/* SPDX-License-Identifier: LGPL-2.1+ */
+#if HAVE_VALGRIND_MEMCHECK_H
+#include <valgrind/memcheck.h>
+#endif
+
#include <errno.h>
#include <fcntl.h>
#include <linux/blkpg.h>
#include <linux/loop.h>
#include <sys/file.h>
#include <sys/ioctl.h>
+#include <unistd.h>
#include "alloc-util.h"
+#include "blockdev-util.h"
+#include "errno-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "loop-util.h"
+#include "missing_loop.h"
#include "parse-util.h"
#include "stat-util.h"
#include "stdio-util.h"
+#include "string-util.h"
+
+static void cleanup_clear_loop_close(int *fd) {
+ if (*fd < 0)
+ return;
-int loop_device_make_full(
+ (void) ioctl(*fd, LOOP_CLR_FD);
+ (void) safe_close(*fd);
+}
+
+static int loop_configure(int fd, const struct loop_config *c) {
+ int r;
+
+ assert(fd >= 0);
+ assert(c);
+
+ if (ioctl(fd, LOOP_CONFIGURE, c) < 0) {
+ /* Do fallback only if LOOP_CONFIGURE is not supported, propagate all other errors. Note that
+ * the kernel is weird: non-existing ioctls currently return EINVAL rather than ENOTTY on
+ * loopback block devices. They should fix that in the kernel, but in the meantime we accept
+ * both here. */
+ if (!ERRNO_IS_NOT_SUPPORTED(errno) && errno != EINVAL)
+ return -errno;
+ } else {
+ if (!FLAGS_SET(c->info.lo_flags, LO_FLAGS_PARTSCAN))
+ return 0;
+
+ /* Kernel 5.8 vanilla doesn't properly propagate the partition scanning flag into the
+ * block device. Let's hence verify if things work correctly here before returning. */
+
+ r = blockdev_partscan_enabled(fd);
+ if (r < 0)
+ goto fail;
+ if (r > 0)
+ return 0; /* All is good. */
+
+ /* Otherwise, undo the attachment and use the old APIs */
+ (void) ioctl(fd, LOOP_CLR_FD);
+ }
+
+ if (ioctl(fd, LOOP_SET_FD, c->fd) < 0)
+ return -errno;
+
+ if (ioctl(fd, LOOP_SET_STATUS64, &c->info) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ (void) ioctl(fd, LOOP_CLR_FD);
+ return r;
+}
+
+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;
+ struct loop_config config;
LoopDevice *d = NULL;
struct stat st;
int nr = -1, r;
return -errno;
if (S_ISBLK(st.st_mode)) {
- if (ioctl(loop, LOOP_GET_STATUS64, &info) >= 0) {
+ if (ioctl(fd, LOOP_GET_STATUS64, &config.info) >= 0) {
/* Oh! This is a loopback device? That's interesting! */
- nr = info.lo_number;
+
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&config.info, sizeof(config.info));
+#endif
+ nr = config.info.lo_number;
if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
return -ENOMEM;
}
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;
+ config = (struct loop_config) {
+ .fd = fd,
+ .info = {
+ /* Use the specified flags, but configure the read-only flag from the open flags, and force autoclear */
+ .lo_flags = (loop_flags & ~LO_FLAGS_READ_ONLY) | ((loop_flags & O_ACCMODE) == O_RDONLY ? LO_FLAGS_READ_ONLY : 0) | LO_FLAGS_AUTOCLEAR,
+ .lo_offset = offset,
+ .lo_sizelimit = size == UINT64_MAX ? 0 : size,
+ },
+ };
+
/* 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 (errno != EBUSY)
+ 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 {
+ r = loop_configure(loop, &config);
+ if (r >= 0) {
+ loop_with_fd = TAKE_FD(loop);
+ break;
+ }
+ if (r != -EBUSY)
+ return r;
+ }
- 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) {
- /* Use the specified flags, but configure the read-only flag from the open flags, and force autoclear */
- .lo_flags = (loop_flags & ~LO_FLAGS_READ_ONLY) | ((loop_flags & O_ACCMODE) == O_RDONLY ? LO_FLAGS_READ_ONLY : 0) | LO_FLAGS_AUTOCLEAR,
- .lo_offset = offset,
- .lo_sizelimit = size == UINT64_MAX ? 0 : size,
- };
-
- if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) {
- r = -errno;
- goto fail;
}
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);
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
- if (ioctl(loop_fd, LOOP_GET_STATUS64, &info) >= 0)
+ if (ioctl(loop_fd, LOOP_GET_STATUS64, &info) >= 0) {
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
nr = info.lo_number;
- else
+ } else
nr = -1;
p = strdup(loop_path);
if (ioctl(d->fd, LOOP_GET_STATUS64, &info) < 0)
return -errno;
+#if HAVE_VALGRIND_MEMCHECK_H
+ /* Valgrind currently doesn't know LOOP_GET_STATUS64. Remove this once it does */
+ VALGRIND_MAKE_MEM_DEFINED(&info, sizeof(info));
+#endif
+
if (size == UINT64_MAX && offset == UINT64_MAX)
return 0;
if (info.lo_sizelimit == size && info.lo_offset == offset)
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