From 916297aad5de2363dccd531873eda55d4d6afb57 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 16 May 2007 15:56:13 -0400 Subject: [PATCH] [DLM] keep dlm from panicing when traversing rsb list in debugfs This problem was originally reported against GFS6.1, but the same issue exists in upstream DLM. This patch keeps the rsb iterator assigning under the rsbtbl list lock. Each time we process an rsb we grab a reference to it to make sure it is not freed out from underneath us, and then put it when we get the next rsb in the list or move onto another list. Signed-off-by: Josef Bacik Signed-off-by: Steven Whitehouse --- fs/dlm/debug_fs.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c index 61ba670b9e02..9e27a1675794 100644 --- a/fs/dlm/debug_fs.c +++ b/fs/dlm/debug_fs.c @@ -17,6 +17,7 @@ #include #include "dlm_internal.h" +#include "lock.h" #define DLM_DEBUG_BUF_LEN 4096 static char debug_buf[DLM_DEBUG_BUF_LEN]; @@ -166,6 +167,9 @@ static int rsb_iter_next(struct rsb_iter *ri) read_lock(&ls->ls_rsbtbl[i].lock); if (!list_empty(&ls->ls_rsbtbl[i].list)) { ri->next = ls->ls_rsbtbl[i].list.next; + ri->rsb = list_entry(ri->next, struct dlm_rsb, + res_hashchain); + dlm_hold_rsb(ri->rsb); read_unlock(&ls->ls_rsbtbl[i].lock); break; } @@ -176,6 +180,7 @@ static int rsb_iter_next(struct rsb_iter *ri) if (ri->entry >= ls->ls_rsbtbl_size) return 1; } else { + struct dlm_rsb *old = ri->rsb; i = ri->entry; read_lock(&ls->ls_rsbtbl[i].lock); ri->next = ri->next->next; @@ -184,11 +189,13 @@ static int rsb_iter_next(struct rsb_iter *ri) ri->next = NULL; ri->entry++; read_unlock(&ls->ls_rsbtbl[i].lock); + dlm_put_rsb(old); goto top; } + ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain); read_unlock(&ls->ls_rsbtbl[i].lock); + dlm_put_rsb(old); } - ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain); return 0; }