From: Peter Korsgaard peter@korsgaard.com
commit 035641b01e72af4f6c6cf22a4bdb5d7dfc4e8e8e upstream.
Just calling wait_for_device_probe() is not enough to ensure that asynchronously probed block devices are available (E.G. mmc, usb), so add a "dm-mod.waitfor=<device1>[,..,<deviceN>]" parameter to get dm-init to explicitly wait for specific block devices before initializing the tables with logic similar to the rootwait logic that was introduced with commit cc1ed7542c8c ("init: wait for asynchronously scanned block devices").
E.G. with dm-verity on mmc using: dm-mod.waitfor="PARTLABEL=hash-a,PARTLABEL=root-a"
[ 0.671671] device-mapper: init: waiting for all devices to be available before creating mapped devices [ 0.671679] device-mapper: init: waiting for device PARTLABEL=hash-a ... [ 0.710695] mmc0: new HS200 MMC card at address 0001 [ 0.711158] mmcblk0: mmc0:0001 004GA0 3.69 GiB [ 0.715954] mmcblk0boot0: mmc0:0001 004GA0 partition 1 2.00 MiB [ 0.722085] mmcblk0boot1: mmc0:0001 004GA0 partition 2 2.00 MiB [ 0.728093] mmcblk0rpmb: mmc0:0001 004GA0 partition 3 512 KiB, chardev (249:0) [ 0.738274] mmcblk0: p1 p2 p3 p4 p5 p6 p7 [ 0.751282] device-mapper: init: waiting for device PARTLABEL=root-a ... [ 0.751306] device-mapper: init: all devices available [ 0.751683] device-mapper: verity: sha256 using implementation "sha256-generic" [ 0.759344] device-mapper: ioctl: dm-0 (vroot) is ready [ 0.766540] VFS: Mounted root (squashfs filesystem) readonly on device 254:0.
Signed-off-by: Peter Korsgaard peter@korsgaard.com Signed-off-by: Mike Snitzer snitzer@kernel.org Cc: Mark-PK Tsai mark-pk.tsai@mediatek.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/admin-guide/device-mapper/dm-init.rst | 8 +++++++ drivers/md/dm-init.c | 22 +++++++++++++++++++- 2 files changed, 29 insertions(+), 1 deletion(-)
--- a/Documentation/admin-guide/device-mapper/dm-init.rst +++ b/Documentation/admin-guide/device-mapper/dm-init.rst @@ -123,3 +123,11 @@ Other examples (per target): 0 1638400 verity 1 8:1 8:2 4096 4096 204800 1 sha256 fb1a5a0f00deb908d8b53cb270858975e76cf64105d412ce764225d53b8f3cfd 51934789604d1b92399c52e7cb149d1b3a1b74bbbcb103b2a0aaacbed5c08584 + +For setups using device-mapper on top of asynchronously probed block +devices (MMC, USB, ..), it may be necessary to tell dm-init to +explicitly wait for them to become available before setting up the +device-mapper tables. This can be done with the "dm-mod.waitfor=" +module parameter, which takes a list of devices to wait for:: + + dm-mod.waitfor=<device1>[,..,<deviceN>] --- a/drivers/md/dm-init.c +++ b/drivers/md/dm-init.c @@ -8,6 +8,7 @@ */
#include <linux/ctype.h> +#include <linux/delay.h> #include <linux/device.h> #include <linux/device-mapper.h> #include <linux/init.h> @@ -18,12 +19,17 @@ #define DM_MAX_DEVICES 256 #define DM_MAX_TARGETS 256 #define DM_MAX_STR_SIZE 4096 +#define DM_MAX_WAITFOR 256
static char *create;
+static char *waitfor[DM_MAX_WAITFOR]; + /* * Format: dm-mod.create=<name>,<uuid>,<minor>,<flags>,<table>[,<table>+][;<name>,<uuid>,<minor>,<flags>,<table>[,<table>+]+] * Table format: <start_sector> <num_sectors> <target_type> <target_args> + * Block devices to wait for to become available before setting up tables: + * dm-mod.waitfor=<device1>[,..,<deviceN>] * * See Documentation/admin-guide/device-mapper/dm-init.rst for dm-mod.create="..." format * details. @@ -266,7 +272,7 @@ static int __init dm_init_init(void) struct dm_device *dev; LIST_HEAD(devices); char *str; - int r; + int i, r;
if (!create) return 0; @@ -286,6 +292,17 @@ static int __init dm_init_init(void) DMINFO("waiting for all devices to be available before creating mapped devices"); wait_for_device_probe();
+ for (i = 0; i < ARRAY_SIZE(waitfor); i++) { + if (waitfor[i]) { + DMINFO("waiting for device %s ...", waitfor[i]); + while (!dm_get_dev_t(waitfor[i])) + msleep(5); + } + } + + if (waitfor[0]) + DMINFO("all devices available"); + list_for_each_entry(dev, &devices, list) { if (dm_early_create(&dev->dmi, dev->table, dev->target_args_array)) @@ -301,3 +318,6 @@ late_initcall(dm_init_init);
module_param(create, charp, 0); MODULE_PARM_DESC(create, "Create a mapped device in early boot"); + +module_param_array(waitfor, charp, NULL, 0); +MODULE_PARM_DESC(waitfor, "Devices to wait for before setting up tables");