erofs: implement fscache-based metadata read

Implement the data plane of reading metadata from primary data blob
over fscache.

Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220425122143.56815-18-jefflexu@linux.alibaba.com
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 14b64d960541169e3c35bb245c2eb8efbb20e58d..bb9c1fd48c1936cc6ddabc26b33cd99bc11d7e8a 100644 (file)
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -6,6 +6,7 @@
  */
 #include "internal.h"
 #include <linux/prefetch.h>
+#include <linux/sched/mm.h>
 #include <linux/dax.h>
 #include <trace/events/erofs.h>
 
@@ -35,14 +36,20 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
        erofs_off_t offset = blknr_to_addr(blkaddr);
        pgoff_t index = offset >> PAGE_SHIFT;
        struct page *page = buf->page;
+       struct folio *folio;
+       unsigned int nofs_flag;
 
        if (!page || page->index != index) {
                erofs_put_metabuf(buf);
-               page = read_cache_page_gfp(mapping, index,
-                               mapping_gfp_constraint(mapping, ~__GFP_FS));
-               if (IS_ERR(page))
-                       return page;
+
+               nofs_flag = memalloc_nofs_save();
+               folio = read_cache_folio(mapping, index, NULL, NULL);
+               memalloc_nofs_restore(nofs_flag);
+               if (IS_ERR(folio))
+                       return folio;
+
                /* should already be PageUptodate, no need to lock page */
+               page = folio_file_page(folio, index);
                buf->page = page;
        }
        if (buf->kmap_type == EROFS_NO_KMAP) {
@@ -63,6 +70,10 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
 void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
                         erofs_blk_t blkaddr, enum erofs_kmap_type type)
 {
+       if (erofs_is_fscache_mode(sb))
+               return erofs_bread(buf, EROFS_SB(sb)->s_fscache->inode,
+                                  blkaddr, type);
+
        return erofs_bread(buf, sb->s_bdev->bd_inode, blkaddr, type);
 }
 

diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index ac02af8cce3ef55b911492207ef3f03c932e94fe..23d7e862eed80429ce03ed939ab2096772b955b5 100644 (file)
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -59,7 +59,32 @@ out:
        return ret;
 }
 
+static int erofs_fscache_meta_readpage(struct file *data, struct page *page)
+{
+       int ret;
+       struct folio *folio = page_folio(page);
+       struct super_block *sb = folio_mapping(folio)->host->i_sb;
+       struct erofs_map_dev mdev = {
+               .m_deviceid = 0,
+               .m_pa = folio_pos(folio),
+       };
+
+       ret = erofs_map_dev(sb, &mdev);
+       if (ret)
+               goto out;
+
+       ret = erofs_fscache_read_folios(mdev.m_fscache->cookie,
+                       folio_mapping(folio), folio_pos(folio),
+                       folio_size(folio), mdev.m_pa);
+       if (!ret)
+               folio_mark_uptodate(folio);
+out:
+       folio_unlock(folio);
+       return ret;
+}
+
 static const struct address_space_operations erofs_fscache_meta_aops = {
+       .readpage = erofs_fscache_meta_readpage,
 };
 
 int erofs_fscache_register_cookie(struct super_block *sb,