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-rw-r--r--src/shared/blockdev-util.c56
1 files changed, 40 insertions, 16 deletions
diff --git a/src/shared/blockdev-util.c b/src/shared/blockdev-util.c
index c906aec..7a2dd1c 100644
--- a/src/shared/blockdev-util.c
+++ b/src/shared/blockdev-util.c
@@ -11,6 +11,7 @@
#include "alloc-util.h"
#include "blockdev-util.h"
#include "btrfs-util.h"
+#include "device-private.h"
#include "device-util.h"
#include "devnum-util.h"
#include "dirent-util.h"
@@ -367,24 +368,36 @@ int lock_whole_block_device(dev_t devt, int operation) {
}
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 */
+ _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+ unsigned capability;
+ int r, ext_range;
- if (fstat(fd, &st) < 0)
- return -errno;
+ /* Checks if partition scanning is correctly enabled on the block device.
+ *
+ * The 'GENHD_FL_NO_PART_SCAN' flag was introduced by
+ * https://github.com/torvalds/linux/commit/d27769ec3df1a8de9ca450d2dcd72d1ab259ba32 (v3.2).
+ * But at that time, the flag is also effectively implied when 'minors' element of 'struct gendisk'
+ * is 1, which can be check with 'ext_range' sysfs attribute. Explicit flag ('GENHD_FL_NO_PART_SCAN')
+ * can be obtained from 'capability' sysattr.
+ *
+ * With https://github.com/torvalds/linux/commit/1ebe2e5f9d68e94c524aba876f27b945669a7879 (v5.17), we
+ * can check the flag from 'ext_range' sysfs attribute directly.
+ *
+ * With https://github.com/torvalds/linux/commit/e81cd5a983bb35dabd38ee472cf3fea1c63e0f23 (v6.3),
+ * the 'capability' sysfs attribute is deprecated, hence we cannot check the flag from it.
+ *
+ * To support both old and new kernels, we need to do the following: first check 'ext_range' sysfs
+ * attribute, and if '1' we can conclude partition scanning is disabled, otherwise check 'capability'
+ * sysattr for older version. */
- if (!S_ISBLK(st.st_mode))
- return -ENOTBLK;
+ assert(fd >= 0);
- if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
- return -ENOMEM;
+ r = block_device_new_from_fd(fd, 0, &dev);
+ if (r < 0)
+ return r;
- 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
+ r = device_get_sysattr_int(dev, "ext_range", &ext_range);
+ if (r == -ENOENT) /* If the ext_range 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). */
@@ -392,7 +405,13 @@ int blockdev_partscan_enabled(int fd) {
if (r < 0)
return r;
- r = safe_atollu_full(buf, 16, &ull);
+ if (ext_range <= 1) /* The valus should be always positive, but the kernel uses '%d' for the
+ * attribute. Let's gracefully handle zero or negative. */
+ return false;
+
+ r = device_get_sysattr_unsigned_full(dev, "capability", 16, &capability);
+ if (r == -ENOENT)
+ return false;
if (r < 0)
return r;
@@ -400,7 +419,12 @@ int blockdev_partscan_enabled(int fd) {
#define GENHD_FL_NO_PART_SCAN (0x0200)
#endif
- return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
+ /* If 0x200 is set, part scanning is definitely off. */
+ if (FLAGS_SET(capability, GENHD_FL_NO_PART_SCAN))
+ return false;
+
+ /* Otherwise, assume part scanning is on, we have no further checks available. Assume the best. */
+ return true;
}
static int blockdev_is_encrypted(const char *sysfs_path, unsigned depth_left) {