svcsubs.c

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/*
 * linux/fs/lockd/svcsubs.c
 *
 * Various support routines for the NLM server.
 *
 * Copyright (C) 1996, Olaf Kirch <[email protected]>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/time.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfsd/nfsfh.h>
#include <linux/nfsd/export.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/share.h>
#include <linux/module.h>
#include <linux/mount.h>

#define NLMDBG_FACILITY     NLMDBG_SVCSUBS


/*
 * Global file hash table
 */
#define FILE_HASH_BITS      7
#define FILE_NRHASH     (1<<FILE_HASH_BITS)
static struct hlist_head    nlm_files[FILE_NRHASH];
static DEFINE_MUTEX(nlm_file_mutex);

#ifdef NFSD_DEBUG
static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
{
    u32 *fhp = (u32*)f->data;

    /* print the first 32 bytes of the fh */
    dprintk("lockd: %s (%08x %08x %08x %08x %08x %08x %08x %08x)\n",
        msg, fhp[0], fhp[1], fhp[2], fhp[3],
        fhp[4], fhp[5], fhp[6], fhp[7]);
}

static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
{
    struct inode *inode = file->f_file->f_path.dentry->d_inode;

    dprintk("lockd: %s %s/%ld\n",
        msg, inode->i_sb->s_id, inode->i_ino);
}
#else
static inline void nlm_debug_print_fh(char *msg, struct nfs_fh *f)
{
    return;
}

static inline void nlm_debug_print_file(char *msg, struct nlm_file *file)
{
    return;
}
#endif

static inline unsigned int file_hash(struct nfs_fh *f)
{
    unsigned int tmp=0;
    int i;
    for (i=0; i<NFS2_FHSIZE;i++)
        tmp += f->data[i];
    return tmp & (FILE_NRHASH - 1);
}

/*
 * Lookup file info. If it doesn't exist, create a file info struct
 * and open a (VFS) file for the given inode.
 *
 * FIXME:
 * Note that we open the file O_RDONLY even when creating write locks.
 * This is not quite right, but for now, we assume the client performs
 * the proper R/W checking.
 */
__be32
nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
                    struct nfs_fh *f)
{
    struct hlist_node *pos;
    struct nlm_file *file;
    unsigned int    hash;
    __be32      nfserr;

    nlm_debug_print_fh("nlm_lookup_file", f);

    hash = file_hash(f);

    /* Lock file table */
    mutex_lock(&nlm_file_mutex);

    hlist_for_each_entry(file, pos, &nlm_files[hash], f_list)
        if (!nfs_compare_fh(&file->f_handle, f))
            goto found;

    nlm_debug_print_fh("creating file for", f);

    nfserr = nlm_lck_denied_nolocks;
    file = kzalloc(sizeof(*file), GFP_KERNEL);
    if (!file)
        goto out_unlock;

    memcpy(&file->f_handle, f, sizeof(struct nfs_fh));
    mutex_init(&file->f_mutex);
    INIT_HLIST_NODE(&file->f_list);
    INIT_LIST_HEAD(&file->f_blocks);

    /* Open the file. Note that this must not sleep for too long, else
     * we would lock up lockd:-) So no NFS re-exports, folks.
     *
     * We have to make sure we have the right credential to open
     * the file.
     */
    if ((nfserr = nlmsvc_ops->fopen(rqstp, f, &file->f_file)) != 0) {
        dprintk("lockd: open failed (error %d)\n", nfserr);
        goto out_free;
    }

    hlist_add_head(&file->f_list, &nlm_files[hash]);

found:
    dprintk("lockd: found file %p (count %d)\n", file, file->f_count);
    *result = file;
    file->f_count++;
    nfserr = 0;

out_unlock:
    mutex_unlock(&nlm_file_mutex);
    return nfserr;

out_free:
    kfree(file);
    goto out_unlock;
}

/*
 * Delete a file after having released all locks, blocks and shares
 */
static inline void
nlm_delete_file(struct nlm_file *file)
{
    nlm_debug_print_file("closing file", file);
    if (!hlist_unhashed(&file->f_list)) {
        hlist_del(&file->f_list);
        nlmsvc_ops->fclose(file->f_file);
        kfree(file);
    } else {
        printk(KERN_WARNING "lockd: attempt to release unknown file!\n");
    }
}

/*
 * Loop over all locks on the given file and perform the specified
 * action.
 */
static int
nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
            nlm_host_match_fn_t match)
{
    struct inode     *inode = nlmsvc_file_inode(file);
    struct file_lock *fl;
    struct nlm_host  *lockhost;

again:
    file->f_locks = 0;
    lock_flocks(); /* protects i_flock list */
    for (fl = inode->i_flock; fl; fl = fl->fl_next) {
        if (fl->fl_lmops != &nlmsvc_lock_operations)
            continue;

        /* update current lock count */
        file->f_locks++;

        lockhost = (struct nlm_host *) fl->fl_owner;
        if (match(lockhost, host)) {
            struct file_lock lock = *fl;

            unlock_flocks();
            lock.fl_type  = F_UNLCK;
            lock.fl_start = 0;
            lock.fl_end   = OFFSET_MAX;
            if (vfs_lock_file(file->f_file, F_SETLK, &lock, NULL) < 0) {
                printk("lockd: unlock failure in %s:%d\n",
                        __FILE__, __LINE__);
                return 1;
            }
            goto again;
        }
    }
    unlock_flocks();

    return 0;
}

static int
nlmsvc_always_match(void *dummy1, struct nlm_host *dummy2)
{
    return 1;
}

