Pass consistent param->type to fs_parse()

As it is, vfs_parse_fs_string() makes "foo" and "foo=" indistinguishable;
both get fs_value_is_string for ->type and NULL for ->string.  To make
it even more unpleasant, that combination is impossible to produce with
fsconfig().

Much saner rules would be
        "foo"           => fs_value_is_flag, NULL
	"foo="          => fs_value_is_string, ""
	"foo=bar"       => fs_value_is_string, "bar"
All cases are distinguishable, all results are expressable by fsconfig(),
->has_value checks are much simpler that way (to the point of the field
being useless) and quite a few regressions go away (gfs2 has no business
accepting -o nodebug=, for example).

Partially based upon patches from Miklos.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 2b184563cd32..9fc686be81ca 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -6433,7 +6433,7 @@ static int rbd_parse_options(char *options, struct rbd_parse_opts_ctx *pctx)
 		if (*key) {
 			struct fs_parameter param = {
 				.key	= key,
-				.type	= fs_value_is_string,
+				.type	= fs_value_is_flag,
 			};
 			char *value = strchr(key, '=');
 			size_t v_len = 0;
@@ -6443,14 +6443,11 @@ static int rbd_parse_options(char *options, struct rbd_parse_opts_ctx *pctx)
 					continue;
 				*value++ = 0;
 				v_len = strlen(value);
-			}
-
-
-			if (v_len > 0) {
 				param.string = kmemdup_nul(value, v_len,
 							   GFP_KERNEL);
 				if (!param.string)
 					return -ENOMEM;
+				param.type = fs_value_is_string;
 			}
 			param.size = v_len;