erofs: improve Zstd, LZMA and DEFLATE error strings

Enable better, more detailed, and unique error reporting.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Author: hsiangkao

fs/erofs/decompressor_deflate.c

@@ -97,12 +97,13 @@ static int z_erofs_load_deflate_config(struct super_block *sb,
 	return -ENOMEM;
 }
 
-static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
-					struct page **pgpl)
+static const char *__z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
+						struct page **pgpl)
 {
 	struct super_block *sb = rq->sb;
 	struct z_erofs_stream_dctx dctx = { .rq = rq, .no = -1, .ni = 0 };
 	struct z_erofs_deflate *strm;
+	const char *reason = NULL;
 	int zerr, err;
 
 	/* 1. get the exact DEFLATE compressed size */
@@ -111,7 +112,7 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 			min(rq->inputsize, sb->s_blocksize - rq->pageofs_in));
 	if (err) {
 		kunmap_local(dctx.kin);
-		return err;
+		return ERR_PTR(err);
 	}
 
 	/* 2. get an available DEFLATE context */
@@ -129,7 +130,7 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	zerr = zlib_inflateInit2(&strm->z, -MAX_WBITS);
 	if (zerr != Z_OK) {
-		err = -EIO;
+		err = -EINVAL;
 		goto failed_zinit;
 	}
 
@@ -157,6 +158,9 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 				break;
 			if (zerr == Z_STREAM_END && !rq->outputsize)
 				break;
+			reason = (zerr == Z_DATA_ERROR ?
+				"corrupted compressed data" :
+				"unexpected end of stream");
 			err = -EFSCORRUPTED;
 			break;
 		}
@@ -173,7 +177,7 @@ static int __z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 	z_erofs_deflate_head = strm;
 	spin_unlock(&z_erofs_deflate_lock);
 	wake_up(&z_erofs_deflate_wq);
-	return err;
+	return reason ?: ERR_PTR(err);
 }
 
 static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
@@ -189,7 +193,7 @@ static const char *z_erofs_deflate_decompress(struct z_erofs_decompress_req *rq,
 
 	}
 #endif
-	return ERR_PTR(__z_erofs_deflate_decompress(rq, pgpl));
+	return __z_erofs_deflate_decompress(rq, pgpl);
 }
 
 const struct z_erofs_decompressor z_erofs_deflate_decomp = {

fs/erofs/decompressor_lzma.c

@@ -154,6 +154,7 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 	struct xz_buf buf = {};
 	struct z_erofs_lzma *strm;
 	enum xz_ret xz_err;
+	const char *reason = NULL;
 	int err;
 
 	/* 1. get the exact LZMA compressed size */
@@ -207,7 +208,9 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 		if (xz_err != XZ_OK) {
 			if (xz_err == XZ_STREAM_END && !rq->outputsize)
 				break;
-			err = -EFSCORRUPTED;
+			reason = (xz_err == XZ_DATA_ERROR ?
+				"corrupted compressed data" :
+				"unexpected end of stream");
 			break;
 		}
 	} while (1);
@@ -221,7 +224,7 @@ static const char *z_erofs_lzma_decompress(struct z_erofs_decompress_req *rq,
 	z_erofs_lzma_head = strm;
 	spin_unlock(&z_erofs_lzma_lock);
 	wake_up(&z_erofs_lzma_wq);
-	return ERR_PTR(err);
+	return reason ?: ERR_PTR(err);
 }
 
 const struct z_erofs_decompressor z_erofs_lzma_decomp = {

fs/erofs/decompressor_zstd.c

@@ -143,6 +143,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	zstd_in_buffer in_buf = { NULL, 0, 0 };
 	zstd_out_buffer out_buf = { NULL, 0, 0 };
 	struct z_erofs_zstd *strm;
+	const char *reason = NULL;
 	zstd_dstream *stream;
 	int zerr, err;
 
@@ -161,7 +162,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	/* 3. multi-call decompress */
 	stream = zstd_init_dstream(z_erofs_zstd_max_dictsize, strm->wksp, strm->wkspsz);
 	if (!stream) {
-		err = -EIO;
+		err = -ENOMEM;
 		goto failed_zinit;
 	}
 
@@ -191,7 +192,8 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 		if (zstd_is_error(zerr) ||
 		    ((rq->outputsize + dctx.avail_out) && (!zerr || (zerr > 0 &&
 				!(rq->inputsize + in_buf.size - in_buf.pos))))) {
-			err = -EFSCORRUPTED;
+			reason = zstd_is_error(zerr) ? zstd_get_error_name(zerr) :
+					"unexpected end of stream";
 			break;
 		}
 	} while (rq->outputsize + dctx.avail_out);
@@ -206,7 +208,7 @@ static const char *z_erofs_zstd_decompress(struct z_erofs_decompress_req *rq,
 	z_erofs_zstd_head = strm;
 	spin_unlock(&z_erofs_zstd_lock);
 	wake_up(&z_erofs_zstd_wq);
-	return ERR_PTR(err);
+	return reason ?: ERR_PTR(err);
 }
 
 const struct z_erofs_decompressor z_erofs_zstd_decomp = {