On Wed, Jun 11, 2025 at 08:54:26AM +0100, Al Viro wrote: > No need to mess with ->d_op at all. Note that ->d_delete that always > returns 1 is equivalent to having DCACHE_DONTCACHE in ->d_flags. > Later the same thing will be placed into ->s_d_flags of the filesystems > where we want that behaviour for all dentries; then the check in > simple_lookup() will at least get unlikely() slapped on it. > > NOTE: there are only two filesystems where > * simple_lookup() might be called > * default ->d_op is non-NULL > * its ->d_delete() doesn't always return 1 > If not for those, we could have simple_lookup() just set DCACHE_DONTCACHE > without even looking at ->d_op. Filesystems in question are btrfs > (where ->d_delete() takes care to recognize the dentries that might > come from simple_lookup() and returns 1 for those) and tracefs. > > The former would be fine with simple_lookup() setting DCACHE_DONTCACHE; > the latter... probably wants DCACHE_DONTCACHE in default d_flags. > > IOW, we might want to drop the check for ->d_op in simple_lookup(); > it's definitely a separate story, though. > > Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > --- Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
