bcachefs: Add an ioctl for resizing journal on a device

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

fs/bcachefs/bcachefs_ioctl.h

@@ -73,6 +73,7 @@ struct bch_ioctl_incremental {
 #define BCH_IOCTL_READ_SUPER	_IOW(0xbc,	12, struct bch_ioctl_read_super)
 #define BCH_IOCTL_DISK_GET_IDX	_IOW(0xbc,	13,  struct bch_ioctl_disk_get_idx)
 #define BCH_IOCTL_DISK_RESIZE	_IOW(0xbc,	14,  struct bch_ioctl_disk_resize)
+#define BCH_IOCTL_DISK_RESIZE_JOURNAL _IOW(0xbc,15,  struct bch_ioctl_disk_resize_journal)
 
 /* ioctl below act on a particular file, not the filesystem as a whole: */
 
@@ -329,4 +330,17 @@ struct bch_ioctl_disk_resize {
 	__u64			nbuckets;
 };
 
+/*
+ * BCH_IOCTL_DISK_RESIZE_JOURNAL: resize journal on a device
+ *
+ * @dev		- member to resize
+ * @nbuckets	- new number of buckets
+ */
+struct bch_ioctl_disk_resize_journal {
+	__u32			flags;
+	__u32			pad;
+	__u64			dev;
+	__u64			nbuckets;
+};
+
 #endif /* _BCACHEFS_IOCTL_H */

fs/bcachefs/chardev.c

@@ -5,6 +5,7 @@
 #include "bcachefs_ioctl.h"
 #include "buckets.h"
 #include "chardev.h"
+#include "journal.h"
 #include "move.h"
 #include "replicas.h"
 #include "super.h"
@@ -563,6 +564,26 @@ static long bch2_ioctl_disk_resize(struct bch_fs *c,
 	return ret;
 }
 
+static long bch2_ioctl_disk_resize_journal(struct bch_fs *c,
+				   struct bch_ioctl_disk_resize_journal arg)
+{
+	struct bch_dev *ca;
+	int ret;
+
+	if ((arg.flags & ~BCH_BY_INDEX) ||
+	    arg.pad)
+		return -EINVAL;
+
+	ca = bch2_device_lookup(c, arg.dev, arg.flags);
+	if (IS_ERR(ca))
+		return PTR_ERR(ca);
+
+	ret = bch2_set_nr_journal_buckets(c, ca, arg.nbuckets);
+
+	percpu_ref_put(&ca->ref);
+	return ret;
+}
+
 #define BCH_IOCTL(_name, _argtype)					\
 do {									\
 	_argtype i;							\
@@ -619,6 +640,8 @@ long bch2_fs_ioctl(struct bch_fs *c, unsigned cmd, void __user *arg)
 		BCH_IOCTL(data, struct bch_ioctl_data);
 	case BCH_IOCTL_DISK_RESIZE:
 		BCH_IOCTL(disk_resize, struct bch_ioctl_disk_resize);
+	case BCH_IOCTL_DISK_RESIZE_JOURNAL:
+		BCH_IOCTL(disk_resize_journal, struct bch_ioctl_disk_resize_journal);
 
 	default:
 		return -ENOTTY;

fs/bcachefs/journal.c

@@ -730,6 +730,12 @@ static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
 			spin_lock(&c->journal.lock);
 		}
 
+		/*
+		 * XXX
+		 * For resize at runtime, we should be writing the new
+		 * superblock before inserting into the journal array
+		 */
+
 		pos = ja->nr ? (ja->cur_idx + 1) % ja->nr : 0;
 		__array_insert_item(ja->buckets,		ja->nr, pos);
 		__array_insert_item(ja->bucket_seq,		ja->nr, pos);
@@ -765,6 +771,8 @@ static int __bch2_set_nr_journal_buckets(struct bch_dev *ca, unsigned nr,
 
 	ret = 0;
 err:
+	bch2_sb_resize_journal(&ca->disk_sb,
+		ja->nr + sizeof(*journal_buckets) / sizeof(u64));
 	kfree(new_bucket_seq);
 	kfree(new_buckets);