linux-kernel - [PATCH AUTOSEL 5.4 25/34] ceph: allow ceph.dir.rctime xattr to be updatable

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Message-Id: <20220607180011.481266-25-sashal@kernel.org>
Date:   Tue,  7 Jun 2022 14:00:00 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Venky Shankar <vshankar@...hat.com>, Xiubo Li <xiubli@...hat.com>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 25/34] ceph: allow ceph.dir.rctime xattr to be updatable

From: Venky Shankar <vshankar@...hat.com>

[ Upstream commit d7a2dc523085f8b8c60548ceedc696934aefeb0e ]

`rctime' has been a pain point in cephfs due to its buggy
nature - inconsistent values reported and those sorts.
Fixing rctime is non-trivial needing an overall redesign
of the entire nested statistics infrastructure.

As a workaround, PR

     http://github.com/ceph/ceph/pull/37938

allows this extended attribute to be manually set. This allows
users to "fixup" inconsistent rctime values. While this sounds
messy, its probably the wisest approach allowing users/scripts
to workaround buggy rctime values.

The above PR enables Ceph MDS to allow manually setting
rctime extended attribute with the corresponding user-land
changes. We may as well allow the same to be done via kclient
for parity.

Signed-off-by: Venky Shankar <vshankar@...hat.com>
Reviewed-by: Xiubo Li <xiubli@...hat.com>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/xattr.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index cb18ee637cb7..4bcf0226818d 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -316,6 +316,14 @@ static ssize_t ceph_vxattrcb_snap_btime(struct ceph_inode_info *ci, char *val,
 	}
 #define XATTR_RSTAT_FIELD(_type, _name)			\
 	XATTR_NAME_CEPH(_type, _name, VXATTR_FLAG_RSTAT)
+#define XATTR_RSTAT_FIELD_UPDATABLE(_type, _name)			\
+	{								\
+		.name = CEPH_XATTR_NAME(_type, _name),			\
+		.name_size = sizeof (CEPH_XATTR_NAME(_type, _name)),	\
+		.getxattr_cb = ceph_vxattrcb_ ## _type ## _ ## _name,	\
+		.exists_cb = NULL,					\
+		.flags = VXATTR_FLAG_RSTAT,				\
+	}
 #define XATTR_LAYOUT_FIELD(_type, _name, _field)			\
 	{								\
 		.name = CEPH_XATTR_NAME2(_type, _name, _field),	\
@@ -353,7 +361,7 @@ static struct ceph_vxattr ceph_dir_vxattrs[] = {
 	XATTR_RSTAT_FIELD(dir, rfiles),
 	XATTR_RSTAT_FIELD(dir, rsubdirs),
 	XATTR_RSTAT_FIELD(dir, rbytes),
-	XATTR_RSTAT_FIELD(dir, rctime),
+	XATTR_RSTAT_FIELD_UPDATABLE(dir, rctime),
 	{
 		.name = "ceph.dir.pin",
 		.name_size = sizeof("ceph.dir.pin"),
-- 
2.35.1