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dlm: fix race between remove and lookup

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It was possible for a remove message on an old
rsb to be sent after a lookup message on a new
rsb, where the rsbs were for the same resource
name.  This could lead to a missing directory
entry for the new rsb.

It is fixed by keeping a copy of the resource
name being removed until after the remove has
been sent.  A lookup checks if this in-progress
remove matches the name it is looking up.

Signed-off-by: David Teigland <teigland@redhat.com>
This commit is contained in:
David Teigland
2012-06-14 12:17:32 -05:00
parent 1d7c484eeb
commit 05c32f47bf
3 changed files with 178 additions and 41 deletions
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13
fs/dlm/dlm_internal.h
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@@ -498,6 +498,13 @@ struct rcom_lock {
char rl_lvb[0];
};
/*
* The max number of resources per rsbtbl bucket that shrink will attempt
* to remove in each iteration.
*/
#define DLM_REMOVE_NAMES_MAX 8
struct dlm_ls {
struct list_head ls_list; /* list of lockspaces */
dlm_lockspace_t *ls_local_handle;
@@ -531,6 +538,12 @@ struct dlm_ls {
int ls_new_rsb_count;
struct list_head ls_new_rsb; /* new rsb structs */
spinlock_t ls_remove_spin;
char ls_remove_name[DLM_RESNAME_MAXLEN+1];
char *ls_remove_names[DLM_REMOVE_NAMES_MAX];
int ls_remove_len;
int ls_remove_lens[DLM_REMOVE_NAMES_MAX];
struct list_head ls_nodes; /* current nodes in ls */
struct list_head ls_nodes_gone; /* dead node list, recovery */
int ls_num_nodes; /* number of nodes in ls */