From: Sergei Shtepa <[email protected]>
Hi all.
I am happy to offer an improved version of the Block Devices Snapshots
Module. It allows creating non-persistent snapshots of any block devices.
The main purpose of such snapshots is to provide backups of block devices.
See more in Documentation/block/blksnap.rst.
The Block Device Filtering Mechanism is added to the block layer. This
allows attaching and detaching block device filters to the block layer.
Filters allow extending the functionality of the block layer. See more
in Documentation/block/blkfilter.rst.
The tool, library and tests for working with blksnap can be found on github.
Link: https://github.com/veeam/blksnap/tree/stable-v2.0
From the documentation, it is possible to learn how to manage the module
using the library and console tool.
In the new version, the method of saving snapshot difference has been
changed. Why this should have been done, Dave Chinner <[email protected]>
described in detail in the comments to the previous version.
Link: https://lore.kernel.org/lkml/[email protected]/T/#mfe9b8f46833011deea4b24714212230ac38db978
The module is incompatible with features hardware inline encryption and
data integrity. Thanks to Eric Biggers <[email protected]>.
Link: https://lore.kernel.org/lkml/[email protected]/T/#m3f13e580876bff1d283eb2a79d1ecdef3b98cc42
Unfortunately, I didn't have a chance to check it, since I don't have such
equipment.
And it is impossible to determine the presence of a blk-crypto-fallback at
the block layer filter level. The filter receives already encrypted data.
The original device continues to work without problems, but the data in
the snapshot is encrypted. Perhaps they can be decrypted if specify the
correct key when mounting the file system for snapshot image.
Tested on amd64 and ppc64le with a page size of 64KiB and a storage block
size of 4KiB.
Based on LK v6.7-rc2.
Compatible with branch 'for-next'.
link: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
P.S.
I'm sorry if I didn't add to 'CC' someone. Script get_maintainer.pl returns
a very large list. I get "Error: too many recipients from 86.49.140.21"
when trying to send an email from the smtp.migadu.com.
v6 changes:
- The difference storage has been changed.
In the previous version, the file was created only to reserve sector
ranges on a block device. The data was stored directly to the block
device in these sector ranges. Now saving and reading data is done using
'VFS' using vfs_iter_write() and vfs_iter_read() functions. This allows
not to depend on the filesystem and use, for example, tmpfs. Using an
unnamed temporary file allows hiding it from other processes and
automatically release it when the snapshot is closed.
However, now the module does not allow adding a block device to the
snapshot on which the difference storage is located. There is no way to
ensure the immutability of file metadata when writing data to a file.
This means that the metadata of the filesystem may change, which may
cause damage to the snapshot.
- _IOW and _IOR were mixed up - fixed.
- Protection against the use of the snapshots for block devices with
hardware inline encryption and data integrity was implemented.
Compatibility with them was not planned and has not been tested at the
moment.
v5 changes:
- Rebase for "kernel/git/axboe/linux-block.git" branch "for-6.5/block".
Link: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/log/?h=for-6.5/block
v4 changes:
- Structures for describing the state of chunks are allocated dynamically.
This reduces memory consumption, since the struct chunk is allocated only
for those blocks for which the snapshot image state differs from the
original block device.
- The algorithm for calculating the chunk size depending on the size of the
block device has been changed. For large block devices, it is now
possible to allocate a larger number of chunks, and their size is smaller.
- For block devices, a 'filter' file has been added to /sys/block/<device>.
It displays the name of the filter that is attached to the block device.
- Fixed a problem with the lack of protection against re-adding a block
device to a snapshot.
- Fixed a bug in the algorithm of allocating the next bio for a chunk.
This problem was occurred on large disks, for which a chunk consists of
at least two bio.
- The ownership mechanism of the diff_area structure has been changed.
This fixed the error of prematurely releasing the diff_area structure
when destroying the snapshot.
- Documentation corrected.
- The Sparse analyzer is passed.
- Use __u64 type instead pointers in UAPI.
v3 changes:
- New block device I/O controls BLKFILTER_ATTACH and BLKFILTER_DETACH allow
to attach and detach filters.
- New block device I/O control BLKFILTER_CTL allow sending command to
attached block device filter.
- The copy-on-write algorithm for processing I/O units has been optimized
and has become asynchronous.
