/* 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/fs.h>
#include <linux/loop.h>
+#include <sys/file.h>
#include <sys/ioctl.h>
-#include <sys/stat.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"
-int loop_device_make(int fd, int open_flags, LoopDevice **ret) {
- const struct loop_info64 info = {
- .lo_flags = LO_FLAGS_AUTOCLEAR|LO_FLAGS_PARTSCAN|(open_flags == O_RDONLY ? LO_FLAGS_READ_ONLY : 0),
- };
+static void cleanup_clear_loop_close(int *fd) {
+ if (*fd < 0)
+ return;
+
+ (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,
+ uint64_t size,
+ uint32_t loop_flags,
+ LoopDevice **ret) {
- _cleanup_close_ int control = -1, loop = -1;
_cleanup_free_ char *loopdev = NULL;
+ struct loop_config config;
+ LoopDevice *d = NULL;
struct stat st;
- LoopDevice *d;
- int nr, r;
+ int nr = -1, r;
assert(fd >= 0);
assert(ret);
return -errno;
if (S_ISBLK(st.st_mode)) {
- int copy;
+ if (ioctl(fd, LOOP_GET_STATUS64, &config.info) >= 0) {
+ /* Oh! This is a loopback device? That's interesting! */
- /* If this is already a block device, store a copy of the fd as it is */
+#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;
- copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
- if (copy < 0)
- return -errno;
+ if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
+ return -ENOMEM;
+ }
- d = new0(LoopDevice, 1);
- if (!d)
- return -ENOMEM;
+ if (offset == 0 && IN_SET(size, 0, UINT64_MAX)) {
+ _cleanup_close_ int copy = -1;
- *d = (LoopDevice) {
- .fd = copy,
- .nr = -1,
- };
+ /* If this is already a block device, store a copy of the fd as it is */
- *ret = d;
+ copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
+ if (copy < 0)
+ return -errno;
- return 0;
+ d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+ *d = (LoopDevice) {
+ .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 */
+ };
+
+ *ret = d;
+ return d->fd;
+ }
+ } else {
+ r = stat_verify_regular(&st);
+ if (r < 0)
+ return r;
}
- r = stat_verify_regular(&st);
- if (r < 0)
- 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;
- nr = ioctl(control, LOOP_CTL_GET_FREE);
- if (nr < 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,
+ },
+ };
- if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
- return -ENOMEM;
+ /* 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;
- loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
- if (loop < 0)
- return -errno;
+ nr = ioctl(control, LOOP_CTL_GET_FREE);
+ if (nr < 0)
+ return -errno;
- if (ioctl(loop, LOOP_SET_FD, fd) < 0)
- return -errno;
+ if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
+ return -ENOMEM;
- if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0)
- return -errno;
+ loop = open(loopdev, 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 != 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;
+
+ loopdev = mfree(loopdev);
+ }
d = new(LoopDevice, 1);
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;
+ return 0;
}
-int loop_device_make_by_path(const char *path, int open_flags, LoopDevice **ret) {
+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. */
+
+ 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;
- return loop_device_make(fd, open_flags, ret);
+ 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);
d->relinquished = true;
}
+
+int loop_device_open(const char *loop_path, int open_flags, LoopDevice **ret) {
+ _cleanup_close_ int loop_fd = -1;
+ _cleanup_free_ char *p = NULL;
+ struct loop_info64 info;
+ struct stat st;
+ LoopDevice *d;
+ int nr;
+
+ assert(loop_path);
+ assert(ret);
+
+ loop_fd = open(loop_path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags);
+ if (loop_fd < 0)
+ return -errno;
+
+ if (fstat(loop_fd, &st) < 0)
+ return -errno;
+ if (!S_ISBLK(st.st_mode))
+ return -ENOTBLK;
+
+ 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
