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Commit a6d88f29 authored by Stanislav Kinsbursky's avatar Stanislav Kinsbursky Committed by J. Bruce Fields
Browse files

NFSd: fix locking in nfsd_forget_delegations() 



This patch adds recall_lock hold to nfsd_forget_delegations() to protect
nfsd_process_n_delegations() call.
Also, looks like it would be better to collect delegations to some local
on-stack list, and then unhash collected list. This split allows to
simplify locking, because delegation traversing is protected by recall_lock,
when delegation unhash is protected by client_mutex.

Signed-off-by: default avatarStanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 5559b50a

fs/nfsd/nfs4state.c

+17 −6
Original line number Diff line number Diff line
@@ -4575,7 +4575,7 @@ void nfsd_forget_openowners(u64 num) 
	printk(KERN_INFO "NFSD: Forgot %d open owners", count);

}



int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegation *))

int nfsd_process_n_delegations(u64 num, struct list_head *list)

{

	int i, count = 0;

	struct nfs4_file *fp, *fnext;
@@ -4584,7 +4584,7 @@ int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegatio 
	for (i = 0; i < FILE_HASH_SIZE; i++) {

		list_for_each_entry_safe(fp, fnext, &file_hashtbl[i], fi_hash) {

			list_for_each_entry_safe(dp, dnext, &fp->fi_delegations, dl_perfile) {

				deleg_func(dp);

				list_move(&dp->dl_recall_lru, list);

				if (++count == num)

					return count;

			}
@@ -4597,9 +4597,16 @@ int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegatio 
void nfsd_forget_delegations(u64 num)

{

	unsigned int count;

	LIST_HEAD(victims);

	struct nfs4_delegation *dp, *dnext;



	spin_lock(&recall_lock);

	count = nfsd_process_n_delegations(num, &victims);

	spin_unlock(&recall_lock);



	nfs4_lock_state();

	count = nfsd_process_n_delegations(num, unhash_delegation);

	list_for_each_entry_safe(dp, dnext, &victims, dl_recall_lru)

		unhash_delegation(dp);

	nfs4_unlock_state();



	printk(KERN_INFO "NFSD: Forgot %d delegations", count);
@@ -4608,12 +4615,16 @@ void nfsd_forget_delegations(u64 num) 
void nfsd_recall_delegations(u64 num)

{

	unsigned int count;

	LIST_HEAD(victims);

	struct nfs4_delegation *dp, *dnext;



	nfs4_lock_state();

	spin_lock(&recall_lock);

	count = nfsd_process_n_delegations(num, nfsd_break_one_deleg);

	count = nfsd_process_n_delegations(num, &victims);

	list_for_each_entry_safe(dp, dnext, &victims, dl_recall_lru) {

		list_del(&dp->dl_recall_lru);

		nfsd_break_one_deleg(dp);

	}

	spin_unlock(&recall_lock);

	nfs4_unlock_state();



	printk(KERN_INFO "NFSD: Recalled %d delegations", count);

}