Commit 59e96e65 authored by Al Viro's avatar Al Viro
Browse files

do_last(): don't bother with keeping got_write in FMODE_OPENED case 



it's easier to drop it right after lookup_open() and regain if
needed (i.e. if we will need to truncate).  On the non-FMODE_OPENED
path we do that anyway.  In case of FMODE_CREATED we won't be
needing it.  And it's easier to prove correctness that way,
especially since the initial failure to get write access is not
always fatal; proving that we'll never end up truncating in that
case is rather convoluted.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3ad5615a

fs/namei.c

+11 −20
Original line number Diff line number Diff line
@@ -3191,11 +3191,14 @@ static const char *do_last(struct nameidata *nd, 
	else

		inode_unlock_shared(dir->d_inode);



	if (IS_ERR(dentry)) {

		error = PTR_ERR(dentry);

		goto out;

	if (got_write) {

		mnt_drop_write(nd->path.mnt);

		got_write = false;

	}



	if (IS_ERR(dentry))

		return ERR_CAST(dentry);



	if (file->f_mode & FMODE_OPENED) {

		if (file->f_mode & FMODE_CREATED) {

			open_flag &= ~O_TRUNC;
@@ -3220,16 +3223,6 @@ static const char *do_last(struct nameidata *nd, 
		goto finish_open_created;

	}



	/*

	 * If atomic_open() acquired write access it is dropped now due to

	 * possible mount and symlink following (this might be optimized away if

	 * necessary...)

	 */

	if (got_write) {

		mnt_drop_write(nd->path.mnt);

		got_write = false;

	}



finish_lookup:

	if (nd->depth)

		put_link(nd);
@@ -3250,27 +3243,25 @@ finish_open: 
		return ERR_PTR(error);

	audit_inode(nd->name, nd->path.dentry, 0);

	if (open_flag & O_CREAT) {

		error = -EISDIR;

		if (d_is_dir(nd->path.dentry))

			goto out;

			return ERR_PTR(-EISDIR);

		error = may_create_in_sticky(dir_mode, dir_uid,

					     d_backing_inode(nd->path.dentry));

		if (unlikely(error))

			goto out;

			return ERR_PTR(error);

	}

	error = -ENOTDIR;

	if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))

		goto out;

		return ERR_PTR(-ENOTDIR);

	if (!d_is_reg(nd->path.dentry))

		will_truncate = false;



finish_open_created:

	if (will_truncate) {

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

		if (error)

			goto out;

			return ERR_PTR(error);

		got_write = true;

	}

finish_open_created:

	error = may_open(&nd->path, acc_mode, open_flag);

	if (error)

		goto out;

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