Em Tue, Oct 09, 2018 at 08:52:26PM -0700, Benjamin Peterson escreveu: > Hi Arnaldo, > Did you get a chance to look at this again?
Thanks, for pinging me about it, will check. - Arnaldo > On Thu, Aug 30, 2018, at 14:50, Benjamin Peterson wrote: > > Thanks for the review. > > > > On Thu, Aug 30, 2018, at 11:28, Arnaldo Carvalho de Melo wrote: > > > Em Mon, Aug 27, 2018 at 08:53:44PM -0700, Benjamin Peterson escreveu: > > > > Example output of perf trace -e mount,umount2: > > > > > > > > 6243.930 ( 0.052 ms): mount/30976 mount(dev_name: 0x55dc541bb920, > > > > dir_name: 0x55dc541bc960, type: 0x55dc541b9c40, flags: BIND) = 0 > > > > 7851.821 (26.015 ms): umount/30983 umount2(name: 0x558daa82cf50, > > > > flags: MNT_FORCE ) = 0 > > > > > > > > Signed-off-by: Benjamin Peterson <benja...@python.org> > > > > > > So, I tried: > > > > > > Before your patch: > > > > > > # perf trace -e *mount* mount /dev/mapper/fedora-home /s > > > 0.000 ( 4.335 ms): mount/3126 mount(dev_name: 0x55deecc4d480, > > > dir_name: 0x55deecc4d4a0, type: 0x55deecc53880, flags: 3236757504) = 0 > > > # > > > # perf trace -e *mount* umount /dev/mapper/fedora-home /s > > > ? ( ): umount/3138 ... [continued]: umount2()) = 0 > > > 11.576 (umount: 0.004 ms): /s: not mounted.umount/ > > > 3138 umount2(arg0: 94501956754656, arg1: 0, arg2: 1, arg3: > > > 140051050083104, arg4: 4, arg5: 94501956755136) = -1 EINVAL Invalid > > > argument > > > # > > > > > > After: > > > > > > [root@jouet ~]# perf trace -e *mount* mount /dev/mapper/fedora-home /s > > > 0.000 ( 1.213 ms): mount/5244 mount(dev_name: 0x5558c1169480, > > > dir_name: 0x5558c11694a0, type: 0x5558c116f880, flags: ) = 0 > > > [root@jouet ~]# perf trace -e *mount* umount /s > > > 0.000 ( 9.241 ms): umount/5251 umount2(name: > > > 0x55f74a986480 ) = 0 > > > > > > The flags for mount got empty? Can you pleaes check that? I.e. using the > > > default mount options, not specifying a 'bind' mount like you did. > > > > That comes from these lines in syscall_arg__scnprintf_mount_flags: > > > > if ((flags & MS_MGC_MSK) == MS_MGC_VAL) > > flags &= ~MS_MGC_MSK; > > > > The reason for this is explained in the comment for do_mount in > > fs/namespace.c: > > > > /* > > * Pre-0.97 versions of mount() didn't have a flags word. > > * When the flags word was introduced its top half was required > > * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. > > * Therefore, if this magic number is present, it carries no information > > * and must be discarded. > > */ > > > > (I used a bind mount for my commit message example because a "default" > > mount() doesn't use any flags.) > > > > > > > > I'm splitting this patch so that the aliasing of 'umount2' to 'umount' > > > gets merged now, > > > > > > Check my perf/core branch at: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git > > > > LGTM. Thanks > >