- The snapshot image reading algorithm has been optimized and has become
asynchronous.
- Optimized the finite state machine for processing chunks.
- Fixed a tracking block size calculation bug.
v2 changes:
- Added documentation for Block Device Filtering Mechanism.
- Added documentation for Block Devices Snapshots Module (blksnap).
- The MAINTAINERS file has been updated.
- Optimized queue code for snapshot images.
- Fixed comments, log messages and code for better readability.
v1 changes:
- Forgotten "static" declarations have been added.
- The text of the comments has been corrected.
- It is possible to connect only one filter, since there are no others in
upstream.
- Do not have additional locks for attach/detach filter.
- blksnap.h moved to include/uapi/.
- #pragma once and commented code removed.
- uuid_t removed from user API.
- Removed default values for module parameters from the configuration file.
- The debugging code for tracking memory leaks has been removed.
- Simplified Makefile.
- Optimized work with large memory buffers, CBT tables are now in virtual
memory.
- The allocation code of minor numbers has been optimized.
- The implementation of the snapshot image block device has been
simplified, now it is a bio-based block device.
- Removed initialization of global variables with null values.
- only one bio is used to copy one chunk.
- Checked on ppc64le.
Sergei Shtepa (11):
documentation: Block Device Filtering Mechanism
block: Block Device Filtering Mechanism
documentation: Block Devices Snapshots Module
blksnap: header file of the module interface
blksnap: module management interface functions
blksnap: handling and tracking I/O units
blksnap: difference storage and chunk
blksnap: event queue from the difference storage
blksnap: snapshot and snapshot image block device
blksnap: Kconfig and Makefile
blksnap: prevents using devices with data integrity or inline
encryption
Documentation/block/blkfilter.rst | 66 ++
Documentation/block/blksnap.rst | 352 +++++++++
Documentation/block/index.rst | 2 +
.../userspace-api/ioctl/ioctl-number.rst | 1 +
MAINTAINERS | 17 +
block/Makefile | 3 +-
block/bdev.c | 2 +
block/blk-core.c | 35 +-
block/blk-filter.c | 238 +++++++
block/blk.h | 11 +
block/genhd.c | 10 +
block/ioctl.c | 7 +
block/partitions/core.c | 9 +
drivers/block/Kconfig | 2 +
drivers/block/Makefile | 2 +
drivers/block/blksnap/Kconfig | 31 +
drivers/block/blksnap/Makefile | 15 +
drivers/block/blksnap/cbt_map.c | 228 ++++++
drivers/block/blksnap/cbt_map.h | 90 +++
drivers/block/blksnap/chunk.c | 667 ++++++++++++++++++
drivers/block/blksnap/chunk.h | 142 ++++
drivers/block/blksnap/diff_area.c | 601 ++++++++++++++++
drivers/block/blksnap/diff_area.h | 175 +++++
drivers/block/blksnap/diff_buffer.c | 115 +++
drivers/block/blksnap/diff_buffer.h | 37 +
drivers/block/blksnap/diff_storage.c | 291 ++++++++
drivers/block/blksnap/diff_storage.h | 104 +++
drivers/block/blksnap/event_queue.c | 81 +++
drivers/block/blksnap/event_queue.h | 64 ++
drivers/block/blksnap/main.c | 475 +++++++++++++
drivers/block/blksnap/params.h | 16 +
drivers/block/blksnap/snapimage.c | 134 ++++
drivers/block/blksnap/snapimage.h | 10 +
drivers/block/blksnap/snapshot.c | 457 ++++++++++++
drivers/block/blksnap/snapshot.h | 64 ++
drivers/block/blksnap/tracker.c | 358 ++++++++++
drivers/block/blksnap/tracker.h | 78 ++
include/linux/blk-filter.h | 51 ++
include/linux/blk_types.h | 1 +
include/linux/blkdev.h | 1 +
include/linux/sched.h | 1 +
include/uapi/linux/blk-filter.h | 35 +
include/uapi/linux/blksnap.h | 388 ++++++++++
include/uapi/linux/fs.h | 3 +
44 files changed, 5468 insertions(+), 2 deletions(-)
create mode 100644 Documentation/block/blkfilter.rst
create mode 100644 Documentation/block/blksnap.rst
create mode 100644 block/blk-filter.c
create mode 100644 drivers/block/blksnap/Kconfig
create mode 100644 drivers/block/blksnap/Makefile
create mode 100644 drivers/block/blksnap/cbt_map.c
