// SPDX-License-Identifier: GPL-2.0
/*
 * Device operations for the pnfs nfs4 file layout driver.
 *
 * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
 *
 * Tao Peng <bergwolf@primarydata.com>
 */

#include <linux/nfs_fs.h>
#include <linux/vmalloc.h>
#include <linux/module.h>
#include <linux/sunrpc/addr.h>

#include "../internal.h"
#include "../nfs4session.h"
#include "flexfilelayout.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

static unsigned int dataserver_timeo = NFS_DEF_TCP_TIMEO;
static unsigned int dataserver_retrans;

static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg);

void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
{
        if (!IS_ERR_OR_NULL(mirror_ds))
                nfs4_put_deviceid_node(&mirror_ds->id_node);
}

void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
{
        nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
        nfs4_pnfs_ds_put(mirror_ds->ds);
        kfree(mirror_ds->ds_versions);
        kfree_rcu(mirror_ds, id_node.rcu);
}

/* Decode opaque device data and construct new_ds using it */
struct nfs4_ff_layout_ds *
nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
                            gfp_t gfp_flags)
{
        struct xdr_stream stream;
        struct xdr_buf buf;
        struct page *scratch;
        struct list_head dsaddrs;
        struct nfs4_pnfs_ds_addr *da;
        struct nfs4_ff_layout_ds *new_ds = NULL;
        struct nfs4_ff_ds_version *ds_versions = NULL;
        u32 mp_count;
        u32 version_count;
        __be32 *p;
        int i, ret = -ENOMEM;

        /* set up xdr stream */
        scratch = alloc_page(gfp_flags);
        if (!scratch)
                goto out_err;

        new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
        if (!new_ds)
                goto out_scratch;

        nfs4_init_deviceid_node(&new_ds->id_node,
                                server,
                                &pdev->dev_id);
        INIT_LIST_HEAD(&dsaddrs);

        xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
        xdr_set_scratch_page(&stream, scratch);

        /* multipath count */
        p = xdr_inline_decode(&stream, 4);
        if (unlikely(!p))
                goto out_err_drain_dsaddrs;
        mp_count = be32_to_cpup(p);
        dprintk("%s: multipath ds count %d\n", __func__, mp_count);

        for (i = 0; i < mp_count; i++) {
                /* multipath ds */
                da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
                                            &stream, gfp_flags);
                if (da)
                        list_add_tail(&da->da_node, &dsaddrs);
        }
        if (list_empty(&dsaddrs)) {
                dprintk("%s: no suitable DS addresses found\n",
                        __func__);
                ret = -ENOMEDIUM;
                goto out_err_drain_dsaddrs;
        }

        /* version count */
        p = xdr_inline_decode(&stream, 4);
        if (unlikely(!p))
                goto out_err_drain_dsaddrs;
        version_count = be32_to_cpup(p);
        dprintk("%s: version count %d\n", __func__, version_count);

        ds_versions = kcalloc(version_count,
                              sizeof(struct nfs4_ff_ds_version),
                              gfp_flags);
        if (!ds_versions)
                goto out_scratch;

        for (i = 0; i < version_count; i++) {
                /* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
                 * tightly_coupled(4) */
                p = xdr_inline_decode(&stream, 20);
                if (unlikely(!p))
                        goto out_err_drain_dsaddrs;
                ds_versions[i].version = be32_to_cpup(p++);
                ds_versions[i].minor_version = be32_to_cpup(p++);
                ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
                ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
                ds_versions[i].tightly_coupled = be32_to_cpup(p);

                if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
                        ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
                if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
                        ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;

