f2fs: expose f2fs_mpage_readpages

This patch implements f2fs_mpage_readpages for further optimization on
encryption support.

The basic code was taken from fs/mpage.c, and changed to be simple by adjusting
that block_size is equal to page_size in f2fs.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 154 insertions, 3 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index aa3c079ffd94..2a3a9cd008da 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -18,6 +18,7 @@
 #include <linux/bio.h>
 #include <linux/prefetch.h>
 #include <linux/uio.h>
+#include <linux/cleancache.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -47,6 +48,30 @@ static void f2fs_read_end_io(struct bio *bio, int err)
         bio_put(bio);
 }
 
+/*
+ * I/O completion handler for multipage BIOs.
+ * copied from fs/mpage.c
+ */
+static void mpage_end_io(struct bio *bio, int err)
+{
+        struct bio_vec *bv;
+        int i;
+
+        bio_for_each_segment_all(bv, bio, i) {
+                struct page *page = bv->bv_page;
+
+                if (!err) {
+                        SetPageUptodate(page);
+                } else {
+                        ClearPageUptodate(page);
+                        SetPageError(page);
+                }
+                unlock_page(page);
+        }
+
+        bio_put(bio);
+}
+
 static void f2fs_write_end_io(struct bio *bio, int err)
 {
         struct f2fs_sb_info *sbi = bio->bi_private;
@@ -1349,6 +1374,133 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                                 start, len, get_data_block_fiemap);
 }
 
+/*
+ * This function was originally taken from fs/mpage.c, and customized for f2fs.
+ * Major change was from block_size == page_size in f2fs by default.
+ */
+static int f2fs_mpage_readpages(struct address_space *mapping,
+                        struct list_head *pages, struct page *page,
+                        unsigned nr_pages)
+{
+        struct bio *bio = NULL;
+        unsigned page_idx;
+        sector_t last_block_in_bio = 0;
+        struct inode *inode = mapping->host;
+        const unsigned blkbits = inode->i_blkbits;
+        const unsigned blocksize = 1 << blkbits;
+        sector_t block_in_file;
+        sector_t last_block;
+        sector_t last_block_in_file;
+        sector_t block_nr;
+        struct block_device *bdev = inode->i_sb->s_bdev;
+        struct f2fs_map_blocks map;
+
+        map.m_pblk = 0;
+        map.m_lblk = 0;
+        map.m_len = 0;
+        map.m_flags = 0;
+
+        for (page_idx = 0; nr_pages; page_idx++, nr_pages--) {
+
+                prefetchw(&page->flags);
+                if (pages) {
+                        page = list_entry(pages->prev, struct page, lru);
+                        list_del(&page->lru);
+                        if (add_to_page_cache_lru(page, mapping,
+                                                  page->index, GFP_KERNEL))
+                                goto next_page;
+                }
+
+                block_in_file = (sector_t)page->index;
+                last_block = block_in_file + nr_pages;
+                last_block_in_file = (i_size_read(inode) + blocksize - 1) >>
+                                                                blkbits;
+                if (last_block > last_block_in_file)
+                        last_block = last_block_in_file;
+
+                /*
+                 * Map blocks using the previous result first.
+                 */
+                if ((map.m_flags & F2FS_MAP_MAPPED) &&
+                                block_in_file > map.m_lblk &&
+                                block_in_file < (map.m_lblk + map.m_len))
+                        goto got_it;
+
+                /*
+                 * Then do more f2fs_map_blocks() calls until we are
+                 * done with this page.
+                 */
+                map.m_flags = 0;
+
+                if (block_in_file < last_block) {
+                        map.m_lblk = block_in_file;
+                        map.m_len = last_block - block_in_file;
+
+                        if (f2fs_map_blocks(inode, &map, 0, false))
+                                goto set_error_page;
+                }
+got_it:
+                if ((map.m_flags & F2FS_MAP_MAPPED)) {
+                        block_nr = map.m_pblk + block_in_file - map.m_lblk;
+                        SetPageMappedToDisk(page);
+
+                        if (!PageUptodate(page) && !cleancache_get_page(page)) {
+                                SetPageUptodate(page);
+                                goto confused;
+                        }
+                } else {
+                        zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+                        SetPageUptodate(page);
+                        unlock_page(page);
+                        goto next_page;
+                }
+
+                /*
+                 * This page will go to BIO.  Do we need to send this
+                 * BIO off first?
+                 */
+                if (bio && (last_block_in_bio != block_nr - 1)) {
+submit_and_realloc:
+                        submit_bio(READ, bio);
+                        bio = NULL;
+                }
+                if (bio == NULL) {
+                        bio = bio_alloc(GFP_KERNEL,
+                                min_t(int, nr_pages, bio_get_nr_vecs(bdev)));
+                        if (!bio)
+                                goto set_error_page;
+                        bio->bi_bdev = bdev;
+                        bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(block_nr);
+                        bio->bi_end_io = mpage_end_io;
+                        bio->bi_private = NULL;
+                }
+
+                if (bio_add_page(bio, page, blocksize, 0) < blocksize)
+                        goto submit_and_realloc;
+
+                last_block_in_bio = block_nr;
+                goto next_page;
+set_error_page:
+                SetPageError(page);
+                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
+                unlock_page(page);
+                goto next_page;
+confused:
+                if (bio) {
+                        submit_bio(READ, bio);
+                        bio = NULL;
+                }
+                unlock_page(page);
+next_page:
+                if (pages)
+                        page_cache_release(page);
+        }
+        BUG_ON(pages && !list_empty(pages));
+        if (bio)
+                submit_bio(READ, bio);
+        return 0;
+}
+
 static int f2fs_read_data_page(struct file *file, struct page *page)
 {
         struct inode *inode = page->mapping->host;
@@ -1360,8 +1512,7 @@ static int f2fs_read_data_page(struct file *file, struct page *page)
         if (f2fs_has_inline_data(inode))
                 ret = f2fs_read_inline_data(inode, page);
         if (ret == -EAGAIN)
-                ret = mpage_readpage(page, get_data_block);
-
+                ret = f2fs_mpage_readpages(page->mapping, NULL, page, 1);
         return ret;
 }
 
@@ -1375,7 +1526,7 @@ static int f2fs_read_data_pages(struct file *file,
         if (f2fs_has_inline_data(inode))
                 return 0;
 
-        return mpage_readpages(mapping, pages, nr_pages, get_data_block);
+        return f2fs_mpage_readpages(mapping, pages, NULL, nr_pages);
 }
 
 int do_write_data_page(struct page *page, struct f2fs_io_info *fio)