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, 13 insertions, 15 deletions

diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c
index 0438d4cd91ef..43e6e28c164f 100644
--- a/fs/fscache/object-list.c
+++ b/fs/fscache/object-list.c
@@ -36,8 +36,6 @@ struct fscache_objlist_data {
 #define FSCACHE_OBJLIST_CONFIG_NOEVENTS	0x00000800	/* show objects without no events */
 #define FSCACHE_OBJLIST_CONFIG_WORK	0x00001000	/* show objects with work */
 #define FSCACHE_OBJLIST_CONFIG_NOWORK	0x00002000	/* show objects without work */
-
-	u8		buf[512];	/* key and aux data buffer */
 };
 
 /*
@@ -170,7 +168,7 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 	struct fscache_cookie *cookie;
 	unsigned long config = data->config;
 	char _type[3], *type;
-	u8 *buf = data->buf, *p;
+	u8 *p;
 
 	if ((unsigned long) v == 1) {
 		seq_puts(m, "OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS"
@@ -254,7 +252,7 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 	if (fscache_use_cookie(obj)) {
 		uint16_t keylen = 0, auxlen = 0;
 
-		switch (cookie->def->type) {
+		switch (cookie->type) {
 		case 0:
 			type = "IX";
 			break;
@@ -263,7 +261,7 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 			break;
 		default:
 			snprintf(_type, sizeof(_type), "%02u",
-				 cookie->def->type);
+				 cookie->type);
 			type = _type;
 			break;
 		}
@@ -274,30 +272,30 @@ static int fscache_objlist_show(struct seq_file *m, void *v)
 			   cookie->flags,
 			   cookie->netfs_data);
 
-		if (cookie->def->get_key &&
-		    config & FSCACHE_OBJLIST_CONFIG_KEY)
-			keylen = cookie->def->get_key(cookie->netfs_data,
-						      buf, 400);
+		if (config & FSCACHE_OBJLIST_CONFIG_KEY)
+			keylen = cookie->key_len;
 
-		if (cookie->def->get_aux &&
-		    config & FSCACHE_OBJLIST_CONFIG_AUX)
-			auxlen = cookie->def->get_aux(cookie->netfs_data,
-						      buf + keylen, 512 - keylen);
-		fscache_unuse_cookie(obj);
+		if (config & FSCACHE_OBJLIST_CONFIG_AUX)
+			auxlen = cookie->aux_len;
 
 		if (keylen > 0 || auxlen > 0) {
 			seq_puts(m, " ");
-			for (p = buf; keylen > 0; keylen--)
+			p = keylen <= sizeof(cookie->inline_key) ?
+				cookie->inline_key : cookie->key;
+			for (; keylen > 0; keylen--)
 				seq_printf(m, "%02x", *p++);
 			if (auxlen > 0) {
 				if (config & FSCACHE_OBJLIST_CONFIG_KEY)
 					seq_puts(m, ", ");
+				p = auxlen <= sizeof(cookie->inline_aux) ?
+					cookie->inline_aux : cookie->aux;
 				for (; auxlen > 0; auxlen--)
 					seq_printf(m, "%02x", *p++);
 			}
 		}
 
 		seq_puts(m, "\n");
+		fscache_unuse_cookie(obj);
 	} else {
 		seq_puts(m, "<no_netfs>\n");
 	}