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umount: check LO_FLAGS_AUTOCLEAR after LOOP_CLR_FD claimed success

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Fixes: #14410
Replaces: #14386
This commit is contained in:
Lennart Poettering 2019-12-20 17:58:03 +01:00
parent 63135a2d8d
commit b877c3b06f
1 changed files with 23 additions and 5 deletions
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28
src/shutdown/umount.c
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@ -328,6 +328,7 @@ static int dm_list_get(MountPoint **head) {
static int delete_loopback(const char *device) {
_cleanup_close_ int fd = -1;
struct loop_info64 info;
assert(device);
@ -335,14 +336,31 @@ static int delete_loopback(const char *device) {
if (fd < 0)
return errno == ENOENT ? 0 : -errno;
if (ioctl(fd, LOOP_CLR_FD, 0) >= 0)
if (ioctl(fd, LOOP_CLR_FD, 0) < 0) {
if (errno == ENXIO) /* Nothing bound, didn't do anything */
return 0;
return -errno;
}
if (ioctl(fd, LOOP_GET_STATUS64, &info) < 0) {
/* If the LOOP_CLR_FD above succeeded we'll see ENXIO here. */
if (errno == ENXIO)
log_debug("Successfully detached loopback device %s.", device);
else
log_debug_errno(errno, "Failed to invoke LOOP_GET_STATUS64 on loopback device %s, ignoring: %m", device); /* the LOOP_CLR_FD at least worked, let's hope for the best */
return 1;
}
/* ENXIO: not bound, so no error */
if (errno == ENXIO)
return 0;
/* Linux makes LOOP_CLR_FD succeed whenever LO_FLAGS_AUTOCLEAR is set without actually doing
* anything. Very confusing. Let's hence not claim we did anything in this case. */
if (FLAGS_SET(info.lo_flags, LO_FLAGS_AUTOCLEAR))
log_debug("Successfully called LOOP_CLR_FD on a loopback device %s with autoclear set, which is a NOP.", device);
else
log_debug("Weird, LOOP_CLR_FD succeeded but the device is still attached on %s.", device);
return -errno;
return -EBUSY; /* Nothing changed, the device is still attached, hence it apparently is still busy */
}
static int delete_dm(dev_t devnum) {