block_write

函数名称：lock_write_begin takes care of the basic task of block allocation and* bringing partial write blocks uptodate first.* The filesystem needs to handle block truncation upon failure.

函数原型：int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, get_block_t *get_block)

返回类型：int

参数：

类型	参数	名称
struct address_space *	mapping
loff_t	pos
unsigned	len
unsigned	flags
struct page **	pagep
get_block_t *	get_block

2109

index等于pos右移PAGE_SHIFT determines the page size 位

2113

page等于Find or create a page at the given pagecache position. Return the locked* page. This function is specifically for buffered writes.

2114

如果非page则返回:负ENOMEM

2117

status等于__block_write_begin(page, pos, len, get_block)

2118

如果此条件成立可能性小(为编译器优化)(status)则

2119

lock_page - unlock a locked page*@page: the page* Unlocks the page and wakes up sleepers in ___wait_on_page_locked().* Also wakes sleepers in wait_on_page_writeback() because the wakeup* mechanism between PageLocked pages and PageWriteback pages is shared.

2120

Perform a free_page(), also freeing any swap cache associated with* this page if it is the last user of the page.

2121

page = NULL

2124

pagep等于page

2125

返回:status

**调用者**
名称	描述
cont_write_begin	For moronic filesystems that do not allow holes in file.* We may have to extend the file.
blkdev_write_begin

源代码转换工具开放的插件接口	X
支持：c/c++/esqlc/java Oracle/Informix/Mysql 插件可实现：逻辑报告代码生成和批量转换代码

函数逻辑报告