C++ F2FS_I_SB函数代码示例

static int f2fs_write_data_page(struct page *page,
					struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	loff_t i_size = i_size_read(inode);
	const pgoff_t end_index = ((unsigned long long) i_size)
							>> PAGE_CACHE_SHIFT;
	unsigned offset = 0;
	bool need_balance_fs = false;
	int err = 0;
	struct f2fs_io_info fio = {
		.sbi = sbi,
		.type = DATA,
		.rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE,
		.page = page,
		.encrypted_page = NULL,
	};

	trace_f2fs_writepage(page, DATA);

	if (page->index < end_index)
		goto write;

	/*
	 * If the offset is out-of-range of file size,
	 * this page does not have to be written to disk.
	 */
	offset = i_size & (PAGE_CACHE_SIZE - 1);
	if ((page->index >= end_index + 1) || !offset)
		goto out;

	zero_user_segment(page, offset, PAGE_CACHE_SIZE);
write:
	if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
		goto redirty_out;
	if (f2fs_is_drop_cache(inode))
		goto out;
	if (f2fs_is_volatile_file(inode) && !wbc->for_reclaim &&
			available_free_memory(sbi, BASE_CHECK))
		goto redirty_out;

	/* Dentry blocks are controlled by checkpoint */
	if (S_ISDIR(inode->i_mode)) {
		if (unlikely(f2fs_cp_error(sbi)))
			goto redirty_out;
		err = do_write_data_page(&fio);
		goto done;
	}

	/* we should bypass data pages to proceed the kworkder jobs */
	if (unlikely(f2fs_cp_error(sbi))) {
		SetPageError(page);
		goto out;
	}

	if (!wbc->for_reclaim)
		need_balance_fs = true;
	else if (has_not_enough_free_secs(sbi, 0))
		goto redirty_out;

	err = -EAGAIN;
	f2fs_lock_op(sbi);
	if (f2fs_has_inline_data(inode))
		err = f2fs_write_inline_data(inode, page);
	if (err == -EAGAIN)
		err = do_write_data_page(&fio);
	f2fs_unlock_op(sbi);
done:
	if (err && err != -ENOENT)
		goto redirty_out;

	clear_cold_data(page);
out:
	inode_dec_dirty_pages(inode);
	if (err)
		ClearPageUptodate(page);
	unlock_page(page);
	if (need_balance_fs)
		f2fs_balance_fs(sbi);
	if (wbc->for_reclaim)
		f2fs_submit_merged_bio(sbi, DATA, WRITE);
	return 0;

redirty_out:
	redirty_page_for_writepage(wbc, page);
	return AOP_WRITEPAGE_ACTIVATE;
}

static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
			void *data)
{
	struct address_space *mapping = data;
	int ret = mapping->a_ops->writepage(page, wbc);
	mapping_set_error(mapping, ret);
	return ret;
}

/*
 * This function was copied from write_cche_pages from mm/page-writeback.c.
//.........这里部分代码省略.........

static int recover_dentry(struct inode *inode, struct page *ipage)
{
	struct f2fs_inode *raw_inode = F2FS_INODE(ipage);
	nid_t pino = le32_to_cpu(raw_inode->i_pino);
	struct f2fs_dir_entry *de;
	struct qstr name;
	struct page *page;
	struct inode *dir, *einode;
	int err = 0;

	dir = f2fs_iget(inode->i_sb, pino);
	if (IS_ERR(dir)) {
		err = PTR_ERR(dir);
		goto out;
	}

	if (file_enc_name(inode)) {
		iput(dir);
		return 0;
	}

	name.len = le32_to_cpu(raw_inode->i_namelen);
	name.name = raw_inode->i_name;

	if (unlikely(name.len > F2FS_NAME_LEN)) {
		WARN_ON(1);
		err = -ENAMETOOLONG;
		goto out_err;
	}
retry:
	de = f2fs_find_entry(dir, &name, &page);
	if (de && inode->i_ino == le32_to_cpu(de->ino))
		goto out_unmap_put;

	if (de) {
		einode = f2fs_iget(inode->i_sb, le32_to_cpu(de->ino));
		if (IS_ERR(einode)) {
			WARN_ON(1);
			err = PTR_ERR(einode);
			if (err == -ENOENT)
				err = -EEXIST;
			goto out_unmap_put;
		}
		err = acquire_orphan_inode(F2FS_I_SB(inode));
		if (err) {
			iput(einode);
			goto out_unmap_put;
		}
		f2fs_delete_entry(de, page, dir, einode);
		iput(einode);
		goto retry;
	}
	err = __f2fs_add_link(dir, &name, inode, inode->i_ino, inode->i_mode);
	if (err)
		goto out_err;

	if (is_inode_flag_set(F2FS_I(dir), FI_DELAY_IPUT)) {
		iput(dir);
	} else {
		add_dirty_dir_inode(dir);
		set_inode_flag(F2FS_I(dir), FI_DELAY_IPUT);
	}

	goto out;

out_unmap_put:
	f2fs_dentry_kunmap(dir, page);
	f2fs_put_page(page, 0);
out_err:
	iput(dir);
out:
	f2fs_msg(inode->i_sb, KERN_NOTICE,
			"%s: ino = %x, name = %s, dir = %lx, err = %d",
			__func__, ino_of_node(ipage), raw_inode->i_name,
			IS_ERR(dir) ? 0 : dir->i_ino, err);
	return err;
}

static int do_read_inode(struct inode *inode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct page *node_page;
	struct f2fs_inode *ri;

