fs/dlm/plock.c

File Facts

System

Linux kernel

Corpus path

fs/dlm/plock.c

Extension

.c

Size

14359 bytes

Lines

631

Domain

Core OS

Bucket

VFS And Filesystem Core

Inferred role

Core OS: operation-table or driver-model contract

Status

pattern implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

• Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.
• Defines an operation table; this is where Linux turns generic core objects into subsystem-specific behavior.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• 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/fs.h
• linux/filelock.h
• linux/miscdevice.h
• linux/poll.h
• linux/dlm.h
• linux/dlm_plock.h
• linux/slab.h
• trace/events/dlm.h
• dlm_internal.h
• lockspace.h

Detected Declarations

• struct plock_async_data
• struct plock_op
• function set_version
• function list_for_each_entry
• function check_version
• function dlm_release_plock_op
• function send_op
• function do_lock_cancel
• function dlm_posix_lock
• function dlm_plock_callback
• function dlm_posix_unlock
• function wait_event
• function dlm_posix_get
• function dev_read
• function dev_write
• function list_for_each_entry
• function dev_poll
• function dlm_plock_init
• function dlm_plock_exit
• export dlm_posix_lock
• export dlm_posix_unlock
• export dlm_posix_cancel
• export dlm_posix_get

Annotated Snippet

static const struct file_operations dev_fops = {
	.read    = dev_read,
	.write   = dev_write,
	.poll    = dev_poll,
	.owner   = THIS_MODULE,
	.llseek  = noop_llseek,
};

static struct miscdevice plock_dev_misc = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = DLM_PLOCK_MISC_NAME,
	.fops = &dev_fops
};

int dlm_plock_init(void)
{
	int rv;

	rv = misc_register(&plock_dev_misc);
	if (rv)
		log_print("dlm_plock_init: misc_register failed %d", rv);
	return rv;
}

void dlm_plock_exit(void)
{
	misc_deregister(&plock_dev_misc);
	WARN_ON(!list_empty(&send_list));
	WARN_ON(!list_empty(&recv_list));
}

Annotation

• Immediate include surface: `linux/fs.h`, `linux/filelock.h`, `linux/miscdevice.h`, `linux/poll.h`, `linux/dlm.h`, `linux/dlm_plock.h`, `linux/slab.h`, `trace/events/dlm.h`.
• Detected declarations: `struct plock_async_data`, `struct plock_op`, `function set_version`, `function list_for_each_entry`, `function check_version`, `function dlm_release_plock_op`, `function send_op`, `function do_lock_cancel`, `function dlm_posix_lock`, `function dlm_plock_callback`.
• Atlas domain: Core OS / VFS And Filesystem Core.
• Implementation status: pattern implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• 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.