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Commit bbf7a8a3 authored by J. Bruce Fields's avatar J. Bruce Fields Committed by Al Viro
Browse files

exportfs: move most of reconnect_path to helper function 



Also replace 3 easily-confused three-letter acronyms by more helpful
variable names.

Just cleanup, no change in functionality, with one exception: the
dentry_connected() check in the "out_reconnected" case will now only
check the ancestors of the current dentry instead of checking all the
way from target_dir.  Since we've already verified connectivity up to
this dentry, that should be sufficient.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent e4b70ebe

fs/exportfs/expfs.c

+86 −78
Original line number Diff line number Diff line
@@ -125,6 +125,86 @@ static void clear_disconnected(struct dentry *dentry) 
	dput(dentry);

}



/*

 * Reconnect a directory dentry with its parent.

 *

 * This can return a dentry, or NULL, or an error.

 *

 * In the first case the returned dentry is the parent of the given

 * dentry, and may itself need to be reconnected to its parent.

 *

 * In the NULL case, a concurrent VFS operation has either renamed or

 * removed this directory.  The concurrent operation has reconnected our

 * dentry, so we no longer need to.

 */

static struct dentry *reconnect_one(struct vfsmount *mnt,

		struct dentry *dentry, char *nbuf)

{

	struct dentry *parent;

	struct dentry *tmp;

	int err;



	parent = ERR_PTR(-EACCES);

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

	if (mnt->mnt_sb->s_export_op->get_parent)

		parent = mnt->mnt_sb->s_export_op->get_parent(dentry);

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



	if (IS_ERR(parent)) {

		dprintk("%s: get_parent of %ld failed, err %d\n",

			__func__, dentry->d_inode->i_ino, PTR_ERR(parent));

		return parent;

	}



	dprintk("%s: find name of %lu in %lu\n", __func__,

		dentry->d_inode->i_ino, parent->d_inode->i_ino);

	err = exportfs_get_name(mnt, parent, nbuf, dentry);

	if (err == -ENOENT)

		goto out_reconnected;

	if (err)

		goto out_err;

	dprintk("%s: found name: %s\n", __func__, nbuf);

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

	tmp = lookup_one_len(nbuf, parent, strlen(nbuf));

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

	if (IS_ERR(tmp)) {

		dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));

		goto out_err;

	}

	if (tmp != dentry) {

		dput(tmp);

		goto out_reconnected;

	}

	dput(tmp);

	if (IS_ROOT(dentry)) {

		err = -ESTALE;

		goto out_err;

	}

	return parent;



out_err:

	dput(parent);

	return ERR_PTR(err);

out_reconnected:

	dput(parent);

	/*

	 * Someone must have renamed our entry into another parent, in

	 * which case it has been reconnected by the rename.

	 *

	 * Or someone removed it entirely, in which case filehandle

	 * lookup will succeed but the directory is now IS_DEAD and

	 * subsequent operations on it will fail.

	 *

	 * Alternatively, maybe there was no race at all, and the

	 * filesystem is just corrupt and gave us a parent that doesn't

	 * actually contain any entry pointing to this inode.  So,

	 * double check that this worked and return -ESTALE if not:

	 */

	if (!dentry_connected(dentry))

		return ERR_PTR(-ESTALE);

	return NULL;

}



/*

 * Make sure target_dir is fully connected to the dentry tree.

 *
@@ -158,76 +238,19 @@ reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf) 
			dput(pd);

			break;

		} else {

			struct dentry *parent;

			/*

			 * We have hit the top of a disconnected path, try to

			 * find parent and connect.

			 *

			 * Racing with some other process renaming a directory

			 * isn't much of a problem here.  If someone renames

			 * the directory, it will end up properly connected,

			 * which is what we want

			 *

			 * Getting the parent can't be supported generically,

			 * the locking is too icky.

			 *

			 * Instead we just return EACCES.  If server reboots

			 * or inodes get flushed, you lose

			 */

			struct dentry *ppd = ERR_PTR(-EACCES);

			struct dentry *npd;



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

			if (mnt->mnt_sb->s_export_op->get_parent)

				ppd = mnt->mnt_sb->s_export_op->get_parent(pd);

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



			if (IS_ERR(ppd)) {

				err = PTR_ERR(ppd);

				dprintk("%s: get_parent of %ld failed, err %d\n",

					__func__, pd->d_inode->i_ino, err);

				dput(pd);

				break;

			}



			dprintk("%s: find name of %lu in %lu\n", __func__,

				pd->d_inode->i_ino, ppd->d_inode->i_ino);

			err = exportfs_get_name(mnt, ppd, nbuf, pd);

			if (err) {

				dput(ppd);

				dput(pd);

				if (err == -ENOENT)

					/* some race between get_parent and

					 * get_name?

					 */

					goto out_reconnected;

				break;

			}

			dprintk("%s: found name: %s\n", __func__, nbuf);

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

			npd = lookup_one_len(nbuf, ppd, strlen(nbuf));

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

			if (IS_ERR(npd)) {

				err = PTR_ERR(npd);

				dprintk("%s: lookup failed: %d\n",

					__func__, err);

				dput(ppd);

				dput(pd);

				break;

			}

			/* we didn't really want npd, we really wanted

			 * a side-effect of the lookup.

			 * hopefully, npd == pd, though it isn't really

			 * a problem if it isn't

			 */

			dput(npd);

			dput(ppd);

			if (npd != pd)

			 parent = reconnect_one(mnt, pd, nbuf);

			 if (!parent)

				goto out_reconnected;

			if (IS_ROOT(pd)) {

				/* something went wrong, we have to give up */

				dput(pd);

			if (IS_ERR(parent)) {

				err = PTR_ERR(parent);

				break;

			}

			dput(parent);

		}

		dput(pd);

	}
@@ -241,21 +264,6 @@ reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf) 


	return 0;

out_reconnected:

	/*

	 * Someone must have renamed our entry into another parent, in

	 * which case it has been reconnected by the rename.

	 *

	 * Or someone removed it entirely, in which case filehandle

	 * lookup will succeed but the directory is now IS_DEAD and

	 * subsequent operations on it will fail.

	 *

	 * Alternatively, maybe there was no race at all, and the

	 * filesystem is just corrupt and gave us a parent that doesn't

	 * actually contain any entry pointing to this inode.  So,

	 * double check that this worked and return -ESTALE if not:

	 */

	if (!dentry_connected(target_dir))

		return -ESTALE;

	clear_disconnected(target_dir);

	return 0;

}