                /*
                 * check for valid major/minor combination.
                 * currently we support dataserver which talk:
                 *   v3, v4.0, v4.1, v4.2
                 */
                if (!((ds_versions[i].version == 3 && ds_versions[i].minor_version == 0) ||
                        (ds_versions[i].version == 4 && ds_versions[i].minor_version < 3))) {
                        dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
                                i, ds_versions[i].version,
                                ds_versions[i].minor_version);
                        ret = -EPROTONOSUPPORT;
                        goto out_err_drain_dsaddrs;
                }

                dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
                        __func__, i, ds_versions[i].version,
                        ds_versions[i].minor_version,
                        ds_versions[i].rsize,
                        ds_versions[i].wsize,
                        ds_versions[i].tightly_coupled);
        }

        new_ds->ds_versions = ds_versions;
        new_ds->ds_versions_cnt = version_count;

        new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
        if (!new_ds->ds)
                goto out_err_drain_dsaddrs;

        /* If DS was already in cache, free ds addrs */
        while (!list_empty(&dsaddrs)) {
                da = list_first_entry(&dsaddrs,
                                      struct nfs4_pnfs_ds_addr,
                                      da_node);
                list_del_init(&da->da_node);
                kfree(da->da_remotestr);
                kfree(da);
        }

        __free_page(scratch);
        return new_ds;

out_err_drain_dsaddrs:
        while (!list_empty(&dsaddrs)) {
                da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
                                      da_node);
                list_del_init(&da->da_node);
                kfree(da->da_remotestr);
                kfree(da);
        }

        kfree(ds_versions);
out_scratch:
        __free_page(scratch);
out_err:
        kfree(new_ds);

        dprintk("%s ERROR: returning %d\n", __func__, ret);
        return NULL;
}

static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
                            u64 offset, u64 length)
{
        u64 end;

        end = max_t(u64, pnfs_end_offset(err->offset, err->length),
                    pnfs_end_offset(offset, length));
        err->offset = min_t(u64, err->offset, offset);
        err->length = end - err->offset;
}

static int
ff_ds_error_match(const struct nfs4_ff_layout_ds_err *e1,
                const struct nfs4_ff_layout_ds_err *e2)
{
        int ret;

        if (e1->opnum != e2->opnum)
                return e1->opnum < e2->opnum ? -1 : 1;
        if (e1->status != e2->status)
                return e1->status < e2->status ? -1 : 1;
        ret = memcmp(e1->stateid.data, e2->stateid.data,
                        sizeof(e1->stateid.data));
        if (ret != 0)
                return ret;
        ret = memcmp(&e1->deviceid, &e2->deviceid, sizeof(e1->deviceid));
        if (ret != 0)
                return ret;
        if (pnfs_end_offset(e1->offset, e1->length) < e2->offset)
                return -1;
        if (e1->offset > pnfs_end_offset(e2->offset, e2->length))
                return 1;
        /* If ranges overlap or are contiguous, they are the same */
        return 0;
}

static void
ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
                              struct nfs4_ff_layout_ds_err *dserr)
{
        struct nfs4_ff_layout_ds_err *err, *tmp;
        struct list_head *head = &flo->error_list;
        int match;

        /* Do insertion sort w/ merges */
        list_for_each_entry_safe(err, tmp, &flo->error_list, list) {
                match = ff_ds_error_match(err, dserr);
                if (match < 0)
                        continue;
                if (match > 0) {
                        /* Add entry "dserr" _before_ entry "err" */
                        head = &err->list;
                        break;
                }
                /* Entries match, so merge "err" into "dserr" */
                extend_ds_error(dserr, err->offset, err->length);
                list_replace(&err->list, &dserr->list);
                kfree(err);
                return;
        }

        list_add_tail(&dserr->list, head);
}

int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
                             struct nfs4_ff_layout_mirror *mirror, u64 offset,
                             u64 length, int status, enum nfs_opnum4 opnum,
                             gfp_t gfp_flags)
{
        struct nfs4_ff_layout_ds_err *dserr;

        if (status == 0)
                return 0;

        if (IS_ERR_OR_NULL(mirror->mirror_ds))
                return -EINVAL;

        dserr = kmalloc(sizeof(*dserr), gfp_flags);
        if (!dserr)
                return -ENOMEM;

        INIT_LIST_HEAD(&dserr->list);
        dserr->offset = offset;
        dserr->length = length;
        dserr->status = status;
        dserr->opnum = opnum;
        nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
        memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
               NFS4_DEVICEID4_SIZE);

        spin_lock(&flo->generic_hdr.plh_inode->i_lock);
        ff_layout_add_ds_error_locked(flo, dserr);
        spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
        return 0;
}

static const struct cred *
ff_layout_get_mirror_cred(struct nfs4_ff_layout_mirror *mirror, u32 iomode)
{
        const struct cred *cred, __rcu **pcred;

        if (iomode == IOMODE_READ)
                pcred = &mirror->ro_cred;
        else
                pcred = &mirror->rw_cred;

        rcu_read_lock();
        do {
                cred = rcu_dereference(*pcred);
                if (!cred)
                        break;

                cred = get_cred_rcu(cred);
        } while(!cred);
        rcu_read_unlock();
        return cred;
}

struct nfs_fh *
nfs4_ff_layout_select_ds_fh(struct nfs4_ff_layout_mirror *mirror)
{
        /* FIXME: For now assume there is only 1 version available for the DS */
        return &mirror->fh_versions[0];
}

void
nfs4_ff_layout_select_ds_stateid(const struct nfs4_ff_layout_mirror *mirror,
                nfs4_stateid *stateid)
{
        if (nfs4_ff_layout_ds_version(mirror) == 4)
                nfs4_stateid_copy(stateid, &mirror->stateid);
}

static bool
ff_layout_init_mirror_ds(struct pnfs_layout_hdr *lo,
                         struct nfs4_ff_layout_mirror *mirror)
{
        if (mirror == NULL)
                goto outerr;
        if (mirror->mirror_ds == NULL) {
                struct nfs4_deviceid_node *node;
                struct nfs4_ff_layout_ds *mirror_ds = ERR_PTR(-ENODEV);

                node = nfs4_find_get_deviceid(NFS_SERVER(lo->plh_inode),
                                &mirror->devid, lo->plh_lc_cred,
                                GFP_KERNEL);
                if (node)
                        mirror_ds = FF_LAYOUT_MIRROR_DS(node);

                /* check for race with another call to this function */
                if (cmpxchg(&mirror->mirror_ds, NULL, mirror_ds) &&
                    mirror_ds != ERR_PTR(-ENODEV))
                        nfs4_put_deviceid_node(node);
        }

        if (IS_ERR(mirror->mirror_ds))
                goto outerr;

        return true;
outerr:
        return false;
}

/**
 * nfs4_ff_layout_prepare_ds - prepare a DS connection for an RPC call
 * @lseg: the layout segment we're operating on
 * @mirror: layout mirror describing the DS to use
 * @fail_return: return layout on connect failure?
 *
 * Try to prepare a DS connection to accept an RPC call. This involves
 * selecting a mirror to use and connecting the client to it if it's not
 * already connected.
 *
 * Since we only need a single functioning mirror to satisfy a read, we don't
 * want to return the layout if there is one. For writes though, any down
 * mirror should result in a LAYOUTRETURN. @fail_return is how we distinguish
 * between the two cases.
 *
 * Returns a pointer to a connected DS object on success or NULL on failure.
 */
struct nfs4_pnfs_ds *
nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
                          struct nfs4_ff_layout_mirror *mirror,
                          bool fail_return)
{
        struct nfs4_pnfs_ds *ds = NULL;
        struct inode *ino = lseg->pls_layout->plh_inode;
        struct nfs_server *s = NFS_SERVER(ino);
        unsigned int max_payload;
        int status;

        if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror))
                goto noconnect;

        ds = mirror->mirror_ds->ds;
        /* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
        smp_rmb();
        if (ds->ds_clp)
                goto out;

