[Patch mdadm-3.2.2] Fix readding of a readwrite drive into a writemostlyarray

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If you create a two drive raid1 array with one device writemostly, then
fail the readwrite drive, when you add a new device, it will get the
writemostly bit copied out of the remaining device's superblock into
it's own. You can then remove the new drive and readd it as readwrite,
which will work for the readd, but it leaves the stale WriteMostly1 bit
in devflags resulting in the device going back to writemostly on the
next assembly.

The fix is to make sure that A) when we readd a device and we might have
filled the st->sb info from a running device instead of the device being
readded, then clear/set the WriteMostly1 bit in the super1 struct in
addition to setting the disk state (ditto for super0, but slightly
different mechanism) and B) when adding a clean device to an array (when
we most certainly did copy the superblock info from an existing device),
then clear any writemostly bits.

Signed-off-by: Doug Ledford

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filename="mdadm-3.2.2-writemostly.patch"

diff -up mdadm-3.2.2/Manage.c.writemostly mdadm-3.2.2/Manage.c
--- mdadm-3.2.2/Manage.c.writemostly 2011-06-13 22:50:01.000000000 -0400
+++ mdadm-3.2.2/Manage.c 2011-07-27 14:12:18.629889841 -0400
@@ -741,11 +741,24 @@ int Manage_subdevs(char *devname, int fd
remove_partitions(tfd);
close(tfd);
tfd = -1;
- if (update) {
+ if (update || dv->writemostly > 0) {
int rv = -1;
tfd = dev_open(dv->devname, O_RDWR);
+ if (tfd < 0) {
+ fprintf(stderr, Name ": failed to open %s for"
+ " superblock update during re-add\n", dv->devname);
+ return 1;
+ }

- if (tfd >= 0)
+ if (dv->writemostly == 1)
+ rv = st->ss->update_super(
+ st, NULL, "writemostly",
+ devname, verbose, 0, NULL);
+ if (dv->writemostly == 2)
+ rv = st->ss->update_super(
+ st, NULL, "readwrite",
+ devname, verbose, 0, NULL);
+ if (update)
rv = st->ss->update_super(
st, NULL, update,
devname, verbose, 0, NULL);
diff -up mdadm-3.2.2/mdadm.h.writemostly mdadm-3.2.2/mdadm.h
--- mdadm-3.2.2/mdadm.h.writemostly 2011-07-27 14:12:28.800779575 -0400
+++ mdadm-3.2.2/mdadm.h 2011-07-27 14:04:34.669932148 -0400
@@ -646,6 +646,8 @@ extern struct superswitch {
* linear-grow-new - add a new device to a linear array, but don't
* change the size: so superblock still matches
* linear-grow-update - now change the size of the array.
+ * writemostly - set the WriteMostly1 bit in the superblock devflags
+ * readwrite - clear the WriteMostly1 bit in the superblock devflags
*/
int (*update_super)(struct supertype *st, struct mdinfo *info,
char *update,
diff -up mdadm-3.2.2/super0.c.writemostly mdadm-3.2.2/super0.c
--- mdadm-3.2.2/super0.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super0.c 2011-07-27 14:12:18.655889559 -0400
@@ -570,6 +570,10 @@ static int update_super0(struct supertyp
sb->state &= ~(1< } else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position = info->reshape_progress;
+ else if (strcmp(update, "writemostly")==0)
+ sb->state |= (1< + else if (strcmp(update, "readwrite")==0)
+ sb->state &= ~(1< else
rv = -1;

@@ -688,6 +692,8 @@ static int add_to_super0(struct supertyp
dk->minor = dinfo->minor;
dk->raid_disk = dinfo->raid_disk;
dk->state = dinfo->state;
+ /* In case our source disk was writemostly, don't copy that bit */
+ dk->state &= ~(1<
sb->this_disk = sb->disks[dinfo->number];
sb->sb_csum = calc_sb0_csum(sb);
diff -up mdadm-3.2.2/super1.c.writemostly mdadm-3.2.2/super1.c
--- mdadm-3.2.2/super1.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super1.c 2011-07-27 14:12:18.656889548 -0400
@@ -803,6 +803,10 @@ static int update_super1(struct supertyp
__le64_to_cpu(sb->data_size));
} else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position = __cpu_to_le64(info->reshape_progress);
+ else if (strcmp(update, "writemostly")==0)
+ sb->devflags |= WriteMostly1;
+ else if (strcmp(update, "readwrite")==0)
+ sb->devflags &= ~WriteMostly1;
else
rv = -1;

