Convert the request assembly loop and error path in ceph_submit_write()
to folios. This drops ceph's uses of the set_page_writeback(),
redirty_page_for_writepage(), and unlock_page() compatibility wrappers
in the writeback submission path.

Add ceph_folio_start_fscache(), a folio counterpart of
ceph_set_page_fscache(). The remaining caller of the latter in
write_folio_nounlock() will be converted separately.

In total, this removes eight calls to compound_head() hidden in the
page-based APIs, while adding four explicit ones via page_folio().

Note that get_writepages_data_length() must still be passed the
possibly-bounce folio, not the unwrapped pagecache folio, as it checks
fscrypt_is_bounce_folio() to round encrypted lengths up to the fscrypt
block size.

No functional change.

Signed-off-by: Tal Zussman <tz2294@columbia.edu>
---
 fs/ceph/addr.c | 37 +++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 28f0b16da2b0..a3324da08123 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -553,6 +553,11 @@ const struct netfs_request_ops ceph_netfs_ops = {
 };
 
 #ifdef CONFIG_CEPH_FSCACHE
+static void ceph_folio_start_fscache(struct folio *folio)
+{
+	folio_start_private_2(folio); /* [DEPRECATED] */
+}
+
 static void ceph_set_page_fscache(struct page *page)
 {
 	folio_start_private_2(page_folio(page)); /* [DEPRECATED] */
@@ -580,6 +585,10 @@ static void ceph_fscache_write_to_cache(struct inode *inode, u64 off, u64 len, b
 			       ceph_fscache_write_terminated, inode, true, caching);
 }
 #else
+static inline void ceph_folio_start_fscache(struct folio *folio)
+{
+}
+
 static inline void ceph_set_page_fscache(struct page *page)
 {
 }
@@ -1448,14 +1457,14 @@ int ceph_submit_write(struct address_space *mapping,
 	struct ceph_client *cl = fsc->client;
 	struct ceph_vino vino = ceph_vino(inode);
 	struct ceph_osd_request *req = NULL;
-	struct page *page = NULL;
+	struct folio *folio = NULL;
 	bool caching = ceph_is_cache_enabled(inode);
 	u64 offset;
 	u64 len;
 	unsigned i;
 
 new_request:
-	offset = ceph_fscrypt_page_offset(ceph_wbc->pages[0]);
+	offset = ceph_fscrypt_folio_offset(page_folio(ceph_wbc->pages[0]));
 	len = ceph_wbc->wsize;
 
 	req = ceph_osdc_new_request(&fsc->client->osdc,
@@ -1479,21 +1488,21 @@ int ceph_submit_write(struct address_space *mapping,
 		BUG_ON(IS_ERR(req));
 	}
 
-	page = ceph_wbc->pages[ceph_wbc->locked_pages - 1];
-	BUG_ON(len < ceph_fscrypt_page_offset(page) + thp_size(page) - offset);
+	folio = page_folio(ceph_wbc->pages[ceph_wbc->locked_pages - 1]);
+	BUG_ON(len < ceph_fscrypt_folio_offset(folio) + folio_size(folio) - offset);
 
 	if (!ceph_inc_osd_stopping_blocker(fsc->mdsc)) {
 		for (i = 0; i < ceph_wbc->locked_pages; i++) {
 			fscrypt_finalize_bounce_page(&ceph_wbc->pages[i]);
-			page = ceph_wbc->pages[i];
+			folio = page_folio(ceph_wbc->pages[i]);
 
 			if (atomic_long_dec_return(&fsc->writeback_count) <
 			    CONGESTION_OFF_THRESH(fsc->mount_options->congestion_kb))
 				fsc->write_congested = false;
 
-			redirty_page_for_writepage(wbc, page);
-			unlock_page(page);
-			put_page(page);
+			folio_redirty_for_writepage(wbc, folio);
+			folio_unlock(folio);
+			folio_put(folio);
 		}
 
 		if (ceph_wbc->from_pool) {
@@ -1519,8 +1528,8 @@ int ceph_submit_write(struct address_space *mapping,
 	for (i = 0; i < ceph_wbc->locked_pages; i++) {
 		u64 cur_offset;
 
-		page = ceph_fscrypt_pagecache_page(ceph_wbc->pages[i]);
-		cur_offset = page_offset(page);
+		folio = ceph_fscrypt_pagecache_folio(page_folio(ceph_wbc->pages[i]));
+		cur_offset = folio_pos(folio);
 
 		/*
 		 * Discontinuity in page range? Ceph can handle that by just passing
@@ -1553,12 +1562,12 @@ int ceph_submit_write(struct address_space *mapping,
 			ceph_wbc->op_idx++;
 		}
 
-		set_page_writeback(page);
+		folio_start_writeback(folio);
 
 		if (caching)
-			ceph_set_page_fscache(page);
+			ceph_folio_start_fscache(folio);
 
-		len += thp_size(page);
+		len += folio_size(folio);
 	}
 
 	ceph_fscache_write_to_cache(inode, offset, len, caching);
@@ -1569,7 +1578,7 @@ int ceph_submit_write(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,
 						 page_folio(ceph_wbc->pages[i - 1]),
 						 offset);

-- 
2.39.5