create mode 100644 drivers/block/blksnap/cbt_map.h
create mode 100644 drivers/block/blksnap/chunk.c
create mode 100644 drivers/block/blksnap/chunk.h
create mode 100644 drivers/block/blksnap/diff_area.c
create mode 100644 drivers/block/blksnap/diff_area.h
create mode 100644 drivers/block/blksnap/diff_buffer.c
create mode 100644 drivers/block/blksnap/diff_buffer.h
create mode 100644 drivers/block/blksnap/diff_storage.c
create mode 100644 drivers/block/blksnap/diff_storage.h
create mode 100644 drivers/block/blksnap/event_queue.c
create mode 100644 drivers/block/blksnap/event_queue.h
create mode 100644 drivers/block/blksnap/main.c
create mode 100644 drivers/block/blksnap/params.h
create mode 100644 drivers/block/blksnap/snapimage.c
create mode 100644 drivers/block/blksnap/snapimage.h
create mode 100644 drivers/block/blksnap/snapshot.c
create mode 100644 drivers/block/blksnap/snapshot.h
create mode 100644 drivers/block/blksnap/tracker.c
create mode 100644 drivers/block/blksnap/tracker.h
create mode 100644 include/linux/blk-filter.h
create mode 100644 include/uapi/linux/blk-filter.h
create mode 100644 include/uapi/linux/blksnap.h
--
2.20.1
From: Sergei Shtepa <[email protected]>
Contains callback functions for loading and unloading the module and
implementation of module management interface functions. The module
parameters and other mandatory declarations for the kernel module are
also defined.
Co-developed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Sergei Shtepa <[email protected]>
---
MAINTAINERS | 1 +
drivers/block/blksnap/main.c | 475 +++++++++++++++++++++++++++++++++
drivers/block/blksnap/params.h | 16 ++
3 files changed, 492 insertions(+)
create mode 100644 drivers/block/blksnap/main.c
create mode 100644 drivers/block/blksnap/params.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 9770c4d4b15d..6f666d772cf5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3598,6 +3598,7 @@ M: Sergei Shtepa <[email protected]>
L: [email protected]
S: Supported
F: Documentation/block/blksnap.rst
+F: drivers/block/blksnap/*
F: include/uapi/linux/blksnap.h
BLOCK LAYER
diff --git a/drivers/block/blksnap/main.c b/drivers/block/blksnap/main.c
new file mode 100644
index 000000000000..a8ae824d580f
--- /dev/null
+++ b/drivers/block/blksnap/main.c
@@ -0,0 +1,475 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023 Veeam Software Group GmbH */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/build_bug.h>
+#include <uapi/linux/blksnap.h>
+#include "snapimage.h"
+#include "snapshot.h"
+#include "tracker.h"
+#include "chunk.h"
+#include "params.h"
+
+/*
+ * The power of 2 for minimum tracking block size.
+ *
+ * If we make the tracking block size small, we will get detailed information
+ * about the changes, but the size of the change tracker table will be too
+ * large, which will lead to inefficient memory usage.
+ */
+static unsigned int tracking_block_minimum_shift = 16;
+
+/*
+ * The maximum number of tracking blocks.
+ *
+ * A table is created in RAM to store information about the status of all
+ * tracking blocks. So, if the size of the tracking block is small, then the
+ * size of the table turns out to be large and memory is consumed inefficiently.
+ * As the size of the block device grows, the size of the tracking block size
+ * should also grow. For this purpose, the limit of the maximum number of block
+ * size is set.
+ */
+static unsigned int tracking_block_maximum_count = 2097152;
+
+/*
+ * The power of 2 for maximum tracking block size.
+ *
+ * On very large capacity disks, the block size may be too large. To prevent
+ * this, the maximum block size is limited. If the limit on the maximum block
+ * size has been reached, then the number of blocks may exceed the
+ * &tracking_block_maximum_count.
+ */
+static unsigned int tracking_block_maximum_shift = 26;
+
+/*
+ * The power of 2 for minimum chunk size.
+ *
+ * The size of the chunk depends on how much data will be copied to the
+ * difference storage when at least one sector of the block device is changed.
+ * If the size is small, then small I/O units will be generated, which will
+ * reduce performance. Too large a chunk size will lead to inefficient use of
+ * the difference storage.
+ */
+static unsigned int chunk_minimum_shift = 18;
+
+/*
+ * The power of 2 for maximum number of chunks.
+ *
+ * A table is created in RAM to store information about the state of the chunks.
+ * So, if the size of the chunk is small, then the size of the table turns out
+ * to be large and memory is consumed inefficiently. As the size of the block
+ * device grows, the size of the chunk should also grow. For this purpose, the
+ * maximum number of chunks is set.
+ *
+ * The table expands dynamically when new chunks are allocated. Therefore,
+ * memory consumption also depends on the intensity of writing to the block
+ * device under the snapshot.
+ */
+static unsigned int chunk_maximum_count_shift = 40;
+
+/*
+ * The power of 2 for maximum chunk size.
+ *
+ * On very large capacity disks, the chunk size may be too large. To prevent
+ * this, the maximum block size is limited. If the limit on the maximum chunk
+ * size has been reached, then the number of chunks may exceed the
+ * &chunk_maximum_count.
+ */
+static unsigned int chunk_maximum_shift = 26;
+
+/*
+ * The maximum number of chunks in queue.
+ *
+ * The chunk is not immediately stored to the difference storage. The chunks
+ * are put in a store queue. The store queue allows to postpone the operation
+ * of storing a chunks data to the difference storage and perform it later in
+ * the worker thread.
+ */
+static unsigned int chunk_maximum_in_queue = 16;
+
+/*
+ * The size of the pool of preallocated difference buffers.
+ *
+ * A buffer can be allocated for each chunk. After use, this buffer is not
+ * released immediately, but is sent to the pool of free buffers. However, if
+ * there are too many free buffers in the pool, then these free buffers will
+ * be released immediately.
+ */
+static unsigned int free_diff_buffer_pool_size = 128;
+
+/*
+ * The minimum allowable size of the difference storage in sectors.
+ *
+ * The difference storage is a part of the disk space allocated for storing
+ * snapshot data. If the free space in difference storage is less than half of
+ * this value, then the process of increasing the size of the difference storage
+ * file will begin. The size of the difference storage file is increased in
+ * portions, the size of which is determined by this value.
+ */
+static unsigned int diff_storage_minimum = 2097152;
+
+#define VERSION_STR "2.0.0.0"
+static const struct blksnap_version version = {
+ .major = 2,
+ .minor = 0,
+ .revision = 0,
+ .build = 0,
+};
+
+unsigned int get_tracking_block_minimum_shift(void)
+{
+ return tracking_block_minimum_shift;
+}
+
+unsigned int get_tracking_block_maximum_shift(void)
+{
+ return tracking_block_maximum_shift;
+}
+
+unsigned int get_tracking_block_maximum_count(void)
+{
+ return tracking_block_maximum_count;
+}
+
+unsigned int get_chunk_minimum_shift(void)
+{
+ return chunk_minimum_shift;
+}
+
+unsigned int get_chunk_maximum_shift(void)
+{
+ return chunk_maximum_shift;
+}
+
+unsigned long get_chunk_maximum_count(void)
+{
+ /*
+ * The XArray is used to store chunks. And 'unsigned long' is used as
+ * chunk number parameter. So, The number of chunks cannot exceed the
+ * limits of ULONG_MAX.
