diff options
Diffstat (limited to 'src/shared/blockdev-util.c')
| -rw-r--r-- | src/shared/blockdev-util.c | 56 |
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) { |