On Mon, May 3, 2010 at 7:48 AM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
> On Apr. 26, 2010, 19:18 +0300, andros@xxxxxxxxxx wrote:
>> From: Andy Adamson <andros@xxxxxxxxxx>
>>
>> A shared RCU device ID cache servicing multiple mounts of a single layout type
>> per meta data server (struct nfs_client).
>>
>> Device IDs of type deviceid4 are required by all layout types, long lived and
>> read at each I/O. They are added to the deviceid cache at first reference by
>> a layout via GETDEVICEINFO and (currently) are only removed at umount.
>>
>> Reference count the device ID cache for each mounted file system
>> in the initialize_mountpoint layoutdriver_io_operation.
>>
>> Dereference the device id cache on file system in the uninitialize_mountpoint
>> layoutdriver_io_operation called at umount
>>
>> Each layoutsegment assigns a pointer and takes a reference to the
>> nfs4_deviceid structure identified by the layout deviceid.
>> This is so that there are no deviceid lookups for the normal I/O path.
>>
>> Even thought required by all layouttypes, the deviceid is not exposed in the
>> LAYOUTGET4res but is instead hidden in the opaque layouttype4.
>>
>> Therefore, each layout type alloc_lseg calls nfs4_set_layout_deviceid,
>> and free_lseg calls nfs4_unset_layout_deviceid.
>>
>> While the file layout driver will not cache very many deviceid's, the object
>> and block layout drivers could cache 100's for a large installation.
>> Use an hlist.
>>
>> Signed-off-by: Andy Adamson <andros@xxxxxxxxxx>
>> ---
>> fs/nfs/pnfs.c | 167 +++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/nfs4_pnfs.h | 50 +++++++++++++
>> include/linux/nfs_fs_sb.h | 1 +
>> 3 files changed, 218 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>> index 91572aa..bf906cc 100644
>> --- a/fs/nfs/pnfs.c
>> +++ b/fs/nfs/pnfs.c
>> @@ -45,6 +45,7 @@
>> #include <linux/nfs4.h>
>> #include <linux/pnfs_xdr.h>
>> #include <linux/nfs4_pnfs.h>
>> +#include <linux/rculist.h>
>>
>> #include "internal.h"
>> #include "nfs4_fs.h"
>> @@ -2296,3 +2297,169 @@ struct pnfs_client_operations pnfs_ops = {
>>
>> EXPORT_SYMBOL(pnfs_unregister_layoutdriver);
>> EXPORT_SYMBOL(pnfs_register_layoutdriver);
>> +
>> +
>> +/* Device ID cache. Supports one layout type per struct nfs_client */
>> +int
>> +nfs4_alloc_init_deviceid_cache(struct nfs_client *clp,
>> + void (*free_callback)(struct kref *))
>> +{
>> + struct nfs4_deviceid_cache *c;
>> +
>> + c = kzalloc(sizeof(struct nfs4_deviceid_cache), GFP_KERNEL);
>> + if (!c)
>> + return -ENOMEM;
>> + spin_lock(&clp->cl_lock);
>> + if (clp->cl_devid_cache != NULL) {
>> + kref_get(&clp->cl_devid_cache->dc_kref);
>> + spin_unlock(&clp->cl_lock);
>> + dprintk("%s [kref [%d]]\n", __func__,
>> + atomic_read(&clp->cl_devid_cache->dc_kref.refcount));
>> + kfree(c);
>> + } else {
>> + int i;
>> +
>> + spin_lock_init(&c->dc_lock);
>> + for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE ; i++)
>> + INIT_HLIST_HEAD(&c->dc_deviceids[i]);
>> + kref_init(&c->dc_kref);
>> + c->dc_free_callback = free_callback;
>> + clp->cl_devid_cache = c;
>> + spin_unlock(&clp->cl_lock);
>> + dprintk("%s [new]\n", __func__);
>> + }
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(nfs4_alloc_init_deviceid_cache);
>> +
>> +void
>> +nfs4_init_deviceid_node(struct nfs4_deviceid *d)
>> +{
>> + INIT_HLIST_NODE(&d->de_node);
>> + kref_init(&d->de_kref);
