/*
 * Module for pnfs flexfile layout driver.
 *
 * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
 *
 * Tao Peng <bergwolf@primarydata.com>
 */

#include <linux/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/module.h>
#include <linux/sched/mm.h>

#include <linux/sunrpc/metrics.h>

#include "flexfilelayout.h"
#include "../nfs4session.h"
#include "../nfs4idmap.h"
#include "../internal.h"
#include "../delegation.h"
#include "../nfs4trace.h"
#include "../iostat.h"
#include "../nfs.h"
#include "../nfs42.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

#define FF_LAYOUT_POLL_RETRY_MAX     (15*HZ)
#define FF_LAYOUTRETURN_MAXERR 20

static void ff_layout_read_record_layoutstats_done(struct rpc_task *task,
                struct nfs_pgio_header *hdr);
static int ff_layout_mirror_prepare_stats(struct pnfs_layout_hdr *lo,
                               struct nfs42_layoutstat_devinfo *devinfo,
                               int dev_limit);
static void ff_layout_encode_ff_layoutupdate(struct xdr_stream *xdr,
                              const struct nfs42_layoutstat_devinfo *devinfo,
                              struct nfs4_ff_layout_mirror *mirror);

static struct pnfs_layout_hdr *
ff_layout_alloc_layout_hdr(struct inode *inode, gfp_t gfp_flags)
{
        struct nfs4_flexfile_layout *ffl;

        ffl = kzalloc(sizeof(*ffl), gfp_flags);
        if (ffl) {
                INIT_LIST_HEAD(&ffl->error_list);
                INIT_LIST_HEAD(&ffl->mirrors);
                ffl->last_report_time = ktime_get();
                return &ffl->generic_hdr;
        } else
                return NULL;
}

static void
ff_layout_free_layout_hdr(struct pnfs_layout_hdr *lo)
{
        struct nfs4_ff_layout_ds_err *err, *n;

        list_for_each_entry_safe(err, n, &FF_LAYOUT_FROM_HDR(lo)->error_list,
                                 list) {
                list_del(&err->list);
                kfree(err);
        }
        kfree(FF_LAYOUT_FROM_HDR(lo));
}

static int decode_pnfs_stateid(struct xdr_stream *xdr, nfs4_stateid *stateid)
{
        __be32 *p;

        p = xdr_inline_decode(xdr, NFS4_STATEID_SIZE);
        if (unlikely(p == NULL))
                return -ENOBUFS;
        stateid->type = NFS4_PNFS_DS_STATEID_TYPE;
        memcpy(stateid->data, p, NFS4_STATEID_SIZE);
        dprintk("%s: stateid id= [%x%x%x%x]\n", __func__,
                p[0], p[1], p[2], p[3]);
        return 0;
}

static int decode_deviceid(struct xdr_stream *xdr, struct nfs4_deviceid *devid)
{
        __be32 *p;

        p = xdr_inline_decode(xdr, NFS4_DEVICEID4_SIZE);
        if (unlikely(!p))
                return -ENOBUFS;
        memcpy(devid, p, NFS4_DEVICEID4_SIZE);
        nfs4_print_deviceid(devid);
        return 0;
}

static int decode_nfs_fh(struct xdr_stream *xdr, struct nfs_fh *fh)
{
        __be32 *p;

        p = xdr_inline_decode(xdr, 4);
        if (unlikely(!p))
                return -ENOBUFS;
        fh->size = be32_to_cpup(p++);
        if (fh->size > sizeof(struct nfs_fh)) {
                printk(KERN_ERR "NFS flexfiles: Too big fh received %d\n",
                       fh->size);
                return -EOVERFLOW;
        }
        /* fh.data */
        p = xdr_inline_decode(xdr, fh->size);
        if (unlikely(!p))
                return -ENOBUFS;
        memcpy(&fh->data, p, fh->size);
        dprintk("%s: fh len %d\n", __func__, fh->size);

        return 0;
}

/*
 * Currently only stringified uids and gids are accepted.
 * I.e., kerberos is not supported to the DSes, so no pricipals.
 *
 * That means that one common function will suffice, but when
 * principals are added, this should be split to accomodate
 * calls to both nfs_map_name_to_uid() and nfs_map_group_to_gid().
 */
static int
decode_name(struct xdr_stream *xdr, u32 *id)
{
        __be32 *p;
        int len;

        /* opaque_length(4)*/
        p = xdr_inline_decode(xdr, 4);
        if (unlikely(!p))
                return -ENOBUFS;
        len = be32_to_cpup(p++);
        if (len < 0)
                return -EINVAL;

        dprintk("%s: len %u\n", __func__, len);

        /* opaque body */
        p = xdr_inline_decode(xdr, len);
        if (unlikely(!p))
                return -ENOBUFS;

        if (!nfs_map_string_to_numeric((char *)p, len, id))
                return -EINVAL;

        return 0;
}

static bool ff_mirror_match_fh(const struct nfs4_ff_layout_mirror *m1,
                const struct nfs4_ff_layout_mirror *m2)
{
        int i, j;

        if (m1->fh_versions_cnt != m2->fh_versions_cnt)
                return false;
        for (i = 0; i < m1->fh_versions_cnt; i++) {
                bool found_fh = false;
                for (j = 0; j < m2->fh_versions_cnt; j++) {
                        if (nfs_compare_fh(&m1->fh_versions[i],
                                        &m2->fh_versions[j]) == 0) {
                                found_fh = true;
                                break;
                        }
                }
                if (!found_fh)
                        return false;
        }
        return true;
}

static struct nfs4_ff_layout_mirror *
ff_layout_add_mirror(struct pnfs_layout_hdr *lo,
                struct nfs4_ff_layout_mirror *mirror)
{
        struct nfs4_flexfile_layout *ff_layout = FF_LAYOUT_FROM_HDR(lo);
        struct nfs4_ff_layout_mirror *pos;
        struct inode *inode = lo->plh_inode;

        spin_lock(&inode->i_lock);
        list_for_each_entry(pos, &ff_layout->mirrors, mirrors) {
                if (memcmp(&mirror->devid, &pos->devid, sizeof(pos->devid)) != 0)
                        continue;
                if (!ff_mirror_match_fh(mirror, pos))
                        continue;
                if (refcount_inc_not_zero(&pos->ref)) {
                        spin_unlock(&inode->i_lock);
                        return pos;
                }
        }
        list_add(&mirror->mirrors, &ff_layout->mirrors);
        mirror->layout = lo;
        spin_unlock(&inode->i_lock);
        return mirror;
}

static void
ff_layout_remove_mirror(struct nfs4_ff_layout_mirror *mirror)
{
        struct inode *inode;
        if (mirror->layout == NULL)
                return;
        inode = mirror->layout->plh_inode;
        spin_lock(&inode->i_lock);
        list_del(&mirror->mirrors);
        spin_unlock(&inode->i_lock);
        mirror->layout = NULL;
}

static struct nfs4_ff_layout_mirror *ff_layout_alloc_mirror(gfp_t gfp_flags)
{
        struct nfs4_ff_layout_mirror *mirror;

        mirror = kzalloc(sizeof(*mirror), gfp_flags);
        if (mirror != NULL) {
                spin_lock_init(&mirror->lock);
                refcount_set(&mirror->ref, 1);
                INIT_LIST_HEAD(&mirror->mirrors);
        }
        return mirror;
}

static void ff_layout_free_mirror(struct nfs4_ff_layout_mirror *mirror)
{
        const struct cred       *cred;

        ff_layout_remove_mirror(mirror);
        kfree(mirror->fh_versions);
        cred = rcu_access_pointer(mirror->ro_cred);
        put_cred(cred);
        cred = rcu_access_pointer(mirror->rw_cred);
        put_cred(cred);
        nfs4_ff_layout_put_deviceid(mirror->mirror_ds);
        kfree(mirror);
}

static void ff_layout_put_mirror(struct nfs4_ff_layout_mirror *mirror)
{
        if (mirror != NULL && refcount_dec_and_test(&mirror->ref))
                ff_layout_free_mirror(mirror);
}

static void ff_layout_free_mirror_array(struct nfs4_ff_layout_segment *fls)
{
        int i;

        if (fls->mirror_array) {
                for (i = 0; i < fls->mirror_array_cnt; i++) {
                        /* normally mirror_ds is freed in
                         * .free_deviceid_node but we still do it here
                         * for .alloc_lseg error path */
                        ff_layout_put_mirror(fls->mirror_array[i]);
                }
                kfree(fls->mirror_array);
                fls->mirror_array = NULL;
        }
}

static int ff_layout_check_layout(struct nfs4_layoutget_res *lgr)
{
        int ret = 0;

        dprintk("--> %s\n", __func__);

        /* FIXME: remove this check when layout segment support is added */
        if (lgr->range.offset != 0 ||
            lgr->range.length != NFS4_MAX_UINT64) {
                dprintk("%s Only whole file layouts supported. Use MDS i/o\n",
                        __func__);
                ret = -EINVAL;
        }

        dprintk("--> %s returns %d\n", __func__, ret);
        return ret;
}

static void _ff_layout_free_lseg(struct nfs4_ff_layout_segment *fls)
{
        if (fls) {
                ff_layout_free_mirror_array(fls);
                kfree(fls);
        }
}

static bool
ff_lseg_range_is_after(const struct pnfs_layout_range *l1,
                const struct pnfs_layout_range *l2)
{
        u64 end1, end2;

        if (l1->iomode != l2->iomode)
                return l1->iomode != IOMODE_READ;
        end1 = pnfs_calc_offset_end(l1->offset, l1->length);
        end2 = pnfs_calc_offset_end(l2->offset, l2->length);
        if (end1 < l2->offset)
                return false;
        if (end2 < l1->offset)
                return true;
        return l2->offset <= l1->offset;
}

static bool
ff_lseg_merge(struct pnfs_layout_segment *new,
                struct pnfs_layout_segment *old)
{
        u64 new_end, old_end;

        if (test_bit(NFS_LSEG_LAYOUTRETURN, &old->pls_flags))
                return false;
        if (new->pls_range.iomode != old->pls_range.iomode)
                return false;
        old_end = pnfs_calc_offset_end(old->pls_range.offset,
                        old->pls_range.length);
        if (old_end < new->pls_range.offset)
                return false;
        new_end = pnfs_calc_offset_end(new->pls_range.offset,
                        new->pls_range.length);
        if (new_end < old->pls_range.offset)
                return false;

        /* Mergeable: copy info from 'old' to 'new' */
        if (new_end < old_end)
                new_end = old_end;
        if (new->pls_range.offset < old->pls_range.offset)
                new->pls_range.offset = old->pls_range.offset;
        new->pls_range.length = pnfs_calc_offset_length(new->pls_range.offset,
                        new_end);
        if (test_bit(NFS_LSEG_ROC, &old->pls_flags))
                set_bit(NFS_LSEG_ROC, &new->pls_flags);
        return true;
}

static void
ff_layout_add_lseg(struct pnfs_layout_hdr *lo,
                struct pnfs_layout_segment *lseg,
                struct list_head *free_me)
{
        pnfs_generic_layout_insert_lseg(lo, lseg,
                        ff_lseg_range_is_after,
                        ff_lseg_merge,
                        free_me);
}

static void ff_layout_sort_mirrors(struct nfs4_ff_layout_segment *fls)
{
        int i, j;

        for (i = 0; i < fls->mirror_array_cnt - 1; i++) {
                for (j = i + 1; j < fls->mirror_array_cnt; j++)
                        if (fls->mirror_array[i]->efficiency <
                            fls->mirror_array[j]->efficiency)
                                swap(fls->mirror_array[i],
                                     fls->mirror_array[j]);
        }
}

static struct pnfs_layout_segment *
ff_layout_alloc_lseg(struct pnfs_layout_hdr *lh,
                     struct nfs4_layoutget_res *lgr,
                     gfp_t gfp_flags)
{
        struct pnfs_layout_segment *ret;
        struct nfs4_ff_layout_segment *fls = NULL;
        struct xdr_stream stream;
        struct xdr_buf buf;
        struct page *scratch;
        u64 stripe_unit;
        u32 mirror_array_cnt;
        __be32 *p;
        int i, rc;

        dprintk("--> %s\n", __func__);
        scratch = alloc_page(gfp_flags);
        if (!scratch)
                return ERR_PTR(-ENOMEM);

        xdr_init_decode_pages(&stream, &buf, lgr->layoutp->pages,
                              lgr->layoutp->len);
        xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);

        /* stripe unit and mirror_array_cnt */
        rc = -EIO;
        p = xdr_inline_decode(&stream, 8 + 4);
        if (!p)
                goto out_err_free;

        p = xdr_decode_hyper(p, &stripe_unit);
        mirror_array_cnt = be32_to_cpup(p++);
        dprintk("%s: stripe_unit=%llu mirror_array_cnt=%u\n", __func__,
                stripe_unit, mirror_array_cnt);

        if (mirror_array_cnt > NFS4_FLEXFILE_LAYOUT_MAX_MIRROR_CNT ||
            mirror_array_cnt == 0)
                goto out_err_free;

        rc = -ENOMEM;
        fls = kzalloc(sizeof(*fls), gfp_flags);
        if (!fls)
                goto out_err_free;

        fls->mirror_array_cnt = mirror_array_cnt;
        fls->stripe_unit = stripe_unit;
        fls->mirror_array = kcalloc(fls->mirror_array_cnt,
                                    sizeof(fls->mirror_array[0]), gfp_flags);
        if (fls->mirror_array == NULL)
                goto out_err_free;

        for (i = 0; i < fls->mirror_array_cnt; i++) {
                struct nfs4_ff_layout_mirror *mirror;
                struct cred *kcred;
                const struct cred *cred;
                kuid_t uid;
                kgid_t gid;
                u32 ds_count, fh_count, id;
                int j;

                rc = -EIO;
                p = xdr_inline_decode(&stream, 4);
                if (!p)
                        goto out_err_free;
                ds_count = be32_to_cpup(p);

                /* FIXME: allow for striping? */
                if (ds_count != 1)
                        goto out_err_free;

                fls->mirror_array[i] = ff_layout_alloc_mirror(gfp_flags);
                if (fls->mirror_array[i] == NULL) {
                        rc = -ENOMEM;
                        goto out_err_free;
                }

                fls->mirror_array[i]->ds_count = ds_count;

                /* deviceid */
                rc = decode_deviceid(&stream, &fls->mirror_array[i]->devid);
                if (rc)
                        goto out_err_free;

                /* efficiency */
                rc = -EIO;
                p = xdr_inline_decode(&stream, 4);
                if (!p)
                        goto out_err_free;
                fls->mirror_array[i]->efficiency = be32_to_cpup(p);

                /* stateid */
                rc = decode_pnfs_stateid(&stream, &fls->mirror_array[i]->stateid);
                if (rc)
                        goto out_err_free;

                /* fh */
                rc = -EIO;
                p = xdr_inline_decode(&stream, 4);
                if (!p)
                        goto out_err_free;
                fh_count = be32_to_cpup(p);

                fls->mirror_array[i]->fh_versions =
                        kcalloc(fh_count, sizeof(struct nfs_fh),
                                gfp_flags);
                if (fls->mirror_array[i]->fh_versions == NULL) {
                        rc = -ENOMEM;
                        goto out_err_free;
                }

                for (j = 0; j < fh_count; j++) {
                        rc = decode_nfs_fh(&stream,
                                           &fls->mirror_array[i]->fh_versions[j]);
                        if (rc)
                                goto out_err_free;
                }

                fls->mirror_array[i]->fh_versions_cnt = fh_count;

                /* user */
                rc = decode_name(&stream, &id);
                if (rc)
                        goto out_err_free;

                uid = make_kuid(&init_user_ns, id);

                /* group */
                rc = decode_name(&stream, &id);
                if (rc)
                        goto out_err_free;

                gid = make_kgid(&init_user_ns, id);

                if (gfp_flags & __GFP_FS)
                        kcred = prepare_kernel_cred(NULL);
                else {
                        unsigned int nofs_flags = memalloc_nofs_save();
                        kcred = prepare_kernel_cred(NULL);
                        memalloc_nofs_restore(nofs_flags);
                }
                rc = -ENOMEM;
                if (!kcred)
                        goto out_err_free;
                kcred->fsuid = uid;
                kcred->fsgid = gid;
                cred = kcred;

                if (lgr->range.iomode == IOMODE_READ)
                        rcu_assign_pointer(fls->mirror_array[i]->ro_cred, cred);
                else
                        rcu_assign_pointer(fls->mirror_array[i]->rw_cred, cred);

                mirror = ff_layout_add_mirror(lh, fls->mirror_array[i]);
                if (mirror != fls->mirror_array[i]) {
                        /* swap cred ptrs so free_mirror will clean up old */
                        if (lgr->range.iomode == IOMODE_READ) {
                                cred = xchg(&mirror->ro_cred, cred);
                                rcu_assign_pointer(fls->mirror_array[i]->ro_cred, cred);
                        } else {
                                cred = xchg(&mirror->rw_cred, cred);
                                rcu_assign_pointer(fls->mirror_array[i]->rw_cred, cred);
                        }
                        ff_layout_free_mirror(fls->mirror_array[i]);
                        fls->mirror_array[i] = mirror;
                }

                dprintk("%s: iomode %s uid %u gid %u\n", __func__,
                        lgr->range.iomode == IOMODE_READ ? "READ" : "RW",
                        from_kuid(&init_user_ns, uid),
                        from_kgid(&init_user_ns, gid));
        }

        p = xdr_inline_decode(&stream, 4);
        if (!p)
                goto out_sort_mirrors;
        fls->flags = be32_to_cpup(p);

        p = xdr_inline_decode(&stream, 4);
        if (!p)
                goto out_sort_mirrors;
        for (i=0; i < fls->mirror_array_cnt; i++)
                fls->mirror_array[i]->report_interval = be32_to_cpup(p);

out_sort_mirrors:
        ff_layout_sort_mirrors(fls);
        rc = ff_layout_check_layout(lgr);
        if (rc)
                goto out_err_free;
        ret = &fls->generic_hdr;
        dprintk("<-- %s (success)\n", __func__);
out_free_page:
        __free_page(scratch);
        return ret;
out_err_free:
        _ff_layout_free_lseg(fls);
        ret = ERR_PTR(rc);
        dprintk("<-- %s (%d)\n", __func__, rc);
        goto out_free_page;
}

static bool ff_layout_has_rw_segments(struct pnfs_layout_hdr *layout)
{
        struct pnfs_layout_segment *lseg;

        list_for_each_entry(lseg, &layout->plh_segs, pls_list)
                if (lseg->pls_range.iomode == IOMODE_RW)
                        return true;

        return false;
}

static void
ff_layout_free_lseg(struct pnfs_layout_segment *lseg)
{
        struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);

        dprintk("--> %s\n", __func__);

        if (lseg->pls_range.iomode == IOMODE_RW) {
                struct nfs4_flexfile_layout *ffl;
                struct inode *inode;

                ffl = FF_LAYOUT_FROM_HDR(lseg->pls_layout);
                inode = ffl->generic_hdr.plh_inode;
                spin_lock(&inode->i_lock);
                if (!ff_layout_has_rw_segments(lseg->pls_layout)) {
                        ffl->commit_info.nbuckets = 0;
                        kfree(ffl->commit_info.buckets);
                        ffl->commit_info.buckets = NULL;
                }
                spin_unlock(&inode->i_lock);
        }
        _ff_layout_free_lseg(fls);
}

/* Return 1 until we have multiple lsegs support */
static int
ff_layout_get_lseg_count(struct nfs4_ff_layout_segment *fls)
{
        return 1;
}

static void
nfs4_ff_start_busy_timer(struct nfs4_ff_busy_timer *timer, ktime_t now)
{
        /* first IO request? */
        if (atomic_inc_return(&timer->n_ops) == 1) {
                timer->start_time = now;
        }
}

static ktime_t
nfs4_ff_end_busy_timer(struct nfs4_ff_busy_timer *timer, ktime_t now)
{
        ktime_t start;

        if (atomic_dec_return(&timer->n_ops) < 0)
                WARN_ON_ONCE(1);

        start = timer->start_time;
        timer->start_time = now;
        return ktime_sub(now, start);
}

static bool
nfs4_ff_layoutstat_start_io(struct nfs4_ff_layout_mirror *mirror,
                            struct nfs4_ff_layoutstat *layoutstat,
                            ktime_t now)
{
        s64 report_interval = FF_LAYOUTSTATS_REPORT_INTERVAL;
        struct nfs4_flexfile_layout *ffl = FF_LAYOUT_FROM_HDR(mirror->layout);

        nfs4_ff_start_busy_timer(&layoutstat->busy_timer, now);
        if (!mirror->start_time)
                mirror->start_time = now;
        if (mirror->report_interval != 0)
                report_interval = (s64)mirror->report_interval * 1000LL;
        else if (layoutstats_timer != 0)
                report_interval = (s64)layoutstats_timer * 1000LL;
        if (ktime_to_ms(ktime_sub(now, ffl->last_report_time)) >=
                        report_interval) {
                ffl->last_report_time = now;
                return true;
        }

        return false;
}

static void
nfs4_ff_layout_stat_io_update_requested(struct nfs4_ff_layoutstat *layoutstat,
                __u64 requested)
{
        struct nfs4_ff_io_stat *iostat = &layoutstat->io_stat;

        iostat->ops_requested++;
        iostat->bytes_requested += requested;
}

static void
nfs4_ff_layout_stat_io_update_completed(struct nfs4_ff_layoutstat *layoutstat,
                __u64 requested,
                __u64 completed,
                ktime_t time_completed,
                ktime_t time_started)
{
        struct nfs4_ff_io_stat *iostat = &layoutstat->io_stat;
        ktime_t completion_time = ktime_sub(time_completed, time_started);
        ktime_t timer;

        iostat->ops_completed++;
        iostat->bytes_completed += completed;
        iostat->bytes_not_delivered += requested - completed;

        timer = nfs4_ff_end_busy_timer(&layoutstat->busy_timer, time_completed);
        iostat->total_busy_time =
                        ktime_add(iostat->total_busy_time, timer);
        iostat->aggregate_completion_time =
                        ktime_add(iostat->aggregate_completion_time,
                                        completion_time);
}

static void
nfs4_ff_layout_stat_io_start_read(struct inode *inode,
                struct nfs4_ff_layout_mirror *mirror,
                __u64 requested, ktime_t now)
{
        bool report;

        spin_lock(&mirror->lock);
        report = nfs4_ff_layoutstat_start_io(mirror, &mirror->read_stat, now);
        nfs4_ff_layout_stat_io_update_requested(&mirror->read_stat, requested);
        set_bit(NFS4_FF_MIRROR_STAT_AVAIL, &mirror->flags);
        spin_unlock(&mirror->lock);

        if (report)
                pnfs_report_layoutstat(inode, GFP_KERNEL);
}

static void
nfs4_ff_layout_stat_io_end_read(struct rpc_task *task,
                struct nfs4_ff_layout_mirror *mirror,
                __u64 requested,
                __u64 completed)
{
        spin_lock(&mirror->lock);
        nfs4_ff_layout_stat_io_update_completed(&mirror->read_stat,
                        requested, completed,
                        ktime_get(), task->tk_start);
        set_bit(NFS4_FF_MIRROR_STAT_AVAIL, &mirror->flags);
        spin_unlock(&mirror->lock);
}

static void
nfs4_ff_layout_stat_io_start_write(struct inode *inode,
                struct nfs4_ff_layout_mirror *mirror,
                __u64 requested, ktime_t now)
{
        bool report;

        spin_lock(&mirror->lock);
        report = nfs4_ff_layoutstat_start_io(mirror , &mirror->write_stat, now);
        nfs4_ff_layout_stat_io_update_requested(&mirror->write_stat, requested);
        set_bit(NFS4_FF_MIRROR_STAT_AVAIL, &mirror->flags);
        spin_unlock(&mirror->lock);

        if (report)
                pnfs_report_layoutstat(inode, GFP_NOIO);
}

static void
nfs4_ff_layout_stat_io_end_write(struct rpc_task *task,
                struct nfs4_ff_layout_mirror *mirror,
                __u64 requested,
                __u64 completed,
                enum nfs3_stable_how committed)
{
        if (committed == NFS_UNSTABLE)
                requested = completed = 0;

        spin_lock(&mirror->lock);
        nfs4_ff_layout_stat_io_update_completed(&mirror->write_stat,
                        requested, completed, ktime_get(), task->tk_start);
        set_bit(NFS4_FF_MIRROR_STAT_AVAIL, &mirror->flags);
        spin_unlock(&mirror->lock);
}

static int
ff_layout_alloc_commit_info(struct pnfs_layout_segment *lseg,
                            struct nfs_commit_info *cinfo,
                            gfp_t gfp_flags)
{
        struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
        struct pnfs_commit_bucket *buckets;
        int size;

        if (cinfo->ds->nbuckets != 0) {
                /* This assumes there is only one RW lseg per file.
                 * To support multiple lseg per file, we need to
                 * change struct pnfs_commit_bucket to allow dynamic
                 * increasing nbuckets.
                 */
                return 0;
        }

        size = ff_layout_get_lseg_count(fls) * FF_LAYOUT_MIRROR_COUNT(lseg);

        buckets = kcalloc(size, sizeof(struct pnfs_commit_bucket),
                          gfp_flags);
        if (!buckets)
                return -ENOMEM;
        else {
                int i;

                spin_lock(&cinfo->inode->i_lock);
                if (cinfo->ds->nbuckets != 0)
                        kfree(buckets);
                else {
                        cinfo->ds->buckets = buckets;
                        cinfo->ds->nbuckets = size;
                        for (i = 0; i < size; i++) {
                                INIT_LIST_HEAD(&buckets[i].written);
                                INIT_LIST_HEAD(&buckets[i].committing);
                                /* mark direct verifier as unset */
                                buckets[i].direct_verf.committed =
                                        NFS_INVALID_STABLE_HOW;
                        }
                }
                spin_unlock(&cinfo->inode->i_lock);
                return 0;
        }
}

static struct nfs4_pnfs_ds *
ff_layout_choose_best_ds_for_read(struct pnfs_layout_segment *lseg,
                                  int start_idx,
                                  int *best_idx)
{
        struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
        struct nfs4_pnfs_ds *ds;
        bool fail_return = false;
        int idx;

        /* mirrors are sorted by efficiency */
        for (idx = start_idx; idx < fls->mirror_array_cnt; idx++) {
                if (idx+1 == fls->mirror_array_cnt)
                        fail_return = true;
                ds = nfs4_ff_layout_prepare_ds(lseg, idx, fail_return);
                if (ds) {
                        *best_idx = idx;
                        return ds;
                }
        }

        return NULL;
}

static void
ff_layout_pg_get_read(struct nfs_pageio_descriptor *pgio,
                      struct nfs_page *req,
                      bool strict_iomode)
{
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                           req->wb_context,
                                           0,
                                           NFS4_MAX_UINT64,
                                           IOMODE_READ,
                                           strict_iomode,
                                           GFP_KERNEL);
        if (IS_ERR(pgio->pg_lseg)) {
                pgio->pg_error = PTR_ERR(pgio->pg_lseg);
                pgio->pg_lseg = NULL;
        }
}

static void
ff_layout_pg_init_read(struct nfs_pageio_descriptor *pgio,
                        struct nfs_page *req)
{
        struct nfs_pgio_mirror *pgm;
        struct nfs4_ff_layout_mirror *mirror;
        struct nfs4_pnfs_ds *ds;
        int ds_idx;

retry:
        pnfs_generic_pg_check_layout(pgio);
        /* Use full layout for now */
        if (!pgio->pg_lseg) {
                ff_layout_pg_get_read(pgio, req, false);
                if (!pgio->pg_lseg)
                        goto out_nolseg;
        }
        if (ff_layout_avoid_read_on_rw(pgio->pg_lseg)) {
                ff_layout_pg_get_read(pgio, req, true);
                if (!pgio->pg_lseg)
                        goto out_nolseg;
        }

        ds = ff_layout_choose_best_ds_for_read(pgio->pg_lseg, 0, &ds_idx);
        if (!ds) {
                if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
                        goto out_mds;
                pnfs_put_lseg(pgio->pg_lseg);
                pgio->pg_lseg = NULL;
                /* Sleep for 1 second before retrying */
                ssleep(1);
                goto retry;
        }

        mirror = FF_LAYOUT_COMP(pgio->pg_lseg, ds_idx);

        pgio->pg_mirror_idx = ds_idx;

        /* read always uses only one mirror - idx 0 for pgio layer */
        pgm = &pgio->pg_mirrors[0];
        pgm->pg_bsize = mirror->mirror_ds->ds_versions[0].rsize;

        return;
out_nolseg:
        if (pgio->pg_error < 0)
                return;
out_mds:
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = NULL;
        nfs_pageio_reset_read_mds(pgio);
}

static void
ff_layout_pg_init_write(struct nfs_pageio_descriptor *pgio,
                        struct nfs_page *req)
{
        struct nfs4_ff_layout_mirror *mirror;
        struct nfs_pgio_mirror *pgm;
        struct nfs_commit_info cinfo;
        struct nfs4_pnfs_ds *ds;
        int i;
        int status;

retry:
        pnfs_generic_pg_check_layout(pgio);
        if (!pgio->pg_lseg) {
                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                                   req->wb_context,
                                                   0,
                                                   NFS4_MAX_UINT64,
                                                   IOMODE_RW,
                                                   false,
                                                   GFP_NOFS);
                if (IS_ERR(pgio->pg_lseg)) {
                        pgio->pg_error = PTR_ERR(pgio->pg_lseg);
                        pgio->pg_lseg = NULL;
                        return;
                }
        }
        /* If no lseg, fall back to write through mds */
        if (pgio->pg_lseg == NULL)
                goto out_mds;

        nfs_init_cinfo(&cinfo, pgio->pg_inode, pgio->pg_dreq);
        status = ff_layout_alloc_commit_info(pgio->pg_lseg, &cinfo, GFP_NOFS);
        if (status < 0)
                goto out_mds;

        /* Use a direct mapping of ds_idx to pgio mirror_idx */
        if (WARN_ON_ONCE(pgio->pg_mirror_count !=
            FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg)))
                goto out_mds;

        for (i = 0; i < pgio->pg_mirror_count; i++) {
                ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, i, true);
                if (!ds) {
                        if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
                                goto out_mds;
                        pnfs_put_lseg(pgio->pg_lseg);
                        pgio->pg_lseg = NULL;
                        /* Sleep for 1 second before retrying */
                        ssleep(1);
                        goto retry;
                }
                pgm = &pgio->pg_mirrors[i];
                mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
                pgm->pg_bsize = mirror->mirror_ds->ds_versions[0].wsize;
        }

        return;

out_mds:
        pnfs_put_lseg(pgio->pg_lseg);
        pgio->pg_lseg = NULL;
        nfs_pageio_reset_write_mds(pgio);
}

static unsigned int
ff_layout_pg_get_mirror_count_write(struct nfs_pageio_descriptor *pgio,
                                    struct nfs_page *req)
{
        if (!pgio->pg_lseg) {
                pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
                                                   req->wb_context,
                                                   0,
                                                   NFS4_MAX_UINT64,
                                                   IOMODE_RW,
                                                   false,
                                                   GFP_NOFS);
                if (IS_ERR(pgio->pg_lseg)) {
                        pgio->pg_error = PTR_ERR(pgio->pg_lseg);
                        pgio->pg_lseg = NULL;
                        goto out;
                }
        }
        if (pgio->pg_lseg)
                return FF_LAYOUT_MIRROR_COUNT(pgio->pg_lseg);

