fs/nilfs2/gcinode.c

Source file repositories/reference/linux-study-clean/fs/nilfs2/gcinode.c

File Facts

System
Linux kernel
Corpus path
fs/nilfs2/gcinode.c
Extension
.c
Size
5316 bytes
Lines
185
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source 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+
/*
 * Dummy inodes to buffer blocks for garbage collection
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Seiji Kihara, Amagai Yoshiji, and Ryusuke Konishi.
 * Revised by Ryusuke Konishi.
 *
 */
/*
 * This file adds the cache of on-disk blocks to be moved in garbage
 * collection.  The disk blocks are held with dummy inodes (called
 * gcinodes), and this file provides lookup function of the dummy
 * inodes and their buffer read function.
 *
 * Buffers and pages held by the dummy inodes will be released each
 * time after they are copied to a new log.  Dirty blocks made on the
 * current generation and the blocks to be moved by GC never overlap
 * because the dirty blocks make a new generation; they rather must be
 * written individually.
 */

#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include "nilfs.h"
#include "btree.h"
#include "btnode.h"
#include "page.h"
#include "mdt.h"
#include "dat.h"
#include "ifile.h"

/*
 * nilfs_gccache_submit_read_data() - add data buffer and submit read request
 * @inode - gc inode
 * @blkoff - dummy offset treated as the key for the page cache
 * @pbn - physical block number of the block
 * @vbn - virtual block number of the block, 0 for non-virtual block
 * @out_bh - indirect pointer to a buffer_head struct to receive the results
 *
 * Description: nilfs_gccache_submit_read_data() registers the data buffer
 * specified by @pbn to the GC pagecache with the key @blkoff.
 * This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
 *
 * Return: 0 on success, or one of the following negative error codes on
 * failure:
 * * %-EIO	- I/O error (including metadata corruption).
 * * %-ENOENT	- The block specified with @pbn does not exist.
 * * %-ENOMEM	- Insufficient memory available.
 */
int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
				   sector_t pbn, __u64 vbn,
				   struct buffer_head **out_bh)
{
	struct buffer_head *bh;
	int err;

	bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
	if (unlikely(!bh))
		return -ENOMEM;

	if (buffer_uptodate(bh))
		goto out;

	if (pbn == 0) {
		struct the_nilfs *nilfs = inode->i_sb->s_fs_info;

		err = nilfs_dat_translate(nilfs->ns_dat, vbn, &pbn);
		if (unlikely(err)) /* -EIO, -ENOMEM, -ENOENT */
			goto failed;
	}

	lock_buffer(bh);
	if (buffer_uptodate(bh)) {
		unlock_buffer(bh);
		goto out;
	}

	if (!buffer_mapped(bh))
		set_buffer_mapped(bh);
	bh->b_blocknr = pbn;
	bh_submit(bh, REQ_OP_READ, bh_end_read);
	if (vbn)
		bh->b_blocknr = vbn;
 out:
	err = 0;

Annotation

Implementation Notes