linux-2.6.33/dio の履歴(No.1)

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• 差分 を表示
• 現在との差分 を表示
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• linux-2.6.33/dio へ行く。
  • 1 (2010-09-30 (木) 10:46:49)

参照元†

• linux-2.6.33/__blockdev_direct_IO
• linux-2.6.33/dio_get_page()
• linux-2.6.33/direct_io_worker()
• linux-2.6.33/do_direct_IO()

説明†

• パス: linux-2.6.33/fs/direct-io.c

• FIXME: これは何？
  • 説明

参考†

実装†

/*
 * This code generally works in units of "dio_blocks".  A dio_block is
 * somewhere between the hard sector size and the filesystem block size.  it
 * is determined on a per-invocation basis.   When talking to the filesystem
 * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity
 * down by dio->blkfactor.  Similarly, fs-blocksize quantities are converted
 * to bio_block quantities by shifting left by blkfactor.
 *
 * If blkfactor is zero then the user's request was aligned to the filesystem's
 * blocksize.
 */

struct dio {
	/* BIO submission state */
	struct bio *bio;		/* bio under assembly */

• • linux-2.6.33/bio

	struct inode *inode;

• • linux-2.6.33/inode

	int rw;
	loff_t i_size;			/* i_size when submitted */
	int flags;			/* doesn't change */
	unsigned blkbits;		/* doesn't change */
	unsigned blkfactor;		/* When we're using an alignment which
					   is finer than the filesystem's soft
					   blocksize, this specifies how much
					   finer.  blkfactor=2 means 1/4-block
					   alignment.  Does not change */
	unsigned start_zero_done;	/* flag: sub-blocksize zeroing has
					   been performed at the start of a
					   write */
	int pages_in_io;		/* approximate total IO pages */
	size_t	size;			/* total request size (doesn't change)*/
	sector_t block_in_file;		/* Current offset into the underlying
					   file in dio_block units. */
	unsigned blocks_available;	/* At block_in_file.  changes */
	sector_t final_block_in_request;/* doesn't change */
	unsigned first_block_in_page;	/* doesn't change, Used only once */
	int boundary;			/* prev block is at a boundary */
	int reap_counter;		/* rate limit reaping */
	get_block_t *get_block;		/* block mapping function */

• • linux-2.6.33/get_block_t

	dio_iodone_t *end_io;		/* IO completion function */

• • linux-2.6.33/dio_inode_t

	sector_t final_block_in_bio;	/* current final block in bio + 1 */
	sector_t next_block_for_io;	/* next block to be put under IO,
					   in dio_blocks units */
	struct buffer_head map_bh;	/* last get_block() result */

• • linux-2.6.33/buffer_head

	/*
	 * Deferred addition of a page to the dio.  These variables are
	 * private to dio_send_cur_page(), submit_page_section() and
	 * dio_bio_add_page().
	 */
	struct page *cur_page;		/* The page */

• • linux-2.6.33/page

	unsigned cur_page_offset;	/* Offset into it, in bytes */
	unsigned cur_page_len;		/* Nr of bytes at cur_page_offset */
	sector_t cur_page_block;	/* Where it starts */

	/* BIO completion state */
	spinlock_t bio_lock;		/* protects BIO fields below */

• • linux-2.6.33/spinlock_t

	unsigned long refcount;		/* direct_io_worker() and bios */
	struct bio *bio_list;		/* singly linked via bi_private */

• • linux-2.6.33/bio

	struct task_struct *waiter;	/* waiting task (NULL if none) */

• • linux-2.6.33/task_struct

	/* AIO related stuff */
	struct kiocb *iocb;		/* kiocb */

• • linux-2.6.33/kiocb

	int is_async;			/* is IO async ? */
	int io_error;			/* IO error in completion path */
	ssize_t result;                 /* IO result */

	/*
	 * Page fetching state. These variables belong to dio_refill_pages().
	 */
	int curr_page;			/* changes */
	int total_pages;		/* doesn't change */
	unsigned long curr_user_address;/* changes */

	/*
	 * Page queue.  These variables belong to dio_refill_pages() and
	 * dio_get_page().
	 */
	unsigned head;			/* next page to process */
	unsigned tail;			/* last valid page + 1 */
	int page_errors;		/* errno from get_user_pages() */

	/*
	 * pages[] (and any fields placed after it) are not zeroed out at
	 * allocation time.  Don't add new fields after pages[] unless you
	 * wish that they not be zeroed.
	 */
	struct page *pages[DIO_PAGES];	/* page buffer */

• • linux-2.6.33/page

};

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