tree 60719e471e80dbbf48f984520de7e8f3e22e1a38
parent 75a2352d0110960aeee1a28ddc09a55f97c99100
author J. Bruce Fields <bfields@redhat.com> 1392677922 -0500
committer Al Viro <viro@zeniv.linux.org.uk> 1407436810 -0400

dcache: d_splice_alias mustn't create directory aliases

Currently if d_splice_alias finds a directory with an alias that is not
IS_ROOT or not DCACHE_DISCONNECTED, it creates a duplicate directory.

Duplicate directory dentries are unacceptable; it is better just to
error out.

(In the case of a local filesystem the most likely case is filesystem
corruption: for example, perhaps two directories point to the same child
directory, and the other parent has already been found and cached.)

Note that distributed filesystems may encounter this case in normal
operation if a remote host moves a directory to a location different
from the one we last cached in the dcache.  For that reason, such
filesystems should instead use d_materialise_unique, which tries to move
the old directory alias to the right place instead of erroring out.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>