fs/fuse/poll.c

Source file repositories/reference/linux-study-clean/fs/fuse/poll.c

File Facts

System
Linux kernel
Corpus path
fs/fuse/poll.c
Extension
.c
Size
3336 bytes
Lines
142
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

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

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only

#include "dev.h"
#include "fuse_i.h"

void fuse_end_polls(struct fuse_conn *fc)
{
	struct rb_node *p;

	spin_lock(&fc->lock);
	p = rb_first(&fc->polled_files);

	while (p) {
		struct fuse_file *ff;
		ff = rb_entry(p, struct fuse_file, polled_node);
		wake_up_interruptible_all(&ff->poll_wait);

		p = rb_next(p);
	}
	spin_unlock(&fc->lock);
}

/*
 * All files which have been polled are linked to RB tree
 * fuse_conn->polled_files which is indexed by kh.  Walk the tree and
 * find the matching one.
 */
static struct rb_node **fuse_find_polled_node(struct fuse_conn *fc, u64 kh,
					      struct rb_node **parent_out)
{
	struct rb_node **link = &fc->polled_files.rb_node;
	struct rb_node *last = NULL;

	while (*link) {
		struct fuse_file *ff;

		last = *link;
		ff = rb_entry(last, struct fuse_file, polled_node);

		if (kh < ff->kh)
			link = &last->rb_left;
		else if (kh > ff->kh)
			link = &last->rb_right;
		else
			return link;
	}

	if (parent_out)
		*parent_out = last;
	return link;
}

/*
 * The file is about to be polled.  Make sure it's on the polled_files
 * RB tree.  Note that files once added to the polled_files tree are
 * not removed before the file is released.  This is because a file
 * polled once is likely to be polled again.
 */
static void fuse_register_polled_file(struct fuse_conn *fc,
				      struct fuse_file *ff)
{
	spin_lock(&fc->lock);
	if (RB_EMPTY_NODE(&ff->polled_node)) {
		struct rb_node **link, *parent;

		link = fuse_find_polled_node(fc, ff->kh, &parent);
		BUG_ON(*link);
		rb_link_node(&ff->polled_node, parent, link);
		rb_insert_color(&ff->polled_node, &fc->polled_files);
	}
	spin_unlock(&fc->lock);
}

__poll_t fuse_file_poll(struct file *file, poll_table *wait)
{
	struct fuse_file *ff = file->private_data;
	struct fuse_mount *fm = ff->fm;
	struct fuse_poll_in inarg = { .fh = ff->fh, .kh = ff->kh };
	struct fuse_poll_out outarg;
	FUSE_ARGS(args);
	int err;

	if (fm->fc->no_poll)
		return DEFAULT_POLLMASK;

	poll_wait(file, &ff->poll_wait, wait);
	inarg.events = mangle_poll(poll_requested_events(wait));

	/*
	 * Ask for notification iff there's someone waiting for it.

Annotation

Implementation Notes