linux-ext4 - [PATCH 2/9] fuse: force a ctime update after a fileattr

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Message-ID: <176169811634.1426244.16405162731946583369.stgit@frogsfrogsfrogs>
Date: Tue, 28 Oct 2025 17:54:20 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: djwong@...nel.org, miklos@...redi.hu
Cc: joannelkoong@...il.com, bernd@...ernd.com, neal@...pa.dev,
 linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 2/9] fuse: force a ctime update after a fileattr_set call when
 in iomap mode

From: Darrick J. Wong <djwong@...nel.org>

In iomap mode, the kernel is in charge of driving ctime updates to
the fuse server and ignores updates coming from the fuse server.
Therefore, when someone calls fileattr_set to change file attributes, we
must force a ctime update.

Found by generic/277.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 fs/fuse/ioctl.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index fdc175e93f7474..07529db21fb781 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -546,8 +546,13 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,
 	struct fuse_file *ff;
 	unsigned int flags = fa->flags;
 	struct fsxattr xfa;
+	struct file_kattr old_ma = { };
+	bool is_wb = (fuse_get_cache_mask(inode) & STATX_CTIME);
 	int err;

+	if (is_wb)
+		vfs_fileattr_get(dentry, &old_ma);
+
 	ff = fuse_priv_ioctl_prepare(inode);
 	if (IS_ERR(ff))
 		return PTR_ERR(ff);
@@ -571,6 +576,12 @@ int fuse_fileattr_set(struct mnt_idmap *idmap,

 cleanup:
 	fuse_priv_ioctl_cleanup(inode, ff);
+	/*
+	 * If we cache ctime updates and the fileattr changed, then force a
+	 * ctime update.
+	 */
+	if (is_wb && memcmp(&old_ma, fa, sizeof(old_ma)))
+		fuse_update_ctime(inode);

 	return err;
 }