        /* no lseg means that pnfs is not in use, so no mirroring here */
        nfs_pageio_reset_write_mds(pgio);
out:
        return 1;
}

static const struct nfs_pageio_ops ff_layout_pg_read_ops = {
        .pg_init = ff_layout_pg_init_read,
        .pg_test = pnfs_generic_pg_test,
        .pg_doio = pnfs_generic_pg_readpages,
        .pg_cleanup = pnfs_generic_pg_cleanup,
};

static const struct nfs_pageio_ops ff_layout_pg_write_ops = {
        .pg_init = ff_layout_pg_init_write,
        .pg_test = pnfs_generic_pg_test,
        .pg_doio = pnfs_generic_pg_writepages,
        .pg_get_mirror_count = ff_layout_pg_get_mirror_count_write,
        .pg_cleanup = pnfs_generic_pg_cleanup,
};

static void ff_layout_reset_write(struct nfs_pgio_header *hdr, bool retry_pnfs)
{
        struct rpc_task *task = &hdr->task;

        pnfs_layoutcommit_inode(hdr->inode, false);

        if (retry_pnfs) {
                dprintk("%s Reset task %5u for i/o through pNFS "

                        "(req %s/%llu, %u bytes @ offset %llu)\n", __func__,
                        hdr->task.tk_pid,
                        hdr->inode->i_sb->s_id,
                        (unsigned long long)NFS_FILEID(hdr->inode),
                        hdr->args.count,
                        (unsigned long long)hdr->args.offset);

                hdr->completion_ops->reschedule_io(hdr);
                return;
        }

        if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
                dprintk("%s Reset task %5u for i/o through MDS "
                        "(req %s/%llu, %u bytes @ offset %llu)\n", __func__,
                        hdr->task.tk_pid,
                        hdr->inode->i_sb->s_id,
                        (unsigned long long)NFS_FILEID(hdr->inode),
                        hdr->args.count,
                        (unsigned long long)hdr->args.offset);

                task->tk_status = pnfs_write_done_resend_to_mds(hdr);
        }
}

static void ff_layout_reset_read(struct nfs_pgio_header *hdr)
{
        struct rpc_task *task = &hdr->task;

        pnfs_layoutcommit_inode(hdr->inode, false);

        if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
                dprintk("%s Reset task %5u for i/o through MDS "
                        "(req %s/%llu, %u bytes @ offset %llu)\n", __func__,
                        hdr->task.tk_pid,
                        hdr->inode->i_sb->s_id,
                        (unsigned long long)NFS_FILEID(hdr->inode),
                        hdr->args.count,
                        (unsigned long long)hdr->args.offset);

                task->tk_status = pnfs_read_done_resend_to_mds(hdr);
        }
}

static int ff_layout_async_handle_error_v4(struct rpc_task *task,
                                           struct nfs4_state *state,
                                           struct nfs_client *clp,
                                           struct pnfs_layout_segment *lseg,
                                           int idx)
{
        struct pnfs_layout_hdr *lo = lseg->pls_layout;
        struct inode *inode = lo->plh_inode;
        struct nfs4_deviceid_node *devid = FF_LAYOUT_DEVID_NODE(lseg, idx);
        struct nfs4_slot_table *tbl = &clp->cl_session->fc_slot_table;

        switch (task->tk_status) {
        case -NFS4ERR_BADSESSION:
        case -NFS4ERR_BADSLOT:
        case -NFS4ERR_BAD_HIGH_SLOT:
        case -NFS4ERR_DEADSESSION:
        case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
        case -NFS4ERR_SEQ_FALSE_RETRY:
        case -NFS4ERR_SEQ_MISORDERED:
                dprintk("%s ERROR %d, Reset session. Exchangeid "
                        "flags 0x%x\n", __func__, task->tk_status,
                        clp->cl_exchange_flags);
                nfs4_schedule_session_recovery(clp->cl_session, task->tk_status);
                break;
        case -NFS4ERR_DELAY:
        case -NFS4ERR_GRACE:
                rpc_delay(task, FF_LAYOUT_POLL_RETRY_MAX);
                break;
        case -NFS4ERR_RETRY_UNCACHED_REP:
                break;
        /* Invalidate Layout errors */
        case -NFS4ERR_PNFS_NO_LAYOUT:
        case -ESTALE:           /* mapped NFS4ERR_STALE */
        case -EBADHANDLE:       /* mapped NFS4ERR_BADHANDLE */
        case -EISDIR:           /* mapped NFS4ERR_ISDIR */
        case -NFS4ERR_FHEXPIRED:
        case -NFS4ERR_WRONG_TYPE:
                dprintk("%s Invalid layout error %d\n", __func__,
                        task->tk_status);
                /*
                 * Destroy layout so new i/o will get a new layout.
                 * Layout will not be destroyed until all current lseg
                 * references are put. Mark layout as invalid to resend failed
                 * i/o and all i/o waiting on the slot table to the MDS until
                 * layout is destroyed and a new valid layout is obtained.
                 */
                pnfs_destroy_layout(NFS_I(inode));
                rpc_wake_up(&tbl->slot_tbl_waitq);
                goto reset;
        /* RPC connection errors */
        case -ECONNREFUSED:
        case -EHOSTDOWN:
        case -EHOSTUNREACH:
        case -ENETUNREACH:
        case -EIO:
        case -ETIMEDOUT:
        case -EPIPE:
                dprintk("%s DS connection error %d\n", __func__,
                        task->tk_status);
                nfs4_delete_deviceid(devid->ld, devid->nfs_client,
                                &devid->deviceid);
                rpc_wake_up(&tbl->slot_tbl_waitq);
                /* fall through */
        default:
                if (ff_layout_avoid_mds_available_ds(lseg))
                        return -NFS4ERR_RESET_TO_PNFS;
reset:
                dprintk("%s Retry through MDS. Error %d\n", __func__,
                        task->tk_status);
                return -NFS4ERR_RESET_TO_MDS;
        }
        task->tk_status = 0;
        return -EAGAIN;
}

/* Retry all errors through either pNFS or MDS except for -EJUKEBOX */
static int ff_layout_async_handle_error_v3(struct rpc_task *task,
                                           struct pnfs_layout_segment *lseg,
                                           int idx)
{
        struct nfs4_deviceid_node *devid = FF_LAYOUT_DEVID_NODE(lseg, idx);

        switch (task->tk_status) {
        /* File access problems. Don't mark the device as unavailable */
        case -EACCES:
        case -ESTALE:
        case -EISDIR:
        case -EBADHANDLE:
        case -ELOOP:
        case -ENOSPC:
                break;
        case -EJUKEBOX:
                nfs_inc_stats(lseg->pls_layout->plh_inode, NFSIOS_DELAY);
                goto out_retry;
        default:
                dprintk("%s DS connection error %d\n", __func__,
                        task->tk_status);
                nfs4_delete_deviceid(devid->ld, devid->nfs_client,
                                &devid->deviceid);
        }
        /* FIXME: Need to prevent infinite looping here. */
        return -NFS4ERR_RESET_TO_PNFS;
out_retry:
        task->tk_status = 0;
        rpc_restart_call_prepare(task);
        rpc_delay(task, NFS_JUKEBOX_RETRY_TIME);
        return -EAGAIN;
}

static int ff_layout_async_handle_error(struct rpc_task *task,
                                        struct nfs4_state *state,
                                        struct nfs_client *clp,
                                        struct pnfs_layout_segment *lseg,
                                        int idx)
{
        int vers = clp->cl_nfs_mod->rpc_vers->number;

        if (task->tk_status >= 0)
                return 0;

        /* Handle the case of an invalid layout segment */
        if (!pnfs_is_valid_lseg(lseg))
                return -NFS4ERR_RESET_TO_PNFS;

        switch (vers) {
        case 3:
                return ff_layout_async_handle_error_v3(task, lseg, idx);
        case 4:
                return ff_layout_async_handle_error_v4(task, state, clp,
                                                       lseg, idx);
        default:
                /* should never happen */
                WARN_ON_ONCE(1);
                return 0;
        }
}

static void ff_layout_io_track_ds_error(struct pnfs_layout_segment *lseg,
                                        int idx, u64 offset, u64 length,
                                        u32 status, int opnum, int error)
{
        struct nfs4_ff_layout_mirror *mirror;
        int err;

        if (status == 0) {
                switch (error) {
                case -ETIMEDOUT:
                case -EPFNOSUPPORT:
                case -EPROTONOSUPPORT:
                case -EOPNOTSUPP:
                case -ECONNREFUSED:
                case -ECONNRESET:
                case -EHOSTDOWN:
                case -EHOSTUNREACH:
                case -ENETUNREACH:
                case -EADDRINUSE:
                case -ENOBUFS:
                case -EPIPE:
                case -EPERM:
                        status = NFS4ERR_NXIO;
                        break;
                case -EACCES:
                        status = NFS4ERR_ACCESS;
                        break;
                default:
                        return;
                }
        }

        switch (status) {
        case NFS4ERR_DELAY:
        case NFS4ERR_GRACE:
                return;
        default:
                break;
        }

        mirror = FF_LAYOUT_COMP(lseg, idx);
        err = ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
                                       mirror, offset, length, status, opnum,
                                       GFP_NOIO);
        pnfs_error_mark_layout_for_return(lseg->pls_layout->plh_inode, lseg);
        dprintk("%s: err %d op %d status %u\n", __func__, err, opnum, status);
}

/* NFS_PROTO call done callback routines */
static int ff_layout_read_done_cb(struct rpc_task *task,
                                struct nfs_pgio_header *hdr)
{
        int err;

        trace_nfs4_pnfs_read(hdr, task->tk_status);
        if (task->tk_status < 0)
                ff_layout_io_track_ds_error(hdr->lseg, hdr->pgio_mirror_idx,
                                            hdr->args.offset, hdr->args.count,
                                            hdr->res.op_status, OP_READ,
                                            task->tk_status);
        err = ff_layout_async_handle_error(task, hdr->args.context->state,
                                           hdr->ds_clp, hdr->lseg,
                                           hdr->pgio_mirror_idx);

        clear_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags);
        clear_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags);
        switch (err) {
        case -NFS4ERR_RESET_TO_PNFS:
                if (ff_layout_choose_best_ds_for_read(hdr->lseg,
                                        hdr->pgio_mirror_idx + 1,
                                        &hdr->pgio_mirror_idx))
                        goto out_eagain;
                set_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags);
                return task->tk_status;
        case -NFS4ERR_RESET_TO_MDS:
                set_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags);
                return task->tk_status;
        case -EAGAIN:
                goto out_eagain;
        }

        return 0;
out_eagain:
        rpc_restart_call_prepare(task);
        return -EAGAIN;
}

static bool
ff_layout_need_layoutcommit(struct pnfs_layout_segment *lseg)
{
        return !(FF_LAYOUT_LSEG(lseg)->flags & FF_FLAGS_NO_LAYOUTCOMMIT);
}

/*
 * We reference the rpc_cred of the first WRITE that triggers the need for
 * a LAYOUTCOMMIT, and use it to send the layoutcommit compound.
 * rfc5661 is not clear about which credential should be used.
 *
 * Flexlayout client should treat DS replied FILE_SYNC as DATA_SYNC, so
 * to follow http://www.rfc-editor.org/errata_search.php?rfc=5661&eid=2751
 * we always send layoutcommit after DS writes.
 */
static void
ff_layout_set_layoutcommit(struct inode *inode,
                struct pnfs_layout_segment *lseg,
                loff_t end_offset)
{
        if (!ff_layout_need_layoutcommit(lseg))
                return;

        pnfs_set_layoutcommit(inode, lseg, end_offset);
        dprintk("%s inode %lu pls_end_pos %llu\n", __func__, inode->i_ino,
                (unsigned long long) NFS_I(inode)->layout->plh_lwb);
}

static bool
ff_layout_device_unavailable(struct pnfs_layout_segment *lseg, int idx)
{
        /* No mirroring for now */
        struct nfs4_deviceid_node *node = FF_LAYOUT_DEVID_NODE(lseg, idx);

        return ff_layout_test_devid_unavailable(node);
}

static void ff_layout_read_record_layoutstats_start(struct rpc_task *task,
                struct nfs_pgio_header *hdr)
{
        if (test_and_set_bit(NFS_IOHDR_STAT, &hdr->flags))
                return;
        nfs4_ff_layout_stat_io_start_read(hdr->inode,
                        FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
                        hdr->args.count,
                        task->tk_start);
}

static void ff_layout_read_record_layoutstats_done(struct rpc_task *task,
                struct nfs_pgio_header *hdr)
{
        if (!test_and_clear_bit(NFS_IOHDR_STAT, &hdr->flags))
                return;
        nfs4_ff_layout_stat_io_end_read(task,
                        FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
                        hdr->args.count,
                        hdr->res.count);
        set_bit(NFS_LSEG_LAYOUTRETURN, &hdr->lseg->pls_flags);
}

static int ff_layout_read_prepare_common(struct rpc_task *task,
                                         struct nfs_pgio_header *hdr)
{
        if (unlikely(test_bit(NFS_CONTEXT_BAD, &hdr->args.context->flags))) {
                rpc_exit(task, -EIO);
                return -EIO;
        }
        if (ff_layout_device_unavailable(hdr->lseg, hdr->pgio_mirror_idx)) {
                rpc_exit(task, -EHOSTDOWN);
                return -EAGAIN;
        }

        ff_layout_read_record_layoutstats_start(task, hdr);
        return 0;
}

/*
 * Call ops for the async read/write cases
 * In the case of dense layouts, the offset needs to be reset to its
 * original value.
 */
static void ff_layout_read_prepare_v3(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        if (ff_layout_read_prepare_common(task, hdr))
                return;

        rpc_call_start(task);
}

static void ff_layout_read_prepare_v4(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        if (nfs4_setup_sequence(hdr->ds_clp,
                                &hdr->args.seq_args,
                                &hdr->res.seq_res,
                                task))
                return;

        ff_layout_read_prepare_common(task, hdr);
}

static void ff_layout_read_call_done(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        dprintk("--> %s task->tk_status %d\n", __func__, task->tk_status);

        if (test_bit(NFS_IOHDR_REDO, &hdr->flags) &&
            task->tk_status == 0) {
                nfs4_sequence_done(task, &hdr->res.seq_res);
                return;
        }

        /* Note this may cause RPC to be resent */
        hdr->mds_ops->rpc_call_done(task, hdr);
}

static void ff_layout_read_count_stats(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        ff_layout_read_record_layoutstats_done(task, hdr);
        rpc_count_iostats_metrics(task,
            &NFS_CLIENT(hdr->inode)->cl_metrics[NFSPROC4_CLNT_READ]);
}

static void ff_layout_read_release(void *data)
{
        struct nfs_pgio_header *hdr = data;

        ff_layout_read_record_layoutstats_done(&hdr->task, hdr);
        if (test_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags))
                pnfs_read_resend_pnfs(hdr);
        else if (test_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags))
                ff_layout_reset_read(hdr);
        pnfs_generic_rw_release(data);
}


static int ff_layout_write_done_cb(struct rpc_task *task,
                                struct nfs_pgio_header *hdr)
{
        loff_t end_offs = 0;
        int err;

        trace_nfs4_pnfs_write(hdr, task->tk_status);
        if (task->tk_status < 0)
                ff_layout_io_track_ds_error(hdr->lseg, hdr->pgio_mirror_idx,
                                            hdr->args.offset, hdr->args.count,
                                            hdr->res.op_status, OP_WRITE,
                                            task->tk_status);
        err = ff_layout_async_handle_error(task, hdr->args.context->state,
                                           hdr->ds_clp, hdr->lseg,
                                           hdr->pgio_mirror_idx);

        clear_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags);
        clear_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags);
        switch (err) {
        case -NFS4ERR_RESET_TO_PNFS:
                set_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags);
                return task->tk_status;
        case -NFS4ERR_RESET_TO_MDS:
                set_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags);
                return task->tk_status;
        case -EAGAIN:
                return -EAGAIN;
        }

        if (hdr->res.verf->committed == NFS_FILE_SYNC ||
            hdr->res.verf->committed == NFS_DATA_SYNC)
                end_offs = hdr->mds_offset + (loff_t)hdr->res.count;

        /* Note: if the write is unstable, don't set end_offs until commit */
        ff_layout_set_layoutcommit(hdr->inode, hdr->lseg, end_offs);

        /* zero out fattr since we don't care DS attr at all */
        hdr->fattr.valid = 0;
        if (task->tk_status >= 0)
                nfs_writeback_update_inode(hdr);

        return 0;
}

static int ff_layout_commit_done_cb(struct rpc_task *task,
                                     struct nfs_commit_data *data)
{
        int err;

        trace_nfs4_pnfs_commit_ds(data, task->tk_status);
        if (task->tk_status < 0)
                ff_layout_io_track_ds_error(data->lseg, data->ds_commit_index,
                                            data->args.offset, data->args.count,
                                            data->res.op_status, OP_COMMIT,
                                            task->tk_status);
        err = ff_layout_async_handle_error(task, NULL, data->ds_clp,
                                           data->lseg, data->ds_commit_index);

        switch (err) {
        case -NFS4ERR_RESET_TO_PNFS:
                pnfs_generic_prepare_to_resend_writes(data);
                return -EAGAIN;
        case -NFS4ERR_RESET_TO_MDS:
                pnfs_generic_prepare_to_resend_writes(data);
                return -EAGAIN;
        case -EAGAIN:
                rpc_restart_call_prepare(task);
                return -EAGAIN;
        }

        ff_layout_set_layoutcommit(data->inode, data->lseg, data->lwb);

        return 0;
}

static void ff_layout_write_record_layoutstats_start(struct rpc_task *task,
                struct nfs_pgio_header *hdr)
{
        if (test_and_set_bit(NFS_IOHDR_STAT, &hdr->flags))
                return;
        nfs4_ff_layout_stat_io_start_write(hdr->inode,
                        FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
                        hdr->args.count,
                        task->tk_start);
}

static void ff_layout_write_record_layoutstats_done(struct rpc_task *task,
                struct nfs_pgio_header *hdr)
{
        if (!test_and_clear_bit(NFS_IOHDR_STAT, &hdr->flags))
                return;
        nfs4_ff_layout_stat_io_end_write(task,
                        FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
                        hdr->args.count, hdr->res.count,
                        hdr->res.verf->committed);
        set_bit(NFS_LSEG_LAYOUTRETURN, &hdr->lseg->pls_flags);
}

static int ff_layout_write_prepare_common(struct rpc_task *task,
                                          struct nfs_pgio_header *hdr)
{
        if (unlikely(test_bit(NFS_CONTEXT_BAD, &hdr->args.context->flags))) {
                rpc_exit(task, -EIO);
                return -EIO;
        }

        if (ff_layout_device_unavailable(hdr->lseg, hdr->pgio_mirror_idx)) {
                rpc_exit(task, -EHOSTDOWN);
                return -EAGAIN;
        }

        ff_layout_write_record_layoutstats_start(task, hdr);
        return 0;
}

static void ff_layout_write_prepare_v3(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        if (ff_layout_write_prepare_common(task, hdr))
                return;

        rpc_call_start(task);
}

static void ff_layout_write_prepare_v4(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        if (nfs4_setup_sequence(hdr->ds_clp,
                                &hdr->args.seq_args,
                                &hdr->res.seq_res,
                                task))
                return;

        ff_layout_write_prepare_common(task, hdr);
}

static void ff_layout_write_call_done(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        if (test_bit(NFS_IOHDR_REDO, &hdr->flags) &&
            task->tk_status == 0) {
                nfs4_sequence_done(task, &hdr->res.seq_res);
                return;
        }