>> +}
>> +EXPORT_SYMBOL(nfs4_init_deviceid_node);
>> +
>> +/* Called from layoutdriver_io_operations->alloc_lseg */
>> +void
>> +nfs4_set_layout_deviceid(struct pnfs_layout_segment *l, struct nfs4_deviceid *d)
>> +{
>> + dprintk("%s [%d]\n", __func__, atomic_read(&d->de_kref.refcount));
>> + l->deviceid = d;
>> + kref_get(&d->de_kref);
>> +}
>> +EXPORT_SYMBOL(nfs4_set_layout_deviceid);
>> +
>> +/* Called from layoutdriver_io_operations->free_lseg */
>> +void
>> +nfs4_unset_layout_deviceid(struct pnfs_layout_segment *l,
>> + struct nfs4_deviceid *d,
>> + void (*free_callback)(struct kref *))
>> +{
>> + dprintk("%s [%d]\n", __func__, atomic_read(&d->de_kref.refcount));
>> + l->deviceid = NULL;
>> + kref_put(&d->de_kref, free_callback);
>> +}
>> +EXPORT_SYMBOL(nfs4_unset_layout_deviceid);
>> +
>> +struct nfs4_deviceid *
>> +nfs4_find_deviceid(struct nfs4_deviceid_cache *c, struct pnfs_deviceid *id)
>> +{
>> + struct nfs4_deviceid *d;
>> + struct hlist_node *n;
>> + long hash = nfs4_deviceid_hash(id);
>> +
>> + dprintk("--> %s hash %ld\n", __func__, hash);
>> + rcu_read_lock();
>> + hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
>> + if (!memcmp(&d->de_id, id, NFS4_PNFS_DEVICEID4_SIZE)) {
>> + rcu_read_unlock();
>> + return d;
>> + }
>> + }
>> + rcu_read_unlock();
>> + return NULL;
>> +}
>> +EXPORT_SYMBOL(nfs4_find_deviceid);
>> +
>> +/*
>> + * Add or kref_get a deviceid.
>> + * GETDEVICEINFOs for same deviceid can race. If deviceid is found, discard new
>> + */
>> +struct nfs4_deviceid *
>> +nfs4_add_deviceid(struct nfs4_deviceid_cache *c, struct nfs4_deviceid *new)
>> +{
>> + struct nfs4_deviceid *d;
>> + struct hlist_node *n;
>> + long hash = nfs4_deviceid_hash(&new->de_id);
>> +
>> + dprintk("--> %s hash %ld\n", __func__, hash);
>> + spin_lock(&c->dc_lock);
>> + hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
>> + if (!memcmp(&d->de_id, &new->de_id, NFS4_PNFS_DEVICEID4_SIZE)) {
>> + spin_unlock(&c->dc_lock);
>> + dprintk("%s [discard]\n", __func__);
>> + c->dc_free_callback(&new->de_kref);
>> + return d;
>> + }
>> + }
>> + hlist_add_head_rcu(&new->de_node, &c->dc_deviceids[hash]);
>> + spin_unlock(&c->dc_lock);
>> + dprintk("%s [new]\n", __func__);
>> + return new;
>> +}
>> +EXPORT_SYMBOL(nfs4_add_deviceid);
>> +
>> +static int
>> +nfs4_remove_deviceid(struct nfs4_deviceid_cache *c, long hash)
>> +{
>> + struct nfs4_deviceid *d;
>> + struct hlist_node *n;
>> +
>> + dprintk("--> %s hash %ld\n", __func__, hash);
>> + spin_lock(&c->dc_lock);
>> + hlist_for_each_entry_rcu(d, n, &c->dc_deviceids[hash], de_node) {
>> + hlist_del_rcu(&d->de_node);
>> + spin_unlock(&c->dc_lock);
>> + synchronize_rcu();
>> + dprintk("%s [%d]\n", __func__,
>> + atomic_read(&d->de_kref.refcount));
>> + kref_put(&d->de_kref, c->dc_free_callback);
>> + return 1;
>> + }
>> + spin_unlock(&c->dc_lock);
>> + return 0;
>> +}
>> +
>> +static void
>> +nfs4_free_deviceid_cache(struct kref *kref)
>> +{
>> + struct nfs4_deviceid_cache *cache =
>> + container_of(kref, struct nfs4_deviceid_cache, dc_kref);
>> + int more;
>> + long i;
>> +
>> + for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i++) {
>> + more = 1;
>> + while (more)
>> + more = nfs4_remove_deviceid(cache, i);
>
> Andy, this can be simplified to
>
> while (nfs4_remove_deviceid(cache, i))
> ;
>
> If ok with you, I'll make this change upon merging.
Yes - looks fine, thanks.
