From: andros@netapp.com Subject: [PATCH 1/3] SQUASHME pnfs_submit: generic device ID cache Date: Mon, 26 Apr 2010 12:18:17 -0400 Message-ID: <1272298699-11411-2-git-send-email-andros@netapp.com> References: <1272298699-11411-1-git-send-email-andros@netapp.com> Cc: linux-nfs@vger.kernel.org, Andy Adamson To: pnfs@linux-nfs.org Return-path: Received: from mx2.netapp.com ([216.240.18.37]:14524 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752918Ab0DZQSR (ORCPT ); Mon, 26 Apr 2010 12:18:17 -0400 In-Reply-To: <1272298699-11411-1-git-send-email-andros@netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: From: Andy Adamson 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 --- 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 #include #include +#include #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); + } + 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 -- 1.6.6