	/* Check if ino is within scope */
	if (check_nid_range(sbi, inode->i_ino)) {
		f2fs_msg(inode->i_sb, KERN_ERR, "bad inode number: %lu",
			 (unsigned long) inode->i_ino);
		WARN_ON(1);
		return -EINVAL;
	}

	node_page = get_node_page(sbi, inode->i_ino);
	if (IS_ERR(node_page))
		return PTR_ERR(node_page);

	ri = F2FS_INODE(node_page);

	inode->i_mode = le16_to_cpu(ri->i_mode);
	inode->i_uid = le32_to_cpu(ri->i_uid);
	inode->i_gid = le32_to_cpu(ri->i_gid);
	set_nlink(inode, le32_to_cpu(ri->i_links));
	inode->i_size = le64_to_cpu(ri->i_size);
	inode->i_blocks = le64_to_cpu(ri->i_blocks);

	inode->i_atime.tv_sec = le64_to_cpu(ri->i_atime);
	inode->i_ctime.tv_sec = le64_to_cpu(ri->i_ctime);
	inode->i_mtime.tv_sec = le64_to_cpu(ri->i_mtime);
	inode->i_atime.tv_nsec = le32_to_cpu(ri->i_atime_nsec);
	inode->i_ctime.tv_nsec = le32_to_cpu(ri->i_ctime_nsec);
	inode->i_mtime.tv_nsec = le32_to_cpu(ri->i_mtime_nsec);
	inode->i_generation = le32_to_cpu(ri->i_generation);

	fi->i_current_depth = le32_to_cpu(ri->i_current_depth);
	fi->i_xattr_nid = le32_to_cpu(ri->i_xattr_nid);
	fi->i_flags = le32_to_cpu(ri->i_flags);
	fi->flags = 0;
	fi->i_advise = ri->i_advise;
	fi->i_pino = le32_to_cpu(ri->i_pino);
	fi->i_dir_level = ri->i_dir_level;

	f2fs_init_extent_tree(inode, &ri->i_ext);

	get_inline_info(fi, ri);

	/* check data exist */
	if (f2fs_has_inline_data(inode) && !f2fs_exist_data(inode))
		__recover_inline_status(inode, node_page);

	/* get rdev by using inline_info */
	__get_inode_rdev(inode, ri);

	if (__written_first_block(ri))
		set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);

	f2fs_put_page(node_page, 1);

	stat_inc_inline_xattr(inode);
	stat_inc_inline_inode(inode);
	stat_inc_inline_dir(inode);

	return 0;
}

static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
				void *txattr_addr, struct page *ipage)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	size_t inline_size = 0;
	void *xattr_addr;
	struct page *xpage;
	nid_t new_nid = 0;
	int err;

	inline_size = inline_xattr_size(inode);

	if (hsize > inline_size && !F2FS_I(inode)->i_xattr_nid)
		if (!alloc_nid(sbi, &new_nid))
			return -ENOSPC;

	/* write to inline xattr */
	if (inline_size) {
		struct page *page = NULL;
		void *inline_addr;

		if (ipage) {
			inline_addr = inline_xattr_addr(ipage);
			f2fs_wait_on_page_writeback(ipage, NODE);
		} else {
			page = get_node_page(sbi, inode->i_ino);
			if (IS_ERR(page)) {
				alloc_nid_failed(sbi, new_nid);
				return PTR_ERR(page);
			}
			inline_addr = inline_xattr_addr(page);
			f2fs_wait_on_page_writeback(page, NODE);
		}
		memcpy(inline_addr, txattr_addr, inline_size);
		f2fs_put_page(page, 1);

		/* no need to use xattr node block */
		if (hsize <= inline_size) {
			err = truncate_xattr_node(inode, ipage);
			alloc_nid_failed(sbi, new_nid);
			return err;
		}
	}

	/* write to xattr node block */
	if (F2FS_I(inode)->i_xattr_nid) {
		xpage = get_node_page(sbi, F2FS_I(inode)->i_xattr_nid);
		if (IS_ERR(xpage)) {
			alloc_nid_failed(sbi, new_nid);
			return PTR_ERR(xpage);
		}
		f2fs_bug_on(sbi, new_nid);
		f2fs_wait_on_page_writeback(xpage, NODE);
	} else {
		struct dnode_of_data dn;
		set_new_dnode(&dn, inode, NULL, NULL, new_nid);
		xpage = new_node_page(&dn, XATTR_NODE_OFFSET, ipage);
		if (IS_ERR(xpage)) {
			alloc_nid_failed(sbi, new_nid);
			return PTR_ERR(xpage);
		}
		alloc_nid_done(sbi, new_nid);
	}

	xattr_addr = page_address(xpage);
	memcpy(xattr_addr, txattr_addr + inline_size, PAGE_SIZE -
						sizeof(struct node_footer));
	set_page_dirty(xpage);
	f2fs_put_page(xpage, 1);

