fscache-index.c

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/* NFS FS-Cache index structure definition
 *
 * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/in6.h>

#include "internal.h"
#include "fscache.h"

#define NFSDBG_FACILITY     NFSDBG_FSCACHE

/*
 * Define the NFS filesystem for FS-Cache.  Upon registration FS-Cache sticks
 * the cookie for the top-level index object for NFS into here.  The top-level
 * index can than have other cache objects inserted into it.
 */
struct fscache_netfs nfs_fscache_netfs = {
    .name       = "nfs",
    .version    = 0,
};

/*
 * Register NFS for caching
 */
int nfs_fscache_register(void)
{
    return fscache_register_netfs(&nfs_fscache_netfs);
}

/*
 * Unregister NFS for caching
 */
void nfs_fscache_unregister(void)
{
    fscache_unregister_netfs(&nfs_fscache_netfs);
}

/*
 * Layout of the key for an NFS server cache object.
 */
struct nfs_server_key {
    uint16_t    nfsversion;     /* NFS protocol version */
    uint16_t    family;         /* address family */
    uint16_t    port;           /* IP port */
    union {
        struct in_addr  ipv4_addr;  /* IPv4 address */
        struct in6_addr ipv6_addr;  /* IPv6 address */
    } addr[0];
};

/*
 * Generate a key to describe a server in the main NFS index
 * - We return the length of the key, or 0 if we can't generate one
 */
static uint16_t nfs_server_get_key(const void *cookie_netfs_data,
                   void *buffer, uint16_t bufmax)
{
    const struct nfs_client *clp = cookie_netfs_data;
    const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
    const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
    struct nfs_server_key *key = buffer;
    uint16_t len = sizeof(struct nfs_server_key);

    key->nfsversion = clp->rpc_ops->version;
    key->family = clp->cl_addr.ss_family;

    memset(key, 0, len);

    switch (clp->cl_addr.ss_family) {
    case AF_INET:
        key->port = sin->sin_port;
        key->addr[0].ipv4_addr = sin->sin_addr;
        len += sizeof(key->addr[0].ipv4_addr);
        break;

    case AF_INET6:
        key->port = sin6->sin6_port;
        key->addr[0].ipv6_addr = sin6->sin6_addr;
        len += sizeof(key->addr[0].ipv6_addr);
        break;

    default:
        printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
               clp->cl_addr.ss_family);
        len = 0;
        break;
    }

    return len;
}

/*
 * Define the server object for FS-Cache.  This is used to describe a server
 * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
 * server address parameters.
 */
const struct fscache_cookie_def nfs_fscache_server_index_def = {
    .name       = "NFS.server",
    .type       = FSCACHE_COOKIE_TYPE_INDEX,
    .get_key    = nfs_server_get_key,
};

/*
 * Generate a key to describe a superblock key in the main NFS index
 */
static uint16_t nfs_super_get_key(const void *cookie_netfs_data,
                  void *buffer, uint16_t bufmax)
{
    const struct nfs_fscache_key *key;
    const struct nfs_server *nfss = cookie_netfs_data;
    uint16_t len;

    key = nfss->fscache_key;
    len = sizeof(key->key) + key->key.uniq_len;
    if (len > bufmax) {
        len = 0;
    } else {
        memcpy(buffer, &key->key, sizeof(key->key));
        memcpy(buffer + sizeof(key->key),
               key->key.uniquifier, key->key.uniq_len);
    }

    return len;
}

/*
 * Define the superblock object for FS-Cache.  This is used to describe a
 * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
 * parameters that might cause a separate superblock.
 */
const struct fscache_cookie_def nfs_fscache_super_index_def = {
    .name       = "NFS.super",
    .type       = FSCACHE_COOKIE_TYPE_INDEX,
    .get_key    = nfs_super_get_key,
};

/*
 * Definition of the auxiliary data attached to NFS inode storage objects
 * within the cache.
 *
 * The contents of this struct are recorded in the on-disk local cache in the
 * auxiliary data attached to the data storage object backing an inode.  This
 * permits coherency to be managed when a new inode binds to an already extant
 * cache object.
 */
struct nfs_fscache_inode_auxdata {
    struct timespec mtime;
    struct timespec ctime;
    loff_t      size;
    u64     change_attr;
};

/*
 * Generate a key to describe an NFS inode in an NFS server's index
 */
static uint16_t nfs_fscache_inode_get_key(const void *cookie_netfs_data,
                      void *buffer, uint16_t bufmax)
{
    const struct nfs_inode *nfsi = cookie_netfs_data;
    uint16_t nsize;

    /* use the inode's NFS filehandle as the key */
    nsize = nfsi->fh.size;
    memcpy(buffer, nfsi->fh.data, nsize);
    return nsize;
}

/*
 * Get certain file attributes from the netfs data
 * - This function can be absent for an index
 * - Not permitted to return an error
 * - The netfs data from the cookie being used as the source is presented
 */
static void nfs_fscache_inode_get_attr(const void *cookie_netfs_data,
                       uint64_t *size)
{
    const struct nfs_inode *nfsi = cookie_netfs_data;

