[PATCH 01/15] ceph: Convert ceph_writepages_start() to use folios a little more

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

After we iterate through the locked folios using filemap_get_folios_tag(),
we currently convert back to a page (and then in some circumstaces back
to a folio again!).  Just use a folio throughout and avoid various hidden
calls to compound_head().  Ceph still uses a page array to interact with
the OSD which should be cleaned up in a subsequent patch.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/ceph/addr.c | 100 ++++++++++++++++++++++++-------------------------
 1 file changed, 49 insertions(+), 51 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index f4863078f7fe..9a0a79833eb0 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1018,7 +1018,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 		int num_ops = 0, op_idx;
 		unsigned i, nr_folios, max_pages, locked_pages = 0;
 		struct page **pages = NULL, **data_pages;
-		struct page *page;
+		struct folio *folio;
 		pgoff_t strip_unit_end = 0;
 		u64 offset = 0, len = 0;
 		bool from_pool = false;
@@ -1032,22 +1032,22 @@ static int ceph_writepages_start(struct address_space *mapping,
 		if (!nr_folios && !locked_pages)
 			break;
 		for (i = 0; i < nr_folios && locked_pages < max_pages; i++) {
-			page = &fbatch.folios[i]->page;
-			dout("? %p idx %lu\n", page, page->index);
+			folio = fbatch.folios[i];
+			dout("? %p idx %lu\n", folio, folio->index);
 			if (locked_pages == 0)
-				lock_page(page);  /* first page */
-			else if (!trylock_page(page))
+				folio_lock(folio);  /* first folio */
+			else if (!folio_trylock(folio))
 				break;
 
 			/* only dirty pages, or our accounting breaks */
-			if (unlikely(!PageDirty(page)) ||
-			    unlikely(page->mapping != mapping)) {
-				dout("!dirty or !mapping %p\n", page);
-				unlock_page(page);
+			if (unlikely(!folio_test_dirty(folio)) ||
+			    unlikely(folio->mapping != mapping)) {
+				dout("!dirty or !mapping %p\n", folio);
+				folio_unlock(folio);
 				continue;
 			}
 			/* only if matching snap context */
-			pgsnapc = page_snap_context(page);
+			pgsnapc = folio->private;
 			if (pgsnapc != snapc) {
 				dout("page snapc %p %lld != oldest %p %lld\n",
 				     pgsnapc, pgsnapc->seq, snapc, snapc->seq);
@@ -1055,12 +1055,10 @@ static int ceph_writepages_start(struct address_space *mapping,
 				    !ceph_wbc.head_snapc &&
 				    wbc->sync_mode != WB_SYNC_NONE)
 					should_loop = true;
-				unlock_page(page);
+				folio_unlock(folio);
 				continue;
 			}
-			if (page_offset(page) >= ceph_wbc.i_size) {
-				struct folio *folio = page_folio(page);
-
+			if (folio_pos(folio) >= ceph_wbc.i_size) {
 				dout("folio at %lu beyond eof %llu\n",
 				     folio->index, ceph_wbc.i_size);
 				if ((ceph_wbc.size_stable ||
@@ -1071,31 +1069,32 @@ static int ceph_writepages_start(struct address_space *mapping,
 				folio_unlock(folio);
 				continue;
 			}
-			if (strip_unit_end && (page->index > strip_unit_end)) {
-				dout("end of strip unit %p\n", page);
-				unlock_page(page);
+			if (strip_unit_end && (folio->index > strip_unit_end)) {
+				dout("end of strip unit %p\n", folio);
+				folio_unlock(folio);
 				break;
 			}
-			if (PageWriteback(page) || PageFsCache(page)) {
+			if (folio_test_writeback(folio) ||
+			    folio_test_fscache(folio)) {
 				if (wbc->sync_mode == WB_SYNC_NONE) {
-					dout("%p under writeback\n", page);
-					unlock_page(page);
+					dout("%p under writeback\n", folio);
+					folio_unlock(folio);
 					continue;
 				}
-				dout("waiting on writeback %p\n", page);
-				wait_on_page_writeback(page);
-				wait_on_page_fscache(page);
+				dout("waiting on writeback %p\n", folio);
+				folio_wait_writeback(folio);
+				folio_wait_fscache(folio);
 			}
 
-			if (!clear_page_dirty_for_io(page)) {
-				dout("%p !clear_page_dirty_for_io\n", page);
-				unlock_page(page);
+			if (!folio_clear_dirty_for_io(folio)) {
+				dout("%p !folio_clear_dirty_for_io\n", folio);
+				folio_unlock(folio);
 				continue;
 			}
 
 			/*
 			 * We have something to write.  If this is
-			 * the first locked page this time through,
+			 * the first locked folio this time through,
 			 * calculate max possinle write size and
 			 * allocate a page array
 			 */
@@ -1105,7 +1104,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 				u32 xlen;
 
 				/* prepare async write request */
-				offset = (u64)page_offset(page);
+				offset = folio_pos(folio);
 				ceph_calc_file_object_mapping(&ci->i_layout,
 							      offset, wsize,
 							      &objnum, &objoff,
@@ -1113,7 +1112,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 				len = xlen;
 
 				num_ops = 1;
-				strip_unit_end = page->index +
+				strip_unit_end = folio->index +
 					((len - 1) >> PAGE_SHIFT);
 
