• Miklos Szeredi's avatar
    [PATCH] fuse: fix handling of moved directory · d2a85164
    Miklos Szeredi authored
    Fuse considered it an error (EIO) if lookup returned a directory inode, to
    which a dentry already refered.  This is because directory aliases are not
    allowed.
    
    But in a network filesystem this could happen legitimately, if a directory is
    moved on a remote client.  This patch attempts to relax the restriction by
    trying to first evict the offending alias from the cache.  If this fails, it
    still returns an error (EBUSY).
    
    A rarer situation is if an mkdir races with an indenpendent lookup, which
    finds the newly created directory already moved.  In this situation the mkdir
    should return success, but that would be incorrect, since the dentry cannot be
    instantiated, so return EBUSY.
    
    Previously checking for a directory alias and instantiation of the dentry
    weren't done atomically in lookup/mkdir, hence two such calls racing with each
    other could create aliased directories.  To prevent this introduce a new
    per-connection mutex: fuse_conn->inst_mutex, which is taken for instantiations
    with a directory inode.
    Signed-off-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    d2a85164
dir.c 32.6 KB