1 files changed, 59 insertions, 3 deletions

diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
index 332ec5f74002..e75edc8f1753 100644
--- a/fs/erofs/decompressor.c
+++ b/fs/erofs/decompressor.c
@@ -24,11 +24,11 @@ struct z_erofs_lz4_decompress_ctx {
 	unsigned int oend;
 };
 
-int z_erofs_load_lz4_config(struct super_block *sb,
-			    struct erofs_super_block *dsb,
-			    struct z_erofs_lz4_cfgs *lz4, int size)
+static int z_erofs_load_lz4_config(struct super_block *sb,
+			    struct erofs_super_block *dsb, void *data, int size)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	struct z_erofs_lz4_cfgs *lz4 = data;
 	u16 distance;
 
 	if (lz4) {
@@ -370,19 +370,75 @@ const struct z_erofs_decompressor erofs_decompressors[] = {
 		.name = "interlaced"
 	},
 	[Z_EROFS_COMPRESSION_LZ4] = {
+		.config = z_erofs_load_lz4_config,
 		.decompress = z_erofs_lz4_decompress,
 		.name = "lz4"
 	},
 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 	[Z_EROFS_COMPRESSION_LZMA] = {
+		.config = z_erofs_load_lzma_config,
 		.decompress = z_erofs_lzma_decompress,
 		.name = "lzma"
 	},
 #endif
 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 	[Z_EROFS_COMPRESSION_DEFLATE] = {
+		.config = z_erofs_load_deflate_config,
 		.decompress = z_erofs_deflate_decompress,
 		.name = "deflate"
 	},
 #endif
 };
+
+int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
+{
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+	unsigned int algs, alg;
+	erofs_off_t offset;
+	int size, ret = 0;
+
+	if (!erofs_sb_has_compr_cfgs(sbi)) {
+		sbi->available_compr_algs = Z_EROFS_COMPRESSION_LZ4;
+		return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
+	}
+
+	sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
+	if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
+		erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
+			  sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
+		return -EOPNOTSUPP;
+	}
+
+	erofs_init_metabuf(&buf, sb);
+	offset = EROFS_SUPER_OFFSET + sbi->sb_size;
+	alg = 0;
+	for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
+		void *data;
+
+		if (!(algs & 1))
+			continue;
+
+		data = erofs_read_metadata(sb, &buf, &offset, &size);
+		if (IS_ERR(data)) {
+			ret = PTR_ERR(data);
+			break;
+		}
+
+		if (alg >= ARRAY_SIZE(erofs_decompressors) ||
+		    !erofs_decompressors[alg].config) {
+			erofs_err(sb, "algorithm %d isn't enabled on this kernel",
+				  alg);
+			ret = -EOPNOTSUPP;
+		} else {
+			ret = erofs_decompressors[alg].config(sb,
+					dsb, data, size);
+		}
+
+		kfree(data);
+		if (ret)
+			break;
+	}
+	erofs_put_metabuf(&buf);
+	return ret;
+}