erofs-utils: fix compact format for large lcluster sizes

Use compact 4B format for large lcluster sizes if possible or fall
back to the non-compact format.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230601113416.71774-1-hsiangkao@linux.alibaba.com

diff --git a/lib/compress.c b/lib/compress.c
index ae0838c07b05d84cdfc1267b0dda91cfb9250cf9..2e1dfb33d92905ea4aa3583a05b952ab831ef4f0 100644 (file)
--- a/lib/compress.c
+++ b/lib/compress.c
@@ -684,9 +684,19 @@ int z_erofs_convert_to_compacted_format(struct erofs_inode *inode,
 
        if (logical_clusterbits < sbi.blkszbits || sbi.blkszbits < 12)
                return -EINVAL;
-       if (logical_clusterbits > 14)   /* currently not supported */
+       if (logical_clusterbits > 14) {
+               erofs_err("compact format is unsupported for lcluster size %u",
+                         1 << logical_clusterbits);
                return -EOPNOTSUPP;
-       if (logical_clusterbits == 12) {
+       }
+
+       if (inode->z_advise & Z_EROFS_ADVISE_COMPACTED_2B) {
+               if (logical_clusterbits != 12) {
+                       erofs_err("compact 2B is unsupported for lcluster size %u",
+                                 1 << logical_clusterbits);
+                       return -EINVAL;
+               }
+
                compacted_4b_initial = (32 - mpos % 32) / 4;
                if (compacted_4b_initial == 32 / 4)
                        compacted_4b_initial = 0;
@@ -847,8 +857,10 @@ int erofs_write_compressed_file(struct erofs_inode *inode, int fd)
 
        /* initialize per-file compression setting */
        inode->z_advise = 0;
-       if (!cfg.c_legacy_compress) {
-               inode->z_advise |= Z_EROFS_ADVISE_COMPACTED_2B;
+       inode->z_logical_clusterbits = sbi.blkszbits;
+       if (!cfg.c_legacy_compress && inode->z_logical_clusterbits <= 14) {
+               if (inode->z_logical_clusterbits <= 12)
+                       inode->z_advise |= Z_EROFS_ADVISE_COMPACTED_2B;
                inode->datalayout = EROFS_INODE_FLAT_COMPRESSION;
        } else {
                inode->datalayout = EROFS_INODE_FLAT_COMPRESSION_LEGACY;
@@ -875,7 +887,6 @@ int erofs_write_compressed_file(struct erofs_inode *inode, int fd)
        ctx.ccfg = &erofs_ccfg[inode->z_algorithmtype[0]];
        inode->z_algorithmtype[0] = ctx.ccfg[0].algorithmtype;
        inode->z_algorithmtype[1] = 0;
-       inode->z_logical_clusterbits = sbi.blkszbits;
 
        inode->idata_size = 0;
        inode->fragment_size = 0;