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[DLM] keep dlm from panicing when traversing rsb list in debugfs

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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 <jwhiter@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Josef Bacik 2007-05-16 15:56:13 -04:00 committed by Steven Whitehouse
parent 2a87ab0806
commit 916297aad5
1 changed files with 8 additions and 1 deletions
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9
fs/dlm/debug_fs.c
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@ -17,6 +17,7 @@
#include <linux/debugfs.h> #include <linux/debugfs.h>
#include "dlm_internal.h" #include "dlm_internal.h"
#include "lock.h"
#define DLM_DEBUG_BUF_LEN 4096 #define DLM_DEBUG_BUF_LEN 4096
static char debug_buf[DLM_DEBUG_BUF_LEN]; 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); read_lock(&ls->ls_rsbtbl[i].lock);
if (!list_empty(&ls->ls_rsbtbl[i].list)) { if (!list_empty(&ls->ls_rsbtbl[i].list)) {
ri->next = ls->ls_rsbtbl[i].list.next; 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); read_unlock(&ls->ls_rsbtbl[i].lock);
break; break;
} }
@ -176,6 +180,7 @@ static int rsb_iter_next(struct rsb_iter *ri)
if (ri->entry >= ls->ls_rsbtbl_size) if (ri->entry >= ls->ls_rsbtbl_size)
return 1; return 1;
} else { } else {
struct dlm_rsb *old = ri->rsb;
i = ri->entry; i = ri->entry;
read_lock(&ls->ls_rsbtbl[i].lock); read_lock(&ls->ls_rsbtbl[i].lock);
ri->next = ri->next->next; ri->next = ri->next->next;
@ -184,11 +189,13 @@ static int rsb_iter_next(struct rsb_iter *ri)
ri->next = NULL; ri->next = NULL;
ri->entry++; ri->entry++;
read_unlock(&ls->ls_rsbtbl[i].lock); read_unlock(&ls->ls_rsbtbl[i].lock);
dlm_put_rsb(old);
goto top; goto top;
} }
ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
read_unlock(&ls->ls_rsbtbl[i].lock); read_unlock(&ls->ls_rsbtbl[i].lock);
dlm_put_rsb(old);
} }
ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
return 0; return 0;
} }