	if (!page) {

		page = __page_cache_alloc(gfp);

		if (!page)

	folio = filemap_get_folio(mapping, index);

	if (!folio) {

		folio = filemap_alloc_folio(gfp, 0);

		if (!folio)

			return ERR_PTR(-ENOMEM);

		err = add_to_page_cache_lru(page, mapping, index, gfp);

		err = filemap_add_folio(mapping, folio, index, gfp);

		if (unlikely(err)) {

			put_page(page);

			folio_put(folio);

			if (err == -EEXIST)

				goto repeat;

			/* Presumably ENOMEM for xarray node */
@@ -3455,21 +3440,24 @@ static struct page *do_read_cache_page(struct address_space *mapping, 


filler:

		if (filler)

			err = filler(data, page);

			err = filler(data, &folio->page);

		else

			err = mapping->a_ops->readpage(data, page);

			err = mapping->a_ops->readpage(data, &folio->page);



		if (err < 0) {

			put_page(page);

			folio_put(folio);

			return ERR_PTR(err);

		}



		page = wait_on_page_read(page);

		if (IS_ERR(page))

			return page;

		folio_wait_locked(folio);

		if (!folio_test_uptodate(folio)) {

			folio_put(folio);

			return ERR_PTR(-EIO);

		}



		goto out;

	}

	if (PageUptodate(page))

	if (folio_test_uptodate(folio))

		goto out;



	/*
@@ -3503,23 +3491,23 @@ static struct page *do_read_cache_page(struct address_space *mapping, 
	 * avoid spurious serialisations and wakeups when multiple processes

	 * wait on the same page for IO to complete.

	 */

	wait_on_page_locked(page);

	if (PageUptodate(page))

	folio_wait_locked(folio);

	if (folio_test_uptodate(folio))

		goto out;



	/* Distinguish between all the cases under the safety of the lock */

	lock_page(page);

	folio_lock(folio);



	/* Case c or d, restart the operation */

	if (!page->mapping) {

		unlock_page(page);

		put_page(page);

	if (!folio->mapping) {

		folio_unlock(folio);

		folio_put(folio);

		goto repeat;

	}



	/* Someone else locked and filled the page in a very small window */

	if (PageUptodate(page)) {

		unlock_page(page);

	if (folio_test_uptodate(folio)) {

		folio_unlock(folio);

		goto out;

	}
@@ -3529,16 +3517,16 @@ static struct page *do_read_cache_page(struct address_space *mapping, 
	 * Clear page error before actual read, PG_error will be

	 * set again if read page fails.

	 */

	ClearPageError(page);

	folio_clear_error(folio);

	goto filler;



out:

	mark_page_accessed(page);

	return page;

	folio_mark_accessed(folio);

	return folio;

}



/**

 * read_cache_page - read into page cache, fill it if needed

 * read_cache_folio - read into page cache, fill it if needed

 * @mapping:	the page's address_space

 * @index:	the page index

 * @filler:	function to perform the read
@@ -3553,10 +3541,27 @@ static struct page *do_read_cache_page(struct address_space *mapping, 
 *

 * Return: up to date page on success, ERR_PTR() on failure.

 */

struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index,

		filler_t filler, void *data)

{

	return do_read_cache_folio(mapping, index, filler, data,

			mapping_gfp_mask(mapping));

}

EXPORT_SYMBOL(read_cache_folio);



static struct page *do_read_cache_page(struct address_space *mapping,

		pgoff_t index, filler_t *filler, void *data, gfp_t gfp)

{

	struct folio *folio;



	folio = do_read_cache_folio(mapping, index, filler, data, gfp);

	if (IS_ERR(folio))

		return &folio->page;

	return folio_file_page(folio, index);

}



struct page *read_cache_page(struct address_space *mapping,

				pgoff_t index,

				int (*filler)(void *, struct page *),

				void *data)

				pgoff_t index, filler_t *filler, void *data)

{

	return do_read_cache_page(mapping, index, filler, data,

			mapping_gfp_mask(mapping));