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libceph, rbd: new bio handling code (aka don't clone bios)

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The reason we clone bios is to be able to give each object request
(and consequently each ceph_osd_data/ceph_msg_data item) its own
pointer to a (list of) bio(s).  The messenger then initializes its
cursor with cloned bio's ->bi_iter, so it knows where to start reading
from/writing to.  That's all the cloned bios are used for: to determine
each object request's starting position in the provided data buffer.

Introduce ceph_bio_iter to do exactly that -- store position within bio
list (i.e. pointer to bio) + position within that bio (i.e. bvec_iter).

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Ilya Dryomov
2018-01-20 10:30:10 +01:00
parent a1fbb5e7bb
commit 5359a17d27
5 changed files with 139 additions and 112 deletions
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59
include/linux/ceph/messenger.h
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@@ -93,14 +93,60 @@ static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
}
}
#ifdef CONFIG_BLOCK
struct ceph_bio_iter {
struct bio *bio;
struct bvec_iter iter;
};
#define __ceph_bio_iter_advance_step(it, n, STEP) do { \
unsigned int __n = (n), __cur_n; \
\
while (__n) { \
BUG_ON(!(it)->iter.bi_size); \
__cur_n = min((it)->iter.bi_size, __n); \
(void)(STEP); \
bio_advance_iter((it)->bio, &(it)->iter, __cur_n); \
if (!(it)->iter.bi_size && (it)->bio->bi_next) { \
dout("__ceph_bio_iter_advance_step next bio\n"); \
(it)->bio = (it)->bio->bi_next; \
(it)->iter = (it)->bio->bi_iter; \
} \
__n -= __cur_n; \
} \
} while (0)
/*
* Advance @it by @n bytes.
*/
#define ceph_bio_iter_advance(it, n) \
__ceph_bio_iter_advance_step(it, n, 0)
/*
* Advance @it by @n bytes, executing BVEC_STEP for each bio_vec.
*/
#define ceph_bio_iter_advance_step(it, n, BVEC_STEP) \
__ceph_bio_iter_advance_step(it, n, ({ \
struct bio_vec bv; \
struct bvec_iter __cur_iter; \
\
__cur_iter = (it)->iter; \
__cur_iter.bi_size = __cur_n; \
__bio_for_each_segment(bv, (it)->bio, __cur_iter, __cur_iter) \
(void)(BVEC_STEP); \
}))
#endif /* CONFIG_BLOCK */
struct ceph_msg_data {
struct list_head links; /* ceph_msg->data */
enum ceph_msg_data_type type;
union {
#ifdef CONFIG_BLOCK
struct {
struct bio *bio;
size_t bio_length;
struct ceph_bio_iter bio_pos;
u32 bio_length;
};
#endif /* CONFIG_BLOCK */
struct {
@@ -122,10 +168,7 @@ struct ceph_msg_data_cursor {
bool need_crc; /* crc update needed */
union {
#ifdef CONFIG_BLOCK
struct { /* bio */
struct bio *bio; /* bio from list */
struct bvec_iter bvec_iter;
};
struct ceph_bio_iter bio_iter;
#endif /* CONFIG_BLOCK */
struct { /* pages */
unsigned int page_offset; /* offset in page */
@@ -290,8 +333,8 @@ extern void ceph_msg_data_add_pages(struct ceph_msg *msg, struct page **pages,
extern void ceph_msg_data_add_pagelist(struct ceph_msg *msg,
struct ceph_pagelist *pagelist);
#ifdef CONFIG_BLOCK
extern void ceph_msg_data_add_bio(struct ceph_msg *msg, struct bio *bio,
size_t length);
void ceph_msg_data_add_bio(struct ceph_msg *msg, struct ceph_bio_iter *bio_pos,
u32 length);
#endif /* CONFIG_BLOCK */
extern struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags,