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gpt-auto-generator: enable auto-discovery logic also for verity root file systems

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verity block devices have two backing devices: the data partition and
the hash partition. Previously the gpt auto-discovery logic would refuse
working on devices with multiple backing devices, losen this up a bit,
to permit them as long as the backing devices are all located on the
same physical media.
This commit is contained in:
Lennart Poettering 2016-12-20 16:04:07 +01:00
parent 5f4bfe56f3
commit 78f0243a44
1 changed files with 34 additions and 2 deletions
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36
src/gpt-auto-generator/gpt-auto-generator.c
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@ -664,8 +664,40 @@ static int get_block_device_harder(const char *path, dev_t *dev) {
if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
continue;
if (found) /* Don't try to support multiple backing block devices */
goto fallback;
if (found) {
_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
/* We found a device backed by multiple other devices. We don't really support automatic
* discovery on such setups, with the exception of dm-verity partitions. In this case there are
* two backing devices: the data partitoin and the hash partition. We are fine with such
* setups, however, only if both partitions are on the same physical device. Hence, let's
* verify this. */
u = strjoin(p, "/", de->d_name, "/../dev");
if (!u)
return -ENOMEM;
v = strjoin(p, "/", found->d_name, "/../dev");
if (!v)
return -ENOMEM;
r = read_one_line_file(u, &a);
if (r < 0) {
log_debug_errno(r, "Failed to read %s: %m", u);
goto fallback;
}
r = read_one_line_file(v, &b);
if (r < 0) {
log_debug_errno(r, "Failed to read %s: %m", v);
goto fallback;
}
/* Check if the parent device is the same. If not, then the two backing devices are on
* different physical devices, and we don't support that. */
if (!streq(a, b))
goto fallback;
}
found = de;
}