C++ d_lookup函数代码示例

/*
 * Walk down the mount stack looking for an autofs mount that
 * has the requested mount type (ie. indirect, direct or offset).
 */
static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
{
	struct dentry *dentry;
	struct autofs_info *ino;
	unsigned int err;

	err = -ENOENT;

	/* Lookup the dentry name at the base of our mount point */
	dentry = d_lookup(nd->path.dentry, &nd->last);
	if (!dentry)
		goto out;

	dput(nd->path.dentry);
	nd->path.dentry = dentry;

	/* And follow the mount stack looking for our autofs mount */
	while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
		ino = autofs4_dentry_ino(nd->path.dentry);
		if (ino && ino->sbi->type & type) {
			err = 0;
			break;
		}
	}
out:
	return err;
}

/*
 * Lookup or create a dentry from within the filesystem.
 *
 * We need to use this instead of lookup_dentry, as the 
 * directory semaphore lock is already held.
 */
struct dentry *umsdos_lookup_dentry(struct dentry *parent, char *name, int len,
					int real)
{
	struct dentry *result, *dentry;
	struct qstr qstr;

	qstr.name = name;
	qstr.len  = len;
	qstr.hash = full_name_hash(name, len);
	result = d_lookup(parent, &qstr);
	if (!result) {
		result = ERR_PTR(-ENOMEM);
		dentry = d_alloc(parent, &qstr);
		if (dentry) {
			result = real ?
				UMSDOS_rlookup(parent->d_inode, dentry) :
				UMSDOS_lookup(parent->d_inode, dentry);
			if (result)
				goto out_fail;
			return dentry;
		}
	}
out:
	return result;

out_fail:
	dput(dentry);
	goto out;
}

/*
 * Find the dentry that matches "name". If there isn't one, create one. If it's
 * a negative dentry or the uniqueid changed, then drop it and recreate it.
 */
static struct dentry *
cifs_readdir_lookup(struct dentry *parent, struct qstr *name,
		    struct cifs_fattr *fattr)
{
	struct dentry *dentry, *alias;
	struct inode *inode;
	struct super_block *sb = parent->d_inode->i_sb;

	cFYI(1, "For %s", name->name);

	if (parent->d_op && parent->d_op->d_hash)
		parent->d_op->d_hash(parent, parent->d_inode, name);
	else
		name->hash = full_name_hash(name->name, name->len);

	dentry = d_lookup(parent, name);
	if (dentry) {
		inode = dentry->d_inode;
		/* update inode in place if i_ino didn't change */
		if (inode && CIFS_I(inode)->uniqueid == fattr->cf_uniqueid) {
			cifs_fattr_to_inode(inode, fattr);
			return dentry;
		}
		d_drop(dentry);
		dput(dentry);
	}

	/*
	 * If we know that the inode will need to be revalidated immediately,
	 * then don't create a new dentry for it. We'll end up doing an on
	 * the wire call either way and this spares us an invalidation.
	 */
	if (fattr->cf_flags & CIFS_FATTR_NEED_REVAL)
		return NULL;

	dentry = d_alloc(parent, name);
	if (dentry == NULL)
		return NULL;

	inode = cifs_iget(sb, fattr);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	alias = d_materialise_unique(dentry, inode);
	if (alias != NULL) {
		dput(dentry);
		if (IS_ERR(alias))
			return NULL;
		dentry = alias;
	}

	return dentry;
}

/*
 * ------ samqfs_notify_dnlc_remove -
 * Look for a dnlc/dcache entry of pip/comp
 * and delete it from the dnlc/dcache.
 */
void
samqfs_notify_dnlc_remove(
	sam_node_t *pip,	/* parent inode */
	char *comp)		/* name to be deleted from the dcache */
{
#ifdef sun
	(void) dnlc_remove(SAM_ITOV(pip), comp);
#endif /* sun */

#ifdef linux
	struct inode *pli;
	int length;
	struct dentry *dir, *de;
	struct qstr qstr;

	if (pip == NULL) {
		return;
	}
	if (comp == NULL) {
		return;
	}

	pli = SAM_SITOLI(pip);
	length = strlen(comp);
	if ((length == 0) || (length > NAME_MAX)) {
		return;
	}

