bb2551bdcb
It appears LOOP_CONFIGURE in 5.8 is even more broken than initially thought: it doesn't properly propgate lo_sizelimit to the block device layer. :-( Let's hence check the block device size immediately after issuing LOOP_CONFIGURE, and if it doesn't match what we just set let's fallback to the old ioctls. This means LOOP_CONFIGURE currently works correctly only for the most simply case: no partition table logic and no size limit. Sad! (Kernel people should really be told about the concepts of tests and even CI, one day!)
514 lines
17 KiB
C
514 lines
17 KiB
C
/* 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 <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;
|
|
|
|
(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 {
|
|
bool good = true;
|
|
|
|
if (c->info.lo_sizelimit != 0) {
|
|
/* Kernel 5.8 vanilla doesn't properly propagate the size limit into the block
|
|
* device. If it's used, let's immediately check if it had the desired effect
|
|
* hence. And if not use classic LOOP_SET_STATUS64. */
|
|
uint64_t z;
|
|
|
|
if (ioctl(fd, BLKGETSIZE64, &z) < 0) {
|
|
r = -errno;
|
|
goto fail;
|
|
}
|
|
|
|
if (z != c->info.lo_sizelimit) {
|
|
log_debug("LOOP_CONFIGURE is broken, doesn't honour .lo_sizelimit. Falling back to LOOP_SET_STATUS64.");
|
|
good = false;
|
|
}
|
|
}
|
|
|
|
if (FLAGS_SET(c->info.lo_flags, LO_FLAGS_PARTSCAN)) {
|
|
/* 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) {
|
|
log_debug("LOOP_CONFIGURE is broken, doesn't honour LO_FLAGS_PARTSCAN. Falling back to LOOP_SET_STATUS64.");
|
|
good = false;
|
|
}
|
|
}
|
|
|
|
if (good)
|
|
return 0;
|
|
|
|
/* 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_free_ char *loopdev = NULL;
|
|
struct loop_config config;
|
|
LoopDevice *d = NULL;
|
|
struct stat st;
|
|
int nr = -1, r;
|
|
|
|
assert(fd >= 0);
|
|
assert(ret);
|
|
assert(IN_SET(open_flags, O_RDWR, O_RDONLY));
|
|
|
|
if (fstat(fd, &st) < 0)
|
|
return -errno;
|
|
|
|
if (S_ISBLK(st.st_mode)) {
|
|
if (ioctl(fd, LOOP_GET_STATUS64, &config.info) >= 0) {
|
|
/* Oh! This is a loopback device? That's interesting! */
|
|
|
|
#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)) {
|
|
_cleanup_close_ int copy = -1;
|
|
|
|
/* If this is already a block device, store a copy of the fd as it is */
|
|
|
|
copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
|
|
if (copy < 0)
|
|
return -errno;
|
|
|
|
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;
|
|
}
|
|
|
|
_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 (unsigned n_attempts = 0;;) {
|
|
_cleanup_close_ int loop = -1;
|
|
|
|
nr = ioctl(control, LOOP_CTL_GET_FREE);
|
|
if (nr < 0)
|
|
return -errno;
|
|
|
|
if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
|
|
return -ENOMEM;
|
|
|
|
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_with_fd),
|
|
.node = TAKE_PTR(loopdev),
|
|
.nr = nr,
|
|
};
|
|
|
|
*ret = d;
|
|
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(open_flags < 0 || IN_SET(open_flags, O_RDWR, O_RDONLY));
|
|
|
|
/* 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;
|
|
|
|
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) {
|
|
if (!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)
|
|
log_debug_errno(errno, "Failed to clear loop device: %m");
|
|
|
|
}
|
|
|
|
safe_close(d->fd);
|
|
}
|
|
|
|
if (d->nr >= 0 && !d->relinquished) {
|
|
_cleanup_close_ int control = -1;
|
|
|
|
control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
|
|
if (control < 0)
|
|
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);
|
|
return mfree(d);
|
|
}
|
|
|
|
void loop_device_relinquish(LoopDevice *d) {
|
|
assert(d);
|
|
|
|
/* Don't attempt to clean up the loop device anymore from this point on. Leave the clean-ing up to the kernel
|
|
* itself, using the loop device "auto-clear" logic we already turned on when creating the device. */
|
|
|
|
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;
|
|
}
|
|
|
|
int loop_device_sync(LoopDevice *d) {
|
|
assert(d);
|
|
|
|
/* We also do this implicitly in loop_device_unref(). Doing this explicitly here has the benefit that
|
|
* we can check the return value though. */
|
|
|
|
if (d->fd < 0)
|
|
return -EBADF;
|
|
|
|
if (fsync(d->fd) < 0)
|
|
return -errno;
|
|
|
|
return 0;
|
|
}
|