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Commit 0713e5f2 authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: optimize pagevec iterating in ceph_writepages_start() 



ceph_writepages_start() supports writing non-continuous pages.
If it encounters a non-dirty or non-writeable page in pagevec,
it can continue to check the rest pages in pagevec.

Signed-off-by: default avatar"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 05455e11

fs/ceph/addr.c

+25 −29
Original line number Diff line number Diff line
@@ -851,7 +851,6 @@ static int ceph_writepages_start(struct address_space *mapping, 


	while (!done && index <= end) {

		unsigned i;

		int first;

		pgoff_t strip_unit_end = 0;

		int num_ops = 0, op_idx;

		int pvec_pages, locked_pages = 0;
@@ -864,7 +863,6 @@ static int ceph_writepages_start(struct address_space *mapping, 
		max_pages = max_pages_ever;



get_more_pages:

		first = -1;

		want = min(end - index,

			   min((pgoff_t)PAGEVEC_SIZE,

			       max_pages - (pgoff_t)locked_pages) - 1)
@@ -888,7 +886,7 @@ static int ceph_writepages_start(struct address_space *mapping, 
			    unlikely(page->mapping != mapping)) {

				dout("!dirty or !mapping %p\n", page);

				unlock_page(page);

				break;

				continue;

			}

			if (!wbc->range_cyclic && page->index > end) {

				dout("end of range %p\n", page);
@@ -901,10 +899,6 @@ static int ceph_writepages_start(struct address_space *mapping, 
				unlock_page(page);

				break;

			}

			if (wbc->sync_mode != WB_SYNC_NONE) {

				dout("waiting on writeback %p\n", page);

				wait_on_page_writeback(page);

			}

			if (page_offset(page) >= ceph_wbc.i_size) {

				dout("%p page eof %llu\n",

				     page, ceph_wbc.i_size);
@@ -913,9 +907,13 @@ static int ceph_writepages_start(struct address_space *mapping, 
				break;

			}

			if (PageWriteback(page)) {

				if (wbc->sync_mode == WB_SYNC_NONE) {

					dout("%p under writeback\n", page);

					unlock_page(page);

				break;

					continue;

				}

				dout("waiting on writeback %p\n", page);

				wait_on_page_writeback(page);

			}



			/* only if matching snap context */
@@ -924,15 +922,13 @@ static int ceph_writepages_start(struct address_space *mapping, 
				dout("page snapc %p %lld > oldest %p %lld\n",

				     pgsnapc, pgsnapc->seq, snapc, snapc->seq);

				unlock_page(page);

				if (!locked_pages)

					continue; /* keep looking for snap */

				break;

				continue;

			}



			if (!clear_page_dirty_for_io(page)) {

				dout("%p !clear_page_dirty_for_io\n", page);

				unlock_page(page);

				break;

				continue;

			}



			/*
@@ -988,8 +984,6 @@ static int ceph_writepages_start(struct address_space *mapping, 
			}



			/* note position of first page in pvec */

			if (first < 0)

				first = i;

			dout("%p will write page %p idx %lu\n",

			     inode, page, page->index);
@@ -1000,8 +994,10 @@ static int ceph_writepages_start(struct address_space *mapping, 
						  BLK_RW_ASYNC);

			}



			pages[locked_pages] = page;

			locked_pages++;



			pages[locked_pages++] = page;

			pvec.pages[i] = NULL;



			len += PAGE_SIZE;

		}
@@ -1009,23 +1005,23 @@ static int ceph_writepages_start(struct address_space *mapping, 
		if (!locked_pages)

			goto release_pvec_pages;

		if (i) {

			int j;

			BUG_ON(!locked_pages || first < 0);

			unsigned j, n = 0;

			/* shift unused page to beginning of pvec */

			for (j = 0; j < pvec_pages; j++) {

				if (!pvec.pages[j])

					continue;

				if (n < j)

					pvec.pages[n] = pvec.pages[j];

				n++;

			}

			pvec.nr = n;



			if (pvec_pages && i == pvec_pages &&

			    locked_pages < max_pages) {

				dout("reached end pvec, trying for more\n");

				pagevec_reinit(&pvec);

				pagevec_release(&pvec);

				goto get_more_pages;

			}



			/* shift unused pages over in the pvec...  we

			 * will need to release them below. */

			for (j = i; j < pvec_pages; j++) {

				dout(" pvec leftover page %p\n", pvec.pages[j]);

				pvec.pages[j-i+first] = pvec.pages[j];

			}

			pvec.nr -= i-first;

		}



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