[PATCH v6 14/19] ext4: Convert from readpages to readahead

Matthew Wilcox
2020-02-17T18:49:27Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Use the new readahead operation in ext4

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/ext4/ext4.h | 3 +--
fs/ext4/inode.c | 23 ++++++++++-------------
fs/ext4/readpage.c | 22 ++++++++--------------
3 files changed, 19 insertions(+), 29 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4441331d06cc..1570a0b51b73 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3279,8 +3279,7 @@ static inline void ext4_set_de_type(struct super_block *sb,

/* readpages.c */
extern int ext4_mpage_readpages(struct address_space *mapping,
- struct list_head *pages, struct page *page,
- unsigned nr_pages, bool is_readahead);
+ struct readahead_control *rac, struct page *page);
extern int __init ext4_init_post_read_processing(void);
extern void ext4_exit_post_read_processing(void);

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e60aca791d3f..b3349bfb75b8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3218,7 +3218,7 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
static int ext4_readpage(struct file *file, struct page *page)
{
int ret = -EAGAIN;
- struct inode *inode = page->mapping->host;
+ struct inode *inode = file_inode(file);

trace_ext4_readpage(page);

@@ -3226,23 +3226,20 @@ static int ext4_readpage(struct file *file, struct page *page)
ret = ext4_readpage_inline(inode, page);

if (ret == -EAGAIN)
- return ext4_mpage_readpages(page->mapping, NULL, page, 1,
- false);
+ return ext4_mpage_readpages(page->mapping, NULL, page);

return ret;
}

-static int
-ext4_readpages(struct file *file, struct address_space *mapping,
- struct list_head *pages, unsigned nr_pages)
+static void ext4_readahead(struct readahead_control *rac)
{
- struct inode *inode = mapping->host;
+ struct inode *inode = rac->mapping->host;

- /* If the file has inline data, no need to do readpages. */
+ /* If the file has inline data, no need to do readahead. */
if (ext4_has_inline_data(inode))
- return 0;
+ return;

- return ext4_mpage_readpages(mapping, pages, NULL, nr_pages, true);
+ ext4_mpage_readpages(rac->mapping, rac, NULL);
}

static void ext4_invalidatepage(struct page *page, unsigned int offset,
@@ -3587,7 +3584,7 @@ static int ext4_set_page_dirty(struct page *page)

static const struct address_space_operations ext4_aops = {
.readpage = ext4_readpage,
- .readpages = ext4_readpages,
+ .readahead = ext4_readahead,
.writepage = ext4_writepage,
.writepages = ext4_writepages,
.write_begin = ext4_write_begin,
@@ -3604,7 +3601,7 @@ static const struct address_space_operations ext4_aops = {

static const struct address_space_operations ext4_journalled_aops = {
.readpage = ext4_readpage,
- .readpages = ext4_readpages,
+ .readahead = ext4_readahead,
.writepage = ext4_writepage,
.writepages = ext4_writepages,
.write_begin = ext4_write_begin,
@@ -3620,7 +3617,7 @@ static const struct address_space_operations ext4_journalled_aops = {

static const struct address_space_operations ext4_da_aops = {
.readpage = ext4_readpage,
- .readpages = ext4_readpages,
+ .readahead = ext4_readahead,
.writepage = ext4_writepage,
.writepages = ext4_writepages,
.write_begin = ext4_da_write_begin,
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index c1769afbf799..e14841ade612 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -7,8 +7,8 @@
*
* This was originally taken from fs/mpage.c
*
- * The intent is the ext4_mpage_readpages() function here is intended
- * to replace mpage_readpages() in the general case, not just for
+ * The ext4_mpage_readahead() function here is intended to
+ * replace mpage_readahead() in the general case, not just for
* encrypted files. It has some limitations (see below), where it
* will fall back to read_block_full_page(), but these limitations
* should only be hit when page_size != block_size.
@@ -222,8 +222,7 @@ static inline loff_t ext4_readpage_limit(struct inode *inode)
}

int ext4_mpage_readpages(struct address_space *mapping,
- struct list_head *pages, struct page *page,
- unsigned nr_pages, bool is_readahead)
+ struct readahead_control *rac, struct page *page)
{
struct bio *bio = NULL;
sector_t last_block_in_bio = 0;
@@ -241,6 +240,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
int length;
unsigned relative_block = 0;
struct ext4_map_blocks map;
+ unsigned int nr_pages = rac ? readahead_count(rac) : 1;

map.m_pblk = 0;
map.m_lblk = 0;
@@ -251,14 +251,9 @@ int ext4_mpage_readpages(struct address_space *mapping,
int fully_mapped = 1;
unsigned first_hole = blocks_per_page;

- if (pages) {
- page = lru_to_page(pages);
-
+ if (rac) {
+ page = readahead_page(rac);
prefetchw(&page->flags);
- list_del(&page->lru);
- if (add_to_page_cache_lru(page, mapping, page->index,
- readahead_gfp_mask(mapping)))
- goto next_page;
}

if (page_has_buffers(page))
@@ -381,7 +376,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9);
bio->bi_end_io = mpage_end_io;
bio_set_op_attrs(bio, REQ_OP_READ,
- is_readahead ? REQ_RAHEAD : 0);
+ rac ? REQ_RAHEAD : 0);
}

length = first_hole << blkbits;
@@ -406,10 +401,9 @@ int ext4_mpage_readpages(struct address_space *mapping,
else
unlock_page(page);
next_page:
- if (pages)
+ if (rac)
put_page(page);
}
- BUG_ON(pages && !list_empty(pages));
if (bio)
submit_bio(bio);
return 0;
--
2.25.0