        /* FIXME: For now we assume the server sent only one version of NFS
         * to use for the DS.
         */
        status = nfs4_pnfs_ds_connect(s, ds, &mirror->mirror_ds->id_node,
                             dataserver_timeo, dataserver_retrans,
                             mirror->mirror_ds->ds_versions[0].version,
                             mirror->mirror_ds->ds_versions[0].minor_version);

        /* connect success, check rsize/wsize limit */
        if (!status) {
                max_payload =
                        nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
                                       NULL);
                if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
                        mirror->mirror_ds->ds_versions[0].rsize = max_payload;
                if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
                        mirror->mirror_ds->ds_versions[0].wsize = max_payload;
                goto out;
        }
noconnect:
        ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
                                 mirror, lseg->pls_range.offset,
                                 lseg->pls_range.length, NFS4ERR_NXIO,
                                 OP_ILLEGAL, GFP_NOIO);
        ff_layout_send_layouterror(lseg);
        if (fail_return || !ff_layout_has_available_ds(lseg))
                pnfs_error_mark_layout_for_return(ino, lseg);
        ds = NULL;
out:
        return ds;
}

const struct cred *
ff_layout_get_ds_cred(struct nfs4_ff_layout_mirror *mirror,
                      const struct pnfs_layout_range *range,
                      const struct cred *mdscred)
{
        const struct cred *cred;

        if (mirror && !mirror->mirror_ds->ds_versions[0].tightly_coupled) {
                cred = ff_layout_get_mirror_cred(mirror, range->iomode);
                if (!cred)
                        cred = get_cred(mdscred);
        } else {
                cred = get_cred(mdscred);
        }
        return cred;
}

/**
 * nfs4_ff_find_or_create_ds_client - Find or create a DS rpc client
 * @mirror: pointer to the mirror
 * @ds_clp: nfs_client for the DS
 * @inode: pointer to inode
 *
 * Find or create a DS rpc client with th MDS server rpc client auth flavor
 * in the nfs_client cl_ds_clients list.
 */
struct rpc_clnt *
nfs4_ff_find_or_create_ds_client(struct nfs4_ff_layout_mirror *mirror,
                                 struct nfs_client *ds_clp, struct inode *inode)
{
        switch (mirror->mirror_ds->ds_versions[0].version) {
        case 3:
                /* For NFSv3 DS, flavor is set when creating DS connections */
                return ds_clp->cl_rpcclient;
        case 4:
                return nfs4_find_or_create_ds_client(ds_clp, inode);
        default:
                BUG();
        }
}

void ff_layout_free_ds_ioerr(struct list_head *head)
{
        struct nfs4_ff_layout_ds_err *err;

        while (!list_empty(head)) {
                err = list_first_entry(head,
                                struct nfs4_ff_layout_ds_err,
                                list);
                list_del(&err->list);
                kfree(err);
        }
}

/* called with inode i_lock held */
int ff_layout_encode_ds_ioerr(struct xdr_stream *xdr, const struct list_head *head)
{
        struct nfs4_ff_layout_ds_err *err;
        __be32 *p;

        list_for_each_entry(err, head, list) {
                /* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
                 * + array length + deviceid(NFS4_DEVICEID4_SIZE)
                 * + status(4) + opnum(4)
                 */
                p = xdr_reserve_space(xdr,
                                28 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
                if (unlikely(!p))
                        return -ENOBUFS;
                p = xdr_encode_hyper(p, err->offset);
                p = xdr_encode_hyper(p, err->length);
                p = xdr_encode_opaque_fixed(p, &err->stateid,
                                            NFS4_STATEID_SIZE);
                /* Encode 1 error */
                *p++ = cpu_to_be32(1);
                p = xdr_encode_opaque_fixed(p, &err->deviceid,
                                            NFS4_DEVICEID4_SIZE);
                *p++ = cpu_to_be32(err->status);
                *p++ = cpu_to_be32(err->opnum);
                dprintk("%s: offset %llu length %llu status %d op %d\n",
                        __func__, err->offset, err->length, err->status,
                        err->opnum);
        }

        return 0;
}

static
unsigned int do_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
                                      const struct pnfs_layout_range *range,
                                      struct list_head *head,
                                      unsigned int maxnum)
{
        struct nfs4_flexfile_layout *flo = FF_LAYOUT_FROM_HDR(lo);
        struct inode *inode = lo->plh_inode;
        struct nfs4_ff_layout_ds_err *err, *n;
        unsigned int ret = 0;

        spin_lock(&inode->i_lock);
        list_for_each_entry_safe(err, n, &flo->error_list, list) {
                if (!pnfs_is_range_intersecting(err->offset,
                                pnfs_end_offset(err->offset, err->length),
                                range->offset,
                                pnfs_end_offset(range->offset, range->length)))
                        continue;
                if (!maxnum)
                        break;
                list_move(&err->list, head);
                maxnum--;
                ret++;
        }
        spin_unlock(&inode->i_lock);
        return ret;
}

unsigned int ff_layout_fetch_ds_ioerr(struct pnfs_layout_hdr *lo,
                                      const struct pnfs_layout_range *range,
                                      struct list_head *head,
                                      unsigned int maxnum)
{
        unsigned int ret;

        ret = do_layout_fetch_ds_ioerr(lo, range, head, maxnum);
        /* If we're over the max, discard all remaining entries */
        if (ret == maxnum) {
                LIST_HEAD(discard);
                do_layout_fetch_ds_ioerr(lo, range, &discard, -1);
                ff_layout_free_ds_ioerr(&discard);
        }
        return ret;
}

static bool ff_read_layout_has_available_ds(struct pnfs_layout_segment *lseg)
{
        struct nfs4_ff_layout_mirror *mirror;
        struct nfs4_deviceid_node *devid;
        u32 idx;

        for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
                mirror = FF_LAYOUT_COMP(lseg, idx);
                if (mirror) {
                        if (!mirror->mirror_ds)
                                return true;
                        if (IS_ERR(mirror->mirror_ds))
                                continue;
                        devid = &mirror->mirror_ds->id_node;
                        if (!nfs4_test_deviceid_unavailable(devid))
                                return true;
                }
        }

        return false;
}

static bool ff_rw_layout_has_available_ds(struct pnfs_layout_segment *lseg)
{
        struct nfs4_ff_layout_mirror *mirror;
        struct nfs4_deviceid_node *devid;
        u32 idx;

        for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
                mirror = FF_LAYOUT_COMP(lseg, idx);
                if (!mirror || IS_ERR(mirror->mirror_ds))
                        return false;
                if (!mirror->mirror_ds)
                        continue;
                devid = &mirror->mirror_ds->id_node;
                if (nfs4_test_deviceid_unavailable(devid))
                        return false;
        }

        return FF_LAYOUT_MIRROR_COUNT(lseg) != 0;
}

static bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
{
        if (lseg->pls_range.iomode == IOMODE_READ)
                return  ff_read_layout_has_available_ds(lseg);
        /* Note: RW layout needs all mirrors available */
        return ff_rw_layout_has_available_ds(lseg);
}

bool ff_layout_avoid_mds_available_ds(struct pnfs_layout_segment *lseg)
{
        return ff_layout_no_fallback_to_mds(lseg) ||
               ff_layout_has_available_ds(lseg);
}

bool ff_layout_avoid_read_on_rw(struct pnfs_layout_segment *lseg)
{
        return lseg->pls_range.iomode == IOMODE_RW &&
               ff_layout_no_read_on_rw(lseg);
}

module_param(dataserver_retrans, uint, 0644);
MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
                        "retries a request before it attempts further "
                        " recovery  action.");
module_param(dataserver_timeo, uint, 0644);
MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
                        "NFSv4.1  client  waits for a response from a "
                        " data server before it retries an NFS request.");