fscache: Attach the index key and aux data to the cookie

Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>

1 files changed, 4 insertions, 116 deletions

diff --git a/fs/afs/cache.c b/fs/afs/cache.c
index cd857db9b112..a16f1e024cf3 100644
--- a/fs/afs/cache.c
+++ b/fs/afs/cache.c
@@ -12,17 +12,8 @@
 #include <linux/sched.h>
 #include "internal.h"
 
-static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
-				       void *buffer, uint16_t buflen);
-static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
-					 void *buffer, uint16_t buflen);
-
-static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
-					void *buffer, uint16_t buflen);
 static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
 				     uint64_t *size);
-static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
-					void *buffer, uint16_t buflen);
 static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
 						       const void *buffer,
 						       uint16_t buflen);
@@ -35,98 +26,21 @@ struct fscache_netfs afs_cache_netfs = {
 struct fscache_cookie_def afs_cell_cache_index_def = {
 	.name		= "AFS.cell",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-	.get_key	= afs_cell_cache_get_key,
 };
 
 struct fscache_cookie_def afs_volume_cache_index_def = {
 	.name		= "AFS.volume",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-	.get_key	= afs_volume_cache_get_key,
 };
 
 struct fscache_cookie_def afs_vnode_cache_index_def = {
-	.name			= "AFS.vnode",
-	.type			= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.get_key		= afs_vnode_cache_get_key,
-	.get_attr		= afs_vnode_cache_get_attr,
-	.get_aux		= afs_vnode_cache_get_aux,
-	.check_aux		= afs_vnode_cache_check_aux,
+	.name		= "AFS.vnode",
+	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
+	.get_attr	= afs_vnode_cache_get_attr,
+	.check_aux	= afs_vnode_cache_check_aux,
 };
 
 /*
- * set the key for the index entry
- */
-static uint16_t afs_cell_cache_get_key(const void *cookie_netfs_data,
-				       void *buffer, uint16_t bufmax)
-{
-	const struct afs_cell *cell = cookie_netfs_data;
-	uint16_t klen;
-
-	_enter("%p,%p,%u", cell, buffer, bufmax);
-
-	klen = strlen(cell->name);
-	if (klen > bufmax)
-		return 0;
-
-	memcpy(buffer, cell->name, klen);
-	return klen;
-}
-
-/*****************************************************************************/
-/*
- * set the key for the volume index entry
- */
-static uint16_t afs_volume_cache_get_key(const void *cookie_netfs_data,
-					 void *buffer, uint16_t bufmax)
-{
-	const struct afs_volume *volume = cookie_netfs_data;
-	struct {
-		u64 volid;
-	} __packed key;
-
-	_enter("{%u},%p,%u", volume->type, buffer, bufmax);
-
-	if (bufmax < sizeof(key))
-		return 0;
-
-	key.volid = volume->vid;
-	memcpy(buffer, &key, sizeof(key));
-	return sizeof(key);
-}
-
-/*****************************************************************************/
-/*
- * set the key for the index entry
- */
-static uint16_t afs_vnode_cache_get_key(const void *cookie_netfs_data,
-					void *buffer, uint16_t bufmax)
-{
-	const struct afs_vnode *vnode = cookie_netfs_data;
-	struct {
-		u32 vnode_id;
-		u32 unique;
-		u32 vnode_id_ext[2];	/* Allow for a 96-bit key */
-	} __packed key;
-
-	_enter("{%x,%x,%llx},%p,%u",
-	       vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
-	       buffer, bufmax);
-
-	/* Allow for a 96-bit key */
-	memset(&key, 0, sizeof(key));
-	key.vnode_id		= vnode->fid.vnode;
-	key.unique		= vnode->fid.unique;
-	key.vnode_id_ext[0]	= 0;
-	key.vnode_id_ext[1]	= 0;
-
-	if (sizeof(key) > bufmax)
-		return 0;
-
-	memcpy(buffer, &key, sizeof(key));
-	return sizeof(key);
-}
-
-/*
  * provide updated file attributes
  */
 static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
@@ -141,32 +55,6 @@ static void afs_vnode_cache_get_attr(const void *cookie_netfs_data,
 	*size = vnode->status.size;
 }
 
-struct afs_vnode_cache_aux {
-	u64 data_version;
-} __packed;
-
-/*
- * provide new auxiliary cache data
- */
-static uint16_t afs_vnode_cache_get_aux(const void *cookie_netfs_data,
-					void *buffer, uint16_t bufmax)
-{
-	const struct afs_vnode *vnode = cookie_netfs_data;
-	struct afs_vnode_cache_aux aux;
-
-	_enter("{%x,%x,%Lx},%p,%u",
-	       vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
-	       buffer, bufmax);
-
-	aux.data_version = vnode->status.data_version;
-
-	if (bufmax < sizeof(aux))
-		return 0;
-
-	memcpy(buffer, &aux, sizeof(aux));
-	return sizeof(aux);
-}
-
 /*
  * check that the auxiliary data indicates that the entry is still valid
  */