	/*
	 * Find the dcache entry of the parent.
	 */
	dir = d_find_alias(pli);

	if (dir) {
		/*
		 * Find the dcache entry of the component.
		 */

		qstr.name = comp;
		qstr.len = length;
		qstr.hash = rfs_full_name_hash(comp, length);

		de = d_lookup(dir, &qstr);
		if (de) {
			rfs_d_drop(de);
			dput(de);
		}
		dput(dir);
	}
#endif /* linux */
}

/* Might check in the future if inode number changed so we can rehash inode */
static int construct_dentry(struct qstr *qstring, struct file *file,
	struct inode **ptmp_inode, struct dentry **pnew_dentry)
{
	struct dentry *tmp_dentry;
	struct cifs_sb_info *cifs_sb;
	struct cifsTconInfo *pTcon;
	int rc = 0;

	cFYI(1, ("For %s", qstring->name));
	cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
	pTcon = cifs_sb->tcon;

	qstring->hash = full_name_hash(qstring->name, qstring->len);
	tmp_dentry = d_lookup(file->f_path.dentry, qstring);
	if (tmp_dentry) {
		cFYI(0, ("existing dentry with inode 0x%p",
			 tmp_dentry->d_inode));
		*ptmp_inode = tmp_dentry->d_inode;
/* BB overwrite old name? i.e. tmp_dentry->d_name and tmp_dentry->d_name.len??*/
		if (*ptmp_inode == NULL) {
			*ptmp_inode = new_inode(file->f_path.dentry->d_sb);
			if (*ptmp_inode == NULL)
				return rc;
			rc = 1;
		}
		if (file->f_path.dentry->d_sb->s_flags & MS_NOATIME)
			(*ptmp_inode)->i_flags |= S_NOATIME | S_NOCMTIME;
	} else {
		tmp_dentry = d_alloc(file->f_path.dentry, qstring);
		if (tmp_dentry == NULL) {
			cERROR(1, ("Failed allocating dentry"));
			*ptmp_inode = NULL;
			return rc;
		}

		*ptmp_inode = new_inode(file->f_path.dentry->d_sb);
		if (pTcon->nocase)
			tmp_dentry->d_op = &cifs_ci_dentry_ops;
		else
			tmp_dentry->d_op = &cifs_dentry_ops;
		if (*ptmp_inode == NULL)
			return rc;
		if (file->f_path.dentry->d_sb->s_flags & MS_NOATIME)
			(*ptmp_inode)->i_flags |= S_NOATIME | S_NOCMTIME;
		rc = 2;
	}

	tmp_dentry->d_time = jiffies;
	*pnew_dentry = tmp_dentry;
	return rc;
}

/* Might check in the future if inode number changed so we can rehash inode */
static int
construct_dentry(struct qstr *qstring, struct file *file,
		 struct inode **ptmp_inode, struct dentry **pnew_dentry,
		 __u64 *inum)
{
	struct dentry *tmp_dentry = NULL;
	struct super_block *sb = file->f_path.dentry->d_sb;
	int rc = 0;

	cFYI(1, ("For %s", qstring->name));

	qstring->hash = full_name_hash(qstring->name, qstring->len);
	tmp_dentry = d_lookup(file->f_path.dentry, qstring);
	if (tmp_dentry) {
		/* BB: overwrite old name? i.e. tmp_dentry->d_name and
		 * tmp_dentry->d_name.len??
		 */
		cFYI(0, ("existing dentry with inode 0x%p",
			 tmp_dentry->d_inode));
		*ptmp_inode = tmp_dentry->d_inode;
		if (*ptmp_inode == NULL) {
			*ptmp_inode = cifs_new_inode(sb, inum);
			if (*ptmp_inode == NULL)
				return rc;
			rc = 1;
		}
	} else {
		tmp_dentry = d_alloc(file->f_path.dentry, qstring);
		if (tmp_dentry == NULL) {
			cERROR(1, ("Failed allocating dentry"));
			*ptmp_inode = NULL;
			return rc;
		}

		if (CIFS_SB(sb)->tcon->nocase)
			tmp_dentry->d_op = &cifs_ci_dentry_ops;
		else
			tmp_dentry->d_op = &cifs_dentry_ops;

