[PATCH v2] bcachefs: early return for negative values when parsing BCH_OPT_UINT

[Integral <integral@archlinuxcn.org>]

Currently, when passing a negative integer as argument, the error
message is "too big" due to casting to an unsigned integer:

    > bcachefs format --block_size=-1 bcachefs.img
    invalid option: block_size: too big (max 65536)

When negative value in argument detected, return early before
calling bch2_opt_validate().

A new error code `BCH_ERR_option_negative` is added.

Signed-off-by: Integral <integral@archlinuxcn.org>
---
 fs/bcachefs/errcode.h |  1 +
 fs/bcachefs/opts.c    | 12 +++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index c4eb0ed9838d..e3c85288fd6d 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -213,6 +213,7 @@
 	x(EINVAL,			inode_unpack_error)			\
 	x(EINVAL,			varint_decode_error)			\
 	x(EINVAL,			erasure_coding_found_btree_node)	\
+	x(EINVAL,			option_negative)			\
 	x(EOPNOTSUPP,			may_not_use_incompat_feature)		\
 	x(EROFS,			erofs_trans_commit)			\
 	x(EROFS,			erofs_no_writes)			\
diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
index e64777ecf44f..1bf2580ab735 100644
--- a/fs/bcachefs/opts.c
+++ b/fs/bcachefs/opts.c
@@ -360,9 +360,15 @@ int bch2_opt_parse(struct bch_fs *c,
 			return -EINVAL;
 		}
 
-		ret = opt->flags & OPT_HUMAN_READABLE
-			? bch2_strtou64_h(val, res)
-			: kstrtou64(val, 10, res);
+		if (*val != '-') {
+			ret = opt->flags & OPT_HUMAN_READABLE
+			    ? bch2_strtou64_h(val, res)
+			    : kstrtou64(val, 10, res);
+		} else {
+			prt_printf(err, "%s: must be a non-negative number", opt->attr.name);
+			return -BCH_ERR_option_negative;
+		}
+
 		if (ret < 0) {
 			if (err)
 				prt_printf(err, "%s: must be a number",
-- 
2.49.0