@@ -923,6 +927,7 @@ static int add_to_super1(struct supertyp
sb->max_dev = __cpu_to_le32(dk->number+1);

sb->dev_number = __cpu_to_le32(dk->number);
+ sb->devflags = 0; /* don't copy another disks flags */
sb->sb_csum = calc_sb_1_csum(sb);

dip = (struct devinfo **)&st->info;

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Re: [Patch mdadm-3.2.2] Fix readding of a readwrite drive into awritemostly array

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On Wed, 27 Jul 2011 14:34:37 -0400 Doug Ledford wrote:

> If you create a two drive raid1 array with one device writemostly, then=20
> fail the readwrite drive, when you add a new device, it will get the=20
> writemostly bit copied out of the remaining device's superblock into=20
> it's own. You can then remove the new drive and readd it as readwrite,=20
> which will work for the readd, but it leaves the stale WriteMostly1 bit=20
> in devflags resulting in the device going back to writemostly on the=20
> next assembly.
>=20
> The fix is to make sure that A) when we readd a device and we might have=
=20
> filled the st->sb info from a running device instead of the device being=
=20
> readded, then clear/set the WriteMostly1 bit in the super1 struct in=20
> addition to setting the disk state (ditto for super0, but slightly=20
> different mechanism) and B) when adding a clean device to an array (when=
=20
> we most certainly did copy the superblock info from an existing device),=
=20
> then clear any writemostly bits.
>=20
> Signed-off-by: Doug Ledford

Applied - thanks.

This function really needs to be refactored though - some of that indenting
is WAY too deep!!