 				BUG_ON(pages);
@@ -1128,23 +1127,23 @@ static int ceph_writepages_start(struct address_space *mapping,
 				}
 
 				len = 0;
-			} else if (page->index !=
+			} else if (folio->index !=
 				   (offset + len) >> PAGE_SHIFT) {
 				if (num_ops >= (from_pool ?  CEPH_OSD_SLAB_OPS :
 							     CEPH_OSD_MAX_OPS)) {
-					redirty_page_for_writepage(wbc, page);
-					unlock_page(page);
+					folio_redirty_for_writepage(wbc, folio);
+					folio_unlock(folio);
 					break;
 				}
 
 				num_ops++;
-				offset = (u64)page_offset(page);
+				offset = (u64)folio_pos(folio);
 				len = 0;
 			}
 
 			/* note position of first page in fbatch */
-			dout("%p will write page %p idx %lu\n",
-			     inode, page, page->index);
+			dout("%p will write folio %p idx %lu\n",
+			     inode, folio, folio->index);
 
 			if (atomic_long_inc_return(&fsc->writeback_count) >
 			    CONGESTION_ON_THRESH(
@@ -1153,7 +1152,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 
 			if (IS_ENCRYPTED(inode)) {
 				pages[locked_pages] =
-					fscrypt_encrypt_pagecache_blocks(page,
+					fscrypt_encrypt_pagecache_blocks(&folio->page,
 						PAGE_SIZE, 0,
 						locked_pages ? GFP_NOWAIT : GFP_NOFS);
 				if (IS_ERR(pages[locked_pages])) {
@@ -1163,17 +1162,17 @@ static int ceph_writepages_start(struct address_space *mapping,
 					/* better not fail on first page! */
 					BUG_ON(locked_pages == 0);
 					pages[locked_pages] = NULL;
-					redirty_page_for_writepage(wbc, page);
-					unlock_page(page);
+					folio_redirty_for_writepage(wbc, folio);
+					folio_unlock(folio);
 					break;
 				}
 				++locked_pages;
 			} else {
-				pages[locked_pages++] = page;
+				pages[locked_pages++] = &folio->page;
 			}
 
 			fbatch.folios[i] = NULL;
-			len += thp_size(page);
+			len += folio_size(folio);
 		}
 
 		/* did we get anything? */
@@ -1222,7 +1221,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 			BUG_ON(IS_ERR(req));
 		}
 		BUG_ON(len < ceph_fscrypt_page_offset(pages[locked_pages - 1]) +
-			     thp_size(pages[locked_pages - 1]) - offset);
+			     folio_size(folio) - offset);
 
 		if (!ceph_inc_osd_stopping_blocker(fsc->mdsc)) {
 			rc = -EIO;
@@ -1236,9 +1235,9 @@ static int ceph_writepages_start(struct address_space *mapping,
 		data_pages = pages;
 		op_idx = 0;
 		for (i = 0; i < locked_pages; i++) {
-			struct page *page = ceph_fscrypt_pagecache_page(pages[i]);
+			struct folio *folio = page_folio(ceph_fscrypt_pagecache_page(pages[i]));
 
-			u64 cur_offset = page_offset(page);
+			u64 cur_offset = folio_pos(folio);
 			/*
 			 * Discontinuity in page range? Ceph can handle that by just passing
 			 * multiple extents in the write op.
@@ -1267,10 +1266,10 @@ static int ceph_writepages_start(struct address_space *mapping,
 				op_idx++;
 			}
 
-			set_page_writeback(page);
+			folio_start_writeback(folio);
 			if (caching)
-				ceph_set_page_fscache(page);
-			len += thp_size(page);
+				ceph_set_page_fscache(pages[i]);
+			len += folio_size(folio);
 		}
 		ceph_fscache_write_to_cache(inode, offset, len, caching);
 
@@ -1280,7 +1279,7 @@ static int ceph_writepages_start(struct address_space *mapping,
 			/* writepages_finish() clears writeback pages
 			 * according to the data length, so make sure
 			 * data length covers all locked pages */
-			u64 min_len = len + 1 - thp_size(page);
+			u64 min_len = len + 1 - folio_size(folio);
 			len = get_writepages_data_length(inode, pages[i - 1],
 							 offset);
 			len = max(len, min_len);
@@ -1360,7 +1359,6 @@ static int ceph_writepages_start(struct address_space *mapping,
 		if (wbc->sync_mode != WB_SYNC_NONE &&
 		    start_index == 0 && /* all dirty pages were checked */
 		    !ceph_wbc.head_snapc) {
-			struct page *page;
 			unsigned i, nr;
 			index = 0;
 			while ((index <= end) &&
@@ -1369,10 +1367,10 @@ static int ceph_writepages_start(struct address_space *mapping,
 						PAGECACHE_TAG_WRITEBACK,
 						&fbatch))) {
 				for (i = 0; i < nr; i++) {
-					page = &fbatch.folios[i]->page;
-					if (page_snap_context(page) != snapc)
+					struct folio *folio = fbatch.folios[i];
+					if (folio->private != snapc)
 						continue;
-					wait_on_page_writeback(page);
+					folio_wait_writeback(folio);
 				}
 				folio_batch_release(&fbatch);
 				cond_resched();
-- 
2.40.1