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Merge pull request #16678 from poettering/loop-configure

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loop-util: use new LOOP_CONFIGURE ioctl added in kernel 5.8
This commit is contained in:
Lennart Poettering
2020-08-11 22:22:27 +02:00
committed by GitHub
parent 6b49257f6b d8857af4d0
commit c53da7ed02
6 changed files with 133 additions and 37 deletions
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TODO
-3
View File
@@ -20,9 +20,6 @@ Features:
* make use of the new statx mountid and rootmount fields in path_get_mnt_id()
and fd_is_mount_point()
* make use of new loopback setup ioctl to setup loopback devices in one atomic
ioctl
* nspawn: move "incoming mount" directory to /run/host, move "inaccessible"
nodes to /run/host, move notify socket (for sd_notify() between payload and
container manager)
src/basic/blockdev-util.c
+37
View File
@@ -214,3 +214,40 @@ int lock_whole_block_device(dev_t devt, int operation) {
return TAKE_FD(lock_fd);
}
int blockdev_partscan_enabled(int fd) {
_cleanup_free_ char *p = NULL, *buf = NULL;
unsigned long long ull;
struct stat st;
int r;
/* Checks if partition scanning is correctly enabled on the block device */
if (fstat(fd, &st) < 0)
return -errno;
if (!S_ISBLK(st.st_mode))
return -ENOTBLK;
if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
return -ENOMEM;
r = read_one_line_file(p, &buf);
if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
* partition block device, not the whole block device. And that means we have no
* partition scanning on for it (we do for its parent, but not for the partition
* itself). */
return false;
if (r < 0)
return r;
r = safe_atollu_full(buf, 16, &ull);
if (r < 0)
return r;
#ifndef GENHD_FL_NO_PART_SCAN
#define GENHD_FL_NO_PART_SCAN (0x0200)
#endif
return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
}
src/basic/blockdev-util.h
+2
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@@ -20,3 +20,5 @@ int get_block_device(const char *path, dev_t *dev);
int get_block_device_harder(const char *path, dev_t *dev);
int lock_whole_block_device(dev_t devt, int operation);
int blockdev_partscan_enabled(int fd);
src/basic/missing_loop.h
+15
View File
@@ -0,0 +1,15 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once
#include <linux/loop.h>
#ifndef LOOP_CONFIGURE
struct loop_config {
__u32 fd;
__u32 block_size;
struct loop_info64 info;
__u64 __reserved[8];
};
#define LOOP_CONFIGURE 0x4C0A
#endif
src/shared/dissect-image.c
+10 -14
View File
@@ -215,22 +215,18 @@ static int wait_for_partitions_to_appear(
break;
r = -errno;
if (r == -EINVAL) {
struct loop_info64 info;
/* If we are running on a block device that has partition scanning off, return an
* explicit recognizable error about this, so that callers can generate a proper
* message explaining the situation. */
/* If we are running on a loop device that has partition scanning off, return
* an explicit recognizable error about this, so that callers can generate a
* proper message explaining the situation. */
r = blockdev_partscan_enabled(fd);
if (r < 0)
return r;
if (r == 0)
return log_debug_errno(EPROTONOSUPPORT,
"Device is a loop device and partition scanning is off!");
if (ioctl(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
if ((info.lo_flags & LO_FLAGS_PARTSCAN) == 0)
return log_debug_errno(EPROTONOSUPPORT,
"Device is a loop device and partition scanning is off!");
}
return -EINVAL; /* original error */
}
if (r != -EBUSY)
return r;
src/shared/loop-util.c
+69 -20
View File
@@ -14,20 +14,68 @@
#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) {
(void) ioctl(*fd, LOOP_CLR_FD);
(void) safe_close(*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(
@@ -39,7 +87,7 @@ int loop_device_make(
LoopDevice **ret) {
_cleanup_free_ char *loopdev = NULL;
struct loop_info64 info;
struct loop_config config;
LoopDevice *d = NULL;
struct stat st;
int nr = -1, r;
@@ -52,14 +100,14 @@ int loop_device_make(
return -errno;
if (S_ISBLK(st.st_mode)) {
if (ioctl(fd, LOOP_GET_STATUS64, &info) >= 0) {
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(&info, sizeof(info));
VALGRIND_MAKE_MEM_DEFINED(&config.info, sizeof(config.info));
#endif
nr = info.lo_number;
nr = config.info.lo_number;
if (asprintf(&loopdev, "/dev/loop%i", nr) < 0)
return -ENOMEM;
@@ -100,6 +148,16 @@ int loop_device_make(
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;;) {
@@ -119,12 +177,13 @@ int loop_device_make(
if (errno != ENOENT)
return -errno;
} else {
if (ioctl(loop, LOOP_SET_FD, fd) >= 0) {
r = loop_configure(loop, &config);
if (r >= 0) {
loop_with_fd = TAKE_FD(loop);
break;
}
if (errno != EBUSY)
return -errno;
if (r != -EBUSY)
return r;
}
if (++n_attempts >= 64) /* Give up eventually */
@@ -133,16 +192,6 @@ int loop_device_make(
loopdev = mfree(loopdev);
}
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_with_fd, LOOP_SET_STATUS64, &info) < 0)
return -errno;
d = new(LoopDevice, 1);
if (!d)
return -ENOMEM;