		*ptmp_inode = cifs_new_inode(sb, inum);
		if (*ptmp_inode == NULL)
			return rc;
		rc = 2;
	}

	tmp_dentry->d_time = jiffies;
	*pnew_dentry = tmp_dentry;
	return rc;
}

static struct dentry *
cifs_readdir_lookup(struct dentry *parent, struct qstr *name,
		    struct cifs_fattr *fattr)
{
	struct dentry *dentry, *alias;
	struct inode *inode;
	struct super_block *sb = parent->d_inode->i_sb;

	cFYI(1, "For %s", name->name);

	if (parent->d_op && parent->d_op->d_hash)
		parent->d_op->d_hash(parent, parent->d_inode, name);
	else
		name->hash = full_name_hash(name->name, name->len);

	dentry = d_lookup(parent, name);
	if (dentry) {
		
		inode = dentry->d_inode;
		/* update inode in place if i_ino didn't change */
		if (inode && CIFS_I(inode)->uniqueid == fattr->cf_uniqueid) {
			cifs_fattr_to_inode(inode, fattr);
 			return dentry;
		}
		d_drop(dentry);
		dput(dentry);
	}

	dentry = d_alloc(parent, name);
	if (dentry == NULL)
		return NULL;

	inode = cifs_iget(sb, fattr);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	alias = d_materialise_unique(dentry, inode);
	if (alias != NULL) {
		dput(dentry);
		if (IS_ERR(alias))
			return NULL;
		dentry = alias;
	}

	return dentry;
}

/* Might check in the future if inode number changed so we can rehash inode */
static int construct_dentry(struct qstr *qstring, struct file *file,
	struct inode **ptmp_inode, struct dentry **pnew_dentry)
{
	struct dentry *tmp_dentry;
	struct cifs_sb_info *cifs_sb;
	struct cifsTconInfo *pTcon;
	int rc = 0;

	cFYI(1, ("For %s", qstring->name));
	cifs_sb = CIFS_SB(file->f_dentry->d_sb);
	pTcon = cifs_sb->tcon;

	qstring->hash = full_name_hash(qstring->name, qstring->len);
	tmp_dentry = d_lookup(file->f_dentry, qstring);
	if (tmp_dentry) {
		cFYI(0, ("existing dentry with inode 0x%p", tmp_dentry->d_inode));
		*ptmp_inode = tmp_dentry->d_inode;
/* BB overwrite old name? i.e. tmp_dentry->d_name and tmp_dentry->d_name.len??*/
		if(*ptmp_inode == NULL) {
			*ptmp_inode = new_inode(file->f_dentry->d_sb);
			if(*ptmp_inode == NULL)
				return rc;
			rc = 1;
			d_instantiate(tmp_dentry, *ptmp_inode);
		}
	} else {
		tmp_dentry = d_alloc(file->f_dentry, qstring);
		if(tmp_dentry == NULL) {
			cERROR(1,("Failed allocating dentry"));
			*ptmp_inode = NULL;
			return rc;
		}

		*ptmp_inode = new_inode(file->f_dentry->d_sb);
		tmp_dentry->d_op = &cifs_dentry_ops;
		if(*ptmp_inode == NULL)
			return rc;
		rc = 1;
		d_instantiate(tmp_dentry, *ptmp_inode);
		d_rehash(tmp_dentry);
	}

	tmp_dentry->d_time = jiffies;
	*pnew_dentry = tmp_dentry;
	return rc;
}

/*
 * Find the dentry that matches "name". If there isn't one, create one. If it's
 * a negative dentry or the uniqueid changed, then drop it and recreate it.
 */
static struct dentry *
cifs_readdir_lookup(struct dentry *parent, struct qstr *name,
		    struct cifs_fattr *fattr)
{
	struct dentry *dentry, *alias;
	struct inode *inode;
	struct super_block *sb = parent->d_inode->i_sb;

