bcachefs: BCH_IOCTL_QUERY_ACCOUNTING

Add a new ioctl that can return the new accounting counter types; it
takes as input a bitmask of accounting types to return.

This will be used for returning e.g. compression accounting and
rebalance_work accounting.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs_ioctl.h

@@ -5,6 +5,7 @@
 #include <linux/uuid.h>
 #include <asm/ioctl.h>
 #include "bcachefs_format.h"
+#include "bkey_types.h"
 
 /*
  * Flags common to multiple ioctls:
@@ -85,6 +86,7 @@ struct bch_ioctl_incremental {
 
 #define BCH_IOCTL_FSCK_OFFLINE	_IOW(0xbc,	19,  struct bch_ioctl_fsck_offline)
 #define BCH_IOCTL_FSCK_ONLINE	_IOW(0xbc,	20,  struct bch_ioctl_fsck_online)
+#define BCH_IOCTL_QUERY_ACCOUNTING _IOW(0xbc,	21,  struct bch_ioctl_query_accounting)
 
 /* ioctl below act on a particular file, not the filesystem as a whole: */
 
@@ -262,6 +264,7 @@ replicas_usage_next(struct bch_replicas_usage *u)
 	return (void *) u + replicas_usage_bytes(u);
 }
 
+/* Obsolete */
 /*
  * BCH_IOCTL_FS_USAGE: query filesystem disk space usage
  *
@@ -287,6 +290,7 @@ struct bch_ioctl_fs_usage {
 	struct bch_replicas_usage replicas[];
 };
 
+/* Obsolete */
 /*
  * BCH_IOCTL_DEV_USAGE: query device disk space usage
  *
@@ -311,6 +315,7 @@ struct bch_ioctl_dev_usage {
 	}			d[10];
 };
 
+/* Obsolete */
 struct bch_ioctl_dev_usage_v2 {
 	__u64			dev;
 	__u32			flags;
@@ -414,4 +419,28 @@ struct bch_ioctl_fsck_online {
 	__u64			opts;		/* string */
 };
 
+/*
+ * BCH_IOCTL_QUERY_ACCOUNTING: query filesystem disk accounting
+ *
+ * Returns disk space usage broken out by data type, number of replicas, and
+ * by component device
+ *
+ * @replica_entries_bytes - size, in bytes, allocated for replica usage entries
+ *
+ * On success, @replica_entries_bytes will be changed to indicate the number of
+ * bytes actually used.
+ *
+ * Returns -ERANGE if @replica_entries_bytes was too small
+ */
+struct bch_ioctl_query_accounting {
+	__u64			capacity;
+	__u64			used;
+	__u64			online_reserved;
+
+	__u32			accounting_u64s; /* input parameter */
+	__u32			accounting_types_mask; /* input parameter */
+
+	struct bkey_i_accounting accounting[];
+};
+
 #endif /* _BCACHEFS_IOCTL_H */

fs/bcachefs/chardev.c

@@ -557,6 +557,34 @@ static long bch2_ioctl_fs_usage(struct bch_fs *c,
 	return ret;
 }
 
+static long bch2_ioctl_query_accounting(struct bch_fs *c,
+			struct bch_ioctl_query_accounting __user *user_arg)
+{
+	struct bch_ioctl_query_accounting arg;
+	darray_char accounting = {};
+	int ret = 0;
+
+	if (!test_bit(BCH_FS_started, &c->flags))
+		return -EINVAL;
+
+	ret   = copy_from_user_errcode(&arg, user_arg, sizeof(arg)) ?:
+		bch2_fs_accounting_read(c, &accounting, arg.accounting_types_mask) ?:
+		(arg.accounting_u64s * sizeof(u64) < accounting.nr ? -ERANGE : 0) ?:
+		copy_to_user_errcode(&user_arg->accounting, accounting.data, accounting.nr);
+	if (ret)
+		goto err;
+
+	arg.capacity		= c->capacity;
+	arg.used		= bch2_fs_usage_read_short(c).used;
+	arg.online_reserved	= percpu_u64_get(c->online_reserved);
+	arg.accounting_u64s	= accounting.nr / sizeof(u64);
+
+	ret = copy_to_user_errcode(user_arg, &arg, sizeof(arg));
+err:
+	darray_exit(&accounting);
+	return ret;
+}
+
 /* obsolete, didn't allow for new data types: */
 static long bch2_ioctl_dev_usage(struct bch_fs *c,
 				 struct bch_ioctl_dev_usage __user *user_arg)
@@ -910,6 +938,8 @@ long bch2_fs_ioctl(struct bch_fs *c, unsigned cmd, void __user *arg)
 		BCH_IOCTL(disk_resize_journal, struct bch_ioctl_disk_resize_journal);
 	case BCH_IOCTL_FSCK_ONLINE:
 		BCH_IOCTL(fsck_online, struct bch_ioctl_fsck_online);
+	case BCH_IOCTL_QUERY_ACCOUNTING:
+		return bch2_ioctl_query_accounting(c, arg);
 	default:
 		return -ENOTTY;
 	}

fs/bcachefs/disk_accounting.c

@@ -315,6 +315,44 @@ int bch2_fs_replicas_usage_read(struct bch_fs *c, darray_char *usage)
 	return ret;
 }
 
+int bch2_fs_accounting_read(struct bch_fs *c, darray_char *out_buf, unsigned accounting_types_mask)
+{
+
+	struct bch_accounting_mem *acc = &c->accounting[0];
+	int ret = 0;
+
+	darray_init(out_buf);
+
+	percpu_down_read(&c->mark_lock);
+	darray_for_each(acc->k, i) {
+		struct disk_accounting_pos a_p;
+		bpos_to_disk_accounting_pos(&a_p, i->pos);
+
+		if (!(accounting_types_mask & BIT(a_p.type)))
+			continue;
+
+		ret = darray_make_room(out_buf, sizeof(struct bkey_i_accounting) +
+				       sizeof(u64) * i->nr_counters);
+		if (ret)
+			break;
+
+		struct bkey_i_accounting *a_out =
+			bkey_accounting_init((void *) &darray_top(*out_buf));
+		set_bkey_val_u64s(&a_out->k, i->nr_counters);
+		a_out->k.p = i->pos;
+		bch2_accounting_mem_read(c, i->pos, a_out->v.d, i->nr_counters);
+
+		if (!bch2_accounting_key_is_zero(accounting_i_to_s_c(a_out)))
+			out_buf->nr += bkey_bytes(&a_out->k);
+	}
+
+	percpu_up_read(&c->mark_lock);
+
+	if (ret)
+		darray_exit(out_buf);
+	return ret;
+}
+
 void bch2_fs_accounting_to_text(struct printbuf *out, struct bch_fs *c)
 {
 	struct bch_accounting_mem *acc = &c->accounting[0];

fs/bcachefs/disk_accounting.h

@@ -193,6 +193,7 @@ static inline void bch2_accounting_mem_read(struct bch_fs *c, struct bpos p,
 }
 
 int bch2_fs_replicas_usage_read(struct bch_fs *, darray_char *);
+int bch2_fs_accounting_read(struct bch_fs *, darray_char *, unsigned);
 void bch2_fs_accounting_to_text(struct printbuf *, struct bch_fs *);
 
 int bch2_accounting_gc_done(struct bch_fs *);