        /* Note this may cause RPC to be resent */
        hdr->mds_ops->rpc_call_done(task, hdr);
}

static void ff_layout_write_count_stats(struct rpc_task *task, void *data)
{
        struct nfs_pgio_header *hdr = data;

        ff_layout_write_record_layoutstats_done(task, hdr);
        rpc_count_iostats_metrics(task,
            &NFS_CLIENT(hdr->inode)->cl_metrics[NFSPROC4_CLNT_WRITE]);
}

static void ff_layout_write_release(void *data)
{
        struct nfs_pgio_header *hdr = data;

        ff_layout_write_record_layoutstats_done(&hdr->task, hdr);
        if (test_bit(NFS_IOHDR_RESEND_PNFS, &hdr->flags))
                ff_layout_reset_write(hdr, true);
        else if (test_bit(NFS_IOHDR_RESEND_MDS, &hdr->flags))
                ff_layout_reset_write(hdr, false);
        pnfs_generic_rw_release(data);
}

static void ff_layout_commit_record_layoutstats_start(struct rpc_task *task,
                struct nfs_commit_data *cdata)
{
        if (test_and_set_bit(NFS_IOHDR_STAT, &cdata->flags))
                return;
        nfs4_ff_layout_stat_io_start_write(cdata->inode,
                        FF_LAYOUT_COMP(cdata->lseg, cdata->ds_commit_index),
                        0, task->tk_start);
}

static void ff_layout_commit_record_layoutstats_done(struct rpc_task *task,
                struct nfs_commit_data *cdata)
{
        struct nfs_page *req;
        __u64 count = 0;

        if (!test_and_clear_bit(NFS_IOHDR_STAT, &cdata->flags))
                return;

        if (task->tk_status == 0) {
                list_for_each_entry(req, &cdata->pages, wb_list)
                        count += req->wb_bytes;
        }
        nfs4_ff_layout_stat_io_end_write(task,
                        FF_LAYOUT_COMP(cdata->lseg, cdata->ds_commit_index),
                        count, count, NFS_FILE_SYNC);
        set_bit(NFS_LSEG_LAYOUTRETURN, &cdata->lseg->pls_flags);
}

static void ff_layout_commit_prepare_common(struct rpc_task *task,
                struct nfs_commit_data *cdata)
{
        ff_layout_commit_record_layoutstats_start(task, cdata);
}

static void ff_layout_commit_prepare_v3(struct rpc_task *task, void *data)
{
        ff_layout_commit_prepare_common(task, data);
        rpc_call_start(task);
}

static void ff_layout_commit_prepare_v4(struct rpc_task *task, void *data)
{
        struct nfs_commit_data *wdata = data;

        if (nfs4_setup_sequence(wdata->ds_clp,
                                &wdata->args.seq_args,
                                &wdata->res.seq_res,
                                task))
                return;
        ff_layout_commit_prepare_common(task, data);
}

static void ff_layout_commit_done(struct rpc_task *task, void *data)
{
        pnfs_generic_write_commit_done(task, data);
}

static void ff_layout_commit_count_stats(struct rpc_task *task, void *data)
{
        struct nfs_commit_data *cdata = data;

        ff_layout_commit_record_layoutstats_done(task, cdata);
        rpc_count_iostats_metrics(task,
            &NFS_CLIENT(cdata->inode)->cl_metrics[NFSPROC4_CLNT_COMMIT]);
}

static void ff_layout_commit_release(void *data)
{
        struct nfs_commit_data *cdata = data;

        ff_layout_commit_record_layoutstats_done(&cdata->task, cdata);
        pnfs_generic_commit_release(data);
}

static const struct rpc_call_ops ff_layout_read_call_ops_v3 = {
        .rpc_call_prepare = ff_layout_read_prepare_v3,
        .rpc_call_done = ff_layout_read_call_done,
        .rpc_count_stats = ff_layout_read_count_stats,
        .rpc_release = ff_layout_read_release,
};

static const struct rpc_call_ops ff_layout_read_call_ops_v4 = {
        .rpc_call_prepare = ff_layout_read_prepare_v4,
        .rpc_call_done = ff_layout_read_call_done,
        .rpc_count_stats = ff_layout_read_count_stats,
        .rpc_release = ff_layout_read_release,
};

static const struct rpc_call_ops ff_layout_write_call_ops_v3 = {
        .rpc_call_prepare = ff_layout_write_prepare_v3,
        .rpc_call_done = ff_layout_write_call_done,
        .rpc_count_stats = ff_layout_write_count_stats,
        .rpc_release = ff_layout_write_release,
};

static const struct rpc_call_ops ff_layout_write_call_ops_v4 = {
        .rpc_call_prepare = ff_layout_write_prepare_v4,
        .rpc_call_done = ff_layout_write_call_done,
        .rpc_count_stats = ff_layout_write_count_stats,
        .rpc_release = ff_layout_write_release,
};

static const struct rpc_call_ops ff_layout_commit_call_ops_v3 = {
        .rpc_call_prepare = ff_layout_commit_prepare_v3,
        .rpc_call_done = ff_layout_commit_done,
        .rpc_count_stats = ff_layout_commit_count_stats,
        .rpc_release = ff_layout_commit_release,
};

static const struct rpc_call_ops ff_layout_commit_call_ops_v4 = {
        .rpc_call_prepare = ff_layout_commit_prepare_v4,
        .rpc_call_done = ff_layout_commit_done,
        .rpc_count_stats = ff_layout_commit_count_stats,
        .rpc_release = ff_layout_commit_release,
};

static enum pnfs_try_status
ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
{
        struct pnfs_layout_segment *lseg = hdr->lseg;
        struct nfs4_pnfs_ds *ds;
        struct rpc_clnt *ds_clnt;
        const struct cred *ds_cred;
        loff_t offset = hdr->args.offset;
        u32 idx = hdr->pgio_mirror_idx;
        int vers;
        struct nfs_fh *fh;

        dprintk("--> %s ino %lu pgbase %u req %zu@%llu\n",
                __func__, hdr->inode->i_ino,
                hdr->args.pgbase, (size_t)hdr->args.count, offset);

        ds = nfs4_ff_layout_prepare_ds(lseg, idx, false);
        if (!ds)
                goto out_failed;

        ds_clnt = nfs4_ff_find_or_create_ds_client(lseg, idx, ds->ds_clp,
                                                   hdr->inode);
        if (IS_ERR(ds_clnt))
                goto out_failed;

        ds_cred = ff_layout_get_ds_cred(lseg, idx, hdr->cred);
        if (!ds_cred)
                goto out_failed;

        vers = nfs4_ff_layout_ds_version(lseg, idx);

        dprintk("%s USE DS: %s cl_count %d vers %d\n", __func__,
                ds->ds_remotestr, refcount_read(&ds->ds_clp->cl_count), vers);

        hdr->pgio_done_cb = ff_layout_read_done_cb;
        refcount_inc(&ds->ds_clp->cl_count);
        hdr->ds_clp = ds->ds_clp;
        fh = nfs4_ff_layout_select_ds_fh(lseg, idx);
        if (fh)
                hdr->args.fh = fh;

        if (vers == 4 &&
                !nfs4_ff_layout_select_ds_stateid(lseg, idx, &hdr->args.stateid))
                goto out_failed;

        /*
         * Note that if we ever decide to split across DSes,
         * then we may need to handle dense-like offsets.
         */
        hdr->args.offset = offset;
        hdr->mds_offset = offset;

        /* Perform an asynchronous read to ds */
        nfs_initiate_pgio(ds_clnt, hdr, ds_cred, ds->ds_clp->rpc_ops,
                          vers == 3 ? &ff_layout_read_call_ops_v3 :
                                      &ff_layout_read_call_ops_v4,
                          0, RPC_TASK_SOFTCONN);
        put_cred(ds_cred);
        return PNFS_ATTEMPTED;

out_failed:
        if (ff_layout_avoid_mds_available_ds(lseg))
                return PNFS_TRY_AGAIN;
        return PNFS_NOT_ATTEMPTED;
}

/* Perform async writes. */
static enum pnfs_try_status
ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync)
{
        struct pnfs_layout_segment *lseg = hdr->lseg;
        struct nfs4_pnfs_ds *ds;
        struct rpc_clnt *ds_clnt;
        const struct cred *ds_cred;
        loff_t offset = hdr->args.offset;
        int vers;
        struct nfs_fh *fh;
        int idx = hdr->pgio_mirror_idx;

        ds = nfs4_ff_layout_prepare_ds(lseg, idx, true);
        if (!ds)
                goto out_failed;

        ds_clnt = nfs4_ff_find_or_create_ds_client(lseg, idx, ds->ds_clp,
                                                   hdr->inode);
        if (IS_ERR(ds_clnt))
                goto out_failed;

        ds_cred = ff_layout_get_ds_cred(lseg, idx, hdr->cred);
        if (!ds_cred)
                goto out_failed;

        vers = nfs4_ff_layout_ds_version(lseg, idx);

        dprintk("%s ino %lu sync %d req %zu@%llu DS: %s cl_count %d vers %d\n",
                __func__, hdr->inode->i_ino, sync, (size_t) hdr->args.count,
                offset, ds->ds_remotestr, refcount_read(&ds->ds_clp->cl_count),
                vers);

        hdr->pgio_done_cb = ff_layout_write_done_cb;
        refcount_inc(&ds->ds_clp->cl_count);
        hdr->ds_clp = ds->ds_clp;
        hdr->ds_commit_idx = idx;
        fh = nfs4_ff_layout_select_ds_fh(lseg, idx);
        if (fh)
                hdr->args.fh = fh;

        if (vers == 4 &&
                !nfs4_ff_layout_select_ds_stateid(lseg, idx, &hdr->args.stateid))
                goto out_failed;

        /*
         * Note that if we ever decide to split across DSes,
         * then we may need to handle dense-like offsets.
         */
        hdr->args.offset = offset;

        /* Perform an asynchronous write */
        nfs_initiate_pgio(ds_clnt, hdr, ds_cred, ds->ds_clp->rpc_ops,
                          vers == 3 ? &ff_layout_write_call_ops_v3 :
                                      &ff_layout_write_call_ops_v4,
                          sync, RPC_TASK_SOFTCONN);
        put_cred(ds_cred);
        return PNFS_ATTEMPTED;

out_failed:
        if (ff_layout_avoid_mds_available_ds(lseg))
                return PNFS_TRY_AGAIN;
        return PNFS_NOT_ATTEMPTED;
}

static u32 calc_ds_index_from_commit(struct pnfs_layout_segment *lseg, u32 i)
{
        return i;
}

static struct nfs_fh *
select_ds_fh_from_commit(struct pnfs_layout_segment *lseg, u32 i)
{
        struct nfs4_ff_layout_segment *flseg = FF_LAYOUT_LSEG(lseg);