	cFYI(1, ("For %s", name->name));

	dentry = d_lookup(parent, name);
	if (dentry) {
		/* FIXME: check for inode number changes? */
		if (dentry->d_inode != NULL)
			return dentry;
		d_drop(dentry);
		dput(dentry);
	}

	dentry = d_alloc(parent, name);
	if (dentry == NULL)
		return NULL;

	inode = cifs_iget(sb, fattr);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	if (CIFS_SB(sb)->tcon->nocase)
		dentry->d_op = &cifs_ci_dentry_ops;
	else
		dentry->d_op = &cifs_dentry_ops;

	alias = d_materialise_unique(dentry, inode);
	if (alias != NULL) {
		dput(dentry);
		if (IS_ERR(alias))
			return NULL;
		dentry = alias;
	}

	return dentry;
}

/* D_NEWPROC -- Process a procedure declaration.  The name of the procedure
 * is passed as the single argument.  The input stream is left positioned
 * with the ( of the argument list as the next token (if present).  INPUT is
 * called repeatedly to read the remainder of the declaration, which may span
 * several lines.  The symbol table is cleared whenever a new procedure
 * declaration is started.
 */
void 
d_newproc (
    char *name,			/* procedure name		*/
    int dtype			/* procedure type (0 if subr)	*/
)
{
	register int	token;
	char	tokstr[SZ_TOKEN+1];



	strncpy (procname, name, SZ_FNAME);
	proctype = dtype;
	nextch = sbuf;
	nsym = 0;

	/* Check for null argument list. */
	if (d_gettok(tokstr,SZ_TOKEN) != '(')
	    return;

	/* Process the argument list.
	 */
	while ((token = d_gettok(tokstr,SZ_TOKEN)) != ')') {
	    if (isalpha(token)) {
		/* Enter argument name into the symbol table.
		 */
		if (d_lookup (tokstr) != NULL) {
		    char lbuf[200];
		    sprintf (lbuf, "%s.%s multiply declared",
			procname, tokstr);
		    xpp_warn (lbuf);
		} else
		    d_enter (tokstr, UNDECL, S_ARGUMENT);
	    } else if (token == '\n') {
		linenum[istkptr]++;
		continue;
	    } else if (token == ',') {
		continue;
	    } else
		error (XPP_SYNTAX, "bad syntax in procedure argument list");
	}
}

int main(int argc, char ** argv)
{
    int i;
    char word[MAX_WORD_SIZE+1];
    char answer[MAX_DESC_SIZE+1];
    
    d_initialise();
    
    for (i=1; i<argc; i++)
        d_read_from_file(argv[i]);
    scanf("%s",word);
    
    while(word[0] != '.') {
        if (d_lookup(word,answer))
           printf("%s:\t%s\n", word, answer);
        else
           printf("%s:\t%s\n", word, "Not in dictionary");
        scanf("%s",word);
    }
}

static int proc_sys_fill_cache(struct file *filp, void *dirent,
				filldir_t filldir,
				struct ctl_table_header *head,
				struct ctl_table *table)
{
	struct dentry *child, *dir = filp->f_path.dentry;
	struct inode *inode;
	struct qstr qname;
	ino_t ino = 0;
	unsigned type = DT_UNKNOWN;

	qname.name = table->procname;
	qname.len  = strlen(table->procname);
	qname.hash = full_name_hash(qname.name, qname.len);

	child = d_lookup(dir, &qname);
	if (!child) {
		child = d_alloc(dir, &qname);
		if (child) {
			inode = proc_sys_make_inode(dir->d_sb, head, table);
			if (!inode) {
				dput(child);
				return -ENOMEM;
			} else {
				d_set_d_op(child, &proc_sys_dentry_operations);
				d_add(child, inode);
			}
		} else {
			return -ENOMEM;
		}
	}
	inode = child->d_inode;
	ino  = inode->i_ino;
	type = inode->i_mode >> 12;
	dput(child);
	return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
}

