v4.19.13 snapshot.
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
new file mode 100644
index 0000000..d3eaaf3
--- /dev/null
+++ b/drivers/md/raid10.h
@@ -0,0 +1,183 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _RAID10_H
+#define _RAID10_H
+
+/* Note: raid10_info.rdev can be set to NULL asynchronously by
+ * raid10_remove_disk.
+ * There are three safe ways to access raid10_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery/reshape is known to be happening - i.e. in code
+ * that is called as part of performing resync/recovery/reshape.
+ * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
+ * and if it is non-NULL, increment rdev->nr_pending before dropping the
+ * RCU lock.
+ * When .rdev is set to NULL, the nr_pending count checked again and if it has
+ * been incremented, the pointer is put back in .rdev.
+ */
+
+struct raid10_info {
+ struct md_rdev *rdev, *replacement;
+ sector_t head_position;
+ int recovery_disabled; /* matches
+ * mddev->recovery_disabled
+ * when we shouldn't try
+ * recovering this device.
+ */
+};
+
+struct r10conf {
+ struct mddev *mddev;
+ struct raid10_info *mirrors;
+ struct raid10_info *mirrors_new, *mirrors_old;
+ spinlock_t device_lock;
+
+ /* geometry */
+ struct geom {
+ int raid_disks;
+ int near_copies; /* number of copies laid out
+ * raid0 style */
+ int far_copies; /* number of copies laid out
+ * at large strides across drives
+ */
+ int far_offset; /* far_copies are offset by 1
+ * stripe instead of many
+ */
+ sector_t stride; /* distance between far copies.
+ * This is size / far_copies unless
+ * far_offset, in which case it is
+ * 1 stripe.
+ */
+ int far_set_size; /* The number of devices in a set,
+ * where a 'set' are devices that
+ * contain far/offset copies of
+ * each other.
+ */
+ int chunk_shift; /* shift from chunks to sectors */
+ sector_t chunk_mask;
+ } prev, geo;
+ int copies; /* near_copies * far_copies.
+ * must be <= raid_disks
+ */
+
+ sector_t dev_sectors; /* temp copy of
+ * mddev->dev_sectors */
+ sector_t reshape_progress;
+ sector_t reshape_safe;
+ unsigned long reshape_checkpoint;
+ sector_t offset_diff;
+
+ struct list_head retry_list;
+ /* A separate list of r1bio which just need raid_end_bio_io called.
+ * This mustn't happen for writes which had any errors if the superblock
+ * needs to be written.
+ */
+ struct list_head bio_end_io_list;
+
+ /* queue pending writes and submit them on unplug */
+ struct bio_list pending_bio_list;
+ int pending_count;
+
+ spinlock_t resync_lock;
+ atomic_t nr_pending;
+ int nr_waiting;
+ int nr_queued;
+ int barrier;
+ int array_freeze_pending;
+ sector_t next_resync;
+ int fullsync; /* set to 1 if a full sync is needed,
+ * (fresh device added).
+ * Cleared when a sync completes.
+ */
+ int have_replacement; /* There is at least one
+ * replacement device.
+ */
+ wait_queue_head_t wait_barrier;
+
+ mempool_t r10bio_pool;
+ mempool_t r10buf_pool;
+ struct page *tmppage;
+ struct bio_set bio_split;
+
+ /* When taking over an array from a different personality, we store
+ * the new thread here until we fully activate the array.
+ */
+ struct md_thread *thread;
+
+ /*
+ * Keep track of cluster resync window to send to other nodes.
+ */
+ sector_t cluster_sync_low;
+ sector_t cluster_sync_high;
+};
+
+/*
+ * this is our 'private' RAID10 bio.
+ *
+ * it contains information about what kind of IO operations were started
+ * for this RAID10 operation, and about their status:
+ */
+
+struct r10bio {
+ atomic_t remaining; /* 'have we finished' count,
+ * used from IRQ handlers
+ */
+ sector_t sector; /* virtual sector number */
+ int sectors;
+ unsigned long state;
+ struct mddev *mddev;
+ /*
+ * original bio going to /dev/mdx
+ */
+ struct bio *master_bio;
+ /*
+ * if the IO is in READ direction, then this is where we read
+ */
+ int read_slot;
+
+ struct list_head retry_list;
+ /*
+ * if the IO is in WRITE direction, then multiple bios are used,
+ * one for each copy.
+ * When resyncing we also use one for each copy.
+ * When reconstructing, we use 2 bios, one for read, one for write.
+ * We choose the number when they are allocated.
+ * We sometimes need an extra bio to write to the replacement.
+ */
+ struct r10dev {
+ struct bio *bio;
+ union {
+ struct bio *repl_bio; /* used for resync and
+ * writes */
+ struct md_rdev *rdev; /* used for reads
+ * (read_slot >= 0) */
+ };
+ sector_t addr;
+ int devnum;
+ } devs[0];
+};
+
+/* bits for r10bio.state */
+enum r10bio_state {
+ R10BIO_Uptodate,
+ R10BIO_IsSync,
+ R10BIO_IsRecover,
+ R10BIO_IsReshape,
+ R10BIO_Degraded,
+/* Set ReadError on bios that experience a read error
+ * so that raid10d knows what to do with them.
+ */
+ R10BIO_ReadError,
+/* If a write for this request means we can clear some
+ * known-bad-block records, we set this flag.
+ */
+ R10BIO_MadeGood,
+ R10BIO_WriteError,
+/* During a reshape we might be performing IO on the
+ * 'previous' part of the array, in which case this
+ * flag is set
+ */
+ R10BIO_Previous,
+/* failfast devices did receive failfast requests. */
+ R10BIO_FailFast,
+};
+#endif