On 10/11/2022 19:49, Ilya Dryomov wrote:
On Thu, Nov 10, 2022 at 3:08 AM <xiubli@xxxxxxxxxx> wrote:
From: Xiubo Li <xiubli@xxxxxxxxxx>
The request's r_session maybe changed when it was forwarded or
resent.
Cc: stable@xxxxxxxxxxxxxxx
URL: https://bugzilla.redhat.com/show_bug.cgi?id=2137955
Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
---
Changed in V4:
- move mdsc->mutex acquisition and max_sessions assignment into "if (req1 || req2)" branch
fs/ceph/caps.c | 54 +++++++++++++++-----------------------------------
1 file changed, 16 insertions(+), 38 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 894adfb4a092..1c84be839087 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2297,7 +2297,6 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
struct ceph_mds_client *mdsc = ceph_sb_to_client(inode->i_sb)->mdsc;
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_mds_request *req1 = NULL, *req2 = NULL;
- unsigned int max_sessions;
int ret, err = 0;
spin_lock(&ci->i_unsafe_lock);
@@ -2315,28 +2314,24 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
}
spin_unlock(&ci->i_unsafe_lock);
- /*
- * The mdsc->max_sessions is unlikely to be changed
- * mostly, here we will retry it by reallocating the
- * sessions array memory to get rid of the mdsc->mutex
- * lock.
- */
-retry:
- max_sessions = mdsc->max_sessions;
-
/*
* Trigger to flush the journal logs in all the relevant MDSes
* manually, or in the worst case we must wait at most 5 seconds
* to wait the journal logs to be flushed by the MDSes periodically.
*/
- if ((req1 || req2) && likely(max_sessions)) {
- struct ceph_mds_session **sessions = NULL;
- struct ceph_mds_session *s;
+ if (req1 || req2) {
struct ceph_mds_request *req;
+ struct ceph_mds_session **sessions;
+ struct ceph_mds_session *s;
+ unsigned int max_sessions;
int i;
+ mutex_lock(&mdsc->mutex);
+ max_sessions = mdsc->max_sessions;
+
sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
if (!sessions) {
+ mutex_unlock(&mdsc->mutex);
err = -ENOMEM;
goto out;
}
@@ -2346,18 +2341,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
list_for_each_entry(req, &ci->i_unsafe_dirops,
r_unsafe_dir_item) {
s = req->r_session;
- if (!s)
+ if (!s || unlikely(s->s_mds >= max_sessions))
Hi Xiubo,
I would be fine with this patch as is but I'm wondering if it can be
simplified further. Now that mdsc->mutex is held while sessions array
is populated, is checking s->s_mds against max_sessions actually
needed? Is it possible for some req->r_session on one of the unsafe
lists to have an "out of bounds" s_mds under mdsc->mutex?
Yeah, this can be simplified.
Let me do that.
Thanks!
- Xiubo
Thanks,
Ilya
