Got it. Thanks Bernd, for the clarification! [fuse] in subject - thanks for pointing out, will make sure next time onwards! Thanks, Prince Kumar. On Fri, Jun 13, 2025 at 6:05 PM Bernd Schubert <bernd@xxxxxxxxxxx> wrote: > > > > On 6/12/25 17:56, Prince Kumar wrote: > > Gentle reminder!! > > It would be ways more visible, if you would add [fuse] to the subject > line. I only noticed by accident during lunch break when I scanned > through fsdevel... > > > > > -Prince. > > > > On Thu, Jun 5, 2025 at 2:53 PM Prince Kumar <princer@xxxxxxxxxx> wrote: > >> > >> Hello Team, > >> > >> I'm implementing Readdirplus support in GCSFuse > >> (https://github.com/googlecloudplatform/gcsfuse) and have observed > >> behavior that seems to contradict my understanding of its purpose. > >> > >> When Readdirplus returns ChildInodeEntry, I expect the kernel to use > >> this information and avoid subsequent lookup calls for those entries. > >> However, I'm seeing lookup calls persist for these entries unless an > >> entry_timeout is explicitly set. > >> > >> One similar open issue on the libfuse github repo: > >> https://github.com/libfuse/libfuse/issues/235, which is closed but > >> seems un-resolved. > >> > >> 1. Could you confirm if this is the expected behavior, or a kernel side issue? > >> 2. Also, is there a way other than setting entry_timeout, to suppress > >> these lookup entries calls after the Readdirplus call? > > I guess the problem is that there is no readdir-plus system call. > > Try something like "strace -f ls -l /tmp" > > Results in > > getdents64(3, 0x6119da3c3640 /* 28 entries */, 32768) = 1768 > statx(AT_FDCWD, "/tmp/snap-private-tmp", AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW|AT_NO_AUTOMOUNT, STATX_MODE|STATX_NLINK|STATX_UID|STATX_GID|STATX_MTIME|STATX_SIZE, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFDIR|0700, stx_size=120, ...}) = 0 > lgetxattr("/tmp/snap-private-tmp", "security.selinux", 0x6119da3c1f40, 255) = -1 ENODATA (No data available) > > getdents64() eventually becomes FUSE_READDIRPLUS and libfuse returns > the entries with their attributes. And these attributes get > filled into the inodes. > > A bit later statx() is called and since there is no cache on the attributes > it has to assume that the attributes are outdated and fetches them again. > > Without cache you would need a single application call, but that syscall > does not exist. > > > Hope it helps, > Bernd >
