>>>>> "Peter" == Peter Korsgaard <peter@xxxxxxxxxxxxx> writes: > 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 in init/do_mounts.c. > E.G. with dm-verity on mmc with > 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 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 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@xxxxxxxxxxxxx> > --- > Changes since v1: > - Fix s/dm-init/dm-mod/ typo in documentation, drop trailing newline Ping? FYI: I was recently made aware that other patches fixing this issue (but less nice, E.G. with a fixed delay) have been posted in the past, so there seems to be a general need for something like this. E.G: https://lore.kernel.org/all/20220406154631.277107-1-fabio.aiuto@xxxxxxxxxxxxxxxxxxxx/ > .../admin-guide/device-mapper/dm-init.rst | 8 +++++++ > drivers/md/dm-init.c | 23 ++++++++++++++++++- > 2 files changed, 30 insertions(+), 1 deletion(-) > diff --git a/Documentation/admin-guide/device-mapper/dm-init.rst b/Documentation/admin-guide/device-mapper/dm-init.rst > index e5242ff17e9b..981d6a907699 100644 > --- 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>] > diff --git a/drivers/md/dm-init.c b/drivers/md/dm-init.c > index b0c45c6ebe0b..fc70b568e072 100644 > --- 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 +292,18 @@ 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 %s", waitfor[i]); > + > + while (!dm_get_dev_t(waitfor[i])) > + msleep(20); > + } > + } > + > + 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 +319,6 @@ 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"); > -- > 2.30.2 -- Bye, Peter Korsgaard -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
