diff options
Diffstat (limited to 'src/basic/blockdev-util.c')
| -rw-r--r-- | src/basic/blockdev-util.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/basic/blockdev-util.c b/src/basic/blockdev-util.c new file mode 100644 index 0000000..3017ecd --- /dev/null +++ b/src/basic/blockdev-util.c @@ -0,0 +1,181 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <sys/stat.h> +#include <sys/statfs.h> + +#include "alloc-util.h" +#include "blockdev-util.h" +#include "btrfs-util.h" +#include "dirent-util.h" +#include "fd-util.h" +#include "fileio.h" +#include "missing.h" +#include "parse-util.h" +#include "stat-util.h" + +int block_get_whole_disk(dev_t d, dev_t *ret) { + char p[SYS_BLOCK_PATH_MAX("/partition")]; + _cleanup_free_ char *s = NULL; + dev_t devt; + int r; + + assert(ret); + + /* If it has a queue this is good enough for us */ + xsprintf_sys_block_path(p, "/queue", d); + if (access(p, F_OK) >= 0) { + *ret = d; + return 0; + } + + /* If it is a partition find the originating device */ + xsprintf_sys_block_path(p, "/partition", d); + if (access(p, F_OK) < 0) + return -ENOENT; + + /* Get parent dev_t */ + xsprintf_sys_block_path(p, "/../dev", d); + r = read_one_line_file(p, &s); + if (r < 0) + return r; + + r = parse_dev(s, &devt); + if (r < 0) + return r; + + /* Only return this if it is really good enough for us. */ + xsprintf_sys_block_path(p, "/queue", devt); + if (access(p, F_OK) < 0) + return -ENOENT; + + *ret = devt; + return 0; +} + +int get_block_device(const char *path, dev_t *dev) { + struct stat st; + struct statfs sfs; + + assert(path); + assert(dev); + + /* Get's the block device directly backing a file system. If + * the block device is encrypted, returns the device mapper + * block device. */ + + if (lstat(path, &st)) + return -errno; + + if (major(st.st_dev) != 0) { + *dev = st.st_dev; + return 1; + } + + if (statfs(path, &sfs) < 0) + return -errno; + + if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) + return btrfs_get_block_device(path, dev); + + *dev = 0; + return 0; +} + +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; + dev_t devt; + int 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) + return -errno; + + FOREACH_DIRENT_ALL(de, d, return -errno) { + + if (dot_or_dot_dot(de->d_name)) + continue; + + if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN)) + continue; + + 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 partition 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) + return log_debug_errno(r, "Failed to read %s: %m", u); + + r = read_one_line_file(v, &b); + 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)) + return -ENOTUNIQ; + } + + found = de; + } + + if (!found) + return -ENOENT; + + q = strjoina(p, "/", found->d_name, "/dev"); + + r = read_one_line_file(q, &t); + if (r < 0) + return r; + + r = parse_dev(t, &devt); + if (r < 0) + return -EINVAL; + + if (major(devt) == 0) + return -ENOENT; + + *ret = devt; + 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); + + return 1; +} |