[v5,04/11] blksnap: header file of the module interface

Message ID	20230612135228.10702-5-sergei.shtepa@veeam.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-block-owner@vger.kernel.org> From: Sergei Shtepa <sergei.shtepa@veeam.com> To: <axboe@kernel.dk>, <hch@infradead.org>, <corbet@lwn.net>, <snitzer@kernel.org> CC: <viro@zeniv.linux.org.uk>, <brauner@kernel.org>, <dchinner@redhat.com>, <willy@infradead.org>, <dlemoal@kernel.org>, <linux@weissschuh.net>, <jack@suse.cz>, <ming.lei@redhat.com>, <linux-block@vger.kernel.org>, <linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>, <sergei.shtepa@veeam.com>, Donald Buczek <buczek@molgen.mpg.de> Subject: [PATCH v5 04/11] blksnap: header file of the module interface Date: Mon, 12 Jun 2023 15:52:21 +0200 Message-ID: <20230612135228.10702-5-sergei.shtepa@veeam.com> In-Reply-To: <20230612135228.10702-1-sergei.shtepa@veeam.com> References: <20230612135228.10702-1-sergei.shtepa@veeam.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk
Series	blksnap - block devices snapshots module \| expand [v5,00/11] blksnap - block devices snapshots module [v5,01/11] documentation: Block Device Filtering Mechanism [v5,02/11] block: Block Device Filtering Mechanism [v5,03/11] documentation: Block Devices Snapshots Module [v5,04/11] blksnap: header file of the module interface [v5,05/11] blksnap: module management interface functions [v5,06/11] blksnap: handling and tracking I/O units [v5,07/11] blksnap: minimum data storage unit of the original block device [v5,08/11] blksnap: difference storage [v5,09/11] blksnap: event queue from the difference storage [v5,10/11] blksnap: snapshot and snapshot image block device [v5,11/11] blksnap: Kconfig and Makefile

diff --git a/MAINTAINERS b/MAINTAINERS index c7dabe785cf1..76b14ad604dc 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3594,6 +3594,7 @@ M: Sergei Shtepa <sergei.shtepa@veeam.com> L: linux-block@vger.kernel.org S: Supported F: Documentation/block/blksnap.rst +F: include/uapi/linux/blksnap.h BLOCK LAYER M: Jens Axboe <axboe@kernel.dk> diff --git a/include/uapi/linux/blksnap.h b/include/uapi/linux/blksnap.h new file mode 100644 index 000000000000..2fe3f2a43bc5 --- /dev/null +++ b/include/uapi/linux/blksnap.h @@ -0,0 +1,421 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* Copyright (C) 2023 Veeam Software Group GmbH */ +#ifndef _UAPI_LINUX_BLKSNAP_H +#define _UAPI_LINUX_BLKSNAP_H + +#include <linux/types.h> + +#define BLKSNAP_CTL "blksnap-control" +#define BLKSNAP_IMAGE_NAME "blksnap-image" +#define BLKSNAP 'V' + +/** + * DOC: Block device filter interface. + * + * Control commands that are transmitted through the block device filter + * interface. + */ + +/** + * enum blkfilter_ctl_blksnap - List of commands for BLKFILTER_CTL ioctl + * + * @blkfilter_ctl_blksnap_cbtinfo: + * Get CBT information. + * The result of executing the command is a &struct blksnap_cbtinfo. + * Return 0 if succeeded, negative errno otherwise. + * @blkfilter_ctl_blksnap_cbtmap: + * Read the CBT map. + * The option passes the &struct blksnap_cbtmap. + * The size of the table can be quite large. Thus, the table is read in + * a loop, in each cycle of which the next offset is set to + * &blksnap_tracker_read_cbt_bitmap.offset. + * Return a count of bytes read if succeeded, negative errno otherwise. + * @blkfilter_ctl_blksnap_cbtdirty: + * Set dirty blocks in the CBT map. + * The option passes the &struct blksnap_cbtdirty. + * There are cases when some blocks need to be marked as changed. + * This ioctl allows to do this. + * Return 0 if succeeded, negative errno otherwise. + * @blkfilter_ctl_blksnap_snapshotadd: + * Add device to snapshot. + * The option passes the &struct blksnap_snapshotadd. + * Return 0 if succeeded, negative errno otherwise. + * @blkfilter_ctl_blksnap_snapshotinfo: + * Get information about snapshot. + * The result of executing the command is a &struct blksnap_snapshotinfo. + * Return 0 if succeeded, negative errno otherwise. + */ +enum blkfilter_ctl_blksnap { + blkfilter_ctl_blksnap_cbtinfo, + blkfilter_ctl_blksnap_cbtmap, + blkfilter_ctl_blksnap_cbtdirty, + blkfilter_ctl_blksnap_snapshotadd, + blkfilter_ctl_blksnap_snapshotinfo, +}; + +#ifndef UUID_SIZE +#define UUID_SIZE 16 +#endif + +/** + * struct blksnap_uuid - Unique 16-byte identifier. + * + * @b: + * An array of 16 bytes. + */ +struct blksnap_uuid { + __u8 b[UUID_SIZE]; +}; + +/** + * struct blksnap_cbtinfo - Result for the command + * &blkfilter_ctl_blksnap.blkfilter_ctl_blksnap_cbtinfo. + * + * @device_capacity: + * Device capacity in bytes. + * @block_size: + * Block size in bytes. + * @block_count: + * Number of blocks. + * @generation_id: + * Unique identifier of change tracking generation. + * @changes_number: + * Current changes number. + */ +struct blksnap_cbtinfo { + __u64 device_capacity; + __u32 block_size; + __u32 block_count; + struct blksnap_uuid