path: root/fs/nilfs2/inode.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * NILFS inode operations.
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Ryusuke Konishi.
 *
 */

#include <linux/buffer_head.h>
#include <linux/gfp.h>
#include <linux/mpage.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/uio.h>
#include <linux/fiemap.h>
#include "nilfs.h"
#include "btnode.h"
#include "segment.h"
#include "page.h"
#include "mdt.h"
#include "cpfile.h"
#include "ifile.h"

/**
 * struct nilfs_iget_args - arguments used during comparison between inodes
 * @ino: inode number
 * @cno: checkpoint number
 * @root: pointer on NILFS root object (mounted checkpoint)
 * @for_gc: inode for GC flag
 */
struct nilfs_iget_args {
	u64 ino;
	__u64 cno;
	struct nilfs_root *root;
	int for_gc;
};

static int nilfs_iget_test(struct inode *inode, void *opaque);

void nilfs_inode_add_blocks(struct inode *inode, int n)
{
	struct nilfs_root *root = NILFS_I(inode)->i_root;

	inode_add_bytes(inode, i_blocksize(inode) * n);
	if (root)
		atomic64_add(n, &root->blocks_count);
}

void nilfs_inode_sub_blocks(struct inode *inode, int n)
{
	struct nilfs_root *root = NILFS_I(inode)->i_root;

	inode_sub_bytes(inode, i_blocksize(inode) * n);
	if (root)
		atomic64_sub(n, &root->blocks_count);
}

/**
 * nilfs_get_block() - get a file block on the filesystem (callback function)
 * @inode - inode struct of the target file
 * @blkoff - file block number
 * @bh_result - buffer head to be mapped on
 * @create - indicate whether allocating the block or not when it has not
 *      been allocated yet.
 *
 * This function does not issue actual read request of the specified data
 * block. It is done by VFS.
 */
int nilfs_get_block(struct inode *inode, sector_t blkoff,
		    struct buffer_head *bh_result, int create)
{
	struct nilfs_inode_info *ii = NILFS_I(inode);
	struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
	__u64 blknum = 0;
	int err = 0, ret;
	unsigned int maxblocks = bh_result->b_size >> inode->i_blkbits;

	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	ret = nilfs_bmap_lookup_contig(ii->i_bmap, blkoff, &blknum, maxblocks);
	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
	if (ret >= 0) {	/* found */
		map_bh(bh_result, inode->i_sb, blknum);
		if (ret > 0)
			bh_result->b_size = (ret << inode->i_blkbits);
		goto out;
	}
	/* data block was not found */
	if (ret == -ENOENT && create) {
		struct nilfs_transaction_info ti;

		bh_result->b_blocknr = 0;
		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
		if (unlikely(err))
			goto out;
		err = nilfs_bmap_insert(ii->i_bmap, blkoff,
					(unsigned long)bh_result);
		if (unlikely(err != 0)) {
			if (err == -EEXIST) {
				/*
				 * The get_block() function could be called
				 * from multiple callers for an inode.
				 * However, the page having this block must
				 * be locked in this case.
				 */
				nilfs_warn(inode->i_sb,
					   "%s (ino=%lu): a race condition while inserting a data block at offset=%llu",
					   __func__, inode->i_ino,
					   (unsigned long long)blkoff);
				err = 0;
			}
			nilfs_transaction_abort(inode->i_sb);
			goto out;
		}
		nilfs_mark_inode_dirty_sync(inode);
		nilfs_transaction_commit(inode->i_sb); /* never fails */
		/* Error handling should be detailed */
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
		map_bh(bh_result, inode->i_sb, 0);
		/* Disk block number must be changed to proper value */

	} else if (ret == -ENOENT) {
		/*
		 * not found is not error (e.g. hole); must return without
		 * the mapped state flag.
		 */
		;
	} else {
		err = ret;
	}

 out:
	return err;
}

/**
 * nilfs_readpage() - implement readpage() method of nilfs_aops {}
 * address_space_operations.
 * @file - file struct of the file to be read
 * @page - the page to be read
 */
static int nilfs_readpage(struct file *file, struct page *page)
{
	return mpage_readpage(page, nilfs_get_block);
}

static void nilfs_readahead(struct readahead_control *rac)
{
	mpage_readahead(rac, nilfs_get_block);
}

static int nilfs_writepages(struct address_space *mapping,
			    struct writeback_control *wbc)
{
	struct inode *inode = mapping->host;
	int err = 0;

	if (sb_rdonly(inode->i_sb)) {
		nilfs_clear_dirty_pages