The dm-init code, waiting for devices specified by dm-mod.waitfor (e.g.,
root=/dev/dm-0, dm-mod.waitfor=/dev/mmcblk0p23), fails sporadically with
dm-verity setups, as reported in:
https://lore.kernel.org/all/e746b8b5-c04c-4982-b4bc-0fa240742...@schwermer.no/T/
This occurs because early_lookup_bdev() uses blk_lookup_devt(), which, since
commit 41b8c853a4954 ("block: fix booting from partitioned md array"),
returns a dev_t for non-existent partitions to support MD RAID booting. This
leads dm-init to proceed with invalid dev_t values, causing "Data device
lookup failed (-ENXIO)". The issue became more noticeable after commit
238d991f054a6e2d ("dm: use fsleep() instead of msleep() for deterministic
sleep duration").
This patch introduces early_lookup_ready_bdev(), a variant of
early_lookup_bdev() that only returns dev_t for devices with ready partitions,
by adding a 'ready' flag to blk_lookup_devt(). The original early_lookup_bdev()
is preserved for MD RAID compatibility, while dm-init switches to the new
function to wait for actual device availability. This resolves dm-verity boot
failures cleanly at the block layer, avoiding DM-specific workarounds.
Tested with dm-verity (root=/dev/dm-0, dm-mod.waitfor=/dev/mmcblk0p23), this
eliminates boot issues without impacting MD RAID.
Signed-off-by: Chanho Min <chanho....@lge.com>
---
block/early-lookup.c | 26 ++++++++++++++++++--------
drivers/md/dm-init.c | 2 +-
include/linux/blkdev.h | 2 ++
3 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/block/early-lookup.c b/block/early-lookup.c
index 3fb57f7d2b127..011cfda5e4843 100644
--- a/block/early-lookup.c
+++ b/block/early-lookup.c
@@ -121,7 +121,7 @@ static int __init devt_from_partlabel(const char *label,
dev_t *devt)
return 0;
}
-static dev_t __init blk_lookup_devt(const char *name, int partno)
+static dev_t __init blk_lookup_devt(const char *name, int partno, bool ready)
{
dev_t devt = MKDEV(0, 0);
struct class_dev_iter iter;
@@ -134,7 +134,7 @@ static dev_t __init blk_lookup_devt(const char *name, int
partno)
if (strcmp(dev_name(dev), name))
continue;
- if (partno < disk->minors) {
+ if (!ready && partno < disk->minors) {
/* We need to return the right devno, even
* if the partition doesn't exist yet.
*/
@@ -150,7 +150,7 @@ static dev_t __init blk_lookup_devt(const char *name, int
partno)
return devt;
}
-static int __init devt_from_devname(const char *name, dev_t *devt)
+static int __init devt_from_devname(const char *name, dev_t *devt, bool ready)
{
int part;
char s[32];
@@ -164,7 +164,7 @@ static int __init devt_from_devname(const char *name, dev_t
*devt)
*p = '!';
}
- *devt = blk_lookup_devt(s, 0);
+ *devt = blk_lookup_devt(s, 0, ready);
if (*devt)
return 0;
@@ -180,7 +180,7 @@ static int __init devt_from_devname(const char *name, dev_t
*devt)
/* try disk name without <part number> */
part = simple_strtoul(p, NULL, 10);
*p = '\0';
- *devt = blk_lookup_devt(s, part);
+ *devt = blk_lookup_devt(s, part, ready);
if (*devt)
return 0;
@@ -188,7 +188,7 @@ static int __init devt_from_devname(const char *name, dev_t
*devt)
if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
return -ENODEV;
p[-1] = '\0';
- *devt = blk_lookup_devt(s, part);
+ *devt = blk_lookup_devt(s, part, ready);
if (*devt)
return 0;
return -ENODEV;
@@ -241,17 +241,27 @@ static int __init devt_from_devnum(const char *name,
dev_t *devt)
* name contains slashes, the device name has them replaced with
* bangs.
*/
-int __init early_lookup_bdev(const char *name, dev_t *devt)
+int __init __early_lookup_bdev(const char *name, dev_t *devt, bool ready)
{
if (strncmp(name, "PARTUUID=", 9) == 0)
return devt_from_partuuid(name + 9, devt);
if (strncmp(name, "PARTLABEL=", 10) == 0)
return devt_from_partlabel(name + 10, devt);
if (strncmp(name, "/dev/", 5) == 0)
- return devt_from_devname(name + 5, devt);
+ return devt_from_devname(name + 5, devt, ready);
return devt_from_devnum(name, devt);
}
+int __init early_lookup_bdev(const char *name, dev_t *devt)
+{
+ return __early_lookup_bdev(name, devt, 0);
+}
+
+int __init early_lookup_ready_bdev(const char *name, dev_t *devt)
+{
+ return __early_lookup_bdev(name, devt, 1);
+}
+
static char __init *bdevt_str(dev_t devt, char *buf)
{
if (MAJOR(devt) <= 0xff && MINOR(devt) <= 0xff) {
diff --git a/drivers/md/dm-init.c b/drivers/md/dm-init.c
index 81b8bbd1b63a8..1adfeb4ff8ce3 100644
--- a/drivers/md/dm-init.c
+++ b/drivers/md/dm-init.c
@@ -301,7 +301,7 @@ static int __init dm_init_init(void)
dev_t dev;
DMINFO("waiting for device %s ...", waitfor[i]);
- while (early_lookup_bdev(waitfor[i], &dev))
+ while (early_lookup_ready_bdev(waitfor[i], &dev))
fsleep(5000);
}
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 50c3b959da281..f520540ad6a69 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1614,7 +1614,9 @@ int sync_blockdev_nowait(struct block_device *bdev);
void sync_bdevs(bool wait);
void bdev_statx(struct path *, struct kstat *, u32);
void printk_all_partitions(void);
+int __init __early_lookup_bdev(const char *pathname, dev_t *dev, bool ready);
int __init early_lookup_bdev(const char *pathname, dev_t *dev);
+int __init early_lookup_ready_bdev(const char *pathname, dev_t *dev);
#else
static inline void invalidate_bdev(struct block_device *bdev)
{
--
2.17.1
