/*
 *  Device operations for the pnfs client.
 *
 *  Copyright (c) 2002
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <dhildebz@umich.edu>
 *  Garth Goodson   <Garth.Goodson@netapp.com>
 *
 *  Permission is granted to use, copy, create derivative works, and
 *  redistribute this software and such derivative works for any purpose,
 *  so long as the name of the University of Michigan is not used in
 *  any advertising or publicity pertaining to the use or distribution
 *  of this software without specific, written prior authorization. If
 *  the above copyright notice or any other identification of the
 *  University of Michigan is included in any copy of any portion of
 *  this software, then the disclaimer below must also be included.
 *
 *  This software is provided as is, without representation or warranty
 *  of any kind either express or implied, including without limitation
 *  the implied warranties of merchantability, fitness for a particular
 *  purpose, or noninfringement.  The Regents of the University of
 *  Michigan shall not be liable for any damages, including special,
 *  indirect, incidental, or consequential damages, with respect to any
 *  claim arising out of or in connection with the use of the software,
 *  even if it has been or is hereafter advised of the possibility of
 *  such damages.
 */

#include <linux/export.h>
#include <linux/nfs_fs.h>
#include "nfs4session.h"
#include "internal.h"
#include "pnfs.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS

/*
 * Device ID RCU cache. A device ID is unique per server and layout type.
 */
#define NFS4_DEVICE_ID_HASH_BITS        5
#define NFS4_DEVICE_ID_HASH_SIZE        (1 << NFS4_DEVICE_ID_HASH_BITS)
#define NFS4_DEVICE_ID_HASH_MASK        (NFS4_DEVICE_ID_HASH_SIZE - 1)


static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
static DEFINE_SPINLOCK(nfs4_deviceid_lock);

#ifdef NFS_DEBUG
void
nfs4_print_deviceid(const struct nfs4_deviceid *id)
{
        u32 *p = (u32 *)id;

        dprintk("%s: device id= [%x%x%x%x]\n", __func__,
                p[0], p[1], p[2], p[3]);
}
EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
#endif

static inline u32
nfs4_deviceid_hash(const struct nfs4_deviceid *id)
{
        unsigned char *cptr = (unsigned char *)id->data;
        unsigned int nbytes = NFS4_DEVICEID4_SIZE;
        u32 x = 0;

        while (nbytes--) {
                x *= 37;
                x += *cptr++;
        }
        return x & NFS4_DEVICE_ID_HASH_MASK;
}

static struct nfs4_deviceid_node *
_lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
                 const struct nfs_client *clp, const struct nfs4_deviceid *id,
                 long hash)
{
        struct nfs4_deviceid_node *d;

        hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
                if (d->ld == ld && d->nfs_client == clp &&
                    !memcmp(&d->deviceid, id, sizeof(*id))) {
                        if (atomic_read(&d->ref))
                                return d;
                        else
                                continue;
                }
        return NULL;
}

static struct nfs4_deviceid_node *
nfs4_get_device_info(struct nfs_server *server,
                const struct nfs4_deviceid *dev_id,
                const struct cred *cred, gfp_t gfp_flags)
{
        struct nfs4_deviceid_node *d = NULL;
        struct pnfs_device *pdev = NULL;
        struct page **pages = NULL;
        u32 max_resp_sz;
        int max_pages;
        int rc, i;

        /*
         * Use the session max response size as the basis for setting
         * GETDEVICEINFO's maxcount
         */
        max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
        if (server->pnfs_curr_ld->max_deviceinfo_size &&
            server->pnfs_curr_ld->max_deviceinfo_size < max_resp_sz)
                max_resp_sz = server->pnfs_curr_ld->max_deviceinfo_size;
        max_pages = nfs_page_array_len(0, max_resp_sz);
        dprintk("%s: server %p max_resp_sz %u max_pages %d\n",
                __func__, server, max_resp_sz, max_pages);

        pdev = kzalloc(sizeof(*pdev), gfp_flags);
        if (!pdev)
                return NULL;

        pages = kcalloc(max_pages, sizeof(struct page *), gfp_flags);
        if (!pages)
                goto out_free_pdev;

        for (i = 0; i < max_pages; i++) {
                pages[i] = alloc_page(gfp_flags);
                if (!pages[i])
                        goto out_free_pages;
        }

        memcpy(&pdev->dev_id, dev_id, sizeof(*dev_id));
        pdev->layout_type = server->pnfs_curr_ld->id;
        pdev->pages = pages;
        pdev->pgbase = 0;
        pdev->pglen = max_resp_sz;
        pdev->mincount = 0;
        pdev->maxcount = max_resp_sz - nfs41_maxgetdevinfo_overhead;

        rc = nfs4_proc_getdeviceinfo(server, pdev, cred);
        dprintk("%s getdevice info returns %d\n", __func__, rc);
        if (rc)
                goto out_free_pages;

        /*
         * Found new device, need to decode it and then add it to the
         * list of known devices for this mountpoint.
         */
        d = server->pnfs_curr_ld->alloc_deviceid_node(server, pdev,
                        gfp_flags);
        if (d && pdev->nocache)
                set_bit(NFS_DEVICEID_NOCACHE, &d->flags);

out_free_pages:
        for (i = 0; i < max_pages; i++)
                __free_page(pages[i]);
        kfree(pages);
out_free_pdev:
        kfree(pdev);
        dprintk("<-- %s d %p\n", __func__, d);
        return d;
}

/*
 * Lookup a deviceid in cache and get a reference count on it if found
 *
 * @clp nfs_client associated with deviceid
 * @id deviceid to look up
 */
static struct nfs4_deviceid_node *
__nfs4_find_get_deviceid(struct nfs_server *server,
                const struct nfs4_deviceid *id, long hash)
{
        struct nfs4_deviceid_node *d;

        rcu_read_lock();
        d = _lookup_deviceid(server->pnfs_curr_ld, server->nfs_client, id,
                        hash);
        if (d != NULL && !atomic_inc_not_zero(&d->ref))
                d = NULL;
        rcu_read_unlock();
        return d;
}

struct nfs4_deviceid_node *
nfs4_find_get_deviceid(struct nfs_server *server,
                const struct nfs4_deviceid *id, const struct cred *cred,
                gfp_t gfp_mask)
{
        long hash = nfs4_deviceid_hash(id);
        struct nfs4_deviceid_node *d, *new;

        d = __nfs4_find_get_deviceid(server, id, hash);
        if (d)
                return d;

        new = nfs4_get_device_info(server, id, cred, gfp_mask);
        if (!new)
                return new;

        spin_lock(&nfs4_deviceid_lock);
        d = __nfs4_find_get_deviceid(server, id, hash);
        if (d) {
                spin_unlock(&nfs4_deviceid_lock);
                server->pnfs_curr_ld->free_deviceid_node(new);
                return d;
        }
        hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
        atomic_inc(&new->ref);
        spin_unlock(&nfs4_deviceid_lock);

        return new;
}
EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);

/*
 * Remove a deviceid from cache
 *
 * @clp nfs_client associated with deviceid
 * @id the deviceid to unhash
 *
 * @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
 */
void
nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
                         const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
        struct nfs4_deviceid_node *d;

        spin_lock(&nfs4_deviceid_lock);
        rcu_read_lock();
        d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
        rcu_read_unlock();
        if (!d) {
                spin_unlock(&nfs4_deviceid_lock);
                return;
        }
        hlist_del_init_rcu(&d->node);
        clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
        spin_unlock(&nfs4_deviceid_lock);

        /* balance the initial ref set in pnfs_insert_deviceid */
        nfs4_put_deviceid_node(d);
}
EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);

void
nfs4_init_deviceid_node(struct nfs4_deviceid_node *d, struct nfs_server *server,
                        const struct nfs4_deviceid *id)
{
        INIT_HLIST_NODE(&d->node);
        INIT_HLIST_NODE(&d->tmpnode);
        d->ld = server->pnfs_curr_ld;
        d->nfs_client = server->nfs_client;
        d->flags = 0;
        d->deviceid = *id;
        atomic_set(&d->ref, 1);
}
EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);

/*
 * Dereference a deviceid node and delete it when its reference count drops
 * to zero.
 *
 * @d deviceid node to put
 *
 * return true iff the node was deleted
 * Note that since the test for d->ref == 0 is sufficient to establish
 * that the node is no longer hashed in the global device id cache.
 */
bool
nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
{
        if (test_bit(NFS_DEVICEID_NOCACHE, &d->flags)) {
                if (atomic_add_unless(&d->ref, -1, 2))
                        return false;
                nfs4_delete_deviceid(d->ld, d->nfs_client, &d->deviceid);
        }
        if (!atomic_dec_and_test(&d->ref))
                return false;
        d->ld->free_deviceid_node(d);
        return true;
}
EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);

void
nfs4_mark_deviceid_available(struct nfs4_deviceid_node *node)
{
        if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
                clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
                smp_mb__after_atomic();
        }
}
EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_available);

void
nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node)
{
        node->timestamp_unavailable = jiffies;
        smp_mb__before_atomic();
        set_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
        smp_mb__after_atomic();
}
EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_unavailable);

bool
nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node)
{
        if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
                unsigned long start, end;

                end = jiffies;
                start = end - PNFS_DEVICE_RETRY_TIMEOUT;
                if (time_in_range(node->timestamp_unavailable, start, end))
                        return true;
                clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
                smp_mb__after_atomic();
        }
        return false;
}
EXPORT_SYMBOL_GPL(nfs4_test_deviceid_unavailable);

static void
_deviceid_purge_client(const struct nfs_client *clp, long hash)
{
        struct nfs4_deviceid_node *d;
        HLIST_HEAD(tmp);

        spin_lock(&nfs4_deviceid_lock);
        rcu_read_lock();
        hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
                if (d->nfs_client == clp && atomic_read(&d->ref)) {
                        hlist_del_init_rcu(&d->node);
                        hlist_add_head(&d->tmpnode, &tmp);
                        clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
                }
        rcu_read_unlock();
        spin_unlock(&nfs4_deviceid_lock);

        if (hlist_empty(&tmp))
                return;

        while (!hlist_empty(&tmp)) {
                d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
                hlist_del(&d->tmpnode);
                nfs4_put_deviceid_node(d);
        }
}

void
nfs4_deviceid_purge_client(const struct nfs_client *clp)
{
        long h;

        if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
                return;
        for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
                _deviceid_purge_client(clp, h);
}

/*
 * Stop use of all deviceids associated with an nfs_client
 */
void
nfs4_deviceid_mark_client_invalid(struct nfs_client *clp)
{
        struct nfs4_deviceid_node *d;
        int i;

        rcu_read_lock();
        for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i ++){
                hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[i], node)
                        if (d->nfs_client == clp)
                                set_bit(NFS_DEVICEID_INVALID, &d->flags);
        }
        rcu_read_unlock();
}