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acrn-kernel/fs/freevxfs/vxfs_lookup.c

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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.
*/
/*
* 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 <linux/smp_lock.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 *, struct nameidata *);
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
* @nd: lookup nameidata
*
* 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 nameidata *nd)
{
struct inode *ip = NULL;
ino_t ino;
if (dp->d_name.len > VXFS_NAMELEN)
return ERR_PTR(-ENAMETOOLONG);
lock_kernel();
ino = vxfs_inode_by_name(dip, dp);
if (ino) {
ip = iget(dip->i_sb, ino);
if (!ip) {
unlock_kernel();
return ERR_PTR(-EACCES);
}
}
unlock_kernel();
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)) {
unlock_kernel();
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:
unlock_kernel();
return 0;
}
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