	/* need to checkpoint during fsync */
	F2FS_I(inode)->xattr_ver = cur_cp_version(F2FS_CKPT(sbi));
	return 0;
}

int f2fs_convert_inline_page(struct dnode_of_data *dn, struct page *page)
{
	void *src_addr, *dst_addr;
	struct f2fs_io_info fio = {
		.type = DATA,
		.rw = WRITE_SYNC | REQ_PRIO,
	};
	int dirty, err;

	f2fs_bug_on(F2FS_I_SB(dn->inode), page->index);

	if (!f2fs_exist_data(dn->inode))
		goto clear_out;

	err = f2fs_reserve_block(dn, 0);
	if (err)
		return err;

	f2fs_wait_on_page_writeback(page, DATA);

	if (PageUptodate(page))
		goto no_update;

	zero_user_segment(page, MAX_INLINE_DATA, PAGE_CACHE_SIZE);

	/* Copy the whole inline data block */
	src_addr = inline_data_addr(dn->inode_page);
	dst_addr = kmap_atomic(page);
	memcpy(dst_addr, src_addr, MAX_INLINE_DATA);
	flush_dcache_page(page);
	kunmap_atomic(dst_addr);
	SetPageUptodate(page);
no_update:
	/* clear dirty state */
	dirty = clear_page_dirty_for_io(page);

	/* write data page to try to make data consistent */
	set_page_writeback(page);
	fio.blk_addr = dn->data_blkaddr;
	write_data_page(page, dn, &fio);
	update_extent_cache(dn);
	f2fs_wait_on_page_writeback(page, DATA);
	if (dirty)
		inode_dec_dirty_pages(dn->inode);

	/* this converted inline_data should be recovered. */
	set_inode_flag(F2FS_I(dn->inode), FI_APPEND_WRITE);

	/* clear inline data and flag after data writeback */
	truncate_inline_data(dn->inode_page);
clear_out:
	stat_dec_inline_inode(dn->inode);
	f2fs_clear_inline_inode(dn->inode);
	sync_inode_page(dn);
	f2fs_put_dnode(dn);
	return 0;
}

int f2fs_convert_inline_inode(struct inode *inode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct dnode_of_data dn;
	struct page *ipage, *page;
	int err = 0;

	page = grab_cache_page(inode->i_mapping, 0);
	if (!page)
		return -ENOMEM;

	f2fs_lock_op(sbi);

	ipage = get_node_page(sbi, inode->i_ino);
	if (IS_ERR(ipage)) {
		err = PTR_ERR(ipage);
		goto out;
	}

	set_new_dnode(&dn, inode, ipage, ipage, 0);

	if (f2fs_has_inline_data(inode))
		err = f2fs_convert_inline_page(&dn, page);

	f2fs_put_dnode(&dn);
out:
	f2fs_unlock_op(sbi);

	f2fs_put_page(page, 1);
	return err;
}

int f2fs_write_inline_data(struct inode *inode, struct page *page)
{
	void *src_addr, *dst_addr;
	struct dnode_of_data dn;
	int err;

	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, 0, LOOKUP_NODE);
	if (err)
		return err;
//.........这里部分代码省略.........

//.........这里部分代码省略.........

	if (size > MAX_VALUE_LEN(inode))
		return -E2BIG;

	error = read_all_xattrs(inode, ipage, &base_addr);
	if (error)
		return error;

	/* find entry with wanted name. */
	here = __find_xattr(base_addr, index, len, name);

	found = IS_XATTR_LAST_ENTRY(here) ? 0 : 1;

	if (found) {
		if ((flags & XATTR_CREATE)) {
			error = -EEXIST;
			goto exit;
		}

		if (f2fs_xattr_value_same(here, value, size))
			goto exit;
	} else if ((flags & XATTR_REPLACE)) {
		error = -ENODATA;
		goto exit;
	}

	last = here;
	while (!IS_XATTR_LAST_ENTRY(last))
		last = XATTR_NEXT_ENTRY(last);

	newsize = XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) + len + size);

	/* 1. Check space */
	if (value) {
		int free;
		/*
		 * If value is NULL, it is remove operation.
		 * In case of update operation, we calculate free.
		 */
		free = MIN_OFFSET(inode) - ((char *)last - (char *)base_addr);
		if (found)
			free = free + ENTRY_SIZE(here);

		if (unlikely(free < newsize)) {
			error = -E2BIG;
			goto exit;
		}
	}

	/* 2. Remove old entry */
	if (found) {
		/*
		 * If entry is found, remove old entry.
		 * If not found, remove operation is not needed.
		 */
		struct f2fs_xattr_entry *next = XATTR_NEXT_ENTRY(here);
		int oldsize = ENTRY_SIZE(here);

		memmove(here, next, (char *)last - (char *)next);
		last = (struct f2fs_xattr_entry *)((char *)last - oldsize);
		memset(last, 0, oldsize);
	}

	new_hsize = (char *)last - (char *)base_addr;

