ceph: scattered page writeback
This patch makes ceph_writepages_start() try using single OSD request
to write all dirty pages within a strip unit. When a nonconsecutive
dirty page is found, ceph_writepages_start() tries starting a new write
operation to existing OSD request. If it succeeds, it uses the new
operation to writeback the dirty page.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 19adeb0..a9f66b6 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -606,71 +606,71 @@
struct inode *inode = req->r_inode;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_osd_data *osd_data;
- unsigned wrote;
struct page *page;
- int num_pages;
- int i;
+ int num_pages, total_pages = 0;
+ int i, j;
+ int rc = req->r_result;
struct ceph_snap_context *snapc = req->r_snapc;
struct address_space *mapping = inode->i_mapping;
- int rc = req->r_result;
- u64 bytes = req->r_ops[0].extent.length;
struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
- long writeback_stat;
- unsigned issued = ceph_caps_issued(ci);
+ bool remove_page;
- osd_data = osd_req_op_extent_osd_data(req, 0);
- BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
- num_pages = calc_pages_for((u64)osd_data->alignment,
- (u64)osd_data->length);
- if (rc >= 0) {
- /*
- * Assume we wrote the pages we originally sent. The
- * osd might reply with fewer pages if our writeback
- * raced with a truncation and was adjusted at the osd,
- * so don't believe the reply.
- */
- wrote = num_pages;
- } else {
- wrote = 0;
+
+ dout("writepages_finish %p rc %d\n", inode, rc);
+ if (rc < 0)
mapping_set_error(mapping, rc);
- }
- dout("writepages_finish %p rc %d bytes %llu wrote %d (pages)\n",
- inode, rc, bytes, wrote);
+
+ /*
+ * We lost the cache cap, need to truncate the page before
+ * it is unlocked, otherwise we'd truncate it later in the
+ * page truncation thread, possibly losing some data that
+ * raced its way in
+ */
+ remove_page = !(ceph_caps_issued(ci) &
+ (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));
/* clean all pages */
- for (i = 0; i < num_pages; i++) {
- page = osd_data->pages[i];
- BUG_ON(!page);
- WARN_ON(!PageUptodate(page));
+ for (i = 0; i < req->r_num_ops; i++) {
+ if (req->r_ops[i].op != CEPH_OSD_OP_WRITE)
+ break;
- writeback_stat =
- atomic_long_dec_return(&fsc->writeback_count);
- if (writeback_stat <
- CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
- clear_bdi_congested(&fsc->backing_dev_info,
- BLK_RW_ASYNC);
+ osd_data = osd_req_op_extent_osd_data(req, i);
+ BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);
+ num_pages = calc_pages_for((u64)osd_data->alignment,
+ (u64)osd_data->length);
+ total_pages += num_pages;
+ for (j = 0; j < num_pages; j++) {
+ page = osd_data->pages[j];
+ BUG_ON(!page);
+ WARN_ON(!PageUptodate(page));
- ceph_put_snap_context(page_snap_context(page));
- page->private = 0;
- ClearPagePrivate(page);
- dout("unlocking %d %p\n", i, page);
- end_page_writeback(page);
+ if (atomic_long_dec_return(&fsc->writeback_count) <
+ CONGESTION_OFF_THRESH(
+ fsc->mount_options->congestion_kb))
+ clear_bdi_congested(&fsc->backing_dev_info,
+ BLK_RW_ASYNC);
- /*
- * We lost the cache cap, need to truncate the page before
- * it is unlocked, otherwise we'd truncate it later in the
- * page truncation thread, possibly losing some data that
- * raced its way in
- */
- if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
- generic_error_remove_page(inode->i_mapping, page);
+ ceph_put_snap_context(page_snap_context(page));
+ page->private = 0;
+ ClearPagePrivate(page);
+ dout("unlocking %p\n", page);
+ end_page_writeback(page);
- unlock_page(page);
+ if (remove_page)
+ generic_error_remove_page(inode->i_mapping,
+ page);
+
+ unlock_page(page);
+ }
+ dout("writepages_finish %p wrote %llu bytes cleaned %d pages\n",
+ inode, osd_data->length, rc >= 0 ? num_pages : 0);
+
+ ceph_release_pages(osd_data->pages, num_pages);
}
- dout("%p wrote+cleaned %d pages\n", inode, wrote);
- ceph_put_wrbuffer_cap_refs(ci, num_pages, snapc);
- ceph_release_pages(osd_data->pages, num_pages);
+ ceph_put_wrbuffer_cap_refs(ci, total_pages, snapc);
+
+ osd_data = osd_req_op_extent_osd_data(req, 0);
if (osd_data->pages_from_pool)
mempool_free(osd_data->pages,
ceph_sb_to_client(inode->i_sb)->wb_pagevec_pool);
@@ -778,17 +778,15 @@
while (!done && index <= end) {
unsigned i;
int first;
- pgoff_t next;
- int pvec_pages, locked_pages;
- struct page **pages = NULL;
+ pgoff_t strip_unit_end = 0;
+ int num_ops = 0, op_idx;
+ int pvec_pages, locked_pages = 0;
+ struct page **pages = NULL, **data_pages;
mempool_t *pool = NULL; /* Becomes non-null if mempool used */
struct page *page;
int want;
- u64 offset, len;
- long writeback_stat;
+ u64 offset = 0, len = 0;
- next = 0;
- locked_pages = 0;
max_pages = max_pages_ever;
get_more_pages:
@@ -824,8 +822,8 @@
unlock_page(page);
break;
}
- if (next && (page->index != next)) {
- dout("not consecutive %p\n", page);
+ if (strip_unit_end && (page->index > strip_unit_end)) {
+ dout("end of strip unit %p\n", page);
unlock_page(page);
break;
}
@@ -867,36 +865,31 @@
/*
* We have something to write. If this is
* the first locked page this time through,
- * allocate an osd request and a page array
- * that it will use.
