util: make get_block_device() available
This commit is contained in:
Franck Bui
parent
3d4ec01269
commit
c43b2b9c71
131
src/basic/util.c
131
src/basic/util.c
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@ -34,6 +34,7 @@
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#include <unistd.h>
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#include "alloc-util.h"
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#include "btrfs-util.h"
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#include "build.h"
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#include "cgroup-util.h"
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#include "def.h"
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@ -719,3 +720,133 @@ int version(void) {
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SYSTEMD_FEATURES);
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return 0;
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}
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int get_block_device(const char *path, dev_t *dev) {
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struct stat st;
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struct statfs sfs;
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assert(path);
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assert(dev);
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/* Get's the block device directly backing a file system. If
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* the block device is encrypted, returns the device mapper
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* block device. */
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if (lstat(path, &st))
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return -errno;
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if (major(st.st_dev) != 0) {
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*dev = st.st_dev;
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return 1;
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}
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if (statfs(path, &sfs) < 0)
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return -errno;
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if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
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return btrfs_get_block_device(path, dev);
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return 0;
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}
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int get_block_device_harder(const char *path, dev_t *dev) {
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_cleanup_closedir_ DIR *d = NULL;
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_cleanup_free_ char *p = NULL, *t = NULL;
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struct dirent *de, *found = NULL;
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const char *q;
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unsigned maj, min;
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dev_t dt;
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int r;
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assert(path);
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assert(dev);
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/* Gets the backing block device for a file system, and
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* handles LUKS encrypted file systems, looking for its
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* immediate parent, if there is one. */
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r = get_block_device(path, &dt);
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if (r <= 0)
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return r;
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if (asprintf(&p, "/sys/dev/block/%u:%u/slaves", major(dt), minor(dt)) < 0)
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return -ENOMEM;
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d = opendir(p);
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if (!d) {
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if (errno == ENOENT)
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goto fallback;
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return -errno;
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}
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FOREACH_DIRENT_ALL(de, d, return -errno) {
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if (dot_or_dot_dot(de->d_name))
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continue;
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if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
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continue;
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if (found) {
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_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
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/* We found a device backed by multiple other devices. We don't really support automatic
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* discovery on such setups, with the exception of dm-verity partitions. In this case there are
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* two backing devices: the data partition and the hash partition. We are fine with such
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* setups, however, only if both partitions are on the same physical device. Hence, let's
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* verify this. */
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u = strjoin(p, "/", de->d_name, "/../dev");
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if (!u)
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return -ENOMEM;
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v = strjoin(p, "/", found->d_name, "/../dev");
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if (!v)
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return -ENOMEM;
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r = read_one_line_file(u, &a);
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if (r < 0) {
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log_debug_errno(r, "Failed to read %s: %m", u);
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goto fallback;
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}
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r = read_one_line_file(v, &b);
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if (r < 0) {
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log_debug_errno(r, "Failed to read %s: %m", v);
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goto fallback;
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}
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/* Check if the parent device is the same. If not, then the two backing devices are on
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* different physical devices, and we don't support that. */
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if (!streq(a, b))
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goto fallback;
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}
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found = de;
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}
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if (!found)
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goto fallback;
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q = strjoina(p, "/", found->d_name, "/dev");
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r = read_one_line_file(q, &t);
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if (r == -ENOENT)
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goto fallback;
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if (r < 0)
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return r;
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if (sscanf(t, "%u:%u", &maj, &min) != 2)
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return -EINVAL;
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if (maj == 0)
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goto fallback;
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*dev = makedev(maj, min);
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return 1;
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fallback:
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*dev = dt;
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return 1;
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}
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@ -192,3 +192,6 @@ uint64_t system_tasks_max_scale(uint64_t v, uint64_t max);
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int update_reboot_parameter_and_warn(const char *param);
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int version(void);
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int get_block_device(const char *path, dev_t *dev);
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int get_block_device_harder(const char *path, dev_t *dev);
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@ -571,136 +571,6 @@ static int enumerate_partitions(dev_t devnum) {
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return r;
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}
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static int get_block_device(const char *path, dev_t *dev) {
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struct stat st;
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struct statfs sfs;
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assert(path);
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assert(dev);
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/* Get's the block device directly backing a file system. If
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* the block device is encrypted, returns the device mapper
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* block device. */
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if (lstat(path, &st))
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return -errno;
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if (major(st.st_dev) != 0) {
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*dev = st.st_dev;
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return 1;
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}
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if (statfs(path, &sfs) < 0)
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return -errno;
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if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC))
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return btrfs_get_block_device(path, dev);
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return 0;
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}
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static int get_block_device_harder(const char *path, dev_t *dev) {
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_cleanup_closedir_ DIR *d = NULL;
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_cleanup_free_ char *p = NULL, *t = NULL;
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struct dirent *de, *found = NULL;
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const char *q;
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unsigned maj, min;
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dev_t dt;
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int r;
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assert(path);
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assert(dev);
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/* Gets the backing block device for a file system, and
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* handles LUKS encrypted file systems, looking for its
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* immediate parent, if there is one. */
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r = get_block_device(path, &dt);
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if (r <= 0)
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return r;
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if (asprintf(&p, "/sys/dev/block/%u:%u/slaves", major(dt), minor(dt)) < 0)
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return -ENOMEM;
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d = opendir(p);
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if (!d) {
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if (errno == ENOENT)
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goto fallback;
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return -errno;
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}
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FOREACH_DIRENT_ALL(de, d, return -errno) {
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if (dot_or_dot_dot(de->d_name))
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continue;
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if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
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continue;
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if (found) {
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_cleanup_free_ char *u = NULL, *v = NULL, *a = NULL, *b = NULL;
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/* We found a device backed by multiple other devices. We don't really support automatic
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* discovery on such setups, with the exception of dm-verity partitions. In this case there are
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* two backing devices: the data partition and the hash partition. We are fine with such
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* setups, however, only if both partitions are on the same physical device. Hence, let's
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* verify this. */
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u = strjoin(p, "/", de->d_name, "/../dev");
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if (!u)
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return -ENOMEM;
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v = strjoin(p, "/", found->d_name, "/../dev");
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if (!v)
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return -ENOMEM;
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r = read_one_line_file(u, &a);
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if (r < 0) {
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log_debug_errno(r, "Failed to read %s: %m", u);
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goto fallback;
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}
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r = read_one_line_file(v, &b);
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if (r < 0) {
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log_debug_errno(r, "Failed to read %s: %m", v);
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goto fallback;
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}
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/* Check if the parent device is the same. If not, then the two backing devices are on
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* different physical devices, and we don't support that. */
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if (!streq(a, b))
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goto fallback;
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}
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found = de;
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}
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if (!found)
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goto fallback;
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q = strjoina(p, "/", found->d_name, "/dev");
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r = read_one_line_file(q, &t);
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if (r == -ENOENT)
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goto fallback;
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if (r < 0)
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return r;
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if (sscanf(t, "%u:%u", &maj, &min) != 2)
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return -EINVAL;
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if (maj == 0)
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goto fallback;
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*dev = makedev(maj, min);
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return 1;
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fallback:
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*dev = dt;
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return 1;
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}
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static int parse_proc_cmdline_item(const char *key, const char *value, void *data) {
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int r;
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