	/* 3. Write new entry */
	if (value) {
		char *pval;
		/*
		 * Before we come here, old entry is removed.
		 * We just write new entry.
		 */
		last->e_name_index = index;
		last->e_name_len = len;
		memcpy(last->e_name, name, len);
		pval = last->e_name + len;
		memcpy(pval, value, size);
		last->e_value_size = cpu_to_le16(size);
		new_hsize += newsize;
	}

	error = write_all_xattrs(inode, new_hsize, base_addr, ipage);
	if (error)
		goto exit;

	if (is_inode_flag_set(inode, FI_ACL_MODE)) {
		inode->i_mode = F2FS_I(inode)->i_acl_mode;
		inode->i_ctime = current_time(inode);
		clear_inode_flag(inode, FI_ACL_MODE);
	}
	if (index == F2FS_XATTR_INDEX_ENCRYPTION &&
			!strcmp(name, F2FS_XATTR_NAME_ENCRYPTION_CONTEXT))
		f2fs_set_encrypted_inode(inode);
	f2fs_mark_inode_dirty_sync(inode, true);
	if (!error && S_ISDIR(inode->i_mode))
		set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_CP);
exit:
	kzfree(base_addr);
	return error;
}

static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	nid_t ino;
	struct inode *inode;
	bool nid_free = false;
	int err;

	inode = new_inode(dir->i_sb);
	if (!inode)
		return ERR_PTR(-ENOMEM);

	f2fs_lock_op(sbi);
	if (!alloc_nid(sbi, &ino)) {
		f2fs_unlock_op(sbi);
		err = -ENOSPC;
		goto fail;
	}
	f2fs_unlock_op(sbi);

	inode_init_owner(inode, dir, mode);

	inode->i_ino = ino;
	inode->i_blocks = 0;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_generation = sbi->s_next_generation++;

	err = insert_inode_locked(inode);
	if (err) {
		err = -EINVAL;
		nid_free = true;
		goto out;
	}

	/* If the directory encrypted, then we should encrypt the inode. */
	if (f2fs_encrypted_inode(dir) && f2fs_may_encrypt(inode))
		f2fs_set_encrypted_inode(inode);

	if (f2fs_may_inline_data(inode))
		set_inode_flag(F2FS_I(inode), FI_INLINE_DATA);
	if (f2fs_may_inline_dentry(inode))
		set_inode_flag(F2FS_I(inode), FI_INLINE_DENTRY);

	f2fs_init_extent_tree(inode, NULL);

	stat_inc_inline_xattr(inode);
	stat_inc_inline_inode(inode);
	stat_inc_inline_dir(inode);

	trace_f2fs_new_inode(inode, 0);
	mark_inode_dirty(inode);
	return inode;

out:
	clear_nlink(inode);
	unlock_new_inode(inode);
fail:
	trace_f2fs_new_inode(inode, err);
	make_bad_inode(inode);
	if (nid_free)
		set_inode_flag(F2FS_I(inode), FI_FREE_NID);
	iput(inode);
	return ERR_PTR(err);
}

static int recover_dentry(struct inode *inode, struct page *ipage,
						struct list_head *dir_list)
{
	struct f2fs_inode *raw_inode = F2FS_INODE(ipage);
	nid_t pino = le32_to_cpu(raw_inode->i_pino);
	struct f2fs_dir_entry *de;
	struct fscrypt_name fname;
	struct page *page;
	struct inode *dir, *einode;
	struct fsync_inode_entry *entry;
	int err = 0;
	char *name;

	entry = get_fsync_inode(dir_list, pino);
	if (!entry) {
		entry = add_fsync_inode(F2FS_I_SB(inode), dir_list,
							pino, false);
		if (IS_ERR(entry)) {
			dir = ERR_CAST(entry);
			err = PTR_ERR(entry);
			goto out;
		}
	}

	dir = entry->inode;

	memset(&fname, 0, sizeof(struct fscrypt_name));
	fname.disk_name.len = le32_to_cpu(raw_inode->i_namelen);
	fname.disk_name.name = raw_inode->i_name;

	if (unlikely(fname.disk_name.len > F2FS_NAME_LEN)) {
		WARN_ON(1);
		err = -ENAMETOOLONG;
		goto out;
	}
retry:
	de = __f2fs_find_entry(dir, &fname, &page);
	if (de && inode->i_ino == le32_to_cpu(de->ino))
		goto out_put;

	if (de) {
		einode = f2fs_iget_retry(inode->i_sb, le32_to_cpu(de->ino));
		if (IS_ERR(einode)) {
			WARN_ON(1);
			err = PTR_ERR(einode);
			if (err == -ENOENT)
				err = -EEXIST;
			goto out_put;
		}

		err = dquot_initialize(einode);
		if (err) {
			iput(einode);
			goto out_put;
		}

		err = f2fs_acquire_orphan_inode(F2FS_I_SB(inode));
		if (err) {
			iput(einode);
			goto out_put;
		}
		f2fs_delete_entry(de, page, dir, einode);
		iput(einode);
		goto retry;
	} else if (IS_ERR(page)) {
		err = PTR_ERR(page);
	} else {
		err = f2fs_add_dentry(dir, &fname, inode,
					inode->i_ino, inode->i_mode);
	}
	if (err == -ENOMEM)
		goto retry;
	goto out;

out_put:
	f2fs_put_page(page, 0);
out:
	if (file_enc_name(inode))
		name = "<encrypted>";
	else
		name = raw_inode->i_name;
	f2fs_msg(inode->i_sb, KERN_NOTICE,
			"%s: ino = %x, name = %s, dir = %lx, err = %d",
			__func__, ino_of_node(ipage), name,
			IS_ERR(dir) ? 0 : dir->i_ino, err);
	return err;
}

//.........这里部分代码省略.........
			goto got_it;

		/*
		 * Then do more f2fs_map_blocks() calls until we are
		 * done with this page.
		 */
		map.m_flags = 0;

		if (block_in_file < last_block) {
			map.m_lblk = block_in_file;
			map.m_len = last_block - block_in_file;

			if (f2fs_map_blocks(inode, &map, 0, false))
				goto set_error_page;
		}
got_it:
		if ((map.m_flags & F2FS_MAP_MAPPED)) {
			block_nr = map.m_pblk + block_in_file - map.m_lblk;
			SetPageMappedToDisk(page);

			if (!PageUptodate(page) && !cleancache_get_page(page)) {
				SetPageUptodate(page);
				goto confused;
			}
		} else {
			zero_user_segment(page, 0, PAGE_CACHE_SIZE);
			SetPageUptodate(page);
			unlock_page(page);
			goto next_page;
		}

		/*
		 * This page will go to BIO.  Do we need to send this
		 * BIO off first?
		 */
		if (bio && (last_block_in_bio != block_nr - 1)) {
submit_and_realloc:
			submit_bio(READ, bio);
			bio = NULL;
		}
		if (bio == NULL) {
			struct f2fs_crypto_ctx *ctx = NULL;

			if (f2fs_encrypted_inode(inode) &&
					S_ISREG(inode->i_mode)) {
				struct page *cpage;

				ctx = f2fs_get_crypto_ctx(inode);
				if (IS_ERR(ctx))
					goto set_error_page;

				/* wait the page to be moved by cleaning */
				cpage = find_lock_page(
						META_MAPPING(F2FS_I_SB(inode)),
						block_nr);
				if (cpage) {
					f2fs_wait_on_page_writeback(cpage,
									DATA);
					f2fs_put_page(cpage, 1);
				}
			}

			bio = bio_alloc(GFP_KERNEL,
				min_t(int, nr_pages, bio_get_nr_vecs(bdev)));
			if (!bio) {
				if (ctx)
					f2fs_release_crypto_ctx(ctx);
				goto set_error_page;
			}
			bio->bi_bdev = bdev;
			bio->bi_sector = SECTOR_FROM_BLOCK(block_nr);
			bio->bi_end_io = f2fs_read_end_io;
			bio->bi_private = ctx;
		}

		if (bio_add_page(bio, page, blocksize, 0) < blocksize)
			goto submit_and_realloc;

		last_block_in_bio = block_nr;
		goto next_page;
set_error_page:
		SetPageError(page);
		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
		unlock_page(page);
		goto next_page;
confused:
		if (bio) {
			submit_bio(READ, bio);
			bio = NULL;
		}
		unlock_page(page);
next_page:
		if (pages)
			page_cache_release(page);
	}
	BUG_ON(pages && !list_empty(pages));
	if (bio)
		submit_bio(READ, bio);
	return 0;
}

/*
 * f2fs_map_blocks() now supported readahead/bmap/rw direct_IO with
 * f2fs_map_blocks structure.
 * If original data blocks are allocated, then give them to blockdev.
 * Otherwise,
 *     a. preallocate requested block addresses
 *     b. do not use extent cache for better performance
 *     c. give the block addresses to blockdev
 */
static int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
						int create, int flag)
{
	unsigned int maxblocks = map->m_len;
	struct dnode_of_data dn;
	int mode = create ? ALLOC_NODE : LOOKUP_NODE_RA;
	pgoff_t pgofs, end_offset;
	int err = 0, ofs = 1;
	struct extent_info ei;
	bool allocated = false;

	map->m_len = 0;
	map->m_flags = 0;

	/* it only supports block size == page size */
	pgofs =	(pgoff_t)map->m_lblk;

	if (f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
		map->m_pblk = ei.blk + pgofs - ei.fofs;
		map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
		map->m_flags = F2FS_MAP_MAPPED;
		goto out;
	}

	if (create)
		f2fs_lock_op(F2FS_I_SB(inode));

