On Tue, Nov 8, 2022 at 1:38 PM Xiubo Li xiubli@redhat.com wrote:
On 08/11/2022 18:50, Ilya Dryomov wrote:
On Tue, Nov 8, 2022 at 6:50 AM xiubli@redhat.com wrote:
From: Xiubo Li xiubli@redhat.com
The request's r_session maybe changed when it was forwarded or resent.
Cc: stable@vger.kernel.org URL: https://bugzilla.redhat.com/show_bug.cgi?id=2137955 Signed-off-by: Xiubo Li xiubli@redhat.com
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.
If you are removing max_session > 0 condition, I don't see a need to move this to "if (req1 || req2)" scope. I suggested that only because existing code was explicitly guarding against max_session == 0.
Thanks,
Ilya