#include <linux/loop.h>
#include <sys/file.h>
#include <sys/ioctl.h>
+#include <unistd.h>
#include "alloc-util.h"
+#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "loop-util.h"
#include "parse-util.h"
#include "stat-util.h"
#include "stdio-util.h"
+#include "string-util.h"
-int loop_device_make_full(
+static void cleanup_clear_loop_close(int *fd) {
+ if (*fd >= 0) {
+ (void) ioctl(*fd, LOOP_CLR_FD);
+ (void) safe_close(*fd);
+ }
+}
+
+int loop_device_make(
int fd,
int open_flags,
uint64_t offset,
uint32_t loop_flags,
LoopDevice **ret) {
- _cleanup_close_ int control = -1, loop = -1;
_cleanup_free_ char *loopdev = NULL;
- unsigned n_attempts = 0;
struct loop_info64 info;
LoopDevice *d = NULL;
struct stat st;
}
if (offset == 0 && IN_SET(size, 0, UINT64_MAX)) {
- int copy;
+ _cleanup_close_ int copy = -1;
/* If this is already a block device, store a copy of the fd as it is */
d = new(LoopDevice, 1);
if (!d)
return -ENOMEM;
-
*d = (LoopDevice) {
- .fd = copy,
+ .fd = TAKE_FD(copy),
.nr = nr,
.node = TAKE_PTR(loopdev),
.relinquished = true, /* It's not allocated by us, don't destroy it when this object is freed */
return r;
}
+ _cleanup_close_ int control = -1;
+ _cleanup_(cleanup_clear_loop_close) int loop_with_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 (;;) {
+ for (unsigned n_attempts = 0;;) {
+ _cleanup_close_ int loop = -1;
+
nr = ioctl(control, LOOP_CTL_GET_FREE);
if (nr < 0)
return -errno;
return -ENOMEM;
loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
- if (loop < 0)
- return -errno;
- if (ioctl(loop, LOOP_SET_FD, fd) < 0) {
+ 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 != ENOENT)
+ return -errno;
+ } else {
+ if (ioctl(loop, LOOP_SET_FD, fd) >= 0) {
+ loop_with_fd = TAKE_FD(loop);
+ break;
+ }
if (errno != EBUSY)
return -errno;
+ }
- if (++n_attempts >= 64) /* Give up eventually */
- return -EBUSY;
- } else
- break;
+ if (++n_attempts >= 64) /* Give up eventually */
+ return -EBUSY;
loopdev = mfree(loopdev);
- loop = safe_close(loop);
}
info = (struct loop_info64) {
.lo_sizelimit = size == UINT64_MAX ? 0 : size,
};
- if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) {
- r = -errno;
- goto fail;
- }
+ if (ioctl(loop_with_fd, LOOP_SET_STATUS64, &info) < 0)
+ return -errno;
d = new(LoopDevice, 1);
- if (!d) {
- r = -ENOMEM;
- goto fail;
- }
-
+ if (!d)
+ return -ENOMEM;
*d = (LoopDevice) {
- .fd = TAKE_FD(loop),
+ .fd = TAKE_FD(loop_with_fd),
.node = TAKE_PTR(loopdev),
.nr = nr,
};
*ret = d;
- return d->fd;
-
-fail:
- if (fd >= 0)
- (void) ioctl(fd, LOOP_CLR_FD);
- if (d && d->fd >= 0)
- (void) ioctl(d->fd, LOOP_CLR_FD);
-
- return r;
+ return 0;
}
int loop_device_make_by_path(const char *path, int open_flags, uint32_t loop_flags, LoopDevice **ret) {
_cleanup_close_ int fd = -1;
+ int r;
assert(path);
assert(ret);
- assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
+ assert(open_flags < 0 || IN_SET(open_flags, O_RDWR, O_RDONLY));
- fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
- if (fd < 0)
- return -errno;
+ /* Passing < 0 as open_flags here means we'll try to open the device writable if we can, retrying
+ * read-only if we cannot. */
- return loop_device_make(fd, open_flags, loop_flags, ret);
+ fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|(open_flags >= 0 ? open_flags : O_RDWR));
+ if (fd < 0) {
+ r = -errno;
+
+ /* Retry read-only? */
+ if (open_flags >= 0 || !(ERRNO_IS_PRIVILEGE(r) || r == -EROFS))
+ return r;
+
+ fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|O_RDONLY);
+ if (fd < 0)
+ return r; /* Propagate original error */
+
+ open_flags = O_RDONLY;
+ } else if (open_flags < 0)
+ open_flags = O_RDWR;
+
+ return loop_device_make(fd, open_flags, 0, 0, loop_flags, ret);
}
LoopDevice* loop_device_unref(LoopDevice *d) {
return NULL;
if (d->fd >= 0) {
+ /* Implicitly sync the device, since otherwise in-flight blocks might not get written */
+ if (fsync(d->fd) < 0)
+ log_debug_errno(errno, "Failed to sync loop block device, ignoring: %m");
if (d->nr >= 0 && !d->relinquished) {
if (ioctl(d->fd, LOOP_CLR_FD) < 0)
control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
if (control < 0)
- log_debug_errno(errno, "Failed to open loop control device: %m");
- else {
- if (ioctl(control, LOOP_CTL_REMOVE, d->nr) < 0)
- log_debug_errno(errno, "Failed to remove loop device: %m");
- }
+ log_warning_errno(errno,
+ "Failed to open loop control device, cannot remove loop device %s: %m",
+ strna(d->node));
+ else
+ for (unsigned n_attempts = 0;;) {
+ if (ioctl(control, LOOP_CTL_REMOVE, d->nr) >= 0)
+ break;
+ if (errno != EBUSY || ++n_attempts >= 64) {
+ log_warning_errno(errno, "Failed to remove device %s: %m", strna(d->node));
+ break;
+ }
+ (void) usleep(50 * USEC_PER_MSEC);
+ }
}
free(d->node);