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Commit d58ffd35 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

vfs: add lookup_open() 



Split out lookup + maybe create from do_last().  This is the part under i_mutex
protection.

The function is called lookup_open() and returns a filp even though the open
part is not used yet.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 71574865

fs/namei.c

+61 −38
Original line number Diff line number Diff line
@@ -2196,6 +2196,60 @@ static inline int open_to_namei_flags(int flag) 
	return flag;

}



/*

 * Lookup, maybe create and open the last component

 *

 * Must be called with i_mutex held on parent.

 *

 * Returns open file or NULL on success, error otherwise.  NULL means no open

 * was performed, only lookup.

 */

static struct file *lookup_open(struct nameidata *nd, struct path *path,

				const struct open_flags *op,

				int *want_write, bool *created)

{

	struct dentry *dir = nd->path.dentry;

	struct dentry *dentry;

	int error;



	*created = false;

	dentry = lookup_hash(nd);

	if (IS_ERR(dentry))

		return ERR_CAST(dentry);



	/* Negative dentry, just create the file */

	if (!dentry->d_inode && (op->open_flag & O_CREAT)) {

		umode_t mode = op->mode;

		if (!IS_POSIXACL(dir->d_inode))

			mode &= ~current_umask();

		/*

		 * This write is needed to ensure that a

		 * rw->ro transition does not occur between

		 * the time when the file is created and when

		 * a permanent write count is taken through

		 * the 'struct file' in nameidata_to_filp().

		 */

		error = mnt_want_write(nd->path.mnt);

		if (error)

			goto out_dput;

		*want_write = 1;

		*created = true;

		error = security_path_mknod(&nd->path, dentry, mode, 0);

		if (error)

			goto out_dput;

		error = vfs_create(dir->d_inode, dentry, mode, nd);

		if (error)

			goto out_dput;

	}

	path->dentry = dentry;

	path->mnt = nd->path.mnt;

	return NULL;



out_dput:

	dput(dentry);

	return ERR_PTR(error);

}



/*

 * Handle the last step of open()

 */
@@ -2203,13 +2257,13 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
			    const struct open_flags *op, const char *pathname)

{

	struct dentry *dir = nd->path.dentry;

	struct dentry *dentry;

	int open_flag = op->open_flag;

	int will_truncate = open_flag & O_TRUNC;

	int want_write = 0;

	int acc_mode = op->acc_mode;

	struct file *filp;

	struct inode *inode;

	bool created;

	int symlink_ok = 0;

	struct path save_parent = { .dentry = NULL, .mnt = NULL };

	bool retried = false;
@@ -2277,53 +2331,24 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 


retry_lookup:

	mutex_lock(&dir->d_inode->i_mutex);



	dentry = lookup_hash(nd);

	error = PTR_ERR(dentry);

	if (IS_ERR(dentry)) {

	filp = lookup_open(nd, path, op, &want_write, &created);

	mutex_unlock(&dir->d_inode->i_mutex);

		goto exit;

	}



	path->dentry = dentry;

	path->mnt = nd->path.mnt;

	if (IS_ERR(filp))

		goto out;



	/* Negative dentry, just create the file */

	if (!dentry->d_inode && (open_flag & O_CREAT)) {

		umode_t mode = op->mode;

		if (!IS_POSIXACL(dir->d_inode))

			mode &= ~current_umask();

		/*

		 * This write is needed to ensure that a

		 * rw->ro transition does not occur between

		 * the time when the file is created and when

		 * a permanent write count is taken through

		 * the 'struct file' in nameidata_to_filp().

		 */

		error = mnt_want_write(nd->path.mnt);

		if (error)

			goto exit_mutex_unlock;

		want_write = 1;

	if (created) {

		/* Don't check for write permission, don't truncate */

		open_flag &= ~O_TRUNC;

		will_truncate = 0;

		acc_mode = MAY_OPEN;

		error = security_path_mknod(&nd->path, dentry, mode, 0);

		if (error)

			goto exit_mutex_unlock;

		error = vfs_create(dir->d_inode, dentry, mode, nd);

		if (error)

			goto exit_mutex_unlock;

		mutex_unlock(&dir->d_inode->i_mutex);

		dput(nd->path.dentry);

		nd->path.dentry = dentry;

		path_to_nameidata(path, nd);

		goto common;

	}



	/*

	 * It already exists.

	 */

	mutex_unlock(&dir->d_inode->i_mutex);

	audit_inode(pathname, path->dentry);



	error = -EEXIST;
@@ -2432,8 +2457,6 @@ static struct file *do_last(struct nameidata *nd, struct path *path, 
	terminate_walk(nd);

	return filp;



exit_mutex_unlock:

	mutex_unlock(&dir->d_inode->i_mutex);

exit_dput:

	path_put_conditional(path, nd);

exit: