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: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 8526359..5ca887b 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -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)) {
- dout("%p under writeback\n", page);
- unlock_page(page);
- break;
+ if (wbc->sync_mode == WB_SYNC_NONE) {
+ dout("%p under writeback\n", page);
+ unlock_page(page);
+ 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;
}
new_request: