pnfs_dev.c

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/*
 *  Device operations for the pnfs client.
 *
 *  Copyright (c) 2002
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <[email protected]>
 *  Garth Goodson   <[email protected]>
 *
 *  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 "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)

#define PNFS_DEVICE_RETRY_TIMEOUT (120*HZ)

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;
    struct hlist_node *n;

    hlist_for_each_entry_rcu(d, n, &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;
}

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

    rcu_read_lock();
    d = _lookup_deviceid(ld, clp, id, hash);
    if (d != NULL)
        atomic_inc(&d->ref);
    rcu_read_unlock();
    return d;
}

struct nfs4_deviceid_node *
nfs4_find_get_deviceid(const struct pnfs_layoutdriver_type *ld,
               const struct nfs_client *clp, const struct nfs4_deviceid *id)
{
    return _find_get_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
}
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);
    spin_unlock(&nfs4_deviceid_lock);
    synchronize_rcu();

    /* balance the initial ref set in pnfs_insert_deviceid */
    if (atomic_dec_and_test(&d->ref))
        d->ld->free_deviceid_node(d);
}
EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);

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

/*
 * Uniquely initialize and insert a deviceid node into cache
 *
 * @new new deviceid node
 *      Note that the caller must set up the following members:
 *        new->ld
 *        new->nfs_client
 *        new->deviceid
 *
 * @ret the inserted node, if none found, otherwise, the found entry.
 */
struct nfs4_deviceid_node *
nfs4_insert_deviceid_node(struct nfs4_deviceid_node *new)
{
    struct nfs4_deviceid_node *d;
    long hash;

    spin_lock(&nfs4_deviceid_lock);
    hash = nfs4_deviceid_hash(&new->deviceid);
    d = _find_get_deviceid(new->ld, new->nfs_client, &new->deviceid, hash);
    if (d) {
        spin_unlock(&nfs4_deviceid_lock);
        return d;
    }

    hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
    spin_unlock(&nfs4_deviceid_lock);
    atomic_inc(&new->ref);

    return new;
}
EXPORT_SYMBOL_GPL(nfs4_insert_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 (!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_unavailable(struct nfs4_deviceid_node *node)
{
    node->timestamp_unavailable = jiffies;
    set_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
}
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);
    }
    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;
    struct hlist_node *n;
    HLIST_HEAD(tmp);

    spin_lock(&nfs4_deviceid_lock);
    rcu_read_lock();
    hlist_for_each_entry_rcu(d, n, &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);
        }
    rcu_read_unlock();
    spin_unlock(&nfs4_deviceid_lock);

    if (hlist_empty(&tmp))
        return;

    synchronize_rcu();
    while (!hlist_empty(&tmp)) {
        d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
        hlist_del(&d->tmpnode);
        if (atomic_dec_and_test(&d->ref))
            d->ld->free_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;
    struct hlist_node *n;
    int i;

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