vxfs_lookup.c

Go to the documentation of this file.

/*
 * Copyright (c) 2000-2001 Christoph Hellwig.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL").
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Veritas filesystem driver - lookup and other directory related code.
 */
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/pagemap.h>

#include "vxfs.h"
#include "vxfs_dir.h"
#include "vxfs_inode.h"
#include "vxfs_extern.h"

/*
 * Number of VxFS blocks per page.
 */
#define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))


static struct dentry *  vxfs_lookup(struct inode *, struct dentry *, unsigned int);
static int      vxfs_readdir(struct file *, void *, filldir_t);

const struct inode_operations vxfs_dir_inode_ops = {
    .lookup =       vxfs_lookup,
};

const struct file_operations vxfs_dir_operations = {
    .llseek =       generic_file_llseek,
    .read =         generic_read_dir,
    .readdir =      vxfs_readdir,
};

 
static inline u_long
dir_pages(struct inode *inode)
{
    return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
}
 
static inline u_long
dir_blocks(struct inode *ip)
{
    u_long          bsize = ip->i_sb->s_blocksize;
    return (ip->i_size + bsize - 1) & ~(bsize - 1);
}

/*
 * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
 *
 * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
 */
static inline int
vxfs_match(int len, const char * const name, struct vxfs_direct *de)
{
    if (len != de->d_namelen)
        return 0;
    if (!de->d_ino)
        return 0;
    return !memcmp(name, de->d_name, len);
}

static inline struct vxfs_direct *
vxfs_next_entry(struct vxfs_direct *de)
{
    return ((struct vxfs_direct *)((char*)de + de->d_reclen));
}

static struct vxfs_direct *
vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
{
    u_long              npages, page, nblocks, pblocks, block;
    u_long              bsize = ip->i_sb->s_blocksize;
    const char          *name = dp->d_name.name;
    int             namelen = dp->d_name.len;

    npages = dir_pages(ip);
    nblocks = dir_blocks(ip);
    pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
    
    for (page = 0; page < npages; page++) {
        caddr_t         kaddr;
        struct page     *pp;

        pp = vxfs_get_page(ip->i_mapping, page);
        if (IS_ERR(pp))
            continue;
        kaddr = (caddr_t)page_address(pp);

        for (block = 0; block <= nblocks && block <= pblocks; block++) {
            caddr_t         baddr, limit;
            struct vxfs_dirblk  *dbp;
            struct vxfs_direct  *de;

            baddr = kaddr + (block * bsize);
            limit = baddr + bsize - VXFS_DIRLEN(1);
            
            dbp = (struct vxfs_dirblk *)baddr;
            de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));

            for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
                if (!de->d_reclen)
                    break;
                if (!de->d_ino)
                    continue;
                if (vxfs_match(namelen, name, de)) {
                    *ppp = pp;
                    return (de);
                }
            }
        }
        vxfs_put_page(pp);
    }

    return NULL;
}

static ino_t
vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
{
    struct vxfs_direct      *de;
    struct page         *pp;
    ino_t               ino = 0;

    de = vxfs_find_entry(dip, dp, &pp);
    if (de) {
        ino = de->d_ino;
        kunmap(pp);
        page_cache_release(pp);
    }
    
    return (ino);
}

static struct dentry *
vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
{
    struct inode        *ip = NULL;
    ino_t           ino;
             
    if (dp->d_name.len > VXFS_NAMELEN)
        return ERR_PTR(-ENAMETOOLONG);
                 
    ino = vxfs_inode_by_name(dip, dp);
    if (ino) {
        ip = vxfs_iget(dip->i_sb, ino);
        if (IS_ERR(ip))
            return ERR_CAST(ip);
    }
    d_add(dp, ip);
    return NULL;
}

static int
vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
{
    struct inode        *ip = fp->f_path.dentry->d_inode;
    struct super_block  *sbp = ip->i_sb;
    u_long          bsize = sbp->s_blocksize;
    u_long          page, npages, block, pblocks, nblocks, offset;
    loff_t          pos;

    switch ((long)fp->f_pos) {
    case 0:
        if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
            goto out;
        fp->f_pos++;
        /* fallthrough */
    case 1:
        if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
            goto out;
        fp->f_pos++;
        /* fallthrough */
    }

    pos = fp->f_pos - 2;
    
    if (pos > VXFS_DIRROUND(ip->i_size))
        return 0;

    npages = dir_pages(ip);
    nblocks = dir_blocks(ip);
    pblocks = VXFS_BLOCK_PER_PAGE(sbp);

    page = pos >> PAGE_CACHE_SHIFT;
    offset = pos & ~PAGE_CACHE_MASK;
    block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;

    for (; page < npages; page++, block = 0) {
        caddr_t         kaddr;
        struct page     *pp;

        pp = vxfs_get_page(ip->i_mapping, page);
        if (IS_ERR(pp))
            continue;
        kaddr = (caddr_t)page_address(pp);

        for (; block <= nblocks && block <= pblocks; block++) {
            caddr_t         baddr, limit;
            struct vxfs_dirblk  *dbp;
            struct vxfs_direct  *de;

            baddr = kaddr + (block * bsize);
            limit = baddr + bsize - VXFS_DIRLEN(1);
    
            dbp = (struct vxfs_dirblk *)baddr;
            de = (struct vxfs_direct *)
                (offset ?
                 (kaddr + offset) :
                 (baddr + VXFS_DIRBLKOV(dbp)));

            for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
                int over;

                if (!de->d_reclen)
                    break;
                if (!de->d_ino)
                    continue;

                offset = (caddr_t)de - kaddr;
                over = filler(retp, de->d_name, de->d_namelen,
                    ((page << PAGE_CACHE_SHIFT) | offset) + 2,
                    de->d_ino, DT_UNKNOWN);
                if (over) {
                    vxfs_put_page(pp);
                    goto done;
                }
            }
            offset = 0;
        }
        vxfs_put_page(pp);
        offset = 0;
    }

done:
    fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
out:
    return 0;
}