/* 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;
};

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;

        seqlock_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 __rcu  *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[];
};

/* bits for r10bio.state */
enum r10bio_state {
        R10BIO_Uptodate,
        R10BIO_IsSync,
        R10BIO_IsRecover,
        R10BIO_IsReshape,
/* Set ReadError on bios that experience a read error
 * so that raid10d knows what to do with them.
 */
        R10BIO_ReadError,
/* For bio_split errors, record that bi_end_io was called. */
        R10BIO_Returned,
/* 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,
        R10BIO_Discard,
};
#endif