[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 <jwhiter@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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@ -17,6 +17,7 @@
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#include <linux/debugfs.h>
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#include <linux/debugfs.h>
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#include "dlm_internal.h"
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#include "dlm_internal.h"
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#include "lock.h"
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#define DLM_DEBUG_BUF_LEN 4096
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#define DLM_DEBUG_BUF_LEN 4096
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static char debug_buf[DLM_DEBUG_BUF_LEN];
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static char debug_buf[DLM_DEBUG_BUF_LEN];
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@ -166,6 +167,9 @@ static int rsb_iter_next(struct rsb_iter *ri)
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read_lock(&ls->ls_rsbtbl[i].lock);
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read_lock(&ls->ls_rsbtbl[i].lock);
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if (!list_empty(&ls->ls_rsbtbl[i].list)) {
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if (!list_empty(&ls->ls_rsbtbl[i].list)) {
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ri->next = ls->ls_rsbtbl[i].list.next;
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ri->next = ls->ls_rsbtbl[i].list.next;
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ri->rsb = list_entry(ri->next, struct dlm_rsb,
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res_hashchain);
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dlm_hold_rsb(ri->rsb);
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read_unlock(&ls->ls_rsbtbl[i].lock);
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read_unlock(&ls->ls_rsbtbl[i].lock);
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break;
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break;
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}
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}
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@ -176,6 +180,7 @@ static int rsb_iter_next(struct rsb_iter *ri)
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if (ri->entry >= ls->ls_rsbtbl_size)
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if (ri->entry >= ls->ls_rsbtbl_size)
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return 1;
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return 1;
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} else {
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} else {
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struct dlm_rsb *old = ri->rsb;
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i = ri->entry;
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i = ri->entry;
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read_lock(&ls->ls_rsbtbl[i].lock);
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read_lock(&ls->ls_rsbtbl[i].lock);
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ri->next = ri->next->next;
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ri->next = ri->next->next;
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@ -184,11 +189,13 @@ static int rsb_iter_next(struct rsb_iter *ri)
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ri->next = NULL;
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ri->next = NULL;
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ri->entry++;
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ri->entry++;
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read_unlock(&ls->ls_rsbtbl[i].lock);
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read_unlock(&ls->ls_rsbtbl[i].lock);
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dlm_put_rsb(old);
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goto top;
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goto top;
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}
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}
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ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
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read_unlock(&ls->ls_rsbtbl[i].lock);
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read_unlock(&ls->ls_rsbtbl[i].lock);
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dlm_put_rsb(old);
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}
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}
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ri->rsb = list_entry(ri->next, struct dlm_rsb, res_hashchain);
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return 0;
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return 0;
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}
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}
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