	/* When reading holes, we need its node page */
	set_new_dnode(&dn, inode, NULL, NULL, 0);
	err = get_dnode_of_data(&dn, pgofs, mode);
	if (err) {
		if (err == -ENOENT)
			err = 0;
		goto unlock_out;
	}
	if (dn.data_blkaddr == NEW_ADDR) {
		if (flag == F2FS_GET_BLOCK_BMAP) {
			err = -ENOENT;
			goto put_out;
		} else if (flag == F2FS_GET_BLOCK_READ ||
				flag == F2FS_GET_BLOCK_DIO) {
			goto put_out;
		}
		/*
		 * if it is in fiemap call path (flag = F2FS_GET_BLOCK_FIEMAP),
		 * mark it as mapped and unwritten block.
		 */
	}

	if (dn.data_blkaddr != NULL_ADDR) {
		map->m_flags = F2FS_MAP_MAPPED;
		map->m_pblk = dn.data_blkaddr;
		if (dn.data_blkaddr == NEW_ADDR)
			map->m_flags |= F2FS_MAP_UNWRITTEN;
	} else if (create) {
		err = __allocate_data_block(&dn);
		if (err)
			goto put_out;
		allocated = true;
		map->m_flags = F2FS_MAP_NEW | F2FS_MAP_MAPPED;
		map->m_pblk = dn.data_blkaddr;
	} else {
		if (flag == F2FS_GET_BLOCK_BMAP)
			err = -ENOENT;
		goto put_out;
	}

	end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
	map->m_len = 1;
	dn.ofs_in_node++;
	pgofs++;

get_next:
	if (dn.ofs_in_node >= end_offset) {
		if (allocated)
			sync_inode_page(&dn);
		allocated = false;
		f2fs_put_dnode(&dn);

		set_new_dnode(&dn, inode, NULL, NULL, 0);
		err = get_dnode_of_data(&dn, pgofs, mode);
		if (err) {
			if (err == -ENOENT)
				err = 0;
			goto unlock_out;
		}

		if (dn.data_blkaddr == NEW_ADDR &&
				flag != F2FS_GET_BLOCK_FIEMAP)
			goto put_out;

//.........这里部分代码省略.........

static int f2fs_write_begin(struct file *file, struct address_space *mapping,
		loff_t pos, unsigned len, unsigned flags,
		struct page **pagep, void **fsdata)
{
	struct inode *inode = mapping->host;
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	struct page *page = NULL;
	struct page *ipage;
	pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
	struct dnode_of_data dn;
	int err = 0;

	trace_f2fs_write_begin(inode, pos, len, flags);

	f2fs_balance_fs(sbi);

	/*
	 * We should check this at this moment to avoid deadlock on inode page
	 * and #0 page. The locking rule for inline_data conversion should be:
	 * lock_page(page #0) -> lock_page(inode_page)
	 */
	if (index != 0) {
		err = f2fs_convert_inline_inode(inode);
		if (err)
			goto fail;
	}
repeat:
	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page) {
		err = -ENOMEM;
		goto fail;
	}

	*pagep = page;

	f2fs_lock_op(sbi);

	/* check inline_data */
	ipage = get_node_page(sbi, inode->i_ino);
	if (IS_ERR(ipage)) {
		err = PTR_ERR(ipage);
		goto unlock_fail;
	}

	set_new_dnode(&dn, inode, ipage, ipage, 0);

	if (f2fs_has_inline_data(inode)) {
		if (pos + len <= MAX_INLINE_DATA) {
			read_inline_data(page, ipage);
			set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
			sync_inode_page(&dn);
			goto put_next;
		}
		err = f2fs_convert_inline_page(&dn, page);
		if (err)
			goto put_fail;
	}

	err = f2fs_get_block(&dn, index);
	if (err)
		goto put_fail;
put_next:
	f2fs_put_dnode(&dn);
	f2fs_unlock_op(sbi);

	f2fs_wait_on_page_writeback(page, DATA);

	if (len == PAGE_CACHE_SIZE)
		goto out_update;
	if (PageUptodate(page))
		goto out_clear;

	if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
		unsigned start = pos & (PAGE_CACHE_SIZE - 1);
		unsigned end = start + len;

		/* Reading beyond i_size is simple: memset to zero */
		zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
		goto out_update;
	}

	if (dn.data_blkaddr == NEW_ADDR) {
		zero_user_segment(page, 0, PAGE_CACHE_SIZE);
	} else {
		struct f2fs_io_info fio = {
			.sbi = sbi,
			.type = DATA,
			.rw = READ_SYNC,
			.blk_addr = dn.data_blkaddr,
			.page = page,
			.encrypted_page = NULL,
		};
		err = f2fs_submit_page_bio(&fio);
		if (err)
			goto fail;

		lock_page(page);
		if (unlikely(!PageUptodate(page))) {
			err = -EIO;
			goto fail;
//.........这里部分代码省略.........

