Commit e6f009b0 authored Feb 22, 2009 by Bryan Donlan Committed by Theodore Ts'o Feb 22, 2009

ext4: return -EIO not -ESTALE on directory traversal through deleted inode



ext4_iget() returns -ESTALE if invoked on a deleted inode, in order to
report errors to NFS properly.  However, in ext4_lookup(), this
-ESTALE can be propagated to userspace if the filesystem is corrupted
such that a directory entry references a deleted inode.  This leads to
a misleading error message - "Stale NFS file handle" - and confusion
on the part of the admin.

The bug can be easily reproduced by creating a new filesystem, making
a link to an unused inode using debugfs, then mounting and attempting
to ls -l said link.

This patch thus changes ext4_lookup to return -EIO if it receives
-ESTALE from ext4_iget(), as ext4 does for other filesystem metadata
corruption; and also invokes the appropriate ext*_error functions when
this case is detected.

Signed-off-by: Bryan Donlan <bdonlan@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

parent a4912123

fs/ext4/namei.c

+10 −2

Original line number	Original line	Diff line number	Diff line
	@@ -1077,9 +1077,17 @@ static struct dentry ext4_lookup(struct inode dir, struct dentry *dentry, stru
	return ERR_PTR(-EIO);		return ERR_PTR(-EIO);
	}		}
	inode = ext4_iget(dir->i_sb, ino);		inode = ext4_iget(dir->i_sb, ino);
	if (IS_ERR(inode))		if (unlikely(IS_ERR(inode))) {
			if (PTR_ERR(inode) == -ESTALE) {
			ext4_error(dir->i_sb, __func__,
			"deleted inode referenced: %u",
			ino);
			return ERR_PTR(-EIO);
			} else {
	return ERR_CAST(inode);		return ERR_CAST(inode);
	}		}
			}
			}
	return d_splice_alias(inode, dentry);		return d_splice_alias(inode, dentry);
	}		}