+ */
+ if ((chunk_maximum_count_shift >> 3) < sizeof(unsigned long))
+ return (1ul << chunk_maximum_count_shift);
+ return ULONG_MAX;
+}
+
+unsigned int get_chunk_maximum_in_queue(void)
+{
+ return chunk_maximum_in_queue;
+}
+
+unsigned int get_free_diff_buffer_pool_size(void)
+{
+ return free_diff_buffer_pool_size;
+}
+
+sector_t get_diff_storage_minimum(void)
+{
+ return (sector_t)diff_storage_minimum;
+}
+
+static int ioctl_version(struct blksnap_version __user *user_version)
+{
+ if (copy_to_user(user_version, &version, sizeof(version))) {
+ pr_err("Unable to get version: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ return 0;
+}
+
+static_assert(sizeof(uuid_t) == sizeof(struct blksnap_uuid),
+ "Invalid size of struct blksnap_uuid.");
+
+static int ioctl_snapshot_create(struct blksnap_snapshot_create __user *uarg)
+{
+ struct blksnap_snapshot_create karg;
+ int ret;
+
+ if (copy_from_user(&karg, uarg, sizeof(karg))) {
+ pr_err("Unable to create snapshot: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ ret = snapshot_create(&karg);
+ if (ret)
+ return ret;
+
+ if (copy_to_user(uarg, &karg, sizeof(karg))) {
+ pr_err("Unable to create snapshot: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ return 0;
+}
+
+static int ioctl_snapshot_destroy(struct blksnap_uuid __user *user_id)
+{
+ uuid_t kernel_id;
+
+ if (copy_from_user(kernel_id.b, user_id->b, sizeof(uuid_t))) {
+ pr_err("Unable to destroy snapshot: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ return snapshot_destroy(&kernel_id);
+}
+
+static int ioctl_snapshot_take(struct blksnap_uuid __user *user_id)
+{
+ uuid_t kernel_id;
+
+ if (copy_from_user(kernel_id.b, user_id->b, sizeof(uuid_t))) {
+ pr_err("Unable to take snapshot: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ return snapshot_take(&kernel_id);
+}
+
+static int ioctl_snapshot_collect(struct blksnap_snapshot_collect __user *uarg)
+{
+ int ret;
+ struct blksnap_snapshot_collect karg;
+
+ if (copy_from_user(&karg, uarg, sizeof(karg))) {
+ pr_err("Unable to collect available snapshots: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ ret = snapshot_collect(&karg.count, u64_to_user_ptr(karg.ids));
+
+ if (copy_to_user(uarg, &karg, sizeof(karg))) {
+ pr_err("Unable to collect available snapshots: invalid user buffer\n");
+ return -ENODATA;
+ }
+
+ return ret;
+}
+
+static_assert(sizeof(struct blksnap_snapshot_event) == 4096,
+ "The size struct blksnap_snapshot_event should be equal to the size of the page.");
+
+static int ioctl_snapshot_wait_event(struct blksnap_snapshot_event __user *uarg)
+{
+ int ret = 0;
+ struct blksnap_snapshot_event *karg;
+ struct event *ev;
+
+ karg = kzalloc(sizeof(struct blksnap_snapshot_event), GFP_KERNEL);
+ if (!karg)
+ return -ENOMEM;
+
+ /* Copy only snapshot ID and timeout*/
+ if (copy_from_user(karg, uarg, sizeof(uuid_t) + sizeof(__u32))) {
+ pr_err("Unable to get snapshot event. Invalid user buffer\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ev = snapshot_wait_event((uuid_t *)karg->id.b, karg->timeout_ms);
+ if (IS_ERR(ev)) {
+ ret = PTR_ERR(ev);
+ goto out;
+ }
+
+ pr_debug("Received event=%lld code=%d data_size=%d\n", ev->time,
+ ev->code, ev->data_size);
+ karg->code = ev->code;
+ karg->time_label = ev->time;
+
+ if (ev->data_size > sizeof(karg->data)) {
+ pr_err("Event size %d is too big\n", ev->data_size);
+ ret = -ENOSPC;
+ /* If we can't copy all the data, we copy only part of it. */
+ }
+ memcpy(karg->data, ev->data, ev->data_size);
+ event_free(ev);
+
+ if (copy_to_user(uarg, karg, sizeof(struct blksnap_snapshot_event))) {
