libceph: use "do" in CRC-related Boolean variables

Change the name (and type) of a few CRC-related Boolean local
variables so they contain the word "do", to distingish their purpose
from variables used for holding an actual CRC value.

Note that in the process of doing this I identified a fairly serious
logic error in write_partial_msg_pages():  the value of "do_crc"
assigned appears to be the opposite of what it should be.  No
attempt to fix this is made here; this change preserves the
erroneous behavior.  The problem I found is documented here:
    http://tracker.newdream.net/issues/2064

Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>

include/linux/ceph/messenger.h

@@ -98,7 +98,7 @@ struct ceph_msg {
 struct ceph_msg_pos {
 	int page, page_pos;  /* which page; offset in page */
 	int data_pos;        /* offset in data payload */
-	int did_page_crc;    /* true if we've calculated crc for current page */
+	bool did_page_crc;   /* true if we've calculated crc for current page */
 };
 
 /* ceph connection fault delay defaults, for exponential backoff */

net/ceph/messenger.c

@@ -595,7 +595,7 @@ static void prepare_write_message(struct ceph_connection *con)
 		else
 			con->out_msg_pos.page_pos = 0;
 		con->out_msg_pos.data_pos = 0;
-		con->out_msg_pos.did_page_crc = 0;
+		con->out_msg_pos.did_page_crc = false;
 		con->out_more = 1;  /* data + footer will follow */
 	} else {
 		/* no, queue up footer too and be done */
@@ -805,7 +805,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 	struct ceph_msg *msg = con->out_msg;
 	unsigned data_len = le32_to_cpu(msg->hdr.data_len);
 	size_t len;
-	int crc = con->msgr->nocrc;
+	bool do_crc = con->msgr->nocrc;
 	int ret;
 	int total_max_write;
 	int in_trail = 0;
@@ -843,17 +843,17 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 
 			page = list_first_entry(&msg->trail->head,
 						struct page, lru);
-			if (crc)
+			if (do_crc)
 				kaddr = kmap(page);
 			max_write = PAGE_SIZE;
 		} else if (msg->pages) {
 			page = msg->pages[con->out_msg_pos.page];
-			if (crc)
+			if (do_crc)
 				kaddr = kmap(page);
 		} else if (msg->pagelist) {
 			page = list_first_entry(&msg->pagelist->head,
 						struct page, lru);
-			if (crc)
+			if (do_crc)
 				kaddr = kmap(page);
 #ifdef CONFIG_BLOCK
 		} else if (msg->bio) {
@@ -862,26 +862,26 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 			bv = bio_iovec_idx(msg->bio_iter, msg->bio_seg);
 			page = bv->bv_page;
 			page_shift = bv->bv_offset;
-			if (crc)
+			if (do_crc)
 				kaddr = kmap(page) + page_shift;
 			max_write = bv->bv_len;
 #endif
 		} else {
 			page = zero_page;
-			if (crc)
+			if (do_crc)
 				kaddr = zero_page_address;
 		}
 		len = min_t(int, max_write - con->out_msg_pos.page_pos,
 			    total_max_write);
 
-		if (crc && !con->out_msg_pos.did_page_crc) {
+		if (do_crc && !con->out_msg_pos.did_page_crc) {
 			void *base = kaddr + con->out_msg_pos.page_pos;
 			u32 tmpcrc = le32_to_cpu(con->out_msg->footer.data_crc);
 
 			BUG_ON(kaddr == NULL);
 			con->out_msg->footer.data_crc =
 				cpu_to_le32(crc32c(tmpcrc, base, len));
-			con->out_msg_pos.did_page_crc = 1;
+			con->out_msg_pos.did_page_crc = true;
 		}
 		ret = kernel_sendpage(con->sock, page,
 				      con->out_msg_pos.page_pos + page_shift,
@@ -889,7 +889,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 				      MSG_DONTWAIT | MSG_NOSIGNAL |
 				      MSG_MORE);
 
-		if (crc &&
+		if (do_crc &&
 		    (msg->pages || msg->pagelist || msg->bio || in_trail))
 			kunmap(page);
 
