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-rw-r--r--src/basic/blockdev-util.c253
1 files changed, 253 insertions, 0 deletions
diff --git a/src/basic/blockdev-util.c b/src/basic/blockdev-util.c
new file mode 100644
index 0000000..0f1e30c
--- /dev/null
+++ b/src/basic/blockdev-util.c
@@ -0,0 +1,253 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/file.h>
+#include <unistd.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_magic.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 (major(d) == 0)
+ return -ENODEV;
+
+ /* 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 (errno != ENOENT)
+ return -errno;
+
+ /* If it is a partition find the originating device */
+ xsprintf_sys_block_path(p, "/partition", d);
+ if (access(p, F_OK) < 0)
+ return -errno;
+
+ /* 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 -errno;
+
+ *ret = devt;
+ return 1;
+}
+
+int get_block_device(const char *path, dev_t *ret) {
+ _cleanup_close_ int fd = -1;
+ struct stat st;
+ int r;
+
+ assert(path);
+ assert(ret);
+
+ /* Gets the block device directly backing a file system. If the block device is encrypted, returns
+ * the device mapper block device. */
+
+ fd = open(path, O_NOFOLLOW|O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ if (fstat(fd, &st))
+ return -errno;
+
+ if (major(st.st_dev) != 0) {
+ *ret = st.st_dev;
+ return 1;
+ }
+
+ r = btrfs_get_block_device_fd(fd, ret);
+ if (r > 0)
+ return 1;
+ if (r != -ENOTTY) /* not btrfs */
+ return r;
+
+ *ret = 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 = path_join(p, de->d_name, "../dev");
+ if (!u)
+ return -ENOMEM;
+
+ v = path_join(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;
+}
+
+int lock_whole_block_device(dev_t devt, int operation) {
+ _cleanup_free_ char *whole_node = NULL;
+ _cleanup_close_ int lock_fd = -1;
+ dev_t whole_devt;
+ int r;
+
+ /* Let's get a BSD file lock on the whole block device, as per: https://systemd.io/BLOCK_DEVICE_LOCKING */
+
+ r = block_get_whole_disk(devt, &whole_devt);
+ if (r < 0)
+ return r;
+
+ r = device_path_make_major_minor(S_IFBLK, whole_devt, &whole_node);
+ if (r < 0)
+ return r;
+
+ lock_fd = open(whole_node, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
+ if (lock_fd < 0)
+ return -errno;
+
+ if (flock(lock_fd, operation) < 0)
+ return -errno;
+
+ return TAKE_FD(lock_fd);
+}
+
+int blockdev_partscan_enabled(int fd) {
+ _cleanup_free_ char *p = NULL, *buf = NULL;
+ unsigned long long ull;
+ struct stat st;
+ int r;
+
+ /* Checks if partition scanning is correctly enabled on the block device */
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (!S_ISBLK(st.st_mode))
+ return -ENOTBLK;
+
+ if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
+ return -ENOMEM;
+
+ r = read_one_line_file(p, &buf);
+ if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
+ * partition block device, not the whole block device. And that means we have no
+ * partition scanning on for it (we do for its parent, but not for the partition
+ * itself). */
+ return false;
+ if (r < 0)
+ return r;
+
+ r = safe_atollu_full(buf, 16, &ull);
+ if (r < 0)
+ return r;
+
+#ifndef GENHD_FL_NO_PART_SCAN
+#define GENHD_FL_NO_PART_SCAN (0x0200)
+#endif
+
+ return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
+}
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