/*
 * Inspect a single file
 */
static inline int
nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, nlm_host_match_fn_t match)
{
    nlmsvc_traverse_blocks(host, file, match);
    nlmsvc_traverse_shares(host, file, match);
    return nlm_traverse_locks(host, file, match);
}

/*
 * Quick check whether there are still any locks, blocks or
 * shares on a given file.
 */
static inline int
nlm_file_inuse(struct nlm_file *file)
{
    struct inode     *inode = nlmsvc_file_inode(file);
    struct file_lock *fl;

    if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
        return 1;

    lock_flocks();
    for (fl = inode->i_flock; fl; fl = fl->fl_next) {
        if (fl->fl_lmops == &nlmsvc_lock_operations) {
            unlock_flocks();
            return 1;
        }
    }
    unlock_flocks();
    file->f_locks = 0;
    return 0;
}

/*
 * Loop over all files in the file table.
 */
static int
nlm_traverse_files(void *data, nlm_host_match_fn_t match,
        int (*is_failover_file)(void *data, struct nlm_file *file))
{
    struct hlist_node *pos, *next;
    struct nlm_file *file;
    int i, ret = 0;

    mutex_lock(&nlm_file_mutex);
    for (i = 0; i < FILE_NRHASH; i++) {
        hlist_for_each_entry_safe(file, pos, next, &nlm_files[i], f_list) {
            if (is_failover_file && !is_failover_file(data, file))
                continue;
            file->f_count++;
            mutex_unlock(&nlm_file_mutex);

            /* Traverse locks, blocks and shares of this file
             * and update file->f_locks count */
            if (nlm_inspect_file(data, file, match))
                ret = 1;

            mutex_lock(&nlm_file_mutex);
            file->f_count--;
            /* No more references to this file. Let go of it. */
            if (list_empty(&file->f_blocks) && !file->f_locks
             && !file->f_shares && !file->f_count) {
                hlist_del(&file->f_list);
                nlmsvc_ops->fclose(file->f_file);
                kfree(file);
            }
        }
    }
    mutex_unlock(&nlm_file_mutex);
    return ret;
}

/*
 * Release file. If there are no more remote locks on this file,
 * close it and free the handle.
 *
 * Note that we can't do proper reference counting without major
 * contortions because the code in fs/locks.c creates, deletes and
 * splits locks without notification. Our only way is to walk the
 * entire lock list each time we remove a lock.
 */
void
nlm_release_file(struct nlm_file *file)
{
    dprintk("lockd: nlm_release_file(%p, ct = %d)\n",
                file, file->f_count);

    /* Lock file table */
    mutex_lock(&nlm_file_mutex);

    /* If there are no more locks etc, delete the file */
    if (--file->f_count == 0 && !nlm_file_inuse(file))
        nlm_delete_file(file);

    mutex_unlock(&nlm_file_mutex);
}

/*
 * Helpers function for resource traversal
 *
 * nlmsvc_mark_host:
 *  used by the garbage collector; simply sets h_inuse only for those
 *  hosts, which passed network check.
 *  Always returns 0.
 *
 * nlmsvc_same_host:
 *  returns 1 iff the two hosts match. Used to release
 *  all resources bound to a specific host.
 *
 * nlmsvc_is_client:
 *  returns 1 iff the host is a client.
 *  Used by nlmsvc_invalidate_all
 */

static int
nlmsvc_mark_host(void *data, struct nlm_host *hint)
{
    struct nlm_host *host = data;

    if ((hint->net == NULL) ||
        (host->net == hint->net))
        host->h_inuse = 1;
    return 0;
}

static int
nlmsvc_same_host(void *data, struct nlm_host *other)
{
    struct nlm_host *host = data;

    return host == other;
}

static int
nlmsvc_is_client(void *data, struct nlm_host *dummy)
{
    struct nlm_host *host = data;

    if (host->h_server) {
        /* we are destroying locks even though the client
         * hasn't asked us too, so don't unmonitor the
         * client
         */
        if (host->h_nsmhandle)
            host->h_nsmhandle->sm_sticky = 1;
        return 1;
    } else
        return 0;
}

/*
 * Mark all hosts that still hold resources
 */
void
nlmsvc_mark_resources(struct net *net)
{
    struct nlm_host hint;

    dprintk("lockd: nlmsvc_mark_resources for net %p\n", net);
    hint.net = net;
    nlm_traverse_files(&hint, nlmsvc_mark_host, NULL);
}

/*
 * Release all resources held by the given client
 */
void
nlmsvc_free_host_resources(struct nlm_host *host)
{
    dprintk("lockd: nlmsvc_free_host_resources\n");

    if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {
        printk(KERN_WARNING
            "lockd: couldn't remove all locks held by %s\n",
            host->h_name);
        BUG();
    }
}

void
nlmsvc_invalidate_all(void)
{
    /*
     * Previously, the code would call
     * nlmsvc_free_host_resources for each client in
     * turn, which is about as inefficient as it gets.
     * Now we just do it once in nlm_traverse_files.
     */
    nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
}

static int
nlmsvc_match_sb(void *datap, struct nlm_file *file)
{
    struct super_block *sb = datap;

    return sb == file->f_file->f_path.dentry->d_sb;
}

int
nlmsvc_unlock_all_by_sb(struct super_block *sb)
{
    int ret;

    ret = nlm_traverse_files(sb, nlmsvc_always_match, nlmsvc_match_sb);
    return ret ? -EIO : 0;
}
EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_sb);

static int
nlmsvc_match_ip(void *datap, struct nlm_host *host)
{
    return rpc_cmp_addr(nlm_srcaddr(host), datap);
}

int
nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr)
{
    int ret;

    ret = nlm_traverse_files(server_addr, nlmsvc_match_ip, NULL);
    return ret ? -EIO : 0;
}
EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_ip);