+ * calculate max possinle write size and
+ * allocate a page array
*/
if (locked_pages == 0) {
- BUG_ON(pages);
+ u64 objnum;
+ u64 objoff;
+
/* prepare async write request */
offset = (u64)page_offset(page);
len = wsize;
- req = ceph_osdc_new_request(&fsc->client->osdc,
- &ci->i_layout, vino,
- offset, &len, 0,
- do_sync ? 2 : 1,
- CEPH_OSD_OP_WRITE,
- CEPH_OSD_FLAG_WRITE |
- CEPH_OSD_FLAG_ONDISK,
- snapc, truncate_seq,
- truncate_size, true);
- if (IS_ERR(req)) {
- rc = PTR_ERR(req);
+
+ rc = ceph_calc_file_object_mapping(&ci->i_layout,
+ offset, len,
+ &objnum, &objoff,
+ &len);
+ if (rc < 0) {
unlock_page(page);
break;
}
- if (do_sync)
- osd_req_op_init(req, 1,
- CEPH_OSD_OP_STARTSYNC, 0);
+ num_ops = 1 + do_sync;
+ strip_unit_end = page->index +
+ ((len - 1) >> PAGE_CACHE_SHIFT);
- req->r_callback = writepages_finish;
- req->r_inode = inode;
-
+ BUG_ON(pages);
max_pages = calc_pages_for(0, (u64)len);
pages = kmalloc(max_pages * sizeof (*pages),
GFP_NOFS);
@@ -905,6 +898,20 @@
pages = mempool_alloc(pool, GFP_NOFS);
BUG_ON(!pages);
}
+
+ len = 0;
+ } else if (page->index !=
+ (offset + len) >> PAGE_CACHE_SHIFT) {
+ if (num_ops >= (pool ? CEPH_OSD_SLAB_OPS :
+ CEPH_OSD_MAX_OPS)) {
+ redirty_page_for_writepage(wbc, page);
+ unlock_page(page);
+ break;
+ }
+
+ num_ops++;
+ offset = (u64)page_offset(page);
+ len = 0;
}
/* note position of first page in pvec */
@@ -913,18 +920,16 @@
dout("%p will write page %p idx %lu\n",
inode, page, page->index);
- writeback_stat =
- atomic_long_inc_return(&fsc->writeback_count);
- if (writeback_stat > CONGESTION_ON_THRESH(
+ if (atomic_long_inc_return(&fsc->writeback_count) >
+ CONGESTION_ON_THRESH(
fsc->mount_options->congestion_kb)) {
set_bdi_congested(&fsc->backing_dev_info,
BLK_RW_ASYNC);
}
- set_page_writeback(page);
pages[locked_pages] = page;
locked_pages++;
- next = page->index + 1;
+ len += PAGE_CACHE_SIZE;
}
/* did we get anything? */
@@ -944,38 +949,119 @@
/* 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]);
+ dout(" pvec leftover page %p\n", pvec.pages[j]);
pvec.pages[j-i+first] = pvec.pages[j];
}
pvec.nr -= i-first;
}
- /* Format the osd request message and submit the write */
+new_request:
offset = page_offset(pages[0]);
- len = (u64)locked_pages << PAGE_CACHE_SHIFT;
- if (snap_size == -1) {
- len = min(len, (u64)i_size_read(inode) - offset);
- /* writepages_finish() clears writeback pages
- * according to the data length, so make sure
- * data length covers all locked pages */
- len = max(len, 1 +
- ((u64)(locked_pages - 1) << PAGE_CACHE_SHIFT));
- } else {
- len = min(len, snap_size - offset);
+ len = wsize;
+
+ req = ceph_osdc_new_request(&fsc->client->osdc,
+ &ci->i_layout, vino,
+ offset, &len, 0, num_ops,
+ CEPH_OSD_OP_WRITE,
+ CEPH_OSD_FLAG_WRITE |
+ CEPH_OSD_FLAG_ONDISK,
+ snapc, truncate_seq,
+ truncate_size, false);
+ if (IS_ERR(req)) {
+ req = ceph_osdc_new_request(&fsc->client->osdc,
+ &ci->i_layout, vino,
+ offset, &len, 0,
+ min(num_ops,
