linux-kernel - [PATCH] fs/ceph/addr: convert `op_idx`, `data

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Message-ID: <20250828120453.748058-1-max.kellermann@ionos.com>
Date: Thu, 28 Aug 2025 14:04:53 +0200
From: Max Kellermann <max.kellermann@...os.com>
To: Slava.Dubeyko@....com,
	xiubli@...hat.com,
	idryomov@...il.com,
	amarkuze@...hat.com,
	ceph-devel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Max Kellermann <max.kellermann@...os.com>
Subject: [PATCH] fs/ceph/addr: convert `op_idx`, `data_pages` back to a local variables

These were local variables until commit f08068df4aa4 ("ceph: extend
ceph_writeback_ctl for ceph_writepages_start() refactoring"), but were
moved to the struct ceph_writeback_ctl for no obvious reason.  Having
these in a struct means overhead, so let's move them back.

For the "allocate new pages array for next request" code block,
however I decided to introduce a new local variable `old_pages`
instead, because reusing `data_pages` for reallocation seemed
confusing to me.

Signed-off-by: Max Kellermann <max.kellermann@...os.com>
---
 fs/ceph/addr.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 8b202d789e93..fc3192c79072 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -611,7 +611,6 @@ struct ceph_writeback_ctl
 
 	bool from_pool;
 	struct page **pages;
-	struct page **data_pages;
 };
 
 /*
@@ -1051,7 +1050,6 @@ void ceph_init_writeback_ctl(struct address_space *mapping,
 		ceph_wbc->tag = PAGECACHE_TAG_DIRTY;
 	}
 
-	ceph_wbc->op_idx = -1;
 	ceph_wbc->num_ops = 0;
 	ceph_wbc->offset = 0;
 	ceph_wbc->len = 0;
@@ -1060,7 +1058,6 @@ void ceph_init_writeback_ctl(struct address_space *mapping,
 	ceph_folio_batch_init(ceph_wbc);
 
 	ceph_wbc->pages = NULL;
-	ceph_wbc->data_pages = NULL;
 }
 
 static inline
@@ -1417,10 +1414,12 @@ int ceph_submit_write(struct address_space *mapping,
 	struct ceph_vino vino = ceph_vino(inode);
 	struct ceph_osd_request *req = NULL;
 	struct page *page = NULL;
+	struct page **data_pages;
 	bool caching = ceph_is_cache_enabled(inode);
 	u64 offset;
 	u64 len;
 	unsigned i;
+	unsigned op_idx;
 
 new_request:
 	offset = ceph_fscrypt_page_offset(ceph_wbc->pages[0]);
@@ -1481,8 +1480,8 @@ int ceph_submit_write(struct address_space *mapping,
 
 	/* Format the osd request message and submit the write */
 	len = 0;
-	ceph_wbc->data_pages = ceph_wbc->pages;
-	ceph_wbc->op_idx = 0;
+	data_pages = ceph_wbc->pages;
+	op_idx = 0;
 	for (i = 0; i < ceph_wbc->locked_pages; i++) {
 		u64 cur_offset;
 
@@ -1495,29 +1494,29 @@ int ceph_submit_write(struct address_space *mapping,
 		 */
 		if (offset + len != cur_offset) {
 			/* If it's full, stop here */
-			if (ceph_wbc->op_idx + 1 == req->r_num_ops)
+			if (op_idx + 1 == req->r_num_ops)
 				break;
 
 			/* Kick off an fscache write with what we have so far. */
 			ceph_fscache_write_to_cache(inode, offset, len, caching);
 
 			/* Start a new extent */
-			osd_req_op_extent_dup_last(req, ceph_wbc->op_idx,
+			osd_req_op_extent_dup_last(req, op_idx,
 						   cur_offset - offset);
 
 			doutc(cl, "got pages at %llu~%llu\n", offset, len);
 
-			osd_req_op_extent_osd_data_pages(req, ceph_wbc->op_idx,
-							 ceph_wbc->data_pages,
+			osd_req_op_extent_osd_data_pages(req, op_idx,
+							 data_pages,
 							 len, 0,
 							 ceph_wbc->from_pool,
 							 false);
-			osd_req_op_extent_update(req, ceph_wbc->op_idx, len);
+			osd_req_op_extent_update(req, op_idx, len);
 
 			len = 0;
 			offset = cur_offset;
-			ceph_wbc->data_pages = ceph_wbc->pages + i;
-			ceph_wbc->op_idx++;
+			data_pages = ceph_wbc->pages + i;
+			op_idx++;
 		}
 
 		set_page_writeback(page);
@@ -1555,25 +1554,27 @@ int ceph_submit_write(struct address_space *mapping,
 			offset, len);
 	}
 
-	osd_req_op_extent_osd_data_pages(req, ceph_wbc->op_idx,
-					 ceph_wbc->data_pages, len,
+	osd_req_op_extent_osd_data_pages(req, op_idx,
+					 data_pages, len,
 					 0, ceph_wbc->from_pool, false);
-	osd_req_op_extent_update(req, ceph_wbc->op_idx, len);
+	osd_req_op_extent_update(req, op_idx, len);
 
-	BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops);
+	BUG_ON(op_idx + 1 != req->r_num_ops);
 
 	ceph_wbc->from_pool = false;
 	if (i < ceph_wbc->locked_pages) {
+		struct page **old_pages;
+
 		BUG_ON(ceph_wbc->num_ops <= req->r_num_ops);
 		ceph_wbc->num_ops -= req->r_num_ops;
 		ceph_wbc->locked_pages -= i;
 
 		/* allocate new pages array for next request */
-		ceph_wbc->data_pages = ceph_wbc->pages;
+		old_pages = ceph_wbc->pages;
 		__ceph_allocate_page_array(ceph_wbc, ceph_wbc->locked_pages);
-		memcpy(ceph_wbc->pages, ceph_wbc->data_pages + i,
+		memcpy(ceph_wbc->pages, old_pages + i,
 			ceph_wbc->locked_pages * sizeof(*ceph_wbc->pages));
-		memset(ceph_wbc->data_pages + i, 0,
+		memset(old_pages + i, 0,
 			ceph_wbc->locked_pages * sizeof(*ceph_wbc->pages));
 	} else {
 		BUG_ON(ceph_wbc->num_ops != req->r_num_ops);
-- 
2.47.2