From: Joseph Qi Date: Mon, 19 Sep 2016 21:43:55 +0000 (-0700) Subject: ocfs2/dlm: fix race between convert and migration X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e6f0c6e6170fec175fe676495f29029aecdf486c;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git ocfs2/dlm: fix race between convert and migration Commit ac7cf246dfdb ("ocfs2/dlm: fix race between convert and recovery") checks if lockres master has changed to identify whether new master has finished recovery or not. This will introduce a race that right after old master does umount ( means master will change), a new convert request comes. In this case, it will reset lockres state to DLM_RECOVERING and then retry convert, and then fail with lockres->l_action being set to OCFS2_AST_INVALID, which will cause inconsistent lock level between ocfs2 and dlm, and then finally BUG. Since dlm recovery will clear lock->convert_pending in dlm_move_lockres_to_recovery_list, we can use it to correctly identify the race case between convert and recovery. So fix it. Fixes: ac7cf246dfdb ("ocfs2/dlm: fix race between convert and recovery") Link: http://lkml.kernel.org/r/57CE1569.8010704@huawei.com Signed-off-by: Joseph Qi Signed-off-by: Jun Piao Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/ocfs2/dlm/dlmconvert.c b/fs/ocfs2/dlm/dlmconvert.c index cdeafb4e7ed6..0bb128659d4b 100644 --- a/fs/ocfs2/dlm/dlmconvert.c +++ b/fs/ocfs2/dlm/dlmconvert.c @@ -268,7 +268,6 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm, struct dlm_lock *lock, int flags, int type) { enum dlm_status status; - u8 old_owner = res->owner; mlog(0, "type=%d, convert_type=%d, busy=%d\n", lock->ml.type, lock->ml.convert_type, res->state & DLM_LOCK_RES_IN_PROGRESS); @@ -335,7 +334,6 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm, spin_lock(&res->spinlock); res->state &= ~DLM_LOCK_RES_IN_PROGRESS; - lock->convert_pending = 0; /* if it failed, move it back to granted queue. * if master returns DLM_NORMAL and then down before sending ast, * it may have already been moved to granted queue, reset to @@ -344,12 +342,14 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm, if (status != DLM_NOTQUEUED) dlm_error(status); dlm_revert_pending_convert(res, lock); - } else if ((res->state & DLM_LOCK_RES_RECOVERING) || - (old_owner != res->owner)) { - mlog(0, "res %.*s is in recovering or has been recovered.\n", - res->lockname.len, res->lockname.name); + } else if (!lock->convert_pending) { + mlog(0, "%s: res %.*s, owner died and lock has been moved back " + "to granted list, retry convert.\n", + dlm->name, res->lockname.len, res->lockname.name); status = DLM_RECOVERING; } + + lock->convert_pending = 0; bail: spin_unlock(&res->spinlock);