vfs_dir.c

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/*
 * linux/fs/9p/vfs_dir.c
 *
 * This file contains vfs directory ops for the 9P2000 protocol.
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <[email protected]>
 *  Copyright (C) 2002 by Ron Minnich <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"

struct p9_rdir {
    struct mutex mutex;
    int head;
    int tail;
    uint8_t *buf;
};

static inline int dt_type(struct p9_wstat *mistat)
{
    unsigned long perm = mistat->mode;
    int rettype = DT_REG;

    if (perm & P9_DMDIR)
        rettype = DT_DIR;
    if (perm & P9_DMSYMLINK)
        rettype = DT_LNK;

    return rettype;
}

static void p9stat_init(struct p9_wstat *stbuf)
{
    stbuf->name  = NULL;
    stbuf->uid   = NULL;
    stbuf->gid   = NULL;
    stbuf->muid  = NULL;
    stbuf->extension = NULL;
}

static int v9fs_alloc_rdir_buf(struct file *filp, int buflen)
{
    struct p9_rdir *rdir;
    struct p9_fid *fid;
    int err = 0;

    fid = filp->private_data;
    if (!fid->rdir) {
        rdir = kmalloc(sizeof(struct p9_rdir) + buflen, GFP_KERNEL);

        if (rdir == NULL) {
            err = -ENOMEM;
            goto exit;
        }
        spin_lock(&filp->f_dentry->d_lock);
        if (!fid->rdir) {
            rdir->buf = (uint8_t *)rdir + sizeof(struct p9_rdir);
            mutex_init(&rdir->mutex);
            rdir->head = rdir->tail = 0;
            fid->rdir = (void *) rdir;
            rdir = NULL;
        }
        spin_unlock(&filp->f_dentry->d_lock);
        kfree(rdir);
    }
exit:
    return err;
}

static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
    int over;
    struct p9_wstat st;
    int err = 0;
    struct p9_fid *fid;
    int buflen;
    int reclen = 0;
    struct p9_rdir *rdir;

    p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
    fid = filp->private_data;

    buflen = fid->clnt->msize - P9_IOHDRSZ;

    err = v9fs_alloc_rdir_buf(filp, buflen);
    if (err)
        goto exit;
    rdir = (struct p9_rdir *) fid->rdir;

    err = mutex_lock_interruptible(&rdir->mutex);
    if (err)
        return err;
    while (err == 0) {
        if (rdir->tail == rdir->head) {
            err = v9fs_file_readn(filp, rdir->buf, NULL,
                            buflen, filp->f_pos);
            if (err <= 0)
                goto unlock_and_exit;

            rdir->head = 0;
            rdir->tail = err;
        }
        while (rdir->head < rdir->tail) {
            p9stat_init(&st);
            err = p9stat_read(fid->clnt, rdir->buf + rdir->head,
                      rdir->tail - rdir->head, &st);
            if (err) {
                p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
                err = -EIO;
                p9stat_free(&st);
                goto unlock_and_exit;
            }
            reclen = st.size+2;

            over = filldir(dirent, st.name, strlen(st.name),
                filp->f_pos, v9fs_qid2ino(&st.qid), dt_type(&st));

            p9stat_free(&st);

            if (over) {
                err = 0;
                goto unlock_and_exit;
            }
            rdir->head += reclen;
            filp->f_pos += reclen;
        }
    }

unlock_and_exit:
    mutex_unlock(&rdir->mutex);
exit:
    return err;
}

static int v9fs_dir_readdir_dotl(struct file *filp, void *dirent,
                        filldir_t filldir)
{
    int over;
    int err = 0;
    struct p9_fid *fid;
    int buflen;
    struct p9_rdir *rdir;
    struct p9_dirent curdirent;
    u64 oldoffset = 0;

    p9_debug(P9_DEBUG_VFS, "name %s\n", filp->f_path.dentry->d_name.name);
    fid = filp->private_data;

    buflen = fid->clnt->msize - P9_READDIRHDRSZ;

    err = v9fs_alloc_rdir_buf(filp, buflen);
    if (err)
        goto exit;
    rdir = (struct p9_rdir *) fid->rdir;

    err = mutex_lock_interruptible(&rdir->mutex);
    if (err)
        return err;

    while (err == 0) {
        if (rdir->tail == rdir->head) {
            err = p9_client_readdir(fid, rdir->buf, buflen,
                        filp->f_pos);
            if (err <= 0)
                goto unlock_and_exit;

            rdir->head = 0;
            rdir->tail = err;
        }

        while (rdir->head < rdir->tail) {

            err = p9dirent_read(fid->clnt, rdir->buf + rdir->head,
                        rdir->tail - rdir->head,
                        &curdirent);
            if (err < 0) {
                p9_debug(P9_DEBUG_VFS, "returned %d\n", err);
                err = -EIO;
                goto unlock_and_exit;
            }

            /* d_off in dirent structure tracks the offset into
             * the next dirent in the dir. However, filldir()
             * expects offset into the current dirent. Hence
             * while calling filldir send the offset from the
             * previous dirent structure.
             */
            over = filldir(dirent, curdirent.d_name,
                    strlen(curdirent.d_name),
                    oldoffset, v9fs_qid2ino(&curdirent.qid),
                    curdirent.d_type);
            oldoffset = curdirent.d_off;

            if (over) {
                err = 0;
                goto unlock_and_exit;
            }

            filp->f_pos = curdirent.d_off;
            rdir->head += err;
        }
    }

unlock_and_exit:
    mutex_unlock(&rdir->mutex);
exit:
    return err;
}


int v9fs_dir_release(struct inode *inode, struct file *filp)
{
    struct p9_fid *fid;

    fid = filp->private_data;
    p9_debug(P9_DEBUG_VFS, "inode: %p filp: %p fid: %d\n",
         inode, filp, fid ? fid->fid : -1);
    if (fid)
        p9_client_clunk(fid);
    return 0;
}

const struct file_operations v9fs_dir_operations = {
    .read = generic_read_dir,
    .llseek = generic_file_llseek,
    .readdir = v9fs_dir_readdir,
    .open = v9fs_file_open,
    .release = v9fs_dir_release,
};

const struct file_operations v9fs_dir_operations_dotl = {
    .read = generic_read_dir,
    .llseek = generic_file_llseek,
    .readdir = v9fs_dir_readdir_dotl,
    .open = v9fs_file_open,
    .release = v9fs_dir_release,
        .fsync = v9fs_file_fsync_dotl,
};