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    Subject[patch 33/33] vfs: fix lookup on deleted directory
    2.6.25-stable review patch.  If anyone has any objections, please let us
    know.

    ------------------

    From: Miklos Szeredi <mszeredi@suse.cz>

    commit d70b67c8bc72ee23b55381bd6a884f4796692f77 upstream

    Lookup can install a child dentry for a deleted directory. This keeps
    the directory dentry alive, and the inode pinned in the cache and on
    disk, even after all external references have gone away.

    This isn't a big problem normally, since memory pressure or umount
    will clear out the directory dentry and its children, releasing the
    inode. But for UBIFS this causes problems because its orphan area can
    overflow.

    Fix this by returning ENOENT for all lookups on a S_DEAD directory
    before creating a child dentry.

    Thanks to Zoltan Sogor for noticing this while testing UBIFS, and
    Artem for the excellent analysis of the problem and testing.

    Reported-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
    Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
    Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/namei.c | 19 +++++++++++++++++--
    1 file changed, 17 insertions(+), 2 deletions(-)

    --- a/fs/namei.c
    +++ b/fs/namei.c
    @@ -514,7 +514,14 @@ static struct dentry * real_lookup(struc
    */
    result = d_lookup(parent, name);
    if (!result) {
    - struct dentry * dentry = d_alloc(parent, name);
    + struct dentry *dentry;
    +
    + /* Don't create child dentry for a dead directory. */
    + result = ERR_PTR(-ENOENT);
    + if (IS_DEADDIR(dir))
    + goto out_unlock;
    +
    + dentry = d_alloc(parent, name);
    result = ERR_PTR(-ENOMEM);
    if (dentry) {
    result = dir->i_op->lookup(dir, dentry, nd);
    @@ -523,6 +530,7 @@ static struct dentry * real_lookup(struc
    else
    result = dentry;
    }
    +out_unlock:
    mutex_unlock(&dir->i_mutex);
    return result;
    }
    @@ -1313,7 +1321,14 @@ static struct dentry *__lookup_hash(stru

    dentry = cached_lookup(base, name, nd);
    if (!dentry) {
    - struct dentry *new = d_alloc(base, name);
    + struct dentry *new;
    +
    + /* Don't create child dentry for a dead directory. */
    + dentry = ERR_PTR(-ENOENT);
    + if (IS_DEADDIR(inode))
    + goto out;
    +
    + new = d_alloc(base, name);
    dentry = ERR_PTR(-ENOMEM);
    if (!new)
    goto out;
    --


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