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md-cluster: fix hanging issue while a new disk adding

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The commit 1bbe254e4336 ("md-cluster: check for timeout while a
new disk adding") is correct in terms of code syntax but not
suite real clustered code logic.

When a timeout occurs while adding a new disk, if recv_daemon()
bypasses the unlock for ack_lockres:CR, another node will be waiting
to grab EX lock. This will cause the cluster to hang indefinitely.

How to fix:

1. In dlm_lock_sync(), change the wait behaviour from forever to a
   timeout, This could avoid the hanging issue when another node
   fails to handle cluster msg. Another result of this change is
   that if another node receives an unknown msg (e.g. a new msg_type),
   the old code will hang, whereas the new code will timeout and fail.
   This could help cluster_md handle new msg_type from different
   nodes with different kernel/module versions (e.g. The user only
   updates one leg's kernel and monitors the stability of the new
   kernel).
2. The old code for __sendmsg() always returns 0 (success) under the
   design (must successfully unlock ->message_lockres). This commit
   makes this function return an error number when an error occurs.

Fixes: 1bbe254e4336 ("md-cluster: check for timeout while a new disk adding")
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Su Yue <glass.su@suse.com>
Acked-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240709104120.22243-1-heming.zhao@suse.com
This commit is contained in:
Heming Zhao 2024-07-09 18:41:19 +08:00 committed by Song Liu
parent 3c1743a685
commit fff42f2138
1 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/md/md-cluster.c
View File

@ -15,6 +15,7 @@
#define LVB_SIZE 64
#define NEW_DEV_TIMEOUT 5000
#define WAIT_DLM_LOCK_TIMEOUT (30 * HZ)
struct dlm_lock_resource {
dlm_lockspace_t *ls;
@ -130,8 +131,13 @@ static int dlm_lock_sync(struct dlm_lock_resource *res, int mode)
0, sync_ast, res, res->bast);
if (ret)
return ret;
wait_event(res->sync_locking, res->sync_locking_done);
ret = wait_event_timeout(res->sync_locking, res->sync_locking_done,
WAIT_DLM_LOCK_TIMEOUT);
res->sync_locking_done = false;
if (!ret) {
pr_err("locking DLM '%s' timeout!\n", res->name);
return -EBUSY;
}
if (res->lksb.sb_status == 0)
res->mode = mode;
return res->lksb.sb_status;
@ -743,7 +749,7 @@ static void unlock_comm(struct md_cluster_info *cinfo)
*/
static int __sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
{
int error;
int error, unlock_error;
int slot = cinfo->slot_number - 1;
cmsg->slot = cpu_to_le32(slot);
@ -751,7 +757,7 @@ static int __sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
error = dlm_lock_sync(cinfo->message_lockres, DLM_LOCK_EX);
if (error) {
pr_err("md-cluster: failed to get EX on MESSAGE (%d)\n", error);
goto failed_message;
return error;
}
memcpy(cinfo->message_lockres->lksb.sb_lvbptr, (void *)cmsg,
@ -781,14 +787,10 @@ static int __sendmsg(struct md_cluster_info *cinfo, struct cluster_msg *cmsg)
}
failed_ack:
error = dlm_unlock_sync(cinfo->message_lockres);
if (unlikely(error != 0)) {
while ((unlock_error = dlm_unlock_sync(cinfo->message_lockres)))
pr_err("md-cluster: failed convert to NL on MESSAGE(%d)\n",
error);
/* in case the message can't be released due to some reason */
goto failed_ack;
}
failed_message:
unlock_error);
return error;
}