nfsd: fix leaked file lock with nfs exported overlayfs

[linux-2.6/btrfs-unstable.git] / fs / lockd / svcsubs.c

/*
 * linux/fs/lockd/svcsubs.c
 *
 * Various support routines for the NLM server.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#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/addr.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/share.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <uapi/linux/nfs2.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 CONFIG_SUNRPC_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 = locks_inode(file->f_file);

        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 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, &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 file_lock_context *flctx = inode->i_flctx;
        struct nlm_host  *lockhost;

        if (!flctx || list_empty_careful(&flctx->flc_posix))
                return 0;
again:
        file->f_locks = 0;
        spin_lock(&flctx->flc_lock);
        list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
                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;

                        spin_unlock(&flctx->flc_lock);
                        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;
                }
        }
        spin_unlock(&flctx->flc_lock);

        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;
        struct file_lock_context *flctx = inode->i_flctx;

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

        if (flctx && !list_empty_careful(&flctx->flc_posix)) {
                spin_lock(&flctx->flc_lock);
                list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
                        if (fl->fl_lmops == &nlmsvc_lock_operations) {
                                spin_unlock(&flctx->flc_lock);
                                return 1;
                        }
                }
                spin_unlock(&flctx->flc_lock);
        }
        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 *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, 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: %s for net %x\n", __func__, net ? net->ns.inum : 0);
        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();
        }
}

/**
 * nlmsvc_invalidate_all - remove all locks held for clients
 *
 * Release all locks held by NFS clients.
 *
 */
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 == locks_inode(file->f_file)->i_sb;
}

/**
 * nlmsvc_unlock_all_by_sb - release locks held on this file system
 * @sb: super block
 *
 * Release all locks held by clients accessing this file system.
 */
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);
}

/**
 * nlmsvc_unlock_all_by_ip - release local locks by IP address
 * @server_addr: server's IP address as seen by clients
 *
 * Release all locks held by clients accessing this host
 * via the passed in IP address.
 */
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);