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blockdev: split out actual DM sysfs code of get_block_device_harder() into function of its own

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That way we can use it in code that already acquired a dev_t from some
source.
This commit is contained in:
Lennart Poettering 2018-06-11 12:06:27 +02:00
parent 66ae5130a0
commit 880f09bd91
2 changed files with 34 additions and 36 deletions
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69
src/basic/blockdev-util.c
View File

@ -85,35 +85,22 @@ int get_block_device(const char *path, dev_t *dev) {
return 0;
}
int get_block_device_harder(const char *path, dev_t *dev) {
int block_get_originating(dev_t dt, dev_t *ret) {
_cleanup_closedir_ DIR *d = NULL;
_cleanup_free_ char *t = NULL;
char p[SYS_BLOCK_PATH_MAX("/slaves")];
struct dirent *de, *found = NULL;
const char *q;
unsigned maj, min;
dev_t dt;
const char *q;
int r;
assert(path);
assert(dev);
/* Gets the backing block device for a file system, and
* handles LUKS encrypted file systems, looking for its
* immediate parent, if there is one. */
r = get_block_device(path, &dt);
if (r <= 0)
return r;
/* For the specified block device tries to chase it through the layers, in case LUKS-style DM stacking is used,
* trying to find the next underlying layer. */
xsprintf_sys_block_path(p, "/slaves", dt);
d = opendir(p);
if (!d) {
if (errno == ENOENT)
goto fallback;
if (!d)
return -errno;
}
FOREACH_DIRENT_ALL(de, d, return -errno) {
@ -141,34 +128,28 @@ int get_block_device_harder(const char *path, dev_t *dev) {
return -ENOMEM;
r = read_one_line_file(u, &a);
if (r < 0) {
log_debug_errno(r, "Failed to read %s: %m", u);
goto fallback;
}
if (r < 0)
return log_debug_errno(r, "Failed to read %s: %m", u);
r = read_one_line_file(v, &b);
if (r < 0) {
log_debug_errno(r, "Failed to read %s: %m", v);
goto fallback;
}
if (r < 0)
return log_debug_errno(r, "Failed to read %s: %m", v);
/* 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;
return -ENOTUNIQ;
}
found = de;
}
if (!found)
goto fallback;
return -ENOENT;
q = strjoina(p, "/", found->d_name, "/dev");
r = read_one_line_file(q, &t);
if (r == -ENOENT)
goto fallback;
if (r < 0)
return r;
@ -176,12 +157,28 @@ int get_block_device_harder(const char *path, dev_t *dev) {
return -EINVAL;
if (maj == 0)
goto fallback;
return -ENOENT;
*ret = makedev(maj, min);
return 1;
}
int get_block_device_harder(const char *path, dev_t *ret) {
int r;
assert(path);
assert(ret);
/* Gets the backing block device for a file system, and handles LUKS encrypted file systems, looking for its
* immediate parent, if there is one. */
r = get_block_device(path, ret);
if (r <= 0)
return r;
r = block_get_originating(*ret, ret);
if (r < 0)
log_debug_errno(r, "Failed to chase block device '%s', ignoring: %m", path);
*dev = makedev(maj, min);
return 1;
fallback:
*dev = dt;
return 1;
}

1
src/basic/blockdev-util.h
View File

@ -19,6 +19,7 @@
xsprintf(buf, "/sys/dev/block/%u:%u%s", major(devno), minor(devno), strempty(suffix))
int block_get_whole_disk(dev_t d, dev_t *ret);
int block_get_originating(dev_t d, dev_t *ret);
int get_block_device(const char *path, dev_t *dev);