erofs: allow partially filled compressed bvecs

In order to reduce memory footprints even further, let's allow
partially filled compressed bvecs for readahead to bail out later.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231221062341.23901-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 8264936b86123d61a3d08ef464eb8752fc1eaadb..692c0c39be638dc4b2454b63968a0467043ddc7a 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1202,34 +1202,27 @@ static int z_erofs_parse_in_bvecs(struct z_erofs_decompress_backend *be,
                struct z_erofs_bvec *bvec = &pcl->compressed_bvecs[i];
                struct page *page = bvec->page;
 
-               /* compressed pages ought to be present before decompressing */
+               /* compressed data ought to be valid before decompressing */
                if (!page) {
-                       DBG_BUGON(1);
+                       err = -EIO;
                        continue;
                }
                be->compressed_pages[i] = page;
 
-               if (z_erofs_is_inline_pcluster(pcl)) {
+               if (z_erofs_is_inline_pcluster(pcl) ||
+                   erofs_page_is_managed(EROFS_SB(be->sb), page)) {
                        if (!PageUptodate(page))
                                err = -EIO;
                        continue;
                }
 
                DBG_BUGON(z_erofs_page_is_invalidated(page));
-               if (!z_erofs_is_shortlived_page(page)) {
-                       if (erofs_page_is_managed(EROFS_SB(be->sb), page)) {
-                               if (!PageUptodate(page))
-                                       err = -EIO;
-                               continue;
-                       }
-                       z_erofs_do_decompressed_bvec(be, bvec);
-                       *overlapped = true;
-               }
+               if (z_erofs_is_shortlived_page(page))
+                       continue;
+               z_erofs_do_decompressed_bvec(be, bvec);
+               *overlapped = true;
        }
-
-       if (err)
-               return err;
-       return 0;
+       return err;
 }
 
 static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
@@ -1238,7 +1231,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
        struct erofs_sb_info *const sbi = EROFS_SB(be->sb);
        struct z_erofs_pcluster *pcl = be->pcl;
        unsigned int pclusterpages = z_erofs_pclusterpages(pcl);
-       const struct z_erofs_decompressor *decompressor =
+       const struct z_erofs_decompressor *decomp =
                                &erofs_decompressors[pcl->algorithmformat];
        int i, err2;
        struct page *page;
@@ -1274,10 +1267,8 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
        err2 = z_erofs_parse_in_bvecs(be, &overlapped);
        if (err2)
                err = err2;
-       if (err)
-               goto out;
-
-       err = decompressor->decompress(&(struct z_erofs_decompress_req) {
+       if (!err)
+               err = decomp->decompress(&(struct z_erofs_decompress_req) {
                                        .sb = be->sb,
                                        .in = be->compressed_pages,
                                        .out = be->decompressed_pages,
@@ -1291,7 +1282,6 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
                                        .fillgaps = pcl->multibases,
                                 }, be->pagepool);
 
-out:
        /* must handle all compressed pages before actual file pages */
        if (z_erofs_is_inline_pcluster(pcl)) {
                page = pcl->compressed_bvecs[0].page;
@@ -1302,7 +1292,7 @@ out:
                        /* consider shortlived pages added when decompressing */
                        page = be->compressed_pages[i];
 
-                       if (erofs_page_is_managed(sbi, page))
+                       if (!page || erofs_page_is_managed(sbi, page))
                                continue;
                        (void)z_erofs_put_shortlivedpage(be->pagepool, page);
                        WRITE_ONCE(pcl->compressed_bvecs[i].page, NULL);