generation_id; + __u8 changes_number; +}; + +/** + * struct blksnap_cbtmap - Option for the command + * &blkfilter_ctl_blksnap.blkfilter_ctl_blksnap_cbtmap. + * + * @offset: + * Offset from the beginning of the CBT bitmap in bytes. + * @length: + * Size of @buffer in bytes. + * @buffer: + * Pointer to the buffer for output. + */ +struct blksnap_cbtmap { + __u32 offset; + __u32 length; + __u64 buffer; +}; + +/** + * struct blksnap_sectors - Description of the block device region. + * + * @offset: + * Offset from the beginning of the disk in sectors. + * @count: + * Count of sectors. + */ +struct blksnap_sectors { + __u64 offset; + __u64 count; +}; + +/** + * struct blksnap_cbtdirty - Option for the command + * &blkfilter_ctl_blksnap.blkfilter_ctl_blksnap_cbtdirty. + * + * @count: + * Count of elements in the @dirty_sectors. + * @dirty_sectors: + * Pointer to the array of &struct blksnap_sectors. + */ +struct blksnap_cbtdirty { + __u32 count; + __u64 dirty_sectors; +}; + +/** + * struct blksnap_snapshotadd - Option for the command + * &blkfilter_ctl_blksnap.blkfilter_ctl_blksnap_snapshotadd. + * + * @id: + * ID of the snapshot to which the block device should be added. + */ +struct blksnap_snapshotadd { + struct blksnap_uuid id; +}; + +#define IMAGE_DISK_NAME_LEN 32 + +/** + * struct blksnap_snapshotinfo - Result for the command + * &blkfilter_ctl_blksnap.blkfilter_ctl_blksnap_snapshotinfo. + * + * @error_code: + * Zero if there were no errors while holding the snapshot. + * The error code -ENOSPC means that while holding the snapshot, a snapshot + * overflow situation has occurred. Other error codes mean other reasons + * for failure. + * The error code is reset when the device is added to a new snapshot. + * @image: + * If the snapshot was taken, it stores the block device name of the + * image, or empty string otherwise. + */ +struct blksnap_snapshotinfo { + __s32 error_code; + __u8 image[IMAGE_DISK_NAME_LEN]; +}; + +/** + * DOC: Interface for managing snapshots + * + * Control commands that are transmitted through the blksnap module interface. + */ +enum blksnap_ioctl { + blksnap_ioctl_version, + blksnap_ioctl_snapshot_create, + blksnap_ioctl_snapshot_destroy, + blksnap_ioctl_snapshot_append_storage, + blksnap_ioctl_snapshot_take, + blksnap_ioctl_snapshot_collect, + blksnap_ioctl_snapshot_wait_event, +}; + +/** + * struct blksnap_version - Module version. + * + * @major: + * Version major part. + * @minor: + * Version minor part. + * @revision: + * Revision number. + * @build: + * Build number. Should be zero. + */ +struct blksnap_version { + __u16 major; + __u16 minor; + __u16 revision; + __u16 build; +}; + +/** + * define IOCTL_BLKSNAP_VERSION - Get module version. + * + * The version may increase when the API changes. But linking the user space + * behavior to the version code does not seem to be a good idea. + * To ensure backward compatibility, API changes should be made by adding new + * ioctl without changing the behavior of existing ones. The version should be + * used for logs. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_VERSION \ + _IOW(BLKSNAP, blksnap_ioctl_version, struct blksnap_version) + + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_CREATE - Create snapshot. + * + * Creates a snapshot structure in the memory and allocates an identifier for + * it. Further interaction with the snapshot is possible by this identifier. + * A snapshot is created for several block devices at once. + * Several snapshots can be created at the same time, but with the condition + * that one block device can only be included in one snapshot. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_CREATE \ + _IOW(BLKSNAP, blksnap_ioctl_snapshot_create, \ + struct blksnap_uuid) + + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_DESTROY - Release and destroy the snapshot. + * + * Destroys snapshot with &blksnap_snapshot_destroy.id. This leads to the + * deletion of all block device images of the snapshot. The difference storage + * is being released. But the change tracker keeps tracking. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_DESTROY \ + _IOR(BLKSNAP, blksnap_ioctl_snapshot_destroy, \ + struct blksnap_uuid) + +/** + * struct blksnap_snapshot_append_storage - Argument for the + * &IOCTL_BLKSNAP_SNAPSHOT_APPEND_STORAGE control. + * + * @id: + * Snapshot ID. + * @bdev_path: + * Device path string buffer. + * @bdev_path_size: + * Device path string buffer size. + * @count: + * Size of @ranges in the number of &struct blksnap_sectors. + * @ranges: + * Pointer to the array of &struct blksnap_sectors. + */ +struct blksnap_snapshot_append_storage { + struct blksnap_uuid id; + __u64 bdev_path; + __u32 bdev_path_size; + __u32 count; + __u64 ranges; +}; + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_APPEND_STORAGE - Append storage to the + * difference storage of the snapshot. + * + * The snapshot difference storage can be set either before or after creating + * the snapshot images. This allows to dynamically expand the difference + * storage while holding the snapshot. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_APPEND_STORAGE \ + _IOW(BLKSNAP, blksnap_ioctl_snapshot_append_storage, \ + struct blksnap_snapshot_append_storage) + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_TAKE - Take snapshot. + * + * Creates snapshot images of block devices and switches change trackers tables. + * The snapshot must be created before this call, and the areas of block + * devices should be added to the difference storage. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_TAKE \ + _IOR(BLKSNAP, blksnap_ioctl_snapshot_take, \ + struct blksnap_uuid) + +/** + * struct blksnap_snapshot_collect - Argument for the + * &IOCTL_BLKSNAP_SNAPSHOT_COLLECT control. + * + * @count: + * Size of &blksnap_snapshot_collect.ids in the number of 16-byte UUID. + * @ids: + * Pointer to the array of struct blksnap_uuid for output. + */ +struct blksnap_snapshot_collect { + __u32 count; + __u64 ids; +}; + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_COLLECT - Get collection of created snapshots. + * + * Multiple snapshots can be created at the same time. This allows for one + * system to create backups for different data with a independent schedules. + * + * If in &blksnap_snapshot_collect.count is less than required to store the + * &blksnap_snapshot_collect.ids, the array is not filled, and the ioctl + * returns the required count for &blksnap_snapshot_collect.ids. + * + * So, it is recommended to call the ioctl twice. The first call with an null + * pointer &blksnap_snapshot_collect.ids and a zero value in + * &blksnap_snapshot_collect.count. It will set the required array size in + * &blksnap_snapshot_collect.count. The second call with a pointer + * &blksnap_snapshot_collect.ids to an array of the required size will allow to + * get collection of active snapshots. + * + * Return: 0 if succeeded, -ENODATA if there is not enough space in the array + * to store collection of active snapshots, or negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_COLLECT \ + _IOW(BLKSNAP, blksnap_ioctl_snapshot_collect, \ + struct blksnap_snapshot_collect) + +/** + * enum blksnap_event_codes - Variants of event codes. + * + * @blksnap_event_code_low_free_space: + * Low free space in difference storage event. + * If the free space in the difference storage is reduced to the specified + * limit, the module generates this event. + * @blksnap_event_code_corrupted: + * Snapshot image is corrupted event. + * If a chunk could not be allocated when trying to save data to the + * difference storage, this event is generated. However, this does not mean + * that the backup process was interrupted with an error. If the snapshot + * image has been read to the end by this time, the backup process is + * considered successful. + */ +enum blksnap_event_codes { + blksnap_event_code_low_free_space, + blksnap_event_code_corrupted, +}; + +/** + * struct blksnap_snapshot_event - Argument for the + * &IOCTL_BLKSNAP_SNAPSHOT_WAIT_EVENT control. + * + * @id: + * Snapshot ID. + * @timeout_ms: + * Timeout for waiting in milliseconds. + * @code: + * Code of the received event &enum blksnap_event_codes. + * @time_label: + * Timestamp of the received event. + * @data: + * The received event body. + */ +struct blksnap_snapshot_event { + struct blksnap_uuid id; + __u32 timeout_ms; + __u32 code; + __s64 time_label; + __u8 data[4096 - 32]; +}; + +/** + * define IOCTL_BLKSNAP_SNAPSHOT_WAIT_EVENT - Wait and get the event from the + * snapshot. + * + * While holding the snapshot, the kernel module can transmit information about + * changes in its state in the form of events to the user level. + * It is very important to receive these events as quickly as possible, so the + * user's thread is in the state of interruptable sleep. + * + * Return: 0 if succeeded, negative errno otherwise. + */ +#define IOCTL_BLKSNAP_SNAPSHOT_WAIT_EVENT \ + _IOW(BLKSNAP, blksnap_ioctl_snapshot_wait_event, \ + struct blksnap_snapshot_event) + +/** + * struct blksnap_event_low_free_space - Data for the + * &blksnap_event_code_low_free_space event. + * + * @requested_nr_sect: + * The required number of sectors. + */ +struct blksnap_event_low_free_space { + __u64 requested_nr_sect; +}; + +/** + * struct blksnap_event_corrupted - Data for the + * &blksnap_event_code_corrupted event. + * + * @dev_id_mj: + * Major part of original device ID. + * @dev_id_mn: + * Minor part of original device ID. + * @err_code: + * Error code. + */ +struct blksnap_event_corrupted { + __u32 dev_id_mj; + __u32 dev_id_mn; + __s32 err_code; +}; + +#endif /* _UAPI_LINUX_BLKSNAP_H */

[v5,04/11] blksnap: header file of the module interface

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