        /* FIXME: Assume that there is only one NFS version available
         * for the DS.
         */
        return &flseg->mirror_array[i]->fh_versions[0];
}

static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how)
{
        struct pnfs_layout_segment *lseg = data->lseg;
        struct nfs4_pnfs_ds *ds;
        struct rpc_clnt *ds_clnt;
        const struct cred *ds_cred;
        u32 idx;
        int vers, ret;
        struct nfs_fh *fh;

        if (!lseg || !(pnfs_is_valid_lseg(lseg) ||
            test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags)))
                goto out_err;

        idx = calc_ds_index_from_commit(lseg, data->ds_commit_index);
        ds = nfs4_ff_layout_prepare_ds(lseg, idx, true);
        if (!ds)
                goto out_err;

        ds_clnt = nfs4_ff_find_or_create_ds_client(lseg, idx, ds->ds_clp,
                                                   data->inode);
        if (IS_ERR(ds_clnt))
                goto out_err;

        ds_cred = ff_layout_get_ds_cred(lseg, idx, data->cred);
        if (!ds_cred)
                goto out_err;

        vers = nfs4_ff_layout_ds_version(lseg, idx);

        dprintk("%s ino %lu, how %d cl_count %d vers %d\n", __func__,
                data->inode->i_ino, how, refcount_read(&ds->ds_clp->cl_count),
                vers);
        data->commit_done_cb = ff_layout_commit_done_cb;
        data->cred = ds_cred;
        refcount_inc(&ds->ds_clp->cl_count);
        data->ds_clp = ds->ds_clp;
        fh = select_ds_fh_from_commit(lseg, data->ds_commit_index);
        if (fh)
                data->args.fh = fh;

        ret = nfs_initiate_commit(ds_clnt, data, ds->ds_clp->rpc_ops,
                                   vers == 3 ? &ff_layout_commit_call_ops_v3 :
                                               &ff_layout_commit_call_ops_v4,
                                   how, RPC_TASK_SOFTCONN);
        put_cred(ds_cred);
        return ret;
out_err:
        pnfs_generic_prepare_to_resend_writes(data);
        pnfs_generic_commit_release(data);
        return -EAGAIN;
}

static int
ff_layout_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
                           int how, struct nfs_commit_info *cinfo)
{
        return pnfs_generic_commit_pagelist(inode, mds_pages, how, cinfo,
                                            ff_layout_initiate_commit);
}

static struct pnfs_ds_commit_info *
ff_layout_get_ds_info(struct inode *inode)
{
        struct pnfs_layout_hdr *layout = NFS_I(inode)->layout;

        if (layout == NULL)
                return NULL;

        return &FF_LAYOUT_FROM_HDR(layout)->commit_info;
}

static void
ff_layout_free_deviceid_node(struct nfs4_deviceid_node *d)
{
        nfs4_ff_layout_free_deviceid(container_of(d, struct nfs4_ff_layout_ds,
                                                  id_node));
}

static int ff_layout_encode_ioerr(struct xdr_stream *xdr,
                                  const struct nfs4_layoutreturn_args *args,
                                  const struct nfs4_flexfile_layoutreturn_args *ff_args)
{
        __be32 *start;

        start = xdr_reserve_space(xdr, 4);
        if (unlikely(!start))
                return -E2BIG;

        *start = cpu_to_be32(ff_args->num_errors);
        /* This assume we always return _ALL_ layouts */
        return ff_layout_encode_ds_ioerr(xdr, &ff_args->errors);
}

static void
encode_opaque_fixed(struct xdr_stream *xdr, const void *buf, size_t len)
{
        WARN_ON_ONCE(xdr_stream_encode_opaque_fixed(xdr, buf, len) < 0);
}

static void
ff_layout_encode_ff_iostat_head(struct xdr_stream *xdr,
                            const nfs4_stateid *stateid,
                            const struct nfs42_layoutstat_devinfo *devinfo)
{
        __be32 *p;

        p = xdr_reserve_space(xdr, 8 + 8);
        p = xdr_encode_hyper(p, devinfo->offset);
        p = xdr_encode_hyper(p, devinfo->length);
        encode_opaque_fixed(xdr, stateid->data, NFS4_STATEID_SIZE);
        p = xdr_reserve_space(xdr, 4*8);
        p = xdr_encode_hyper(p, devinfo->read_count);
        p = xdr_encode_hyper(p, devinfo->read_bytes);
        p = xdr_encode_hyper(p, devinfo->write_count);
        p = xdr_encode_hyper(p, devinfo->write_bytes);
        encode_opaque_fixed(xdr, devinfo->dev_id.data, NFS4_DEVICEID4_SIZE);
}

static void
ff_layout_encode_ff_iostat(struct xdr_stream *xdr,
                            const nfs4_stateid *stateid,
                            const struct nfs42_layoutstat_devinfo *devinfo)
{
        ff_layout_encode_ff_iostat_head(xdr, stateid, devinfo);
        ff_layout_encode_ff_layoutupdate(xdr, devinfo,
                        devinfo->ld_private.data);
}

/* report nothing for now */
static void ff_layout_encode_iostats_array(struct xdr_stream *xdr,
                const struct nfs4_layoutreturn_args *args,
                struct nfs4_flexfile_layoutreturn_args *ff_args)
{
        __be32 *p;
        int i;

        p = xdr_reserve_space(xdr, 4);
        *p = cpu_to_be32(ff_args->num_dev);
        for (i = 0; i < ff_args->num_dev; i++)
                ff_layout_encode_ff_iostat(xdr,
                                &args->layout->plh_stateid,
                                &ff_args->devinfo[i]);
}

static void
ff_layout_free_iostats_array(struct nfs42_layoutstat_devinfo *devinfo,
                unsigned int num_entries)
{
        unsigned int i;

        for (i = 0; i < num_entries; i++) {
                if (!devinfo[i].ld_private.ops)
                        continue;

                if (!devinfo[i].ld_private.ops->free)
                        continue;
                devinfo[i].ld_private.ops->free(&devinfo[i].ld_private);
        }
}

static struct nfs4_deviceid_node *
ff_layout_alloc_deviceid_node(struct nfs_server *server,
                              struct pnfs_device *pdev, gfp_t gfp_flags)
{
        struct nfs4_ff_layout_ds *dsaddr;

        dsaddr = nfs4_ff_alloc_deviceid_node(server, pdev, gfp_flags);
        if (!dsaddr)
                return NULL;
        return &dsaddr->id_node;
}

static void
ff_layout_encode_layoutreturn(struct xdr_stream *xdr,
                const void *voidargs,
                const struct nfs4_xdr_opaque_data *ff_opaque)
{
        const struct nfs4_layoutreturn_args *args = voidargs;
        struct nfs4_flexfile_layoutreturn_args *ff_args = ff_opaque->data;
        struct xdr_buf tmp_buf = {
                .head = {
                        [0] = {
                                .iov_base = page_address(ff_args->pages[0]),
                        },
                },
                .buflen = PAGE_SIZE,
        };
        struct xdr_stream tmp_xdr;
        __be32 *start;

        dprintk("%s: Begin\n", __func__);

        xdr_init_encode(&tmp_xdr, &tmp_buf, NULL);

        ff_layout_encode_ioerr(&tmp_xdr, args, ff_args);
        ff_layout_encode_iostats_array(&tmp_xdr, args, ff_args);

        start = xdr_reserve_space(xdr, 4);
        *start = cpu_to_be32(tmp_buf.len);
        xdr_write_pages(xdr, ff_args->pages, 0, tmp_buf.len);

        dprintk("%s: Return\n", __func__);
}

static void
ff_layout_free_layoutreturn(struct nfs4_xdr_opaque_data *args)
{
        struct nfs4_flexfile_layoutreturn_args *ff_args;

        if (!args->data)
                return;
        ff_args = args->data;
        args->data = NULL;

        ff_layout_free_ds_ioerr(&ff_args->errors);
        ff_layout_free_iostats_array(ff_args->devinfo, ff_args->num_dev);

        put_page(ff_args->pages[0]);
        kfree(ff_args);
}

static const struct nfs4_xdr_opaque_ops layoutreturn_ops = {
        .encode = ff_layout_encode_layoutreturn,
        .free = ff_layout_free_layoutreturn,
};

static int
ff_layout_prepare_layoutreturn(struct nfs4_layoutreturn_args *args)
{
        struct nfs4_flexfile_layoutreturn_args *ff_args;
        struct nfs4_flexfile_layout *ff_layout = FF_LAYOUT_FROM_HDR(args->layout);

        ff_args = kmalloc(sizeof(*ff_args), GFP_KERNEL);
        if (!ff_args)
                goto out_nomem;
        ff_args->pages[0] = alloc_page(GFP_KERNEL);
        if (!ff_args->pages[0])
                goto out_nomem_free;

        INIT_LIST_HEAD(&ff_args->errors);
        ff_args->num_errors = ff_layout_fetch_ds_ioerr(args->layout,
                        &args->range, &ff_args->errors,
                        FF_LAYOUTRETURN_MAXERR);

        spin_lock(&args->inode->i_lock);
        ff_args->num_dev = ff_layout_mirror_prepare_stats(&ff_layout->generic_hdr,
                        &ff_args->devinfo[0], ARRAY_SIZE(ff_args->devinfo));
        spin_unlock(&args->inode->i_lock);

        args->ld_private->ops = &layoutreturn_ops;
        args->ld_private->data = ff_args;
        return 0;
out_nomem_free:
        kfree(ff_args);
out_nomem:
        return -ENOMEM;
}

static int
ff_layout_ntop4(const struct sockaddr *sap, char *buf, const size_t buflen)
{
        const struct sockaddr_in *sin = (struct sockaddr_in *)sap;

        return snprintf(buf, buflen, "%pI4", &sin->sin_addr);
}

static size_t
ff_layout_ntop6_noscopeid(const struct sockaddr *sap, char *buf,
                          const int buflen)
{
        const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
        const struct in6_addr *addr = &sin6->sin6_addr;

        /*
         * RFC 4291, Section 2.2.2
         *
         * Shorthanded ANY address
         */
        if (ipv6_addr_any(addr))
                return snprintf(buf, buflen, "::");

        /*
         * RFC 4291, Section 2.2.2
         *
         * Shorthanded loopback address
         */
        if (ipv6_addr_loopback(addr))
                return snprintf(buf, buflen, "::1");

        /*
         * RFC 4291, Section 2.2.3
         *
         * Special presentation address format for mapped v4
         * addresses.
         */
        if (ipv6_addr_v4mapped(addr))
                return snprintf(buf, buflen, "::ffff:%pI4",
                                        &addr->s6_addr32[3]);

        /*
         * RFC 4291, Section 2.2.1
         */
        return snprintf(buf, buflen, "%pI6c", addr);
}

