}
static int loop_configure(
- sd_device *dev,
- int fd,
int nr,
+ int open_flags,
+ int lock_op,
const struct loop_config *c,
- uint64_t *ret_seqnum_not_before,
- usec_t *ret_timestamp_not_before,
- int *ret_lock_fd) {
+ LoopDevice **ret) {
static bool loop_configure_broken = false;
- _cleanup_close_ int lock_fd = -1;
- uint64_t seqnum;
- usec_t timestamp;
+ _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
+ _cleanup_(cleanup_clear_loop_close) int loop_with_fd = -1; /* This must be declared before lock_fd. */
+ _cleanup_close_ int fd = -1, lock_fd = -1;
+ _cleanup_free_ char *node = NULL;
+ uint64_t diskseq = 0, seqnum = UINT64_MAX;
+ usec_t timestamp = USEC_INFINITY;
+ dev_t devno;
int r;
- assert(fd >= 0);
assert(nr >= 0);
assert(c);
+ assert(ret);
+
+ if (asprintf(&node, "/dev/loop%i", nr) < 0)
+ return -ENOMEM;
+
+ r = sd_device_new_from_devname(&dev, node);
+ if (r < 0)
+ return r;
+
+ r = sd_device_get_devnum(dev, &devno);
+ if (r < 0)
+ return r;
+
+ fd = sd_device_open(dev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
+ if (fd < 0)
+ return fd;
/* Let's lock the device before we do anything. We take the BSD lock on a second, separately opened
* fd for the device. udev after all watches for close() events (specifically IN_CLOSE_WRITE) on
loop_configure_broken = true;
} else {
- r = loop_configure_verify(fd, c);
+ loop_with_fd = TAKE_FD(fd);
+
+ r = loop_configure_verify(loop_with_fd, c);
if (r < 0)
- goto fail;
+ return r;
if (r == 0) {
/* LOOP_CONFIGURE doesn't work. Remember that. */
loop_configure_broken = true;
* good chance we cannot actually reuse the loopback device right-away. Hence
* let's assume it's busy, avoid the trouble and let the calling loop call us
* again with a new, likely unused device. */
- r = -EBUSY;
- goto fail;
+ return -EBUSY;
}
}
}
if (ioctl(fd, LOOP_SET_FD, c->fd) < 0)
return -errno;
- r = loop_configure_fallback(fd, c);
+ loop_with_fd = TAKE_FD(fd);
+
+ r = loop_configure_fallback(loop_with_fd, c);
if (r < 0)
- goto fail;
+ return r;
}
- if (ret_seqnum_not_before)
- *ret_seqnum_not_before = seqnum;
- if (ret_timestamp_not_before)
- *ret_timestamp_not_before = timestamp;
- if (ret_lock_fd)
- *ret_lock_fd = TAKE_FD(lock_fd);
+ r = fd_get_diskseq(loop_with_fd, &diskseq);
+ if (r < 0 && r != -EOPNOTSUPP)
+ return r;
- return 0;
+ switch (lock_op & ~LOCK_NB) {
+ case LOCK_EX: /* Already in effect */
+ break;
+ case LOCK_SH: /* Downgrade */
+ if (flock(lock_fd, lock_op) < 0)
+ return -errno;
+ break;
+ case LOCK_UN: /* Release */
+ lock_fd = safe_close(lock_fd);
+ break;
+ default:
+ assert_not_reached();
+ }
+
+ LoopDevice *d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+
+ *d = (LoopDevice) {
+ .fd = TAKE_FD(loop_with_fd),
+ .lock_fd = TAKE_FD(lock_fd),
+ .node = TAKE_PTR(node),
+ .nr = nr,
+ .devno = devno,
+ .dev = TAKE_PTR(dev),
+ .diskseq = diskseq,
+ .uevent_seqnum_not_before = seqnum,
+ .timestamp_not_before = timestamp,
+ };
-fail:
- /* Close the lock fd explicitly before clearing the loopback block device, since an additional open
- * fd would block the clearing to succeed */
- lock_fd = safe_close(lock_fd);
- (void) ioctl(fd, LOOP_CLR_FD);
- return r;
+ *ret = TAKE_PTR(d);
+ return 0;
}
static int loop_device_make_internal(
int lock_op,
LoopDevice **ret) {
- _cleanup_(sd_device_unrefp) sd_device *dev = NULL;
- _cleanup_close_ int direct_io_fd = -1;
- _cleanup_free_ char *node = NULL, *backing_file = NULL;
+ _cleanup_(loop_device_unrefp) LoopDevice *d = NULL;
+ _cleanup_close_ int direct_io_fd = -1, control = -1;
+ _cleanup_free_ char *backing_file = NULL;
struct loop_config config;
- LoopDevice *d;
- uint64_t seqnum = UINT64_MAX;
- usec_t timestamp = USEC_INFINITY;
- int nr, r, f_flags;
+ int r, f_flags;
struct stat st;
assert(fd >= 0);
fd = direct_io_fd; /* From now on, operate on our new O_DIRECT fd */
}
- /* On failure, lock_fd must be closed at first, otherwise LOOP_CLR_FD will fail. */
- _cleanup_close_ int control = -1;
- _cleanup_(cleanup_clear_loop_close) int loop_with_fd = -1;
- _cleanup_close_ int lock_fd = -1;
-
control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
if (control < 0)
return -errno;
/* Loop around LOOP_CTL_GET_FREE, since at the moment we attempt to open the returned device it might
* be gone already, taken by somebody else racing against us. */
for (unsigned n_attempts = 0;;) {
- _cleanup_close_ int loop = -1;
+ int nr;
/* Let's take a lock on the control device first. On a busy system, where many programs
* attempt to allocate a loopback device at the same time, we might otherwise keep looping
if (nr < 0)
return -errno;
- node = mfree(node);
- if (asprintf(&node, "/dev/loop%i", nr) < 0)
- return -ENOMEM;
-
- dev = sd_device_unref(dev);
- r = sd_device_new_from_devname(&dev, node);
- if (r < 0)
- return r;
+ r = loop_configure(nr, open_flags, lock_op, &config, &d);
+ if (r >= 0)
+ break;
- loop = sd_device_open(dev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
- if (loop < 0) {
- /* Somebody might've gotten the same number from the kernel, used the device,
- * and called LOOP_CTL_REMOVE on it. Let's retry with a new number. */
- if (!ERRNO_IS_DEVICE_ABSENT(errno))
- return -errno;
- } else {
- r = loop_configure(dev, loop, nr, &config, &seqnum, ×tamp, &lock_fd);
- if (r >= 0) {
- loop_with_fd = TAKE_FD(loop);
- break;
- }
- if (!IN_SET(r, -EBUSY, -EUCLEAN)) /* Busy, or some left-over partition devices that
- * were cleaned up. */
- return r;
- }
+ /* -ENODEV or friends: Somebody might've gotten the same number from the kernel, used the
+ * device, and called LOOP_CTL_REMOVE on it. Let's retry with a new number.
+ * -EBUSY: a file descriptor is already bound to the loopback block device.
+ * -EUCLEAN: some left-over partition devices that were cleaned up. */
+ if (!ERRNO_IS_DEVICE_ABSENT(errno) && !IN_SET(r, -EBUSY, -EUCLEAN))
+ return -errno;
/* OK, this didn't work, let's try again a bit later, but first release the lock on the
* control device */
if (++n_attempts >= 64) /* Give up eventually */
return -EBUSY;
- /* Now close the loop device explicitly. This will release any lock acquired by
- * attach_empty_file() or similar, while we sleep below. */
- loop = safe_close(loop);
-
/* Wait some random time, to make collision less likely. Let's pick a random time in the
* range 0ms…250ms, linearly scaled by the number of failed attempts. */
(void) usleep(random_u64_range(UINT64_C(10) * USEC_PER_MSEC +
UINT64_C(240) * USEC_PER_MSEC * n_attempts/64));
}
- if (fstat(loop_with_fd, &st) < 0)
- return -errno;
- assert(S_ISBLK(st.st_mode));
-
- uint64_t diskseq = 0;
- r = fd_get_diskseq(loop_with_fd, &diskseq);
- if (r < 0 && r != -EOPNOTSUPP)
- return r;
-
- switch (lock_op & ~LOCK_NB) {
- case LOCK_EX: /* Already in effect */
- break;
- case LOCK_SH: /* Downgrade */
- if (flock(lock_fd, lock_op) < 0)
- return -errno;
- break;
- case LOCK_UN: /* Release */
- lock_fd = safe_close(lock_fd);
- break;
- default:
- assert_not_reached();
- }
-
- d = new(LoopDevice, 1);
- if (!d)
- return -ENOMEM;
- *d = (LoopDevice) {
- .fd = TAKE_FD(loop_with_fd),
- .lock_fd = TAKE_FD(lock_fd),
- .node = TAKE_PTR(node),
- .nr = nr,
- .devno = st.st_rdev,
- .dev = TAKE_PTR(dev),
- .backing_file = TAKE_PTR(backing_file),
- .diskseq = diskseq,
- .uevent_seqnum_not_before = seqnum,
- .timestamp_not_before = timestamp,
- };
+ d->backing_file = TAKE_PTR(backing_file);
log_debug("Successfully acquired %s, devno=%u:%u, nr=%i, diskseq=%" PRIu64,
d->node,
d->nr,
d->diskseq);
- *ret = d;
- return d->fd;
+ *ret = TAKE_PTR(d);
+ return 0;
}
static uint32_t loop_flags_mangle(uint32_t loop_flags) {
projects / thirdparty / systemd.git / commitdiff
