linux-kernel - [PATCH] fuse: remove WARN_ON_ONCE() from fuse_iomap_writeback

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Message-ID: <20250902152234.35173-1-luis@igalia.com>
Date: Tue,  2 Sep 2025 16:22:34 +0100
From: Luis Henriques <luis@...lia.com>
To: Miklos Szeredi <miklos@...redi.hu>,
	Joanne Koong <joannelkoong@...il.com>
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Luis Henriques <luis@...lia.com>
Subject: [PATCH] fuse: remove WARN_ON_ONCE() from fuse_iomap_writeback_{range,submit}()

The usage of WARN_ON_ONCE doesn't seem to be necessary in these functions.
All fuse_iomap_writeback_submit() call sites already ensure that wpc->wb_ctx
contains a valid fuse_fill_wb_data.

Function fuse_iomap_writeback_range() also seems to always be called with a
valid value.  But even if this wasn't the case, there would be a crash
before this WARN_ON_ONCE() because ->wpa is being accessed before it.

Signed-off-by: Luis Henriques <luis@...lia.com>
---
As I'm saying above, I _think_ there's no need for these WARN_ON_ONCE().
However, if I'm wrong and they are required, I believe there's a need for
a different patch (I can send one) to actually prevent a kernel crash.

 fs/fuse/file.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 5525a4520b0f..fac52f9fb333 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2142,8 +2142,6 @@ static ssize_t fuse_iomap_writeback_range(struct iomap_writepage_ctx *wpc,
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	loff_t offset = offset_in_folio(folio, pos);
 
-	WARN_ON_ONCE(!data);
-
 	if (!data->ff) {
 		data->ff = fuse_write_file_get(fi);
 		if (!data->ff)
@@ -2182,8 +2180,6 @@ static int fuse_iomap_writeback_submit(struct iomap_writepage_ctx *wpc,
 {
 	struct fuse_fill_wb_data *data = wpc->wb_ctx;
 
-	WARN_ON_ONCE(!data);
-
 	if (data->wpa) {
 		WARN_ON(!data->wpa->ia.ap.num_folios);
 		fuse_writepages_send(wpc->inode, data);