On Tue, May 22, 2012 at 02:25:14PM +0400, Stanislav Kinsbursky wrote:
> 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.
All this indirection is getting a little much.
How about replacing nfsd_process_n_delegations by something that always
does the list-move?:
void nfsd_forget_delegations(u64 num)
{
unsigned int count;
list_head victims;
nfs4_lock_state();
count = nfsd_get_n_delegations(num, &victims);
list_for_each_entry_safe(..., &victims, ...)
unhash_delegation();
unlock_state();
}
ditto for recall_delegations, and take the recall_lock inside
nfsd_get_n_delegations?
Or something like that.
--b.
>
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 32 ++++++++++++++++++++++++--------
> 1 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 21266c7..f004e61 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -2597,7 +2597,7 @@ out:
> return ret;
> }
>
> -static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
> +static void nfsd_break_one_deleg(struct nfs4_delegation *dp, void *data)
> {
> /* We're assuming the state code never drops its reference
> * without first removing the lease. Since we're in this lease
> @@ -2633,7 +2633,7 @@ static void nfsd_break_deleg_cb(struct file_lock *fl)
> spin_lock(&recall_lock);
> fp->fi_had_conflict = true;
> list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
> - nfsd_break_one_deleg(dp);
> + nfsd_break_one_deleg(dp, NULL);
> spin_unlock(&recall_lock);
> }
>
> @@ -4694,7 +4694,7 @@ 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, void (*deleg_func)(struct nfs4_delegation *, void *), void *data)
> {
> int i, count = 0;
> struct nfs4_file *fp, *fnext;
> @@ -4703,7 +4703,7 @@ 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);
> + deleg_func(dp, data);
> if (++count == num)
> return count;
> }
> @@ -4713,15 +4713,31 @@ int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegatio
> return count;
> }
>
> +/* Called under the recall_lock spinlock. */
> +static void
> +collect_delegation(struct nfs4_delegation *dp, void *data)
> +{
> + struct list_head *list = data;
> +
> + list_move(&dp->dl_perfile, list);
> +}
> +
> void nfsd_forget_delegations(u64 num)
> {
> unsigned int count;
> + struct nfs4_delegation *dp, *dnext;
> + LIST_HEAD(unhash_list);
>
> - nfs4_lock_state();
> - count = nfsd_process_n_delegations(num, unhash_delegation);
> - nfs4_unlock_state();
> + spin_lock(&recall_lock);
> + count = nfsd_process_n_delegations(num, collect_delegation, &unhash_list);
> + spin_unlock(&recall_lock);
>
> printk(KERN_INFO "NFSD: Forgot %d delegations", count);
> +
> + nfs4_lock_state();
> + list_for_each_entry_safe(dp, dnext, &unhash_list, dl_perfile)
> + unhash_delegation(dp);
> + nfs4_unlock_state();
> }
>
> void nfsd_recall_delegations(u64 num)
> @@ -4730,7 +4746,7 @@ void nfsd_recall_delegations(u64 num)
>
> nfs4_lock_state();
> spin_lock(&recall_lock);
> - count = nfsd_process_n_delegations(num, nfsd_break_one_deleg);
> + count = nfsd_process_n_delegations(num, nfsd_break_one_deleg, NULL);
> spin_unlock(&recall_lock);
> nfs4_unlock_state();
>
>
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