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Commit 8d63e318 authored by Alex Elder's avatar Alex Elder
Browse files

libceph: isolate kmap() call in write_partial_msg_pages() 



In write_partial_msg_pages(), every case now does an identical call
to kmap(page).  Instead, just call it once inside the CRC-computing
block where it's needed.  Move the definition of kaddr inside that
block, and make it a (char *) to ensure portable pointer arithmetic.

We still don't kunmap() it until after the sendpage() call, in case
that also ends up needing to use the mapping.

Signed-off-by: default avatarAlex Elder <elder@dreamhost.com>
Reviewed-by: default avatarSage Weil <sage@newdream.net>
parent 9bd19663

net/ceph/messenger.c

+2 −11
Original line number Diff line number Diff line
@@ -835,7 +835,6 @@ static int write_partial_msg_pages(struct ceph_connection *con) 


	while (data_len > con->out_msg_pos.data_pos) {

		struct page *page = NULL;

		void *kaddr = NULL;

		int max_write = PAGE_SIZE;

		int bio_offset = 0;
@@ -856,18 +855,12 @@ static int write_partial_msg_pages(struct ceph_connection *con) 


			page = list_first_entry(&msg->trail->head,

						struct page, lru);

			if (do_datacrc)

				kaddr = kmap(page);

			max_write = PAGE_SIZE;

		} else if (msg->pages) {

			page = msg->pages[con->out_msg_pos.page];

			if (do_datacrc)

				kaddr = kmap(page);

		} else if (msg->pagelist) {

			page = list_first_entry(&msg->pagelist->head,

						struct page, lru);

			if (do_datacrc)

				kaddr = kmap(page);

#ifdef CONFIG_BLOCK

		} else if (msg->bio) {

			struct bio_vec *bv;
@@ -875,14 +868,10 @@ static int write_partial_msg_pages(struct ceph_connection *con) 
			bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);

			page = bv->bv_page;

			bio_offset = bv->bv_offset;

			if (do_datacrc)

				kaddr = kmap(page);

			max_write = bv->bv_len;

#endif

		} else {

			page = zero_page;

			if (do_datacrc)

				kaddr = kmap(page);

		}

		len = min_t(int, max_write - con->out_msg_pos.page_pos,

			    total_max_write);
@@ -891,7 +880,9 @@ static int write_partial_msg_pages(struct ceph_connection *con) 
			void *base;

			u32 crc;

			u32 tmpcrc = le32_to_cpu(con->out_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);