drivers/md/dm-snap.c

File Facts

System

Linux kernel

Corpus path

drivers/md/dm-snap.c

Extension

.c

Size

69270 bytes

Lines

2858

Domain

Driver Families

Bucket

drivers/md

Inferred role

Driver Families: exported/initcall integration point

Status

integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

• Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.
• Exports symbols or registers init work; inspect boot/module ordering and who consumes the exported contract.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/blkdev.h
• linux/device-mapper.h
• linux/delay.h
• linux/fs.h
• linux/init.h
• linux/kdev_t.h
• linux/list.h
• linux/list_bl.h
• linux/mempool.h
• linux/module.h
• linux/slab.h
• linux/vmalloc.h
• linux/log2.h
• linux/dm-kcopyd.h
• dm.h
• dm-exception-store.h

Detected Declarations

• struct dm_hlist_head
• struct dm_exception_table
• struct dm_snapshot
• struct dm_snap_pending_exception
• struct dm_snap_tracked_chunk
• struct origin
• struct dm_origin
• struct dm_exception_table_lock
• function chunk_to_sector
• function bdev_equal
• function init_tracked_chunk
• function is_bio_tracked
• function track_chunk
• function stop_tracking_chunk
• function __chunk_is_tracked
• function hlist_for_each_entry
• function fsleep
• function init_origin_hash
• function exit_origin_hash
• function origin_hash
• function __insert_origin
• function __insert_dm_origin
• function __remove_dm_origin
• function __find_snapshots_sharing_cow
• function list_for_each_entry
• function __validate_exception_handover
• function __insert_snapshot
• function register_snapshot
• function reregister_snapshot
• function unregister_snapshot
• function dm_exception_table_lock_init
• function dm_exception_table_lock
• function dm_exception_table_unlock
• function dm_exception_table_init
• function dm_exception_table_exit
• function hlist_for_each_entry_safe
• function exception_hash
• function dm_remove_exception
• function free_completed_exception
• function free_pending_exception
• function dm_insert_exception
• function dm_add_exception
• function __minimum_chunk_size
• function calc_max_buckets
• function init_hash_tables
• function merge_shutdown
• function __remove_single_exception_chunk
• function dm_consecutive_chunk_count

Annotated Snippet

module_init(dm_snapshot_init);
module_exit(dm_snapshot_exit);

MODULE_DESCRIPTION(DM_NAME " snapshot target");
MODULE_AUTHOR("Joe Thornber");
MODULE_LICENSE("GPL");
MODULE_ALIAS("dm-snapshot-origin");
MODULE_ALIAS("dm-snapshot-merge");

Annotation

• Immediate include surface: `linux/blkdev.h`, `linux/device-mapper.h`, `linux/delay.h`, `linux/fs.h`, `linux/init.h`, `linux/kdev_t.h`, `linux/list.h`, `linux/list_bl.h`.
• Detected declarations: `struct dm_hlist_head`, `struct dm_exception_table`, `struct dm_snapshot`, `struct dm_snap_pending_exception`, `struct dm_snap_tracked_chunk`, `struct origin`, `struct dm_origin`, `struct dm_exception_table_lock`, `function chunk_to_sector`, `function bdev_equal`.
• Atlas domain: Driver Families / drivers/md.
• Implementation status: integration implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.