int f2fs_add_inline_entry(struct inode *dir, const struct qstr *new_name,
				const struct qstr *orig_name,
				struct inode *inode, nid_t ino, umode_t mode)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	struct page *ipage;
	unsigned int bit_pos;
	f2fs_hash_t name_hash;
	struct f2fs_inline_dentry *inline_dentry = NULL;
	struct f2fs_dentry_ptr d;
	int slots = GET_DENTRY_SLOTS(new_name->len);
	struct page *page = NULL;
	int err = 0;

	ipage = get_node_page(sbi, dir->i_ino);
	if (IS_ERR(ipage))
		return PTR_ERR(ipage);

	inline_dentry = inline_data_addr(ipage);
	bit_pos = room_for_filename(&inline_dentry->dentry_bitmap,
						slots, NR_INLINE_DENTRY);
	if (bit_pos >= NR_INLINE_DENTRY) {
		err = f2fs_convert_inline_dir(dir, ipage, inline_dentry);
		if (err)
			return err;
		err = -EAGAIN;
		goto out;
	}

	if (inode) {
		down_write(&F2FS_I(inode)->i_sem);
		page = init_inode_metadata(inode, dir, new_name,
						orig_name, ipage);
		if (IS_ERR(page)) {
			err = PTR_ERR(page);
			goto fail;
		}
	}

	f2fs_wait_on_page_writeback(ipage, NODE, true);

	name_hash = f2fs_dentry_hash(new_name, NULL);
	make_dentry_ptr_inline(NULL, &d, inline_dentry);
	f2fs_update_dentry(ino, mode, &d, new_name, name_hash, bit_pos);

	set_page_dirty(ipage);

	/* we don't need to mark_inode_dirty now */
	if (inode) {
		f2fs_i_pino_write(inode, dir->i_ino);
		f2fs_put_page(page, 1);
	}

	update_parent_metadata(dir, inode, 0);
fail:
	if (inode)
		up_write(&F2FS_I(inode)->i_sem);
out:
	f2fs_put_page(ipage, 1);
	return err;
}

static inline int write_all_xattrs(struct inode *inode, __u32 hsize,
				void *txattr_addr, struct page *ipage)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
	size_t inline_size = inline_xattr_size(inode);
	struct page *in_page = NULL;
	void *xattr_addr;
	void *inline_addr = NULL;
	struct page *xpage;
	nid_t new_nid = 0;
	int err = 0;

	if (hsize > inline_size && !F2FS_I(inode)->i_xattr_nid)
		if (!alloc_nid(sbi, &new_nid))
			return -ENOSPC;

	/* write to inline xattr */
	if (inline_size) {
		if (ipage) {
			inline_addr = inline_xattr_addr(inode, ipage);
		} else {
			in_page = get_node_page(sbi, inode->i_ino);
			if (IS_ERR(in_page)) {
				alloc_nid_failed(sbi, new_nid);
				return PTR_ERR(in_page);
			}
			inline_addr = inline_xattr_addr(inode, in_page);
		}

		f2fs_wait_on_page_writeback(ipage ? ipage : in_page,
							NODE, true);
		/* no need to use xattr node block */
		if (hsize <= inline_size) {
			err = truncate_xattr_node(inode);
			alloc_nid_failed(sbi, new_nid);
			if (err) {
				f2fs_put_page(in_page, 1);
				return err;
			}
			memcpy(inline_addr, txattr_addr, inline_size);
			set_page_dirty(ipage ? ipage : in_page);
			goto in_page_out;
		}
	}

	/* write to xattr node block */
	if (F2FS_I(inode)->i_xattr_nid) {
		xpage = get_node_page(sbi, F2FS_I(inode)->i_xattr_nid);
		if (IS_ERR(xpage)) {
			alloc_nid_failed(sbi, new_nid);
			goto in_page_out;
		}
		f2fs_bug_on(sbi, new_nid);
		f2fs_wait_on_page_writeback(xpage, NODE, true);
	} else {
		struct dnode_of_data dn;
		set_new_dnode(&dn, inode, NULL, NULL, new_nid);
		xpage = new_node_page(&dn, XATTR_NODE_OFFSET);
		if (IS_ERR(xpage)) {
			alloc_nid_failed(sbi, new_nid);
			goto in_page_out;
		}
		alloc_nid_done(sbi, new_nid);
	}
	xattr_addr = page_address(xpage);

	if (inline_size)
		memcpy(inline_addr, txattr_addr, inline_size);
	memcpy(xattr_addr, txattr_addr + inline_size, VALID_XATTR_BLOCK_SIZE);

	if (inline_size)
		set_page_dirty(ipage ? ipage : in_page);
	set_page_dirty(xpage);

	f2fs_put_page(xpage, 1);
in_page_out:
	f2fs_put_page(in_page, 1);
	return err;
}

struct dentry *f2fs_get_parent(struct dentry *child)
{
	struct qstr dotdot = {.len = 2, .name = ".."};
	unsigned long ino = f2fs_inode_by_name(child->d_inode, &dotdot);
	if (!ino)
		return ERR_PTR(-ENOENT);
	return d_obtain_alias(f2fs_iget(child->d_inode->i_sb, ino));
}

static int __recover_dot_dentries(struct inode *dir, nid_t pino)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	struct qstr dot = {.len = 1, .name = "."};
	struct qstr dotdot = {.len = 2, .name = ".."};
	struct f2fs_dir_entry *de;
	struct page *page;
	int err = 0;

	f2fs_lock_op(sbi);

	de = f2fs_find_entry(dir, &dot, &page);
	if (de) {
		f2fs_dentry_kunmap(dir, page);
		f2fs_put_page(page, 0);
	} else {
		err = __f2fs_add_link(dir, &dot, NULL, dir->i_ino, S_IFDIR);
		if (err)
			goto out;
	}