+ nr = -1;
+
+ p = strdup(loop_path);
+ if (!p)
+ return -ENOMEM;
+
+ d = new(LoopDevice, 1);
+ if (!d)
+ return -ENOMEM;
+
+ *d = (LoopDevice) {
+ .fd = TAKE_FD(loop_fd),
+ .nr = nr,
+ .node = TAKE_PTR(p),
+ .relinquished = true, /* It's not ours, don't try to destroy it when this object is freed */
+ };
+
+ *ret = d;
+ return d->fd;
+}
+
+static int resize_partition(int partition_fd, uint64_t offset, uint64_t size) {
+ char sysfs[STRLEN("/sys/dev/block/:/partition") + 2*DECIMAL_STR_MAX(dev_t) + 1];
+ _cleanup_free_ char *whole = NULL, *buffer = NULL;
+ uint64_t current_offset, current_size, partno;
+ _cleanup_close_ int whole_fd = -1;
+ struct stat st;
+ dev_t devno;
+ int r;
+
+ assert(partition_fd >= 0);
+
+ /* Resizes the partition the loopback device refer to (assuming it refers to one instead of an actual
+ * loopback device), and changes the offset, if needed. This is a fancy wrapper around
+ * BLKPG_RESIZE_PARTITION. */
+
+ if (fstat(partition_fd, &st) < 0)
+ return -errno;
+
+ assert(S_ISBLK(st.st_mode));
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/partition", major(st.st_rdev), minor(st.st_rdev));
+ r = read_one_line_file(sysfs, &buffer);
+ if (r == -ENOENT) /* not a partition, cannot resize */
+ return -ENOTTY;
+ if (r < 0)
+ return r;
+ r = safe_atou64(buffer, &partno);
+ if (r < 0)
+ return r;
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/start", major(st.st_rdev), minor(st.st_rdev));
+
+ buffer = mfree(buffer);
+ r = read_one_line_file(sysfs, &buffer);
+ if (r < 0)
+ return r;
+ r = safe_atou64(buffer, ¤t_offset);
+ if (r < 0)
+ return r;
+ if (current_offset > UINT64_MAX/512U)
+ return -EINVAL;
+ current_offset *= 512U;
+
+ if (ioctl(partition_fd, BLKGETSIZE64, ¤t_size) < 0)
+ return -EINVAL;
+
+ if (size == UINT64_MAX && offset == UINT64_MAX)
+ return 0;
+ if (current_size == size && current_offset == offset)
+ return 0;
+
+ xsprintf(sysfs, "/sys/dev/block/%u:%u/../dev", major(st.st_rdev), minor(st.st_rdev));
+
+ buffer = mfree(buffer);
+ r = read_one_line_file(sysfs, &buffer);
+ if (r < 0)
+ return r;
+ r = parse_dev(buffer, &devno);
+ if (r < 0)
+ return r;
+
+ r = device_path_make_major_minor(S_IFBLK, devno, &whole);
+ if (r < 0)
+ return r;
+
+ whole_fd = open(whole, O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
+ if (whole_fd < 0)
+ return -errno;
+
+ struct blkpg_partition bp = {
+ .pno = partno,
+ .start = offset == UINT64_MAX ? current_offset : offset,
+ .length = size == UINT64_MAX ? current_size : size,
+ };
+
+ struct blkpg_ioctl_arg ba = {
+ .op = BLKPG_RESIZE_PARTITION,
+ .data = &bp,
+ .datalen = sizeof(bp),
+ };
+
+ if (ioctl(whole_fd, BLKPG, &ba) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int loop_device_refresh_size(LoopDevice *d, uint64_t offset, uint64_t size) {
+ struct loop_info64 info;
+ assert(d);
+
+ /* Changes the offset/start of the loop device relative to the beginning of the underlying file or
+ * block device. If this loop device actually refers to a partition and not a loopback device, we'll
+ * try to adjust the partition offsets instead.
+ *
+ * If either offset or size is UINT64_MAX we won't change that parameter. */
+
+ if (d->fd < 0)
+ return -EBADF;
+
+ if (d->nr < 0) /* not a loopback device */
+ return resize_partition(d->fd, offset, size);
+
+ 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)
+ return 0;
+
+ if (size != UINT64_MAX)
+ info.lo_sizelimit = size;
+ if (offset != UINT64_MAX)
+ info.lo_offset = offset;
+
+ if (ioctl(d->fd, LOOP_SET_STATUS64, &info) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int loop_device_flock(LoopDevice *d, int operation) {
+ assert(d);
+
+ if (d->fd < 0)
+ return -EBADF;
+
+ if (flock(d->fd, operation) < 0)
+ return -errno;
+
+ return 0;
+}
projects / thirdparty / systemd.git / blobdiff