On 08/11/2022 18:50, Ilya Dryomov wrote:
On Tue, Nov 8, 2022 at 6:50 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>
---
fs/ceph/caps.c | 88 +++++++++++++++++++-------------------------------
1 file changed, 33 insertions(+), 55 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 894adfb4a092..172f18f7459d 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2297,8 +2297,9 @@ 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;
+ struct ceph_mds_session *s, **sessions = NULL;
Hi Xiubo,
Nit: mixing pointers and double pointers coupled with differing
initialization is generally frowned upon. Keep it on two lines as
before:
struct ceph_mds_session **sessions = NULL;
struct ceph_mds_session *s;
Sure, will fix it.
unsigned int max_sessions;
- int ret, err = 0;
+ int i, ret, err = 0;
spin_lock(&ci->i_unsafe_lock);
if (S_ISDIR(inode->i_mode) && !list_empty(&ci->i_unsafe_dirops)) {
@@ -2315,31 +2316,22 @@ 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.
*/
+ 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;
+ }
+
if ((req1 || req2) && likely(max_sessions)) {
Just curious, when can max_sessions be zero here?
Checked the code again, just before registering the first session, and
this is monotone increasing. It should be safe to remove this here.
- struct ceph_mds_session **sessions = NULL;
- struct ceph_mds_session *s;
struct ceph_mds_request *req;
- int i;
-
- sessions = kcalloc(max_sessions, sizeof(s), GFP_KERNEL);
- if (!sessions) {
- err = -ENOMEM;
- goto out;
- }
spin_lock(&ci->i_unsafe_lock);
if (req1) {
@@ -2348,16 +2340,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
s = req->r_session;
if (!s)
continue;
- if (unlikely(s->s_mds >= max_sessions)) {
- spin_unlock(&ci->i_unsafe_lock);
- for (i = 0; i < max_sessions; i++) {
- s = sessions[i];
- if (s)
- ceph_put_mds_session(s);
- }
- kfree(sessions);
- goto retry;
- }
+ if (unlikely(s->s_mds >= max_sessions))
+ continue;
Nit: this could be combined with the previous condition:
if (!s || unlikely(s->s_mds >= max_sessions))
continue;
Sure.
if (!sessions[s->s_mds]) {
s = ceph_get_mds_session(s);
sessions[s->s_mds] = s;
@@ -2370,16 +2354,8 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
s = req->r_session;
if (!s)
continue;
- if (unlikely(s->s_mds >= max_sessions)) {
- spin_unlock(&ci->i_unsafe_lock);
- for (i = 0; i < max_sessions; i++) {
- s = sessions[i];
- if (s)
- ceph_put_mds_session(s);
- }
- kfree(sessions);
- goto retry;
- }
+ if (unlikely(s->s_mds >= max_sessions))
+ continue;
ditto
if (!sessions[s->s_mds]) {
s = ceph_get_mds_session(s);
sessions[s->s_mds] = s;
@@ -2387,25 +2363,26 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
}
}
spin_unlock(&ci->i_unsafe_lock);
+ }
+ mutex_unlock(&mdsc->mutex);
- /* the auth MDS */
- spin_lock(&ci->i_ceph_lock);
- if (ci->i_auth_cap) {
- s = ci->i_auth_cap->session;
- if (!sessions[s->s_mds])
- sessions[s->s_mds] = ceph_get_mds_session(s);
- }
- spin_unlock(&ci->i_ceph_lock);
+ /* the auth MDS */
+ spin_lock(&ci->i_ceph_lock);
Why was this "auth MDS" block moved outside of max_sessions > 0
branch? Logically, it very much belongs there. Is there a problem
with taking ci->i_ceph_lock under mdsc->mutex?
I will remove the 'likely(max_session)' and there is no any problem for
this.
+ if (ci->i_auth_cap) {
+ s = ci->i_auth_cap->session;
+ if (!sessions[s->s_mds] &&
+ likely(s->s_mds < max_sessions))
This is wrong: s->s_mds must be checked against max_sessions before
indexing into sessions array. Also, the entire condition should fit on
a single line.
I am moving it to the if(req1 || req2) {} scope and it will exceed 80
chars. And will keep it in two lines.
+ sessions[s->s_mds] = ceph_get_mds_session(s);
+ }
+ spin_unlock(&ci->i_ceph_lock);
- /* send flush mdlog request to MDSes */
- for (i = 0; i < max_sessions; i++) {
- s = sessions[i];
- if (s) {
- send_flush_mdlog(s);
- ceph_put_mds_session(s);
- }
+ /* send flush mdlog request to MDSes */
+ for (i = 0; i < max_sessions; i++) {
+ s = sessions[i];
+ if (s) {
+ send_flush_mdlog(s);
+ ceph_put_mds_session(s);
}
- kfree(sessions);
}
dout("%s %p wait on tid %llu %llu\n", __func__,
@@ -2428,6 +2405,7 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
ceph_mdsc_put_request(req1);
if (req2)
ceph_mdsc_put_request(req2);
+ kfree(sessions);
Nit: since sessions array is allocated after references to req1 and
req2 are grabbed, I would free it before these references are put.
Sure!
Thanks!
- Xiubo
Thanks,
Ilya
