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libceph: small changes to messenger.c

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This patch gathers a few small changes in "net/ceph/messenger.c":
  out_msg_pos_next()
    - small logic change that mostly affects indentation
  write_partial_msg_pages().
    - use a local variable trail_off to represent the offset into
      a message of the trail portion of the data (if present)
    - once we are in the trail portion we will always be there, so we
      don't always need to check against our data position
    - avoid computing len twice after we've reached the trail
    - get rid of the variable tmpcrc, which is not needed
    - trail_off and trail_len never change so mark them const
    - update some comments
  read_partial_message_bio()
    - bio_iovec_idx() will never return an error, so don't bother
      checking for it

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
This commit is contained in:
Alex Elder 2012-06-11 14:57:13 -05:00 committed by Sage Weil
parent 7593af920b
commit 5821bd8ccd
1 changed files with 31 additions and 32 deletions
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63
net/ceph/messenger.c
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@ -907,21 +907,23 @@ static void out_msg_pos_next(struct ceph_connection *con, struct page *page,
con->out_msg_pos.data_pos += sent;
con->out_msg_pos.page_pos += sent;
if (sent == len) {
con->out_msg_pos.page_pos = 0;
con->out_msg_pos.page++;
con->out_msg_pos.did_page_crc = false;
if (in_trail)
list_move_tail(&page->lru,
&msg->trail->head);
else if (msg->pagelist)
list_move_tail(&page->lru,
&msg->pagelist->head);
if (sent < len)
return;
BUG_ON(sent != len);
con->out_msg_pos.page_pos = 0;
con->out_msg_pos.page++;
con->out_msg_pos.did_page_crc = false;
if (in_trail)
list_move_tail(&page->lru,
&msg->trail->head);
else if (msg->pagelist)
list_move_tail(&page->lru,
&msg->pagelist->head);
#ifdef CONFIG_BLOCK
else if (msg->bio)
iter_bio_next(&msg->bio_iter, &msg->bio_seg);
else if (msg->bio)
iter_bio_next(&msg->bio_iter, &msg->bio_seg);
#endif
}
}
/*
@ -940,30 +942,31 @@ static int write_partial_msg_pages(struct ceph_connection *con)
int ret;
int total_max_write;
bool in_trail = false;
size_t trail_len = (msg->trail ? msg->trail->length : 0);
const size_t trail_len = (msg->trail ? msg->trail->length : 0);
const size_t trail_off = data_len - trail_len;
dout("write_partial_msg_pages %p msg %p page %d/%d offset %d\n",
con, msg, con->out_msg_pos.page, msg->nr_pages,
con->out_msg_pos.page_pos);
/*
* Iterate through each page that contains data to be
* written, and send as much as possible for each.
*
* If we are calculating the data crc (the default), we will
* need to map the page. If we have no pages, they have
* been revoked, so use the zero page.
*/
while (data_len > con->out_msg_pos.data_pos) {
struct page *page = NULL;
int max_write = PAGE_SIZE;
int bio_offset = 0;
total_max_write = data_len - trail_len -
con->out_msg_pos.data_pos;
/*
* if we are calculating the data crc (the default), we need
* to map the page. if our pages[] has been revoked, use the
* zero page.
*/
/* have we reached the trail part of the data? */
if (con->out_msg_pos.data_pos >= data_len - trail_len) {
in_trail = true;
in_trail = in_trail || con->out_msg_pos.data_pos >= trail_off;
if (!in_trail)
total_max_write = trail_off - con->out_msg_pos.data_pos;
if (in_trail) {
total_max_write = data_len - con->out_msg_pos.data_pos;
page = list_first_entry(&msg->trail->head,
@ -990,14 +993,13 @@ static int write_partial_msg_pages(struct ceph_connection *con)
if (do_datacrc && !con->out_msg_pos.did_page_crc) {
void *base;
u32 crc;
u32 tmpcrc = le32_to_cpu(msg->footer.data_crc);
u32 crc = le32_to_cpu(msg->footer.data_crc);
char *kaddr;
kaddr = kmap(page);
BUG_ON(kaddr == NULL);
base = kaddr + con->out_msg_pos.page_pos + bio_offset;
crc = crc32c(tmpcrc, base, len);
crc = crc32c(crc, base, len);
msg->footer.data_crc = cpu_to_le32(crc);
con->out_msg_pos.did_page_crc = true;
}
@ -1702,9 +1704,6 @@ static int read_partial_message_bio(struct ceph_connection *con,
void *p;
int ret, left;
if (IS_ERR(bv))
return PTR_ERR(bv);
left = min((int)(data_len - con->in_msg_pos.data_pos),
(int)(bv->bv_len - con->in_msg_pos.page_pos));