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/*

 * 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.

 */

#ident "$Id: vxfs_lookup.c,v 1.1.1.1 2004-04-15 01:11:44 phoenix Exp $"

/*

 * Veritas filesystem driver - lookup and other directory related code.

 */

#include <linux/fs.h>

#include <linux/sched.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 *);

static int              vxfs_readdir(struct file *, void *, filldir_t);

struct inode_operations vxfs_dir_inode_ops = {

        .lookup =               vxfs_lookup,

};

struct file_operations vxfs_dir_operations = {

        .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));

}

/**

 * vxfs_find_entry - find a mathing directory entry for a dentry

 * @ip:         directory inode

 * @dp:         dentry for which we want to find a direct

 * @ppp:        gets filled with the page the return value sits in

 *

 * Description:

 *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory

 *   cache entry @dp.  @ppp will be filled with the page the return

 *   value resides in.

 *

 * Returns:

 *   The wanted direct on success, else a NULL pointer.

 */

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;

}

/**

 * vxfs_inode_by_name - find inode number for dentry

 * @dip:        directory to search in

 * @dp:         dentry we seach for

 *

 * Description:

 *   vxfs_inode_by_name finds out the inode number of

 *   the path component described by @dp in @dip.

 *

 * Returns:

 *   The wanted inode number on success, else Zero.

 */

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);

}

/**

 * vxfs_lookup - lookup pathname component

 * @dip:        dir in which we lookup

 * @dp:         dentry we lookup

 *

 * Description:

 *   vxfs_lookup tries to lookup the pathname component described

 *   by @dp in @dip.

 *

 * Returns:

 *   A NULL-pointer on success, else an negative error code encoded

 *   in the return pointer.

 */

static struct dentry *

vxfs_lookup(struct inode *dip, struct dentry *dp)

{

        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 == 0)

                return NULL;

        ip = iget(dip->i_sb, ino);

        if (!ip)

                return ERR_PTR(-EACCES);

        d_add(dp, ip);

        return NULL;

}

/**

 * vxfs_readdir - read a directory

 * @fp:         the directory to read

 * @retp:       return buffer

 * @filler:     filldir callback

 *

 * Description:

 *   vxfs_readdir fills @retp with directory entries from @fp

 *   using the VFS supplied callback @filler.

 *

 * Returns:

 *   Zero.

 */

static int

vxfs_readdir(struct file *fp, void *retp, filldir_t filler)

{

        struct inode            *ip = fp->f_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;

}