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filemap: Add read_cache_folio and read_mapping_folio

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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: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2020-12-16 11:45:30 -05:00
parent e292e6d644
commit 539a3322f2
2 changed files with 61 additions and 48 deletions
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12
include/linux/pagemap.h
View File

@ -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)

97
mm/filemap.c
View File

@ -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 @@ repeat:
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 @@ filler:
* 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 @@ filler:
* 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 @@ out:
*
* 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));