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Subject[patch 44/60] ext4: return -EIO not -ESTALE on directory traversal through deleted inode

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Bryan Donlan <bdonlan@gmail.com>
(cherry picked from commit e6f009b0b45220c004672d41a58865e94946104d)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/ext4/namei.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1055,8 +1055,16 @@ static struct dentry *ext4_lookup(struct
return ERR_PTR(-EIO);
}
inode = ext4_iget(dir->i_sb, ino);
- if (IS_ERR(inode))
- return ERR_CAST(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 d_splice_alias(inode, dentry);
}



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