bcachefs: Add flags to indicate if inode opts were inherited or explicitly set

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs_format.h

@@ -714,7 +714,8 @@ struct bch_inode_generation {
 	x(bi_promote_target,		16)	\
 	x(bi_foreground_target,		16)	\
 	x(bi_background_target,		16)	\
-	x(bi_erasure_code,		16)
+	x(bi_erasure_code,		16)	\
+	x(bi_fields_set,		16)
 
 /* subset of BCH_INODE_FIELDS */
 #define BCH_INODE_OPTS()			\
@@ -728,6 +729,14 @@ struct bch_inode_generation {
 	x(background_target,		16)	\
 	x(erasure_code,			16)
 
+enum inode_opt_id {
+#define x(name, ...)				\
+	Inode_opt_##name,
+	BCH_INODE_OPTS()
+#undef  x
+	Inode_opt_nr,
+};
+
 enum {
 	/*
 	 * User flags (get/settable with FS_IOC_*FLAGS, correspond to FS_*_FL

fs/bcachefs/fs-ioctl.c

@@ -122,7 +122,14 @@ static int fssetxattr_inode_update_fn(struct bch_inode_info *inode,
 {
 	struct flags_set *s = p;
 
-	bi->bi_project = s->projid;
+	if (s->projid != bi->bi_project) {
+		if (s->projid)
+			bi->bi_fields_set |= 1U << Inode_opt_project;
+		else
+			bi->bi_fields_set &= ~(1U << Inode_opt_project);
+
+		bi->bi_project = s->projid;
+	}
 
 	return bch2_inode_flags_set(inode, bi, p);
 }

fs/bcachefs/inode.h

@@ -80,6 +80,10 @@ static inline void __bch2_inode_opt_set(struct bch_inode_unpacked *inode,
 #define x(_name, ...)					\
 	case Opt_##_name:						\
 		inode->bi_##_name = v;					\
+		if (v)							\
+			inode->bi_fields_set |= 1U << Inode_opt_##_name;\
+		else							\
+			inode->bi_fields_set &= ~(1U << Inode_opt_##_name);\
 		break;
 	BCH_INODE_OPTS()
 #undef x