    *size = nfsi->vfs_inode.i_size;
}

/*
 * Get the auxiliary data from netfs data
 * - This function can be absent if the index carries no state data
 * - Should store the auxiliary data in the buffer
 * - Should return the amount of amount stored
 * - Not permitted to return an error
 * - The netfs data from the cookie being used as the source is presented
 */
static uint16_t nfs_fscache_inode_get_aux(const void *cookie_netfs_data,
                      void *buffer, uint16_t bufmax)
{
    struct nfs_fscache_inode_auxdata auxdata;
    const struct nfs_inode *nfsi = cookie_netfs_data;

    memset(&auxdata, 0, sizeof(auxdata));
    auxdata.size = nfsi->vfs_inode.i_size;
    auxdata.mtime = nfsi->vfs_inode.i_mtime;
    auxdata.ctime = nfsi->vfs_inode.i_ctime;

    if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
        auxdata.change_attr = nfsi->vfs_inode.i_version;

    if (bufmax > sizeof(auxdata))
        bufmax = sizeof(auxdata);

    memcpy(buffer, &auxdata, bufmax);
    return bufmax;
}

/*
 * Consult the netfs about the state of an object
 * - This function can be absent if the index carries no state data
 * - The netfs data from the cookie being used as the target is
 *   presented, as is the auxiliary data
 */
static
enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
                          const void *data,
                          uint16_t datalen)
{
    struct nfs_fscache_inode_auxdata auxdata;
    struct nfs_inode *nfsi = cookie_netfs_data;

    if (datalen != sizeof(auxdata))
        return FSCACHE_CHECKAUX_OBSOLETE;

    memset(&auxdata, 0, sizeof(auxdata));
    auxdata.size = nfsi->vfs_inode.i_size;
    auxdata.mtime = nfsi->vfs_inode.i_mtime;
    auxdata.ctime = nfsi->vfs_inode.i_ctime;

    if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
        auxdata.change_attr = nfsi->vfs_inode.i_version;

    if (memcmp(data, &auxdata, datalen) != 0)
        return FSCACHE_CHECKAUX_OBSOLETE;

    return FSCACHE_CHECKAUX_OKAY;
}

/*
 * Indication from FS-Cache that the cookie is no longer cached
 * - This function is called when the backing store currently caching a cookie
 *   is removed
 * - The netfs should use this to clean up any markers indicating cached pages
 * - This is mandatory for any object that may have data
 */
static void nfs_fscache_inode_now_uncached(void *cookie_netfs_data)
{
    struct nfs_inode *nfsi = cookie_netfs_data;
    struct pagevec pvec;
    pgoff_t first;
    int loop, nr_pages;

    pagevec_init(&pvec, 0);
    first = 0;

    dprintk("NFS: nfs_inode_now_uncached: nfs_inode 0x%p\n", nfsi);

    for (;;) {
        /* grab a bunch of pages to unmark */
        nr_pages = pagevec_lookup(&pvec,
                      nfsi->vfs_inode.i_mapping,
                      first,
                      PAGEVEC_SIZE - pagevec_count(&pvec));
        if (!nr_pages)
            break;

        for (loop = 0; loop < nr_pages; loop++)
            ClearPageFsCache(pvec.pages[loop]);

        first = pvec.pages[nr_pages - 1]->index + 1;

        pvec.nr = nr_pages;
        pagevec_release(&pvec);
        cond_resched();
    }
}

/*
 * Get an extra reference on a read context.
 * - This function can be absent if the completion function doesn't require a
 *   context.
 * - The read context is passed back to NFS in the event that a data read on the
 *   cache fails with EIO - in which case the server must be contacted to
 *   retrieve the data, which requires the read context for security.
 */
static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
{
    get_nfs_open_context(context);
}

/*
 * Release an extra reference on a read context.
 * - This function can be absent if the completion function doesn't require a
 *   context.
 */
static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
{
    if (context)
        put_nfs_open_context(context);
}

/*
 * Define the inode object for FS-Cache.  This is used to describe an inode
 * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
 * an inode.
 *
 * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
 * held in the cache auxiliary data for the data storage object with those in
 * the inode struct in memory.
 */
const struct fscache_cookie_def nfs_fscache_inode_object_def = {
    .name       = "NFS.fh",
    .type       = FSCACHE_COOKIE_TYPE_DATAFILE,
    .get_key    = nfs_fscache_inode_get_key,
    .get_attr   = nfs_fscache_inode_get_attr,
    .get_aux    = nfs_fscache_inode_get_aux,
    .check_aux  = nfs_fscache_inode_check_aux,
    .now_uncached   = nfs_fscache_inode_now_uncached,
    .get_context    = nfs_fh_get_context,
    .put_context    = nfs_fh_put_context,
};