From: Alex Zhuravlev <bzzz@whamcloud.com>
Date: Mon, 2 May 2022 18:38:47 +0000 (+0300)
Subject: LU-15761 obdclass: fix locking in llog_cat_refresh()
X-Git-Tag: 2.15.0-RC4~2
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=69cdcbe3cf732124b3b5be1a1f235aa1b78f6c85;p=fs%2Flustre-release.git

LU-15761 obdclass: fix locking in llog_cat_refresh()

the patch fixes two problems:
1) pairing up_write() should be used with cathandle
2) llog_read_header() manipulates loghandle's internal
   structures (header, last_idx, etc) which are supposed
   to stay consistent from another user's point of view
   (like llog_add_rec())

Fixes: 71f409c9b31b ("LU-11418 llog: refresh remote llog upon -ESTALE")
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: Ib86e10a925b541d02c22d74e6ddbc4368345ac11
Reviewed-on: https://review.whamcloud.com/47185
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/lustre/obdclass/llog_cat.c b/lustre/obdclass/llog_cat.c
index 97f15e4..3f53dab 100644
--- a/lustre/obdclass/llog_cat.c
+++ b/lustre/obdclass/llog_cat.c
@@ -246,14 +246,16 @@ static int llog_cat_refresh(const struct lu_env *env,
 		if (!llog_exist(loghandle))
 			continue;
 
+		down_write(&loghandle->lgh_lock);
 		rc = llog_read_header(env, loghandle, NULL);
+		up_write(&loghandle->lgh_lock);
 		if (rc)
 			goto unlock;
 	}
 
 	rc = llog_read_header(env, cathandle, NULL);
 unlock:
-	up_write(&loghandle->lgh_lock);
+	up_write(&cathandle->lgh_lock);
 
 	return rc;
 }