Merge pull request #58 from alexlarsson/dentry-size

Limit in-memory use for inodes

fuzzing/main.c

@@ -29,10 +29,11 @@ bool iter_cb(void *private, const char *name, int namelen, u64 ino, unsigned int
 	struct cfs_xattr_header_s *xattrs;
 	struct cfs_inode_s *s_ino;
 	struct cfs_inode_s buffer;
-	struct cfs_dir_s *dir;
+	struct cfs_dir_data_s dirdata;
 	loff_t out_size;
 	char *out_path;
 	char *payload;
+	int res;
 
         if (test_ctx->dirs_left == 0)
 		return false;
@@ -67,11 +68,9 @@ bool iter_cb(void *private, const char *name, int namelen, u64 ino, unsigned int
 		free(xattrs);
 	}
 
-	dir = cfs_get_dir(test_ctx->ctx, s_ino, ino);
-	if (!IS_ERR(dir)) {
-		cfs_dir_get_link_count(dir);
-		cfs_dir_iterate(dir, 0, iter_cb, test_ctx);
-		free(dir);
+	res = cfs_get_dir_data(test_ctx->ctx, s_ino, ino, &dirdata);
+	if (res >= 0) {
+		cfs_dir_iterate(test_ctx->ctx, s_ino->payload_length, ino, &dirdata, 0, iter_cb, test_ctx);
 	}
 	return true;
 }
@@ -129,12 +128,13 @@ int LLVMFuzzerTestOneInput(uint8_t *buf, size_t len)
 	struct cfs_context_s *ctx;
 	struct cfs_inode_s ino_buf;
 	struct cfs_inode_s *ino;
-	struct cfs_dir_s *dir;
+	struct cfs_dir_data_s dirdata;
 	char name[NAME_MAX];
 	char value[256];
 	u64 index;
 	u64 off;
 	int fd;
+	int res;
 
 	cfs_digest_from_payload((const char *) buf, len, digest_out);
 
@@ -156,16 +156,12 @@ int LLVMFuzzerTestOneInput(uint8_t *buf, size_t len)
 	for (off = 0; off < 1000; off++) {
 		ino = cfs_get_ino_index(ctx, off, &ino_buf);
 		if (!IS_ERR(ino)) {
-			struct cfs_dir_s *dir;
-
-			dir = cfs_get_dir(ctx, ino, off);
-			if (!IS_ERR(dir)) {
-				cfs_dir_get_link_count(dir);
-	                        if (dir) {
-					cfs_dir_lookup(dir, name, strlen(name), &index);
-					cfs_dir_iterate(dir, 0, iter_cb, &test_ctx);
-                                }
-				free(dir);
+			res = cfs_get_dir_data(ctx, ino, off, &dirdata);
+			if (res >= 0) {
+				if ((ino->st_mode & S_IFMT) == S_IFDIR) {
+					cfs_dir_lookup(ctx, ino->payload_length, off, &dirdata, name, strlen(name), &index);
+					cfs_dir_iterate(ctx, ino->payload_length, off, &dirdata, 0, iter_cb, &test_ctx);
+				}
 			}
 		}
 	}
@@ -178,12 +174,11 @@ int LLVMFuzzerTestOneInput(uint8_t *buf, size_t len)
 	if (!IS_ERR(xattrs))
 		free(xattrs);
 
-	dir = cfs_get_dir(ctx, ino, index);
-	if (IS_ERR(dir))
+	res = cfs_get_dir_data(ctx, ino, index, &dirdata);
+	if (res < 0)
 		goto cleanup;
 
-	cfs_dir_iterate(dir, 0, iter_cb, &test_ctx);
-	free(dir);
+	cfs_dir_iterate(ctx, ino->payload_length, index, &dirdata, 0, iter_cb, &test_ctx);
 
 cleanup:
 	cfs_destroy_ctx(ctx);

kernel/Documentation/filesystems/composefs.rst

@@ -141,7 +141,8 @@ payload length attribute gives the size of the variable chunk.
 
 The inode variable chunk contains different things depending on the
 file type.  For regular files it is the backing filename. For symlinks
-it is the symlink target. For directories it is a list of dentries.
+it is the symlink target. For directories it is a list of dentries,
+stored in chunks of maximum 4k.
 
 The variable data section is stored after the inode section, and you
 can find it from the offset in the header. It contains Xattrs data