+ CEPH_OSD_SLAB_OPS),
+ CEPH_OSD_OP_WRITE,
+ CEPH_OSD_FLAG_WRITE |
+ CEPH_OSD_FLAG_ONDISK,
+ snapc, truncate_seq,
+ truncate_size, true);
+ BUG_ON(IS_ERR(req));
}
- dout("writepages got %d pages at %llu~%llu\n",
- locked_pages, offset, len);
+ BUG_ON(len < page_offset(pages[locked_pages - 1]) +
+ PAGE_CACHE_SIZE - offset);
- osd_req_op_extent_osd_data_pages(req, 0, pages, len, 0,
+ req->r_callback = writepages_finish;
+ req->r_inode = inode;
+
+ /* Format the osd request message and submit the write */
+ len = 0;
+ data_pages = pages;
+ op_idx = 0;
+ for (i = 0; i < locked_pages; i++) {
+ u64 cur_offset = page_offset(pages[i]);
+ if (offset + len != cur_offset) {
+ if (op_idx + do_sync + 1 == req->r_num_ops)
+ break;
+ osd_req_op_extent_dup_last(req, op_idx,
+ cur_offset - offset);
+ dout("writepages got pages at %llu~%llu\n",
+ offset, len);
+ osd_req_op_extent_osd_data_pages(req, op_idx,
+ data_pages, len, 0,
!!pool, false);
+ osd_req_op_extent_update(req, op_idx, len);
- pages = NULL; /* request message now owns the pages array */
+ len = 0;
+ offset = cur_offset;
+ data_pages = pages + i;
+ op_idx++;
+ }
+
+ set_page_writeback(pages[i]);
+ len += PAGE_CACHE_SIZE;
+ }
+
+ if (snap_size != -1) {
+ len = min(len, snap_size - offset);
+ } else if (i == locked_pages) {
+ /* writepages_finish() clears writeback pages
+ * according to the data length, so make sure
+ * data length covers all locked pages */
+ u64 min_len = len + 1 - PAGE_CACHE_SIZE;
+ len = min(len, (u64)i_size_read(inode) - offset);
+ len = max(len, min_len);
+ }
+ dout("writepages got pages at %llu~%llu\n", offset, len);
+
+ osd_req_op_extent_osd_data_pages(req, op_idx, data_pages, len,
+ 0, !!pool, false);
+ osd_req_op_extent_update(req, op_idx, len);
+
+ if (do_sync) {
+ op_idx++;
+ osd_req_op_init(req, op_idx, CEPH_OSD_OP_STARTSYNC, 0);
+ }
+ BUG_ON(op_idx + 1 != req->r_num_ops);
+
pool = NULL;
+ if (i < locked_pages) {
+ BUG_ON(num_ops <= req->r_num_ops);
+ num_ops -= req->r_num_ops;
+ num_ops += do_sync;
+ locked_pages -= i;
- /* Update the write op length in case we changed it */
-
- osd_req_op_extent_update(req, 0, len);
+ /* allocate new pages array for next request */
+ data_pages = pages;
+ pages = kmalloc(locked_pages * sizeof (*pages),
+ GFP_NOFS);
+ if (!pages) {
+ pool = fsc->wb_pagevec_pool;
+ pages = mempool_alloc(pool, GFP_NOFS);
+ BUG_ON(!pages);
+ }
+ memcpy(pages, data_pages + i,
+ locked_pages * sizeof(*pages));
+ memset(data_pages + i, 0,
+ locked_pages * sizeof(*pages));
+ } else {
+ BUG_ON(num_ops != req->r_num_ops);
+ index = pages[i - 1]->index + 1;
+ /* request message now owns the pages array */
+ pages = NULL;
+ }
vino = ceph_vino(inode);
ceph_osdc_build_request(req, offset, snapc, vino.snap,
@@ -985,9 +1071,10 @@
BUG_ON(rc);
req = NULL;
- /* continue? */
- index = next;
- wbc->nr_to_write -= locked_pages;
+ wbc->nr_to_write -= i;
+ if (pages)
+ goto new_request;
+
if (wbc->nr_to_write <= 0)
done = 1;