	de = f2fs_find_entry(dir, &dotdot, &page);
	if (de) {
		f2fs_dentry_kunmap(dir, page);
		f2fs_put_page(page, 0);
	} else {
		err = __f2fs_add_link(dir, &dotdot, NULL, pino, S_IFDIR);
	}
out:
	if (!err) {
		clear_inode_flag(F2FS_I(dir), FI_INLINE_DOTS);
		mark_inode_dirty(dir);
	}

	f2fs_unlock_op(sbi);
	return err;
}

static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
					struct nameidata *nd)
{
	struct inode *inode = NULL;
	struct f2fs_dir_entry *de;
	struct page *page;
	nid_t ino;
	int err = 0;

	if (dentry->d_name.len > F2FS_NAME_LEN)
		return ERR_PTR(-ENAMETOOLONG);

	de = f2fs_find_entry(dir, &dentry->d_name, &page);
	if (!de)
		return d_splice_alias(inode, dentry);

	ino = le32_to_cpu(de->ino);
	f2fs_dentry_kunmap(dir, page);
	f2fs_put_page(page, 0);

	inode = f2fs_iget(dir->i_sb, ino);
	if (IS_ERR(inode))
		return ERR_CAST(inode);

	if (f2fs_has_inline_dots(inode)) {
		err = __recover_dot_dentries(inode, dir->i_ino);
		if (err)
			goto err_out;
	}
	return d_splice_alias(inode, dentry);

err_out:
	iget_failed(inode);
	return ERR_PTR(err);
}

static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	struct inode *inode = dentry->d_inode;
	struct f2fs_dir_entry *de;
	struct page *page;
	int err = -ENOENT;

	trace_f2fs_unlink_enter(dir, dentry);
	f2fs_balance_fs(sbi);

	de = f2fs_find_entry(dir, &dentry->d_name, &page);
	if (!de)
		goto fail;

	f2fs_lock_op(sbi);
	err = acquire_orphan_inode(sbi);
//.........这里部分代码省略.........

struct dentry *f2fs_get_parent(struct dentry *child)
{
	struct qstr dotdot = {.len = 2, .name = ".."};
	unsigned long ino = f2fs_inode_by_name(child->d_inode, &dotdot);
	if (!ino)
		return ERR_PTR(-ENOENT);
	return d_obtain_alias(f2fs_iget(child->d_inode->i_sb, ino));
}

static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
					struct nameidata *nd)
{
	struct inode *inode = NULL;
	struct f2fs_dir_entry *de;
	struct page *page;

	if (dentry->d_name.len > F2FS_NAME_LEN)
		return ERR_PTR(-ENAMETOOLONG);

	de = f2fs_find_entry(dir, &dentry->d_name, &page, nd ? nd->flags : 0);
	if (de) {
		nid_t ino = le32_to_cpu(de->ino);
		if (!f2fs_has_inline_dentry(dir))
			kunmap(page);
		f2fs_put_page(page, 0);

		inode = f2fs_iget(dir->i_sb, ino);
		if (IS_ERR(inode))
			return ERR_CAST(inode);
	}

	return d_splice_alias(inode, dentry);
}

static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	struct inode *inode = dentry->d_inode;
	struct f2fs_dir_entry *de;
	struct page *page;
	int err = -ENOENT;

	trace_f2fs_unlink_enter(dir, dentry);
	f2fs_balance_fs(sbi);

	de = f2fs_find_entry(dir, &dentry->d_name, &page, 0);
	if (!de)
		goto fail;

	f2fs_lock_op(sbi);
	err = acquire_orphan_inode(sbi);
	if (err) {
		f2fs_unlock_op(sbi);
		if (!f2fs_has_inline_dentry(dir))
			kunmap(page);
		f2fs_put_page(page, 0);
		goto fail;
	}
	f2fs_delete_entry(de, page, dir, inode);
	f2fs_unlock_op(sbi);

	/* In order to evict this inode, we set it dirty */
	mark_inode_dirty(inode);
fail:
	trace_f2fs_unlink_exit(inode, err);
	return err;
}

static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
					const char *symname)
{
	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
	struct inode *inode;
	size_t symlen = strlen(symname) + 1;
	int err;

	f2fs_balance_fs(sbi);

	inode = f2fs_new_inode(dir, S_IFLNK | S_IRWXUGO);
	if (IS_ERR(inode))
		return PTR_ERR(inode);

	inode->i_op = &f2fs_symlink_inode_operations;
	inode->i_mapping->a_ops = &f2fs_dblock_aops;

	f2fs_lock_op(sbi);
	err = f2fs_add_link(dentry, inode);
	if (err)
		goto out;
	f2fs_unlock_op(sbi);

	err = page_symlink(inode, symname, symlen);
	alloc_nid_done(sbi, inode->i_ino);

	d_instantiate(dentry, inode);
	unlock_new_inode(inode);
	return err;
out:
	handle_failed_inode(inode);
	return err;
//.........这里部分代码省略.........