v4.19.13 snapshot.
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
new file mode 100644
index 0000000..e7ccad8
--- /dev/null
+++ b/drivers/md/raid1.h
@@ -0,0 +1,218 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _RAID1_H
+#define _RAID1_H
+
+/*
+ * each barrier unit size is 64MB fow now
+ * note: it must be larger than RESYNC_DEPTH
+ */
+#define BARRIER_UNIT_SECTOR_BITS 17
+#define BARRIER_UNIT_SECTOR_SIZE (1<<17)
+/*
+ * In struct r1conf, the following members are related to I/O barrier
+ * buckets,
+ * atomic_t *nr_pending;
+ * atomic_t *nr_waiting;
+ * atomic_t *nr_queued;
+ * atomic_t *barrier;
+ * Each of them points to array of atomic_t variables, each array is
+ * designed to have BARRIER_BUCKETS_NR elements and occupy a single
+ * memory page. The data width of atomic_t variables is 4 bytes, equal
+ * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
+ * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
+ * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
+ * occupies a single memory page.
+ */
+#define BARRIER_BUCKETS_NR_BITS (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
+#define BARRIER_BUCKETS_NR (1<<BARRIER_BUCKETS_NR_BITS)
+
+/* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
+ * There are three safe ways to access raid1_info.rdev.
+ * 1/ when holding mddev->reconfig_mutex
+ * 2/ when resync/recovery is known to be happening - i.e. in code that is
+ * called as part of performing resync/recovery.
+ * 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 raid1_info {
+ struct md_rdev *rdev;
+ sector_t head_position;
+
+ /* When choose the best device for a read (read_balance())
+ * we try to keep sequential reads one the same device
+ */
+ sector_t next_seq_sect;
+ sector_t seq_start;
+};
+
+/*
+ * memory pools need a pointer to the mddev, so they can force an unplug
+ * when memory is tight, and a count of the number of drives that the
+ * pool was allocated for, so they know how much to allocate and free.
+ * mddev->raid_disks cannot be used, as it can change while a pool is active
+ * These two datums are stored in a kmalloced struct.
+ * The 'raid_disks' here is twice the raid_disks in r1conf.
+ * This allows space for each 'real' device can have a replacement in the
+ * second half of the array.
+ */
+
+struct pool_info {
+ struct mddev *mddev;
+ int raid_disks;
+};
+
+struct r1conf {
+ struct mddev *mddev;
+ struct raid1_info *mirrors; /* twice 'raid_disks' to
+ * allow for replacements.
+ */
+ int raid_disks;
+
+ spinlock_t device_lock;
+
+ /* list of 'struct r1bio' 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;
+ /* 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 to be submitted on unplug */
+ struct bio_list pending_bio_list;
+ int pending_count;
+
+ /* 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;
+ atomic_t nr_sync_pending;
+ atomic_t *nr_pending;
+ atomic_t *nr_waiting;
+ atomic_t *nr_queued;
+ atomic_t *barrier;
+ int array_frozen;
+
+ /* 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;
+ mempool_t r1bio_pool;
+ mempool_t r1buf_pool;
+
+ struct bio_set bio_split;
+
+ /* 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.
+ */
+ 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' RAID1 bio.
+ *
+ * it contains information about what kind of IO operations were started
+ * for this RAID1 operation, and about their status:
+ */
+
+struct r1bio {
+ atomic_t remaining; /* 'have we finished' count,
+ * used from IRQ handlers
+ */
+ atomic_t behind_remaining; /* number of write-behind ios remaining
+ * in this BehindIO request
+ */
+ sector_t sector;
+ 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_disk;
+
+ struct list_head retry_list;
+
+ /*
+ * When R1BIO_BehindIO is set, we store pages for write behind
+ * in behind_master_bio.
+ */
+ struct bio *behind_master_bio;
+
+ /*
+ * if the IO is in WRITE direction, then multiple bios are used.
+ * We choose the number when they are allocated.
+ */
+ struct bio *bios[0];
+ /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
+};
+
+/* bits for r1bio.state */
+enum r1bio_state {
+ R1BIO_Uptodate,
+ R1BIO_IsSync,
+ R1BIO_Degraded,
+ R1BIO_BehindIO,
+/* Set ReadError on bios that experience a readerror so that
+ * raid1d knows what to do with them.
+ */
+ R1BIO_ReadError,
+/* For write-behind requests, we call bi_end_io when
+ * the last non-write-behind device completes, providing
+ * any write was successful. Otherwise we call when
+ * any write-behind write succeeds, otherwise we call
+ * with failure when last write completes (and all failed).
+ * Record that bi_end_io was called with this flag...
+ */
+ R1BIO_Returned,
+/* If a write for this request means we can clear some
+ * known-bad-block records, we set this flag
+ */
+ R1BIO_MadeGood,
+ R1BIO_WriteError,
+ R1BIO_FailFast,
+};
+
+static inline int sector_to_idx(sector_t sector)
+{
+ return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
+ BARRIER_BUCKETS_NR_BITS);
+}
+#endif