/* Derived from rpc_sockaddr2uaddr */
static void
ff_layout_encode_netaddr(struct xdr_stream *xdr, struct nfs4_pnfs_ds_addr *da)
{
        struct sockaddr *sap = (struct sockaddr *)&da->da_addr;
        char portbuf[RPCBIND_MAXUADDRPLEN];
        char addrbuf[RPCBIND_MAXUADDRLEN];
        char *netid;
        unsigned short port;
        int len, netid_len;
        __be32 *p;

        switch (sap->sa_family) {
        case AF_INET:
                if (ff_layout_ntop4(sap, addrbuf, sizeof(addrbuf)) == 0)
                        return;
                port = ntohs(((struct sockaddr_in *)sap)->sin_port);
                netid = "tcp";
                netid_len = 3;
                break;
        case AF_INET6:
                if (ff_layout_ntop6_noscopeid(sap, addrbuf, sizeof(addrbuf)) == 0)
                        return;
                port = ntohs(((struct sockaddr_in6 *)sap)->sin6_port);
                netid = "tcp6";
                netid_len = 4;
                break;
        default:
                /* we only support tcp and tcp6 */
                WARN_ON_ONCE(1);
                return;
        }

        snprintf(portbuf, sizeof(portbuf), ".%u.%u", port >> 8, port & 0xff);
        len = strlcat(addrbuf, portbuf, sizeof(addrbuf));

        p = xdr_reserve_space(xdr, 4 + netid_len);
        xdr_encode_opaque(p, netid, netid_len);

        p = xdr_reserve_space(xdr, 4 + len);
        xdr_encode_opaque(p, addrbuf, len);
}

static void
ff_layout_encode_nfstime(struct xdr_stream *xdr,
                         ktime_t t)
{
        struct timespec64 ts;
        __be32 *p;

        p = xdr_reserve_space(xdr, 12);
        ts = ktime_to_timespec64(t);
        p = xdr_encode_hyper(p, ts.tv_sec);
        *p++ = cpu_to_be32(ts.tv_nsec);
}

static void
ff_layout_encode_io_latency(struct xdr_stream *xdr,
                            struct nfs4_ff_io_stat *stat)
{
        __be32 *p;

        p = xdr_reserve_space(xdr, 5 * 8);
        p = xdr_encode_hyper(p, stat->ops_requested);
        p = xdr_encode_hyper(p, stat->bytes_requested);
        p = xdr_encode_hyper(p, stat->ops_completed);
        p = xdr_encode_hyper(p, stat->bytes_completed);
        p = xdr_encode_hyper(p, stat->bytes_not_delivered);
        ff_layout_encode_nfstime(xdr, stat->total_busy_time);
        ff_layout_encode_nfstime(xdr, stat->aggregate_completion_time);
}

static void
ff_layout_encode_ff_layoutupdate(struct xdr_stream *xdr,
                              const struct nfs42_layoutstat_devinfo *devinfo,
                              struct nfs4_ff_layout_mirror *mirror)
{
        struct nfs4_pnfs_ds_addr *da;
        struct nfs4_pnfs_ds *ds = mirror->mirror_ds->ds;
        struct nfs_fh *fh = &mirror->fh_versions[0];
        __be32 *p;

        da = list_first_entry(&ds->ds_addrs, struct nfs4_pnfs_ds_addr, da_node);
        dprintk("%s: DS %s: encoding address %s\n",
                __func__, ds->ds_remotestr, da->da_remotestr);
        /* netaddr4 */
        ff_layout_encode_netaddr(xdr, da);
        /* nfs_fh4 */
        p = xdr_reserve_space(xdr, 4 + fh->size);
        xdr_encode_opaque(p, fh->data, fh->size);
        /* ff_io_latency4 read */
        spin_lock(&mirror->lock);
        ff_layout_encode_io_latency(xdr, &mirror->read_stat.io_stat);
        /* ff_io_latency4 write */
        ff_layout_encode_io_latency(xdr, &mirror->write_stat.io_stat);
        spin_unlock(&mirror->lock);
        /* nfstime4 */
        ff_layout_encode_nfstime(xdr, ktime_sub(ktime_get(), mirror->start_time));
        /* bool */
        p = xdr_reserve_space(xdr, 4);
        *p = cpu_to_be32(false);
}

static void
ff_layout_encode_layoutstats(struct xdr_stream *xdr, const void *args,
                             const struct nfs4_xdr_opaque_data *opaque)
{
        struct nfs42_layoutstat_devinfo *devinfo = container_of(opaque,
                        struct nfs42_layoutstat_devinfo, ld_private);
        __be32 *start;

        /* layoutupdate length */
        start = xdr_reserve_space(xdr, 4);
        ff_layout_encode_ff_layoutupdate(xdr, devinfo, opaque->data);

        *start = cpu_to_be32((xdr->p - start - 1) * 4);
}

static void
ff_layout_free_layoutstats(struct nfs4_xdr_opaque_data *opaque)
{
        struct nfs4_ff_layout_mirror *mirror = opaque->data;

        ff_layout_put_mirror(mirror);
}

static const struct nfs4_xdr_opaque_ops layoutstat_ops = {
        .encode = ff_layout_encode_layoutstats,
        .free   = ff_layout_free_layoutstats,
};

static int
ff_layout_mirror_prepare_stats(struct pnfs_layout_hdr *lo,
                               struct nfs42_layoutstat_devinfo *devinfo,
                               int dev_limit)
{
        struct nfs4_flexfile_layout *ff_layout = FF_LAYOUT_FROM_HDR(lo);
        struct nfs4_ff_layout_mirror *mirror;
        struct nfs4_deviceid_node *dev;
        int i = 0;

        list_for_each_entry(mirror, &ff_layout->mirrors, mirrors) {
                if (i >= dev_limit)
                        break;
                if (IS_ERR_OR_NULL(mirror->mirror_ds))
                        continue;
                if (!test_and_clear_bit(NFS4_FF_MIRROR_STAT_AVAIL, &mirror->flags))
                        continue;
                /* mirror refcount put in cleanup_layoutstats */
                if (!refcount_inc_not_zero(&mirror->ref))
                        continue;
                dev = &mirror->mirror_ds->id_node; 
                memcpy(&devinfo->dev_id, &dev->deviceid, NFS4_DEVICEID4_SIZE);
                devinfo->offset = 0;
                devinfo->length = NFS4_MAX_UINT64;
                spin_lock(&mirror->lock);
                devinfo->read_count = mirror->read_stat.io_stat.ops_completed;
                devinfo->read_bytes = mirror->read_stat.io_stat.bytes_completed;
                devinfo->write_count = mirror->write_stat.io_stat.ops_completed;
                devinfo->write_bytes = mirror->write_stat.io_stat.bytes_completed;
                spin_unlock(&mirror->lock);
                devinfo->layout_type = LAYOUT_FLEX_FILES;
                devinfo->ld_private.ops = &layoutstat_ops;
                devinfo->ld_private.data = mirror;

                devinfo++;
                i++;
        }
        return i;
}

static int
ff_layout_prepare_layoutstats(struct nfs42_layoutstat_args *args)
{
        struct nfs4_flexfile_layout *ff_layout;
        const int dev_count = PNFS_LAYOUTSTATS_MAXDEV;

        /* For now, send at most PNFS_LAYOUTSTATS_MAXDEV statistics */
        args->devinfo = kmalloc_array(dev_count, sizeof(*args->devinfo), GFP_NOIO);
        if (!args->devinfo)
                return -ENOMEM;

        spin_lock(&args->inode->i_lock);
        ff_layout = FF_LAYOUT_FROM_HDR(NFS_I(args->inode)->layout);
        args->num_dev = ff_layout_mirror_prepare_stats(&ff_layout->generic_hdr,
                        &args->devinfo[0], dev_count);
        spin_unlock(&args->inode->i_lock);
        if (!args->num_dev) {
                kfree(args->devinfo);
                args->devinfo = NULL;
                return -ENOENT;
        }

        return 0;
}

static int
ff_layout_set_layoutdriver(struct nfs_server *server,
                const struct nfs_fh *dummy)
{
#if IS_ENABLED(CONFIG_NFS_V4_2)
        server->caps |= NFS_CAP_LAYOUTSTATS;
#endif
        return 0;
}

static struct pnfs_layoutdriver_type flexfilelayout_type = {
        .id                     = LAYOUT_FLEX_FILES,
        .name                   = "LAYOUT_FLEX_FILES",
        .owner                  = THIS_MODULE,
        .flags                  = PNFS_LAYOUTGET_ON_OPEN,
        .max_layoutget_response = 4096, /* 1 page or so... */
        .set_layoutdriver       = ff_layout_set_layoutdriver,
        .alloc_layout_hdr       = ff_layout_alloc_layout_hdr,
        .free_layout_hdr        = ff_layout_free_layout_hdr,
        .alloc_lseg             = ff_layout_alloc_lseg,
        .free_lseg              = ff_layout_free_lseg,
        .add_lseg               = ff_layout_add_lseg,
        .pg_read_ops            = &ff_layout_pg_read_ops,
        .pg_write_ops           = &ff_layout_pg_write_ops,
        .get_ds_info            = ff_layout_get_ds_info,
        .free_deviceid_node     = ff_layout_free_deviceid_node,
        .mark_request_commit    = pnfs_layout_mark_request_commit,
        .clear_request_commit   = pnfs_generic_clear_request_commit,
        .scan_commit_lists      = pnfs_generic_scan_commit_lists,
        .recover_commit_reqs    = pnfs_generic_recover_commit_reqs,
        .commit_pagelist        = ff_layout_commit_pagelist,
        .read_pagelist          = ff_layout_read_pagelist,
        .write_pagelist         = ff_layout_write_pagelist,
        .alloc_deviceid_node    = ff_layout_alloc_deviceid_node,
        .prepare_layoutreturn   = ff_layout_prepare_layoutreturn,
        .sync                   = pnfs_nfs_generic_sync,
        .prepare_layoutstats    = ff_layout_prepare_layoutstats,
};

static int __init nfs4flexfilelayout_init(void)
{
        printk(KERN_INFO "%s: NFSv4 Flexfile Layout Driver Registering...\n",
               __func__);
        return pnfs_register_layoutdriver(&flexfilelayout_type);
}

static void __exit nfs4flexfilelayout_exit(void)
{
        printk(KERN_INFO "%s: NFSv4 Flexfile Layout Driver Unregistering...\n",
               __func__);
        pnfs_unregister_layoutdriver(&flexfilelayout_type);
}

MODULE_ALIAS("nfs-layouttype4-4");

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("The NFSv4 flexfile layout driver");

module_init(nfs4flexfilelayout_init);
module_exit(nfs4flexfilelayout_exit);