Thanks,
NeilBrown



diff -up mdadm-3.2.2/Manage.c.writemostly mdadm-3.2.2/Manage.c
--- mdadm-3.2.2/Manage.c.writemostly 2011-06-13 22:50:01.000000000 -0400
+++ mdadm-3.2.2/Manage.c 2011-07-27 14:12:18.629889841 -0400
@@ -741,11 +741,24 @@ int Manage_subdevs(char *devname, int fd
remove_partitions(tfd);
close(tfd);
tfd =3D -1;
- if (update) {
+ if (update || dv->writemostly > 0) {
int rv =3D -1;
tfd =3D dev_open(dv->devname, O_RDWR);
+ if (tfd < 0) {
+ fprintf(stderr, Name ": failed to open %s for"
+ " superblock update during re-add\n", dv->devname);
+ return 1;
+ }
=20
- if (tfd >=3D 0)
+ if (dv->writemostly == 1)
+ rv =3D st->ss->update_super(
+ st, NULL, "writemostly",
+ devname, verbose, 0, NULL);
+ if (dv->writemostly == 2)
+ rv =3D st->ss->update_super(
+ st, NULL, "readwrite",
+ devname, verbose, 0, NULL);
+ if (update)
rv =3D st->ss->update_super(
st, NULL, update,
devname, verbose, 0, NULL);
diff -up mdadm-3.2.2/mdadm.h.writemostly mdadm-3.2.2/mdadm.h
--- mdadm-3.2.2/mdadm.h.writemostly 2011-07-27 14:12:28.800779575 -0400
+++ mdadm-3.2.2/mdadm.h 2011-07-27 14:04:34.669932148 -0400
@@ -646,6 +646,8 @@ extern struct superswitch {
* linear-grow-new - add a new device to a linear array, but don't
* change the size: so superblock still matches
* linear-grow-update - now change the size of the array.
+ * writemostly - set the WriteMostly1 bit in the superblock devflags
+ * readwrite - clear the WriteMostly1 bit in the superblock devflags
*/
int (*update_super)(struct supertype *st, struct mdinfo *info,
char *update,
diff -up mdadm-3.2.2/super0.c.writemostly mdadm-3.2.2/super0.c
--- mdadm-3.2.2/super0.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super0.c 2011-07-27 14:12:18.655889559 -0400
@@ -570,6 +570,10 @@ static int update_super0(struct supertyp
sb->state &=3D ~(1< } else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position =3D info->reshape_progress;
+ else if (strcmp(update, "writemostly")==0)
+ sb->state |=3D (1< + else if (strcmp(update, "readwrite")==0)
+ sb->state &=3D ~(1< else
rv =3D -1;
=20
@@ -688,6 +692,8 @@ static int add_to_super0(struct supertyp
dk->minor =3D dinfo->minor;
dk->raid_disk =3D dinfo->raid_disk;
dk->state =3D dinfo->state;
+ /* In case our source disk was writemostly, don't copy that bit */
+ dk->state &=3D ~(1< =20
sb->this_disk =3D sb->disks[dinfo->number];
sb->sb_csum =3D calc_sb0_csum(sb);
diff -up mdadm-3.2.2/super1.c.writemostly mdadm-3.2.2/super1.c
--- mdadm-3.2.2/super1.c.writemostly 2011-06-17 01:15:50.000000000 -0400
+++ mdadm-3.2.2/super1.c 2011-07-27 14:12:18.656889548 -0400
@@ -803,6 +803,10 @@ static int update_super1(struct supertyp
__le64_to_cpu(sb->data_size));
} else if (strcmp(update, "_reshape_progress")==0)
sb->reshape_position =3D __cpu_to_le64(info->reshape_progress);
+ else if (strcmp(update, "writemostly")==0)
+ sb->devflags |=3D WriteMostly1;
+ else if (strcmp(update, "readwrite")==0)
+ sb->devflags &=3D ~WriteMostly1;
else
rv =3D -1;
=20
@@ -923,6 +927,7 @@ static int add_to_super1(struct supertyp
sb->max_dev =3D __cpu_to_le32(dk->number+1);
=20
sb->dev_number =3D __cpu_to_le32(dk->number);
+ sb->devflags =3D 0; /* don't copy another disks flags */
sb->sb_csum =3D calc_sb_1_csum(sb);
=20
dip =3D (struct devinfo **)&st->info;

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Re: [Patch mdadm-3.2.2] Fix readding of a readwrite drive into a writemostly array

I don't deny the need to refactor, but at the time I wrote it I was in "fix the problem" mode, not "clean up the code" mode ;-)

