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

#include <linux/config.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/in.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/lockd/sm_inter.h>

#define NLMDBG_FACILITY         NLMDBG_SVCSUBS


/*
 * Global file hash table
 */
#define FILE_HASH_BITS          5
#define FILE_NRHASH             (1<<FILE_HASH_BITS)
static struct nlm_file *        nlm_files[FILE_NRHASH];
static DECLARE_MUTEX(nlm_file_sema);

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.
 */
u32
nlm_lookup_file(struct svc_rqst *rqstp, struct nlm_file **result,
                                        struct nfs_fh *f)
{
        struct nlm_file *file;
        unsigned int    hash;
        u32             nfserr;
        u32             *fhp = (u32*)f->data;

        dprintk("lockd: nlm_file_lookup(%08x %08x %08x %08x %08x %08x)\n",
                fhp[0], fhp[1], fhp[2], fhp[3], fhp[4], fhp[5]);


        hash = file_hash(f);

        /* Lock file table */
        down(&nlm_file_sema);

        for (file = nlm_files[hash]; file; file = file->f_next)
                if (!memcmp(&file->f_handle, f, sizeof(*f)))
                        goto found;

        dprintk("lockd: creating file for (%08x %08x %08x %08x %08x %08x)\n",
                fhp[0], fhp[1], fhp[2], fhp[3], fhp[4], fhp[5]);

        nfserr = nlm_lck_denied_nolocks;
        file = (struct nlm_file *) kmalloc(sizeof(*file), GFP_KERNEL);
        if (!file)
                goto out_unlock;

        memset(file, 0, sizeof(*file));
        memcpy(&file->f_handle, f, sizeof(struct nfs_fh));
        file->f_hash = hash;
        init_MUTEX(&file->f_sema);

        /* 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 (nfserr %d)\n", ntohl(nfserr));
                goto out_free;
        }

        file->f_next = nlm_files[hash];
        nlm_files[hash] = file;

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

out_unlock:
        up(&nlm_file_sema);
        return nfserr;

out_free:
        kfree(file);
#ifdef CONFIG_LOCKD_V4
        if (nfserr == 1)
                nfserr = nlm4_stale_fh;
        else
#endif
        nfserr = nlm_lck_denied;
        goto out_unlock;
}

/*
 * Delete a file after having released all locks, blocks and shares
 */
static inline void
nlm_delete_file(struct nlm_file *file)
{
        struct inode *inode = file->f_file.f_dentry->d_inode;
        struct nlm_file **fp, *f;

        dprintk("lockd: closing file %s/%ld\n",
                kdevname(inode->i_dev), inode->i_ino);
        fp = nlm_files + file->f_hash;
        while ((f = *fp) != NULL) {
                if (f == file) {
                        *fp = file->f_next;
                        nlmsvc_ops->fclose(&file->f_file);
                        kfree(file);
                        return;
                }
                fp = &f->f_next;
        }

        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, int action)
{
        struct inode     *inode = nlmsvc_file_inode(file);
        struct file_lock *fl;
        struct nlm_host  *lockhost;

again:
        file->f_locks = 0;
        for (fl = inode->i_flock; fl; fl = fl->fl_next) {
                if (!(fl->fl_flags & FL_LOCKD))
                        continue;

                /* update current lock count */
                file->f_locks++;
                lockhost = (struct nlm_host *) fl->fl_owner;
                if (action == NLM_ACT_MARK)
                        lockhost->h_inuse = 1;
                else if (action == NLM_ACT_CHECK)
                        return 1;
                else if (action == NLM_ACT_UNLOCK) {
                        struct file_lock lock = *fl;

                        if (host && lockhost != host)
                                continue;

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

        return 0;
}

/*
 * Operate on a single file
 */
static inline int
nlm_inspect_file(struct nlm_host *host, struct nlm_file *file, int action)
{
        if (action == NLM_ACT_CHECK) {
                /* Fast path for mark and sweep garbage collection */
                if (file->f_count || file->f_blocks || file->f_shares)
                        return 1;
        } else {
                if (nlmsvc_traverse_blocks(host, file, action)
                 || nlmsvc_traverse_shares(host, file, action))
                        return 1;
        }
        return nlm_traverse_locks(host, file, action);
}

/*
 * Loop over all files in the file table.
 */
static int
nlm_traverse_files(struct nlm_host *host, int action)
{
        struct nlm_file *file, **fp;
        int             i;

        down(&nlm_file_sema);
        for (i = 0; i < FILE_NRHASH; i++) {
                fp = nlm_files + i;
                while ((file = *fp) != NULL) {
                        /* Traverse locks, blocks and shares of this file
                         * and update file->f_locks count */
                        if (nlm_inspect_file(host, file, action)) {
                                up(&nlm_file_sema);
                                return 1;
                        }

                        /* No more references to this file. Let go of it. */
                        if (!file->f_blocks && !file->f_locks
                         && !file->f_shares && !file->f_count) {
                                *fp = file->f_next;
                                nlmsvc_ops->fclose(&file->f_file);
                                kfree(file);
                        } else {
                                fp = &file->f_next;
                        }
                }
        }
        up(&nlm_file_sema);
        return 0;
}

/*
 * 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 */
        down(&nlm_file_sema);

        /* If there are no more locks etc, delete the file */
        if(--file->f_count == 0) {
                if(!nlm_inspect_file(NULL, file, NLM_ACT_CHECK))
                        nlm_delete_file(file);
        }

        up(&nlm_file_sema);
}

/*
 * Mark all hosts that still hold resources
 */
void
nlmsvc_mark_resources(void)
{
        dprintk("lockd: nlmsvc_mark_resources\n");

        nlm_traverse_files(NULL, NLM_ACT_MARK);
}

/*
 * 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, NLM_ACT_UNLOCK))
                printk(KERN_WARNING
                        "lockd: couldn't remove all locks held by %s",
                        host->h_name);
}

/*
 * Delete a client when the nfsd entry is removed.
 */
void
nlmsvc_invalidate_client(struct svc_client *clnt)
{
        struct nlm_host *host;

        if ((host = nlm_lookup_host(clnt, NULL, 0, 0)) != NULL) {
                dprintk("lockd: invalidating client for %s\n", host->h_name);
                nlmsvc_free_host_resources(host);
                host->h_expires = 0;
                host->h_killed = 1;
                nlm_release_host(host);
        }
}