@@ -903,7 +903,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 		if (ret == len) {
 			con->out_msg_pos.page_pos = 0;
 			con->out_msg_pos.page++;
-			con->out_msg_pos.did_page_crc = 0;
+			con->out_msg_pos.did_page_crc = false;
 			if (in_trail)
 				list_move_tail(&page->lru,
 					       &msg->trail->head);
@@ -920,7 +920,7 @@ static int write_partial_msg_pages(struct ceph_connection *con)
 	dout("write_partial_msg_pages %p msg %p done\n", con, msg);
 
 	/* prepare and queue up footer, too */
-	if (!crc)
+	if (!do_crc)
 		con->out_msg->footer.flags |= CEPH_MSG_FOOTER_NOCRC;
 	ceph_con_out_kvec_reset(con);
 	prepare_write_message_footer(con);
@@ -1557,7 +1557,7 @@ static struct ceph_msg *ceph_alloc_msg(struct ceph_connection *con,
 
 static int read_partial_message_pages(struct ceph_connection *con,
 				      struct page **pages,
-				      unsigned data_len, int datacrc)
+				      unsigned data_len, bool do_datacrc)
 {
 	void *p;
 	int ret;
@@ -1570,7 +1570,7 @@ static int read_partial_message_pages(struct ceph_connection *con,
 	p = kmap(pages[con->in_msg_pos.page]);
 	ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos,
 			       left);
-	if (ret > 0 && datacrc)
+	if (ret > 0 && do_datacrc)
 		con->in_data_crc =
 			crc32c(con->in_data_crc,
 				  p + con->in_msg_pos.page_pos, ret);
@@ -1590,7 +1590,7 @@ static int read_partial_message_pages(struct ceph_connection *con,
 #ifdef CONFIG_BLOCK
 static int read_partial_message_bio(struct ceph_connection *con,
 				    struct bio **bio_iter, int *bio_seg,
-				    unsigned data_len, int datacrc)
+				    unsigned data_len, bool do_datacrc)
 {
 	struct bio_vec *bv = bio_iovec_idx(*bio_iter, *bio_seg);
 	void *p;
@@ -1606,7 +1606,7 @@ static int read_partial_message_bio(struct ceph_connection *con,
 
 	ret = ceph_tcp_recvmsg(con->sock, p + con->in_msg_pos.page_pos,
 			       left);
-	if (ret > 0 && datacrc)
+	if (ret > 0 && do_datacrc)
 		con->in_data_crc =
 			crc32c(con->in_data_crc,
 				  p + con->in_msg_pos.page_pos, ret);
@@ -1633,7 +1633,7 @@ static int read_partial_message(struct ceph_connection *con)
 	int ret;
 	int to, left;
 	unsigned front_len, middle_len, data_len;
-	int datacrc = con->msgr->nocrc;
+	bool do_datacrc = con->msgr->nocrc;
 	int skip;
 	u64 seq;
 
@@ -1744,7 +1744,7 @@ static int read_partial_message(struct ceph_connection *con)
 	while (con->in_msg_pos.data_pos < data_len) {
 		if (m->pages) {
 			ret = read_partial_message_pages(con, m->pages,
-						 data_len, datacrc);
+						 data_len, do_datacrc);
 			if (ret <= 0)
 				return ret;
 #ifdef CONFIG_BLOCK
@@ -1752,7 +1752,7 @@ static int read_partial_message(struct ceph_connection *con)
 
 			ret = read_partial_message_bio(con,
 						 &m->bio_iter, &m->bio_seg,
-						 data_len, datacrc);
+						 data_len, do_datacrc);
 			if (ret <= 0)
 				return ret;
 #endif
@@ -1787,7 +1787,7 @@ static int read_partial_message(struct ceph_connection *con)
 		       m, con->in_middle_crc, m->footer.middle_crc);
 		return -EBADMSG;
 	}
-	if (datacrc &&
+	if (do_datacrc &&
 	    (m->footer.flags & CEPH_MSG_FOOTER_NOCRC) == 0 &&
 	    con->in_data_crc != le32_to_cpu(m->footer.data_crc)) {
 		pr_err("read_partial_message %p data crc %u != exp. %u\n", m,