md/raid1: add documentation to r1_private_data_s data structure.
There wasn't much and it is inconsistent.
Also rearrange fields to keep related fields together.
Reported-by: Aapo Laine <aapo.laine@shiftmail.org>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index e0d676b..a3d5483 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -28,42 +28,67 @@
mddev_t *mddev;
mirror_info_t *mirrors;
int raid_disks;
+
+ /* When choose the best device for a read (read_balance())
+ * we try to keep sequential reads one the same device
+ * using 'last_used' and 'next_seq_sect'
+ */
int last_used;
sector_t next_seq_sect;
+ /* During resync, read_balancing is only allowed on the part
+ * of the array that has been resynced. 'next_resync' tells us
+ * where that is.
+ */
+ sector_t next_resync;
+
spinlock_t device_lock;
+ /* list of 'r1bio_t' that need to be processed by raid1d, whether
+ * to retry a read, writeout a resync or recovery block, or
+ * anything else.
+ */
struct list_head retry_list;
- /* queue pending writes and submit them on unplug */
+
+ /* queue pending writes to be submitted on unplug */
struct bio_list pending_bio_list;
- /* for use when syncing mirrors: */
-
+ /* for use when syncing mirrors:
+ * We don't allow both normal IO and resync/recovery IO at
+ * the same time - resync/recovery can only happen when there
+ * is no other IO. So when either is active, the other has to wait.
+ * See more details description in raid1.c near raise_barrier().
+ */
+ wait_queue_head_t wait_barrier;
spinlock_t resync_lock;
int nr_pending;
int nr_waiting;
int nr_queued;
int barrier;
- sector_t next_resync;
- int fullsync; /* set to 1 if a full sync is needed,
- * (fresh device added).
- * Cleared when a sync completes.
- */
- int recovery_disabled; /* when the same as
- * mddev->recovery_disabled
- * we don't allow recovery
- * to be attempted as we
- * expect a read error
- */
- wait_queue_head_t wait_barrier;
+ /* Set to 1 if a full sync is needed, (fresh device added).
+ * Cleared when a sync completes.
+ */
+ int fullsync;
+ /* When the same as mddev->recovery_disabled we don't allow
+ * recovery to be attempted as we expect a read error.
+ */
+ int recovery_disabled;
+
+
+ /* poolinfo contains information about the content of the
+ * mempools - it changes when the array grows or shrinks
+ */
struct pool_info *poolinfo;
-
- struct page *tmppage;
-
mempool_t *r1bio_pool;
mempool_t *r1buf_pool;
+ /* temporary buffer to synchronous IO when attempting to repair
+ * a read error.
+ */
+ struct page *tmppage;
+
+
/* When taking over an array from a different personality, we store
* the new thread here until we fully activate the array.
*/