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 + 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 + set RAID0_ALT_MULTIZONE_LAYOUT. If its only been written to by a + pre-3.14 kernel its safe to select RAID0_ORIG_LAYOUT. If its 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" + 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 \ -- 2.7.4
