函数逻辑报告

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:fs\iomap\direct-io.c Create Date:2022-07-29 11:07:44
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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函数名称：iomap_dio_bio_actor

函数原型：static loff_t iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, struct iomap_dio *dio, struct iomap *iomap)

返回类型：loff_t

参数：

类型参数名称
struct inode *inode
loff_tpos
loff_tlength
struct iomap_dio *dio
struct iomap *iomap
201  blkbits等于assumes size > 256
202  fs_block_size等于i_blocksize(inode)
203  align等于iov_iter_alignment(iter)
205  bool need_zeroout = false
206  bool use_fua = false
207  ret等于0
208  copied等于0
211  如果pos按位或length按位或align的值按位与1左移blkbits位的值减1则返回:负EINVAL
214  如果 type of mapping 恒等于locks allocated at @addr in unwritten state 则
215  flags或等于covers unwritten extent(s)
216  need_zeroout = true
219  如果 flags for mapping 按位与IOMAP_F_SHARED则flags或等于covers COW extent(s)
222  如果 flags for mapping 按位与Flags reported by the file system from iomap_begin:* IOMAP_F_NEW indicates that the blocks have been newly allocated and need* zeroing for areas that no data is copied to.* IOMAP_F_DIRTY indicates the inode has uncommitted metadata needed to access则
223  need_zeroout = true
224  否则如果 type of mapping 恒等于locks allocated at @addr 则
232  如果非 flags for mapping 按位与IOMAP_F_SHARED按位或IOMAP_F_DIRTY的值的值且flags按位与Private flags for iomap_dio, must not overlap with the public ones in* iomap.h:且blk_queue_fua(bdev_get_queue( block device for I/O ))则use_fua = true
243  orig_count等于iov_iter_count(iter)
244  Cap the iov_iter by given limit; note that the second argument is* *not* the new size - it's upper limit for such. Passing it a value* greater than the amount of data in iov_iter is fine - it'll just do* nothing in that case.
246  nr_pages等于iov_iter_npages(iter, BIO_MAX_PAGES)
247  如果nr_pages小于等于0则
248  ret等于nr_pages
249  转到:out
252  如果need_zeroout则
254  pad等于pos按位与fs_block_size减1
255  如果pad则iomap_dio_zero(dio, iomap, pos - pad, pad)
259  循环
261  如果error则
262  iov_iter_revert(iter, copied)
263  copied等于ret等于0
264  转到:out
267  bio等于bio_alloc(GFP_KERNEL, nr_pages)
268  bio_set_dev(bio, block device for I/O )
269  device address in 512 byte sectors 等于iomap_sector(iomap, pos)
270  bi_write_hint等于ki_hint
271  bi_ioprio等于 See linux/ioprio.h
272  bi_private等于dio
273  bi_end_io等于iomap_dio_bio_end_io
275  ret等于bio_iov_iter_get_pages(bio, iter)
276  如果此条件成立可能性小(为编译器优化)(ret)则
283  bio_put(bio)
284  转到:zero_tail
287  n等于 residual I/O count
288  如果flags按位与IOMAP_DIO_WRITE则
289  bottom bits req flags, * top bits REQ_OP. Use * accessors.等于REQ_OP_WRITE按位或REQ_SYNC按位或REQ_IDLE
290  如果use_fua则 bottom bits req flags, * top bits REQ_OP. Use * accessors.或等于REQ_FUA
292  否则flags与等于Private flags for iomap_dio, must not overlap with the public ones in* iomap.h:的反
294  task_io_account_write(n)
295  否则
296  bottom bits req flags, * top bits REQ_OP. Use * accessors.等于REQ_OP_READ
297  如果flags按位与IOMAP_DIO_DIRTY则bio_set_pages_dirty(bio)
301  size加等于n
302  pos加等于n
303  copied加等于n
305  nr_pages等于iov_iter_npages(iter, BIO_MAX_PAGES)
306  iomap_dio_submit_bio(dio, iomap, bio)
307  当nr_pages循环
315  zero_tail :
316  如果need_zeroout或flags按位与IOMAP_DIO_WRITE且pos大于等于NOTE: in a 32bit arch with a preemptable kernel and* an UP compile the i_size_read/write must be atomic* with respect to the local cpu (unlike with preempt disabled),* but they don't need to be atomic with respect to other cpus like in* true SMP (so they 则
319  pad等于pos按位与fs_block_size减1
320  如果pad则iomap_dio_zero(dio, iomap, pos, fs_block_size - pad)
323  out :
325  xpand a previously truncated iterator; count must be no more than how much* we had shrunk it.
326  如果copied则返回:copied
328  返回:ret
调用者
名称描述
iomap_dio_actor