+ pr_err("Unable to get snapshot event. Invalid user buffer\n");
+ ret = -EINVAL;
+ }
+out:
+ kfree(karg);
+
+ return ret;
+}
+
+static long blksnap_ctrl_unlocked_ioctl(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ void *argp = (void __user *)arg;
+
+ switch (cmd) {
+ case IOCTL_BLKSNAP_VERSION:
+ return ioctl_version(argp);
+ case IOCTL_BLKSNAP_SNAPSHOT_CREATE:
+ return ioctl_snapshot_create(argp);
+ case IOCTL_BLKSNAP_SNAPSHOT_DESTROY:
+ return ioctl_snapshot_destroy(argp);
+ case IOCTL_BLKSNAP_SNAPSHOT_TAKE:
+ return ioctl_snapshot_take(argp);
+ case IOCTL_BLKSNAP_SNAPSHOT_COLLECT:
+ return ioctl_snapshot_collect(argp);
+ case IOCTL_BLKSNAP_SNAPSHOT_WAIT_EVENT:
+ return ioctl_snapshot_wait_event(argp);
+ default:
+ return -ENOTTY;
+ }
+
+}
+
+static const struct file_operations blksnap_ctrl_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = blksnap_ctrl_unlocked_ioctl,
+};
+
+static struct miscdevice blksnap_ctrl_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = BLKSNAP_CTL,
+ .fops = &blksnap_ctrl_fops,
+};
+
+static inline sector_t chunk_minimum_sectors(void)
+{
+ return (1ull << (chunk_minimum_shift - SECTOR_SHIFT));
+};
+
+static int __init parameters_init(void)
+{
+ pr_debug("tracking_block_minimum_shift: %d\n",
+ tracking_block_minimum_shift);
+ pr_debug("tracking_block_maximum_shift: %d\n",
+ tracking_block_maximum_shift);
+ pr_debug("tracking_block_maximum_count: %d\n",
+ tracking_block_maximum_count);
+
+ pr_debug("chunk_minimum_shift: %d\n", chunk_minimum_shift);
+ pr_debug("chunk_maximum_shift: %d\n", chunk_maximum_shift);
+ pr_debug("chunk_maximum_count_shift: %u\n", chunk_maximum_count_shift);
+
+ pr_debug("chunk_maximum_in_queue: %d\n", chunk_maximum_in_queue);
+ pr_debug("free_diff_buffer_pool_size: %d\n",
+ free_diff_buffer_pool_size);
+ pr_debug("diff_storage_minimum: %d\n", diff_storage_minimum);
+
+ if (tracking_block_maximum_shift < tracking_block_minimum_shift) {
+ tracking_block_maximum_shift = tracking_block_minimum_shift;
+ pr_warn("fixed tracking_block_maximum_shift: %d\n",
+ tracking_block_maximum_shift);
+ }
+
+ if (chunk_minimum_shift < PAGE_SHIFT) {
+ chunk_minimum_shift = PAGE_SHIFT;
+ pr_warn("fixed chunk_minimum_shift: %d\n",
+ chunk_minimum_shift);
+ }
+ if (chunk_maximum_shift < chunk_minimum_shift) {
+ chunk_maximum_shift = chunk_minimum_shift;
+ pr_warn("fixed chunk_maximum_shift: %d\n",
+ chunk_maximum_shift);
+ }
+ if (diff_storage_minimum < (chunk_minimum_sectors() * 2)) {
+ diff_storage_minimum = chunk_minimum_sectors() * 2;
+ pr_warn("fixed diff_storage_minimum: %d\n",
+ diff_storage_minimum);
+ }
+ if (diff_storage_minimum & (chunk_minimum_sectors() - 1)) {
+ diff_storage_minimum &= ~(chunk_minimum_sectors() - 1);
+ pr_warn("fixed diff_storage_minimum: %d\n",
+ diff_storage_minimum);
+ }
+
+ return 0;
+}
+
+static int __init blksnap_init(void)
+{
+ int ret;
+
+ pr_debug("Loading\n");
+ pr_debug("Version: %s\n", VERSION_STR);
+
+ ret = parameters_init();
+ if (ret)
+ return ret;
+
+ ret = chunk_init();
+ if (ret)
+ goto fail_chunk_init;
+
+ ret = tracker_init();
+ if (ret)
+ goto fail_tracker_init;
+
+ ret = misc_register(&blksnap_ctrl_misc);
+ if (ret)
+ goto fail_misc_register;
+
+ return 0;
+
+fail_misc_register:
+ tracker_done();
+fail_tracker_init:
+ chunk_done();
+fail_chunk_init:
+
+ return ret;
+}
+
+static void __exit blksnap_exit(void)
+{
+ pr_debug("Unloading module\n");
+
+ misc_deregister(&blksnap_ctrl_misc);
+
+ chunk_done();
+ snapshot_done();
+ tracker_done();
+
+ pr_debug("Module was unloaded\n");
+}
+