-->Andy
>
> Benny
>
>> + }
>> + kfree(cache);
>> +}
>> +
>> +void
>> +nfs4_put_deviceid_cache(struct nfs_client *clp)
>> +{
>> + struct nfs4_deviceid_cache *tmp = clp->cl_devid_cache;
>> + int refcount;
>> +
>> + dprintk("--> %s cl_devid_cache %p\n", __func__, clp->cl_devid_cache);
>> + spin_lock(&clp->cl_lock);
>> + refcount = atomic_read(&clp->cl_devid_cache->dc_kref.refcount);
>> + if (refcount == 1)
>> + clp->cl_devid_cache = NULL;
>> + spin_unlock(&clp->cl_lock);
>> + dprintk("%s [%d]\n", __func__, refcount);
>> + kref_put(&tmp->dc_kref, nfs4_free_deviceid_cache);
>> +}
>> +EXPORT_SYMBOL(nfs4_put_deviceid_cache);
>> diff --git a/include/linux/nfs4_pnfs.h b/include/linux/nfs4_pnfs.h
>> index 3caac60..3b7aeb7 100644
>> --- a/include/linux/nfs4_pnfs.h
>> +++ b/include/linux/nfs4_pnfs.h
>> @@ -106,6 +106,7 @@ struct pnfs_layout_segment {
>> struct kref kref;
>> bool valid;
>> struct pnfs_layout_type *layout;
>> + struct nfs4_deviceid *deviceid;
>> u8 ld_data[]; /* layout driver private data */
>> };
>>
>> @@ -275,6 +276,55 @@ struct pnfs_devicelist {
>> struct pnfs_deviceid dev_id[NFS4_PNFS_GETDEVLIST_MAXNUM];
>> };
>>
>> +/*
>> + * Device ID RCU cache. A device ID is unique per client ID and layout type.
>> + */
>> +#define NFS4_DEVICE_ID_HASH_BITS 5
>> +#define NFS4_DEVICE_ID_HASH_SIZE (1 << NFS4_DEVICE_ID_HASH_BITS)
>> +#define NFS4_DEVICE_ID_HASH_MASK (NFS4_DEVICE_ID_HASH_SIZE - 1)
>> +
>> +static inline u32
>> +nfs4_deviceid_hash(struct pnfs_deviceid *id)
>> +{
>> + unsigned char *cptr = (unsigned char *)id->data;
>> + unsigned int nbytes = NFS4_PNFS_DEVICEID4_SIZE;
>> + u32 x = 0;
>> +
>> + while (nbytes--) {
>> + x *= 37;
>> + x += *cptr++;
>> + }
>> + return x & NFS4_DEVICE_ID_HASH_MASK;
>> +}
>> +
>> +struct nfs4_deviceid_cache {
>> + spinlock_t dc_lock;
>> + struct kref dc_kref;
>> + void (*dc_free_callback)(struct kref *);
>> + struct hlist_head dc_deviceids[NFS4_DEVICE_ID_HASH_SIZE];
>> +};
>> +
>> +/* Device ID cache node */
>> +struct nfs4_deviceid {
>> + struct hlist_node de_node;
>> + struct pnfs_deviceid de_id;
>> + struct kref de_kref;
>> +};
>> +
>> +extern int nfs4_alloc_init_deviceid_cache(struct nfs_client *,
>> + void (*free_callback)(struct kref *));
>> +extern void nfs4_put_deviceid_cache(struct nfs_client *);
>> +extern void nfs4_init_deviceid_node(struct nfs4_deviceid *);
>> +extern struct nfs4_deviceid *nfs4_find_deviceid(struct nfs4_deviceid_cache *,
>> + struct pnfs_deviceid *);
>> +extern struct nfs4_deviceid *nfs4_add_deviceid(struct nfs4_deviceid_cache *,
>> + struct nfs4_deviceid *);
>> +extern void nfs4_set_layout_deviceid(struct pnfs_layout_segment *,
>> + struct nfs4_deviceid *);
>> +extern void nfs4_unset_layout_deviceid(struct pnfs_layout_segment *,
>> + struct nfs4_deviceid *,
>> + void (*free_callback)(struct kref *));
>> +
>> /* pNFS client callback functions.
>> * These operations allow the layout driver to access pNFS client
>> * specific information or call pNFS client->server operations.
>> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
>> index 8522461..ef2e18e 100644
>> --- a/include/linux/nfs_fs_sb.h
>> +++ b/include/linux/nfs_fs_sb.h
>> @@ -87,6 +87,7 @@ struct nfs_client {
>> u32 cl_exchange_flags;
>> struct nfs4_session *cl_session; /* sharred session */
>> struct list_head cl_lo_inodes; /* Inodes having layouts */
>> + struct nfs4_deviceid_cache *cl_devid_cache; /* pNFS deviceid cache */
>> #endif /* CONFIG_NFS_V4_1 */
>>
>> #ifdef CONFIG_NFS_FSCACHE
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