----- Original Message -----
> On Wed, 27 Jul 2011 14:34:37 -0400 Doug Ledford
> wrote:
>
> > If you create a two drive raid1 array with one device writemostly,
> > then
> > fail the readwrite drive, when you add a new device, it will get
> > the
> > writemostly bit copied out of the remaining device's superblock
> > into
> > it's own. You can then remove the new drive and readd it as
> > readwrite,
> > which will work for the readd, but it leaves the stale WriteMostly1
> > bit
> > in devflags resulting in the device going back to writemostly on
> > the
> > next assembly.
> >
> > The fix is to make sure that A) when we readd a device and we might
> > have
> > filled the st->sb info from a running device instead of the device
> > being
> > readded, then clear/set the WriteMostly1 bit in the super1 struct
> > in
> > addition to setting the disk state (ditto for super0, but slightly
> > different mechanism) and B) when adding a clean device to an array
> > (when
> > we most certainly did copy the superblock info from an existing
> > device),
> > then clear any writemostly bits.
> >
> > Signed-off-by: Doug Ledford
>
> Applied - thanks.
>
> This function really needs to be refactored though - some of that
> indenting
> is WAY too deep!!
>
> Thanks,
> NeilBrown
>
>
>
> diff -up mdadm-3.2.2/Manage.c.writemostly mdadm-3.2.2/Manage.c
> --- mdadm-3.2.2/Manage.c.writemostly 2011-06-13 22:50:01.000000000
> -0400
> +++ mdadm-3.2.2/Manage.c 2011-07-27 14:12:18.629889841 -0400
> @@ -741,11 +741,24 @@ int Manage_subdevs(char *devname, int fd
> remove_partitions(tfd);
> close(tfd);
> tfd = -1;
> - if (update) {
> + if (update || dv->writemostly > 0) {
> int rv = -1;
> tfd = dev_open(dv->devname, O_RDWR);
> + if (tfd < 0) {
> + fprintf(stderr, Name ": failed to open %s for"
> + " superblock update during re-add\n", dv->devname);
> + return 1;
> + }
>
> - if (tfd >= 0)
> + if (dv->writemostly == 1)
> + rv = st->ss->update_super(
> + st, NULL, "writemostly",
> + devname, verbose, 0, NULL);
> + if (dv->writemostly == 2)
> + rv = st->ss->update_super(
> + st, NULL, "readwrite",
> + devname, verbose, 0, NULL);
> + if (update)
> rv = st->ss->update_super(
> st, NULL, update,
> devname, verbose, 0, NULL);
> diff -up mdadm-3.2.2/mdadm.h.writemostly mdadm-3.2.2/mdadm.h
> --- mdadm-3.2.2/mdadm.h.writemostly 2011-07-27 14:12:28.800779575
> -0400
> +++ mdadm-3.2.2/mdadm.h 2011-07-27 14:04:34.669932148 -0400
> @@ -646,6 +646,8 @@ extern struct superswitch {
> * linear-grow-new - add a new device to a linear array, but
> don't
> * change the size: so superblock still matches
> * linear-grow-update - now change the size of the array.
> + * writemostly - set the WriteMostly1 bit in the superblock
> devflags
> + * readwrite - clear the WriteMostly1 bit in the superblock
> devflags
> */
> int (*update_super)(struct supertype *st, struct mdinfo *info,
> char *update,
> diff -up mdadm-3.2.2/super0.c.writemostly mdadm-3.2.2/super0.c
> --- mdadm-3.2.2/super0.c.writemostly 2011-06-17 01:15:50.000000000
> -0400
> +++ mdadm-3.2.2/super0.c 2011-07-27 14:12:18.655889559 -0400
> @@ -570,6 +570,10 @@ static int update_super0(struct supertyp
> sb->state &= ~(1< > } else if (strcmp(update, "_reshape_progress")==0)
> sb->reshape_position = info->reshape_progress;
> + else if (strcmp(update, "writemostly")==0)
> + sb->state |= (1< > + else if (strcmp(update, "readwrite")==0)
> + sb->state &= ~(1< > else
> rv = -1;
>
> @@ -688,6 +692,8 @@ static int add_to_super0(struct supertyp
> dk->minor = dinfo->minor;
> dk->raid_disk = dinfo->raid_disk;
> dk->state = dinfo->state;
> + /* In case our source disk was writemostly, don't copy that bit */
> + dk->state &= ~(1< >
> sb->this_disk = sb->disks[dinfo->number];
> sb->sb_csum = calc_sb0_csum(sb);
> diff -up mdadm-3.2.2/super1.c.writemostly mdadm-3.2.2/super1.c
> --- mdadm-3.2.2/super1.c.writemostly 2011-06-17 01:15:50.000000000
> -0400
> +++ mdadm-3.2.2/super1.c 2011-07-27 14:12:18.656889548 -0400
> @@ -803,6 +803,10 @@ static int update_super1(struct supertyp
> __le64_to_cpu(sb->data_size));
> } else if (strcmp(update, "_reshape_progress")==0)
> sb->reshape_position = __cpu_to_le64(info->reshape_progress);
> + else if (strcmp(update, "writemostly")==0)
> + sb->devflags |= WriteMostly1;
> + else if (strcmp(update, "readwrite")==0)
> + sb->devflags &= ~WriteMostly1;
> else
> rv = -1;
>
> @@ -923,6 +927,7 @@ static int add_to_super1(struct supertyp
> sb->max_dev = __cpu_to_le32(dk->number+1);
>
> sb->dev_number = __cpu_to_le32(dk->number);
> + sb->devflags = 0; /* don't copy another disks flags */
> sb->sb_csum = calc_sb_1_csum(sb);
>
> dip = (struct devinfo **)&st->info;
>
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