+module_init(blksnap_init);
+module_exit(blksnap_exit);
+
+module_param_named(tracking_block_minimum_shift, tracking_block_minimum_shift,
+ uint, 0644);
+MODULE_PARM_DESC(tracking_block_minimum_shift,
+ "The power of 2 for minimum tracking block size");
+module_param_named(tracking_block_maximum_count, tracking_block_maximum_count,
+ uint, 0644);
+MODULE_PARM_DESC(tracking_block_maximum_count,
+ "The maximum number of tracking blocks");
+module_param_named(tracking_block_maximum_shift, tracking_block_maximum_shift,
+ uint, 0644);
+MODULE_PARM_DESC(tracking_block_maximum_shift,
+ "The power of 2 for maximum trackings block size");
+module_param_named(chunk_minimum_shift, chunk_minimum_shift, uint, 0644);
+MODULE_PARM_DESC(chunk_minimum_shift,
+ "The power of 2 for minimum chunk size");
+module_param_named(chunk_maximum_count_shift, chunk_maximum_count_shift,
+ uint, 0644);
+MODULE_PARM_DESC(chunk_maximum_count_shift,
+ "The power of 2 for maximum number of chunks");
+module_param_named(chunk_maximum_shift, chunk_maximum_shift, uint, 0644);
+MODULE_PARM_DESC(chunk_maximum_shift,
+ "The power of 2 for maximum snapshots chunk size");
+module_param_named(chunk_maximum_in_queue, chunk_maximum_in_queue, uint, 0644);
+MODULE_PARM_DESC(chunk_maximum_in_queue,
+ "The maximum number of chunks in store queue");
+module_param_named(free_diff_buffer_pool_size, free_diff_buffer_pool_size,
+ uint, 0644);
+MODULE_PARM_DESC(free_diff_buffer_pool_size,
+ "The size of the pool of preallocated difference buffers");
+module_param_named(diff_storage_minimum, diff_storage_minimum, uint, 0644);
+MODULE_PARM_DESC(diff_storage_minimum,
+ "The minimum allowable size of the difference storage in sectors");
+
+MODULE_DESCRIPTION("Block Device Snapshots Module");
+MODULE_VERSION(VERSION_STR);
+MODULE_AUTHOR("Veeam Software Group GmbH");
+MODULE_LICENSE("GPL");
diff --git a/drivers/block/blksnap/params.h b/drivers/block/blksnap/params.h
new file mode 100644
index 000000000000..3ec4cce4de39
--- /dev/null
+++ b/drivers/block/blksnap/params.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2023 Veeam Software Group GmbH */
+#ifndef __BLKSNAP_PARAMS_H
+#define __BLKSNAP_PARAMS_H
+
+unsigned int get_tracking_block_minimum_shift(void);
+unsigned int get_tracking_block_maximum_shift(void);
+unsigned int get_tracking_block_maximum_count(void);
+unsigned int get_chunk_minimum_shift(void);
+unsigned int get_chunk_maximum_shift(void);
+unsigned long get_chunk_maximum_count(void);
+unsigned int get_chunk_maximum_in_queue(void);
+unsigned int get_free_diff_buffer_pool_size(void);
+sector_t get_diff_storage_minimum(void);
+
+#endif /* __BLKSNAP_PARAMS_H */
--
2.20.1
On 11/24/23 9:59 AM, Sergei Shtepa wrote:
> From: Sergei Shtepa <[email protected]>
>
> Hi all.
>
> I am happy to offer an improved version of the Block Devices Snapshots
> Module. It allows creating non-persistent snapshots of any block devices.
> The main purpose of such snapshots is to provide backups of block devices.
> See more in Documentation/block/blksnap.rst.
Please stop posting the same version, this is the third one of the
morning. What's going on?
--
Jens Axboe
I'm very sorry.
Script get_maintainer.pl returns a very large list.
I get "Error: too many recipients from 86.49.140.21"
when trying to send an email from the smtp.migadu.com.
But it seems that for the third time it was possible to send
a whole set of patches.
I'm sorry for the inconvenience.
Sending patches by mail gives me pain...
It seems that I have already gone through all the rakes,
but there are new ones.