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

Use the new readahead operation in ext4

Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
Reviewed-by: William Kucharski <william.kuchar...@oracle.com>
Reviewed-by: Eric Biggers <ebigg...@google.com>
---
 fs/ext4/ext4.h     |  3 +--
 fs/ext4/inode.c    | 21 +++++++++------------
 fs/ext4/readpage.c | 22 ++++++++--------------
 3 files changed, 18 insertions(+), 28 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 91eb4381cae5..9f2d3cd1df81 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3317,8 +3317,7 @@ 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 e416096fc081..fafd2862d7cd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3224,23 +3224,20 @@ 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,
@@ -3605,7 +3602,7 @@ 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,
@@ -3622,7 +3619,7 @@ 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,
@@ -3638,7 +3635,7 @@ 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..66275f25235d 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_readpages() 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;
-- 
2.25.1


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