/*
 * Walk down the mount stack looking for an autofs mount that
 * has the requested device number (aka. new_encode_dev(sb->s_dev).
 */
static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
{
	struct dentry *dentry;
	struct inode *inode;
	struct super_block *sb;
	dev_t s_dev;
	unsigned int err;

	err = -ENOENT;

	/* Lookup the dentry name at the base of our mount point */
	dentry = d_lookup(nd->path.dentry, &nd->last);
	if (!dentry)
		goto out;

	dput(nd->path.dentry);
	nd->path.dentry = dentry;

	/* And follow the mount stack looking for our autofs mount */
	while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
		inode = nd->path.dentry->d_inode;
		if (!inode)
			break;

		sb = inode->i_sb;
		s_dev = new_encode_dev(sb->s_dev);
		if (devno == s_dev) {
			if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
				err = 0;
				break;
			}
		}
	}
out:
	return err;
}

int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
			     struct qstr *name)
{
	int err = -ENOTDIR;
	struct inode *parent;
	struct dentry *dir;
	struct dentry *entry;

	parent = ilookup5(sb, parent_nodeid, fuse_inode_eq, &parent_nodeid);
	if (!parent)
		return -ENOENT;

	mutex_lock(&parent->i_mutex);
	if (!S_ISDIR(parent->i_mode))
		goto unlock;

	err = -ENOENT;
	dir = d_find_alias(parent);
	if (!dir)
		goto unlock;

	entry = d_lookup(dir, name);
	dput(dir);
	if (!entry)
		goto unlock;

	fuse_invalidate_attr(parent);
	fuse_invalidate_entry(entry);
	dput(entry);
	err = 0;

 unlock:
	mutex_unlock(&parent->i_mutex);
	iput(parent);
	return err;
}

/*
 * Main driver function for wrapfs's lookup.
 *
 * Returns: NULL (ok), ERR_PTR if an error occurred.
 * Fills in lower_parent_path with <dentry,mnt> on success.
 */
static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flags,
				      struct path *lower_parent_path)
{
	int err = 0;
	struct vfsmount *lower_dir_mnt;
	struct dentry *lower_dir_dentry = NULL;
	struct dentry *lower_dentry;
	const char *name;
	struct path lower_path;
	struct qstr this;

	/* must initialize dentry operations */
	d_set_d_op(dentry, &wrapfs_dops);

	if (IS_ROOT(dentry))
		goto out;

	name = dentry->d_name.name;

	/* now start the actual lookup procedure */
	lower_dir_dentry = lower_parent_path->dentry;
	lower_dir_mnt = lower_parent_path->mnt;

	/* Use vfs_path_lookup to check if the dentry exists or not */
	err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name, 0,
			      &lower_path);

	/* no error: handle positive dentries */
	if (!err) {
		wrapfs_set_lower_path(dentry, &lower_path);
		err = wrapfs_interpose(dentry, dentry->d_sb, &lower_path);
		if (err) /* path_put underlying path on error */
			wrapfs_put_reset_lower_path(dentry);
		goto out;
	}

	/*
	 * We don't consider ENOENT an error, and we want to return a
	 * negative dentry.
	 */
	if (err && err != -ENOENT)
		goto out;

	/* instatiate a new negative dentry */
	this.name = name;
	this.len = strlen(name);
	this.hash = full_name_hash(this.name, this.len);
	lower_dentry = d_lookup(lower_dir_dentry, &this);
	if (lower_dentry)
		goto setup_lower;

	lower_dentry = d_alloc(lower_dir_dentry, &this);
	if (!lower_dentry) {
		err = -ENOMEM;
		goto out;
	}
	d_add(lower_dentry, NULL); /* instantiate and hash */

setup_lower:
	lower_path.dentry = lower_dentry;
	lower_path.mnt = mntget(lower_dir_mnt);
	wrapfs_set_lower_path(dentry, &lower_path);

	/*
	 * If the intent is to create a file, then don't return an error, so
	 * the VFS will continue the process of making this negative dentry
	 * into a positive one.
	 */
	if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
		err = 0;

out:
	return ERR_PTR(err);
}