From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: After reshaping raid1 to raid0 with bitmap, then stop md panic Date: Fri, 8 Aug 2014 15:45:06 +1000 Message-ID: <20140808154506.544472c2@notabene.brown> References: <324320204.17911195.1407221719669.JavaMail.zimbra@redhat.com> <11051344.17913061.1407222186494.JavaMail.zimbra@redhat.com> <20140806163702.15592dc6@notabene.brown> <1783178354.19231525.1407405817606.JavaMail.zimbra@redhat.com> <20140807202913.570be307@notabene.brown> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; boundary="Sig_/eTgI4V3Gn+jx0REs.1A2B9C"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20140807202913.570be307@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: Xiao Ni Cc: linux-raid@vger.kernel.org, Jes Sorensen List-Id: linux-raid.ids --Sig_/eTgI4V3Gn+jx0REs.1A2B9C Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 7 Aug 2014 20:29:13 +1000 NeilBrown wrote: > On Thu, 7 Aug 2014 06:03:37 -0400 (EDT) Xiao Ni wrote: >=20 > >=20 > >=20 > > ----- Original Message ----- > > > From: "NeilBrown" > > > To: "Xiao Ni" > > > Cc: linux-raid@vger.kernel.org, "Jes Sorensen" > > > Sent: Wednesday, August 6, 2014 2:37:02 PM > > > Subject: Re: After reshaping raid1 to raid0 with bitmap, then stop md= panic > > >=20 > > > On Tue, 5 Aug 2014 03:03:06 -0400 (EDT) Xiao Ni wrot= e: > > >=20 > > > > Dear all > > > >=20 > > > >=20 > > > > I faced one problem that the system panic after reshaping raid1 = to raid0 > > > > with bitmap. > > > > The dmesg and calltrace information is like this: > > > >=20 > > > > You can easily reproduce this by those steps: > > > > 1. mdadm -CR /dev/md0 -l1 -n2 /dev/loop[0-1] --bitmap=3Dinternal > > > > 2. mdadm --wait /dev/md0 > > > > 3. mdadm --grow -l0 /dev/md0 > > > > 4. mdadm -S /dev/md0 > > > ... > > > >=20 > > > > [ 1485.646746] BUG: unable to handle kernel NULL pointer dereferenc= e at > > > > 0000000000000038 > > > > [ 1485.654724] IP: [] bitmap_daemon_work+0x24e/0x= 450 > > >=20 > > > Yes, RAID0 doesn't support bitmaps, so this cannot possibly work. > > >=20 > > > Following patch should turn the crash into a clean failure. > > >=20 > > > Thanks for the report, > > > NeilBrown > > >=20 > > >=20 > > > From 1bdb20e16166240a4ca3b861c48defefaf218874 Mon Sep 17 00:00:00 2001 > > > From: NeilBrown > > > Date: Wed, 6 Aug 2014 16:34:27 +1000 > > > Subject: [PATCH] md: check for bitmap compatability when changing raid > > > levels. > > >=20 > > > If an array has a bitmap, then it cannot be converted to > > > a level which does not support bitmaps. > > >=20 > > > Reported-by: Xiao Ni > > > Signed-off-by: NeilBrown > > >=20 > > > diff --git a/drivers/md/md.c b/drivers/md/md.c > > > index 1379b1a3b9ff..3bd13b276e45 100644 > > > --- a/drivers/md/md.c > > > +++ b/drivers/md/md.c > > > @@ -3500,6 +3500,12 @@ level_store(struct mddev *mddev, const char *b= uf, > > > size_t len) > > > mdname(mddev), clevel); > > > return -EINVAL; > > > } > > > + if (mddev->bitmap && !pers->quiesce) { > > > + module_put(pers->owner); > > > + printk(KERN_WARNING "md: %s: %s does not support a bitmap\n", > > > + mdname(mddev), clevel); > > > + return -EINVAL; > > > + } > > > =20 > > > rdev_for_each(rdev, mddev) > > > rdev->new_raid_disk =3D rdev->raid_disk; > > >=20 > >=20 > > Hi Neil > >=20 > > I have tried the patch, but it can reshape to raid0 still, then stop= the raid0, the system > > panics. > >=20 > > What does pers->quiesce mean? I'm not familiar with md code.=20 > >=20 > > Best Regards > > Xiao >=20 >=20 > "quiesce" is a function that makes the array "quiescent" - it stops all IO > from happening. > The set_bitmap_file() function has: >=20 > if (mddev->pers) { > if (!mddev->pers->quiesce) > return -EBUSY; >=20 >=20 > So I thought it was safe to assume that if there was a quiesce function t= hen > the personality handled bitmaps. Obviously not. > I'll have to fix that up... Can you confirm that this works please? Thanks. NeilBrown =46rom a8461a61c241a25afedbe493c13d98a6e0cf4246 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 6 Aug 2014 16:34:27 +1000 Subject: [PATCH] md/raid0: check for bitmap compatability when changing raid levels. If an array has a bitmap, then it cannot be converted to raid0. Reported-by: Xiao Ni Signed-off-by: NeilBrown diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index 407a99e46f69..cf91f5910c7c 100644 --- a/drivers/md/raid0.c +++ b/drivers/md/raid0.c @@ -685,6 +685,12 @@ static void *raid0_takeover(struct mddev *mddev) * raid10 - assuming we have all necessary active disks * raid1 - with (N -1) mirror drives faulty */ + + if (mddev->bitmap) { + printk(KERN_ERR "md/raid0: %s: cannot takeover array with bitmap\n", + mdname(mddev)); + return ERR_PTR(-EBUSY); + } if (mddev->level =3D=3D 4) return raid0_takeover_raid45(mddev); =20 --Sig_/eTgI4V3Gn+jx0REs.1A2B9C Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIVAwUBU+Rj4jnsnt1WYoG5AQLWVxAAnK7azVYzxU+5HU4yOwatjx9csF6a7kbH csd+zNvCw9kh0UGyMkdGcNj0eE16oh1Fx4ujeBgHzfmgK60FI355DONeGrhjLLAK lUOsZAsNXFXtjv3ccZdc82VIn+WMJC/9TzG+Kz4qSMjX207tHlkfXPJlbeB6yUZu fOP2MW4PSHq7F37+YxzQrMFOKSGa4fr8ysGSabYcEry0UMu9HpVs7jK5/ITNhNpv ucHedc0TsDJnMcufgMoVgl+A00vXisB06uC3VX0DmbIJs8t2LfeJSy4cnt3GIcFu dNr/PmRRP5sC/IcnqunxFg7pINPwC3wMKjIQAmbw7zo5huBWQ6XlQzFycnqamHXA 23plPR/HgyU7wFafXN5v+3RoGMwtXPT0t080Q5AKN/Q1p2YxknD9q2pnHyvEhXIq bC5E+Fx0yUTFgj8j+vrpia8LsFXJTW+FsQ5fT87NzfBU8tdpk96h/rXLWVIJC3hL 59ihxDPL8/pvgwQ0Nm7Mc0J+tZOoMxzQUe4t+CpiQ5EIVGYXoA5m53jIFkvY8K7r yAT6Z0D7P2lbERZc8OwHbJcZQncy23C5XjGMbeqxMR85Z/A/R9eGKZEniZQkC3H4 vjVO40eLIiNKP7rptsBjePpiBy/X+rxhaXx1QWb7hhJCh8DrGK406KHoGdYit/dV Px2gH3RAzXs= =dccY -----END PGP SIGNATURE----- --Sig_/eTgI4V3Gn+jx0REs.1A2B9C--