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, 1 insertions, 48 deletions

diff --git a/fs/fscache/fsdef.c b/fs/fscache/fsdef.c
index 5a117df2a9ef..1122e97d56e8 100644
--- a/fs/fscache/fsdef.c
+++ b/fs/fscache/fsdef.c
@@ -13,12 +13,6 @@
 #include <linux/module.h>
 #include "internal.h"
 
-static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
-					    void *buffer, uint16_t bufmax);
-
-static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
-					    void *buffer, uint16_t bufmax);
-
 static
 enum fscache_checkaux fscache_fsdef_netfs_check_aux(void *cookie_netfs_data,
 						    const void *data,
@@ -60,6 +54,7 @@ struct fscache_cookie fscache_fsdef_index = {
 	.backing_objects = HLIST_HEAD_INIT,
 	.def		= &fscache_fsdef_index_def,
 	.flags		= 1 << FSCACHE_COOKIE_ENABLED,
+	.type		= FSCACHE_COOKIE_TYPE_INDEX,
 };
 EXPORT_SYMBOL(fscache_fsdef_index);
 
@@ -71,52 +66,10 @@ EXPORT_SYMBOL(fscache_fsdef_index);
 struct fscache_cookie_def fscache_fsdef_netfs_def = {
 	.name		= "FSDEF.netfs",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-	.get_key	= fscache_fsdef_netfs_get_key,
-	.get_aux	= fscache_fsdef_netfs_get_aux,
 	.check_aux	= fscache_fsdef_netfs_check_aux,
 };
 
 /*
- * get the key data for an FSDEF index record - this is the name of the netfs
- * for which this entry is created
- */
-static uint16_t fscache_fsdef_netfs_get_key(const void *cookie_netfs_data,
-					    void *buffer, uint16_t bufmax)
-{
-	const struct fscache_netfs *netfs = cookie_netfs_data;
-	unsigned klen;
-
-	_enter("{%s.%u},", netfs->name, netfs->version);
-
-	klen = strlen(netfs->name);
-	if (klen > bufmax)
-		return 0;
-
-	memcpy(buffer, netfs->name, klen);
-	return klen;
-}
-
-/*
- * get the auxiliary data for an FSDEF index record - this is the index
- * structure version number of the netfs for which this version is created
- */
-static uint16_t fscache_fsdef_netfs_get_aux(const void *cookie_netfs_data,
-					    void *buffer, uint16_t bufmax)
-{
-	const struct fscache_netfs *netfs = cookie_netfs_data;
-	unsigned dlen;
-
-	_enter("{%s.%u},", netfs->name, netfs->version);
-
-	dlen = sizeof(uint32_t);
-	if (dlen > bufmax)
-		return 0;
-
-	memcpy(buffer, &netfs->version, dlen);
-	return dlen;
-}
-
-/*
  * check that the index structure version number stored in the auxiliary data
  * matches the one the netfs gave us
  */