On 3/26/20 8:28 AM, Jason Baron wrote: > Let's add some CONFIG_* options to directly configure the raid0 layout > if you know in advance how your raid0 array was created. This can be > simpler than having to manage module or kernel command-line parameters. > > If the raid0 array was created by a pre-3.14 kernel, use > RAID0_ORIG_LAYOUT. If the raid0 array was created by a 3.14 or newer > kernel then select RAID0_ALT_MULTIZONE_LAYOUT. Otherwise, the default > setting is RAID0_LAYOUT_NONE, in which case the current behavior of > needing to specify a module parameter raid0.default_layout=1|2 is > preserved. > > Cc: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx> > Cc: NeilBrown <neilb@xxxxxxx> > Cc: Song Liu <songliubraving@xxxxxx> > Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx> > --- > drivers/md/Kconfig | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > drivers/md/raid0.c | 7 +++++++ > 2 files changed, 62 insertions(+) > > diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig > index d6d5ab2..c0c6d82 100644 > --- a/drivers/md/Kconfig > +++ b/drivers/md/Kconfig > @@ -79,6 +79,61 @@ config MD_RAID0 > > If unsure, say Y. > > +choice > + prompt "RAID0 Layout" > + default RAID0_LAYOUT_NONE > + depends on MD_RAID0 > + help > + A change was made in Linux 3.14 that unintentinally changed the unintentionally > + the layout for RAID0. This can result in data corruption if a pre-3.14 > + and a 3.14 or later kernel both wrote to the array. However, if the > + devices in the array are all of the same size then the layout would > + have been unaffected by this change, and there is no risk of data > + corruption from this issue. > + > + Unfortunately, the layout can not be determined by the kernel. If the > + array has only been written to by a 3.14 or later kernel its safe to it's > + set RAID0_ALT_MULTIZONE_LAYOUT. If its only been written to by a it has > + pre-3.14 kernel its safe to select RAID0_ORIG_LAYOUT. If its been it's If it has been > + written by both then select RAID0_LAYOUT_NONE, which will not > + configure the array. The array can then be examined for corruption. > + > + For new arrays you may choose either layout version. Neither version > + is inherently better than the other. > + > + Alternatively, these parameters can also be specified via the module > + parameter raid0.default_layout=<N>. N=2 selects the 'new' or multizone > + layout, while N=1 selects the 'old' layout or original layout. If > + unset the array will not be configured. > + > + The layout can also be written directly to the raid0 array via the > + mdadm command, which can be auto-detected by the kernel. See: > + <https://www.kernel.org/doc/html/latest/admin-guide/md.html#multi-zone-raid0-layout-migration> > + > +config RAID0_ORIG_LAYOUT > + bool "raid0 layout for arrays only written to by a pre-3.14 kernel" > + help > + If the raid0 array was only created and written to by a pre-3.14 kernel. > + > +config RAID0_ALT_MULTIZONE_LAYOUT > + bool "raid0 layout for arrays only written to be a 3.14 or newer kernel" by > + help > + If the raid0 array was only created and written to by a 3.14 or later > + kernel. > + > +config RAID0_LAYOUT_NONE > + bool "raid0 layout must be specified via a module parameter" > + help > + If a raid0 array was written to by both a pre-3.14 and a 3.14 or > + later kernel, you may have data corruption. This option will not > + auto configure the array and thus you can examine the array offline > + to determine the best way to proceed. With RAID0_LAYOUT_NONE > + set, the choice for raid0 layout can be set via a module parameter > + raid0.default_layout=<N>. Or the layout can be written directly > + to the raid0 array via the mdadm command. > + > +endchoice > + > config MD_RAID1 > tristate "RAID-1 (mirroring) mode" > depends on BLK_DEV_MD > diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c > index 322386f..576eaa6 100644 > --- a/drivers/md/raid0.c > +++ b/drivers/md/raid0.c > @@ -19,7 +19,14 @@ > #include "raid0.h" > #include "raid5.h" > > +#if defined(CONFIG_RAID0_ORIG_LAYOUT) > +static int default_layout = RAID0_ORIG_LAYOUT; > +#elif defined(CONFIG_RAID0_ALT_MULTIZONE_LAYOUT) > +static int default_layout = RAID0_ALT_MULTIZONE_LAYOUT; > +#else > static int default_layout = 0; > +#endif > + > module_param(default_layout, int, 0644); > > #define UNSUPPORTED_MDDEV_FLAGS \ > -- ~Randy Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
