erofs: support multi-page folios for erofs_bread()

If the requested page is part of the previous multi-page folio, there
is no need to call read_mapping_folio() again.

Also, get rid of the remaining one of page->index [1] in our codebase.

[1] https://lore.kernel.org/r/Zp8fgUSIBGQ1TN0D@casper.infradead.org

Cc: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240723073024.875290-1-hsiangkao@linux.alibaba.com

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 8be60797ea2fffdd91a27a28026a81a90c97e2e1..1b7eba38ba1e42998ce27d23545beb1c99671a9a 100644 (file)
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -21,38 +21,32 @@ void erofs_put_metabuf(struct erofs_buf *buf)
        if (!buf->page)
                return;
        erofs_unmap_metabuf(buf);
-       put_page(buf->page);
+       folio_put(page_folio(buf->page));
        buf->page = NULL;
 }
 
-/*
- * Derive the block size from inode->i_blkbits to make compatible with
- * anonymous inode in fscache mode.
- */
 void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
                  enum erofs_kmap_type type)
 {
        pgoff_t index = offset >> PAGE_SHIFT;
-       struct page *page = buf->page;
-       struct folio *folio;
-       unsigned int nofs_flag;
+       struct folio *folio = NULL;
 
-       if (!page || page->index != index) {
+       if (buf->page) {
+               folio = page_folio(buf->page);
+               if (folio_file_page(folio, index) != buf->page)
+                       erofs_unmap_metabuf(buf);
+       }
+       if (!folio || !folio_contains(folio, index)) {
                erofs_put_metabuf(buf);
-
-               nofs_flag = memalloc_nofs_save();
-               folio = read_cache_folio(buf->mapping, index, NULL, NULL);
-               memalloc_nofs_restore(nofs_flag);
+               folio = read_mapping_folio(buf->mapping, index, NULL);
                if (IS_ERR(folio))
                        return folio;
-
-               /* should already be PageUptodate, no need to lock page */
-               page = folio_file_page(folio, index);
-               buf->page = page;
        }
+       buf->page = folio_file_page(folio, index);
+
        if (buf->kmap_type == EROFS_NO_KMAP) {
                if (type == EROFS_KMAP)
-                       buf->base = kmap_local_page(page);
+                       buf->base = kmap_local_page(buf->page);
                buf->kmap_type = type;
        } else if (buf->kmap_type != type) {
                DBG_BUGON(1);