From: NeilBrown <[email protected]> Rather than using lock_rename(), use the more obvious is_subdir() for ensuring that neither upper nor workdir contain the other. Also be explicit in the comment that the two directories cannot be the same.
As this is a point-it-time sanity check and does not provide any on-going guarantees, the removal of locking does not introduce any interesting races. Reviewed-by: Amir Goldstein <[email protected]> Reviewed-by: Jeff Layton <[email protected]> Signed-off-by: NeilBrown <[email protected]> --- fs/overlayfs/super.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 109643930b9f..58adefb1c5b8 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -451,18 +451,13 @@ static int ovl_lower_dir(const char *name, const struct path *path, return 0; } -/* Workdir should not be subdir of upperdir and vice versa */ +/* + * Workdir should not be subdir of upperdir and vice versa, and + * they should not be the same. + */ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) { - bool ok = false; - - if (workdir != upperdir) { - struct dentry *trap = lock_rename(workdir, upperdir); - if (!IS_ERR(trap)) - unlock_rename(workdir, upperdir); - ok = (trap == NULL); - } - return ok; + return !is_subdir(workdir, upperdir) && !is_subdir(upperdir, workdir); } static int ovl_setup_trap(struct super_block *sb, struct dentry *dir, -- 2.50.0.107.gf914562f5916.dirty
