From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH 1/2] md/raid0: Introduce new array state 'broken' for raid0 Date: Tue, 30 Jul 2019 10:11:17 +1000 Message-ID: <87wog0l6u2.fsf@notabene.neil.brown.name> References: <20190729203135.12934-1-gpiccoli@canonical.com> <20190729203135.12934-2-gpiccoli@canonical.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============3643406624535424492==" Return-path: In-Reply-To: <20190729203135.12934-2-gpiccoli@canonical.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: "Guilherme G. Piccoli" , linux-raid@vger.kernel.org Cc: linux-block@vger.kernel.org, jay.vosburgh@canonical.com, songliubraving@fb.com, dm-devel@redhat.com, Neil F Brown List-Id: linux-raid.ids --===============3643406624535424492== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, Jul 29 2019, Guilherme G. Piccoli wrote: > Currently if a md/raid0 array gets one or more members removed while > being mounted, kernel keeps showing state 'clean' in the 'array_state' > sysfs attribute. Despite udev signaling the member device is gone, 'mdadm' > cannot issue the STOP_ARRAY ioctl successfully, given the array is mounte= d. > > Nothing else hints that something is wrong (except that the removed devic= es > don't show properly in the output of 'mdadm detail' command). There is no > other property to be checked, and if user is not performing reads/writes > to the array, even kernel log is quiet and doesn't give a clue about the > missing member. > > This patch changes this behavior; when 'array_state' is read we introduce > a non-expensive check (only for raid0) that relies in the comparison of > the total number of disks when array was assembled with gendisk flags of > those devices to validate if all members are available and functional. > A new array state 'broken' was added: it mimics the state 'clean' in every > aspect, being useful only to distinguish if such array has some member > missing. Also, we show a rate-limited warning in kernel log in such case. > > This patch has no proper functional change other than adding a 'clean'-li= ke > state; it was tested with ext4 and xfs filesystems. It requires a 'mdadm' > counterpart to handle the 'broken' state. > > Cc: NeilBrown > Cc: Song Liu > Signed-off-by: Guilherme G. Piccoli > --- > drivers/md/md.c | 23 +++++++++++++++++++---- > drivers/md/md.h | 2 ++ > drivers/md/raid0.c | 26 ++++++++++++++++++++++++++ > 3 files changed, 47 insertions(+), 4 deletions(-) > > diff --git a/drivers/md/md.c b/drivers/md/md.c > index fba49918d591..b80f36084ec1 100644 > --- a/drivers/md/md.c > +++ b/drivers/md/md.c > @@ -4160,12 +4160,18 @@ __ATTR_PREALLOC(resync_start, S_IRUGO|S_IWUSR, > * active-idle > * like active, but no writes have been seen for a while (100msec). > * > + * broken > + * RAID0-only: same as clean, but array is missing a member. > + * It's useful because RAID0 mounted-arrays aren't stopped > + * when a member is gone, so this state will at least alert > + * the user that something is wrong. > + * > */ > enum array_state { clear, inactive, suspended, readonly, read_auto, clea= n, active, > - write_pending, active_idle, bad_word}; > + write_pending, active_idle, broken, bad_word}; > static char *array_states[] =3D { > "clear", "inactive", "suspended", "readonly", "read-auto", "clean", "ac= tive", > - "write-pending", "active-idle", NULL }; > + "write-pending", "active-idle", "broken", NULL }; >=20=20 > static int match_word(const char *word, char **list) > { > @@ -4181,7 +4187,7 @@ array_state_show(struct mddev *mddev, char *page) > { > enum array_state st =3D inactive; >=20=20 > - if (mddev->pers) > + if (mddev->pers) { > switch(mddev->ro) { > case 1: > st =3D readonly; > @@ -4201,7 +4207,15 @@ array_state_show(struct mddev *mddev, char *page) > st =3D active; > spin_unlock(&mddev->lock); > } > - else { > + > + if ((mddev->pers->level =3D=3D 0) && Don't test if ->level is 0. Instead, test if ->is_missing_dev is not NULL. NeilBrown > + ((st =3D=3D clean) || (st =3D=3D broken))) { > + if (mddev->pers->is_missing_dev(mddev)) > + st =3D broken; > + else > + st =3D clean; > + } > + } else { > if (list_empty(&mddev->disks) && > mddev->raid_disks =3D=3D 0 && > mddev->dev_sectors =3D=3D 0) > @@ -4315,6 +4329,7 @@ array_state_store(struct mddev *mddev, const char *= buf, size_t len) > break; > case write_pending: > case active_idle: > + case broken: > /* these cannot be set */ > break; > } > diff --git a/drivers/md/md.h b/drivers/md/md.h > index 41552e615c4c..e7b42b75701a 100644 > --- a/drivers/md/md.h > +++ b/drivers/md/md.h > @@ -590,6 +590,8 @@ struct md_personality > int (*congested)(struct mddev *mddev, int bits); > /* Changes the consistency policy of an active array. */ > int (*change_consistency_policy)(struct mddev *mddev, const char *buf); > + /* Check if there is any missing/failed members - RAID0 only for now. */ > + bool (*is_missing_dev)(struct mddev *mddev); > }; >=20=20 > struct md_sysfs_entry { > diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c > index 58a9cc5193bf..79618a6ae31a 100644 > --- a/drivers/md/raid0.c > +++ b/drivers/md/raid0.c > @@ -455,6 +455,31 @@ static inline int is_io_in_chunk_boundary(struct mdd= ev *mddev, > } > } >=20=20 > +bool raid0_is_missing_dev(struct mddev *mddev) > +{ > + struct md_rdev *rdev; > + static int already_missing; > + int def_disks, work_disks =3D 0; > + struct r0conf *conf =3D mddev->private; > + > + def_disks =3D conf->strip_zone[0].nb_dev; > + rdev_for_each(rdev, mddev) > + if (rdev->bdev->bd_disk->flags & GENHD_FL_UP) > + work_disks++; > + > + if (unlikely(def_disks - work_disks)) { > + if (!already_missing) { > + already_missing =3D 1; > + pr_warn("md: %s: raid0 array has %d missing/failed members\n", > + mdname(mddev), (def_disks - work_disks)); > + } > + return true; > + } > + > + already_missing =3D 0; > + return false; > +} > + > static void raid0_handle_discard(struct mddev *mddev, struct bio *bio) > { > struct r0conf *conf =3D mddev->private; > @@ -789,6 +814,7 @@ static struct md_personality raid0_personality=3D > .takeover =3D raid0_takeover, > .quiesce =3D raid0_quiesce, > .congested =3D raid0_congested, > + .is_missing_dev =3D raid0_is_missing_dev, > }; >=20=20 > static int __init raid0_init (void) > --=20 > 2.22.0 --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAl0/iyUACgkQOeye3VZi gblnEQ/+NamZPUglUnNVstM5Jl6QtOiUnrvb2fgle89GT0fps4Ef3ZhRcXM8TQ4l fr2ooqdO0tgdPXY7m/pJhvg7IQLKedll9KDsuOe4DzTjBxxSs8kOutkHlFwmK8iL P+rFdOd59xg1EFuLEkPteiGI8JaZzfUd/cFhQukOy+yFVWk7Pvh4xLCIUCfG3sp/ jSwRrym+rHyEYlaPxOT0qn6rrONVDs/fayXvCqvjeLWwMRP9hFkYd8fZBfgXmB5j 3jzSBtAafp4WlK/+z5OT94QB+43rOK+WM2pLL25aEnamjZF/SmmjIy+6+VV1/bUf WFduwc6Sc1ILNbiPF09bNV7ul1X7XW8kF7xt49Kkpaqf3Hr1vAajlNvFU1ye49co DwpR0MGx0TGulB/S9Hg+oGryfGwQgLQn7+noKh3Fpjktjy5q1KOnB4KpsPypu1/1 nBXOXzO6f3KHLr2RiSdTqa/wl/3r1mUHCSWFMDe1wupuFVxltEVm/WtRzVpGDEAw pM63fd5/IHnIqweTJN2YAThKc5Lyc4Ou7BN3lg/VQtnirWCuJPS7c4/JIiUpqluH uhg9qzSiuKXtlhXEEo7E/OEhE2NH4Rg+/JrntygSNQJoQ8oQJrDx67bH0PoWjV1p MjLl855yMwXwOaHOhEKSbE/erRLklajWJ9oeKaO4tOB6TXe3zPI= =pDFz -----END PGP SIGNATURE----- --=-=-=-- --===============3643406624535424492== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============3643406624535424492==--