[PATCH 09/12] ext4: Convert from readpages to readahead

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>

Use the new readahead operation in ext4

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
---
 fs/ext4/ext4.h     |  2 +-
 fs/ext4/inode.c    | 24 ++++++++++++------------
 fs/ext4/readpage.c | 20 +++++++-------------
 3 files changed, 20 insertions(+), 26 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f8578caba40d..a035694f3d9b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3216,7 +3216,7 @@ 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,
+				pgoff_t start, struct page *page,
 				unsigned nr_pages, bool is_readahead);
 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 629a25d999f0..4afefc991b01 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3217,7 +3217,7 @@ 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);
 
@@ -3225,23 +3225,23 @@ 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, 0, page, 1, false);
 
 	return ret;
 }
 
-static int
-ext4_readpages(struct file *file, struct address_space *mapping,
-		struct list_head *pages, unsigned nr_pages)
+static unsigned
+ext4_readahead(struct file *file, struct address_space *mapping,
+		pgoff_t start, unsigned nr_pages)
 {
 	struct inode *inode = 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 nr_pages;
 
-	return ext4_mpage_readpages(mapping, pages, NULL, nr_pages, true);
+	ext4_mpage_readpages(mapping, start, NULL, nr_pages, true);
+	return 0;
 }
 
 static void ext4_invalidatepage(struct page *page, unsigned int offset,
@@ -3565,7 +3565,7 @@ 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,
@@ -3582,7 +3582,7 @@ 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,
@@ -3598,7 +3598,7 @@ 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 fef7755300c3..aa3f46a237ef 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.
@@ -209,9 +209,8 @@ static inline loff_t ext4_readpage_limit(struct inode *inode)
 	return i_size_read(inode);
 }
 
-int ext4_mpage_readpages(struct address_space *mapping,
-			 struct list_head *pages, struct page *page,
-			 unsigned nr_pages, bool is_readahead)
+int ext4_mpage_readpages(struct address_space *mapping, pgoff_t start,
+		struct page *page, unsigned nr_pages, bool is_readahead)
 {
 	struct bio *bio = NULL;
 	sector_t last_block_in_bio = 0;
@@ -239,14 +238,10 @@ 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 (is_readahead) {
+			page = readahead_page(mapping, start++);
 
 			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))
@@ -402,10 +397,9 @@ int ext4_mpage_readpages(struct address_space *mapping,
 		else
 			unlock_page(page);
 	next_page:
-		if (pages)
+		if (is_readahead)
 			put_page(page);
 	}
-	BUG_ON(pages && !list_empty(pages));
 	if (bio)
 		submit_bio(bio);
 	return 0;
-- 
2.24.1