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, 25 insertions, 68 deletions

diff --git a/fs/ceph/cache.c b/fs/ceph/cache.c
index a3ab265d3215..fee869061f05 100644
--- a/fs/ceph/cache.c
+++ b/fs/ceph/cache.c
@@ -41,34 +41,15 @@ static LIST_HEAD(ceph_fscache_list);
 struct ceph_fscache_entry {
 	struct list_head list;
 	struct fscache_cookie *fscache;
-	struct ceph_fsid fsid;
 	size_t uniq_len;
+	/* The following members must be last */
+	struct ceph_fsid fsid;
 	char uniquifier[0];
 };
 
-static uint16_t ceph_fscache_session_get_key(const void *cookie_netfs_data,
-					     void *buffer, uint16_t maxbuf)
-{
-	const struct ceph_fs_client* fsc = cookie_netfs_data;
-	const char *fscache_uniq = fsc->mount_options->fscache_uniq;
-	uint16_t fsid_len, uniq_len;
-
-	fsid_len = sizeof(fsc->client->fsid);
-	uniq_len = fscache_uniq ? strlen(fscache_uniq) : 0;
-	if (fsid_len + uniq_len > maxbuf)
-		return 0;
-
-	memcpy(buffer, &fsc->client->fsid, fsid_len);
-	if (uniq_len)
-		memcpy(buffer + fsid_len, fscache_uniq, uniq_len);
-
-	return fsid_len + uniq_len;
-}
-
 static const struct fscache_cookie_def ceph_fscache_fsid_object_def = {
 	.name		= "CEPH.fsid",
 	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-	.get_key	= ceph_fscache_session_get_key,
 };
 
 int ceph_fscache_register(void)
@@ -110,16 +91,19 @@ int ceph_fscache_register_fs(struct ceph_fs_client* fsc)
 		goto out_unlock;
 	}
 
+	memcpy(&ent->fsid, fsid, sizeof(*fsid));
+	if (uniq_len > 0) {
+		memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
+		ent->uniq_len = uniq_len;
+	}
+
 	fsc->fscache = fscache_acquire_cookie(ceph_cache_netfs.primary_index,
 					      &ceph_fscache_fsid_object_def,
+					      &ent->fsid, sizeof(ent->fsid) + uniq_len,
+					      NULL, 0,
 					      fsc, true);
 
 	if (fsc->fscache) {
-		memcpy(&ent->fsid, fsid, sizeof(*fsid));
-		if (uniq_len > 0) {
-			memcpy(&ent->uniquifier, fscache_uniq, uniq_len);
-			ent->uniq_len = uniq_len;
-		}
 		ent->fscache = fsc->fscache;
 		list_add_tail(&ent->list, &ceph_fscache_list);
 	} else {
@@ -133,38 +117,6 @@ out_unlock:
 	return err;
 }
 
-static uint16_t ceph_fscache_inode_get_key(const void *cookie_netfs_data,
-					   void *buffer, uint16_t maxbuf)
-{
-	const struct ceph_inode_info* ci = cookie_netfs_data;
-	uint16_t klen;
-
-	/* use ceph virtual inode (id + snapshot) */
-	klen = sizeof(ci->i_vino);
-	if (klen > maxbuf)
-		return 0;
-
-	memcpy(buffer, &ci->i_vino, klen);
-	return klen;
-}
-
-static uint16_t ceph_fscache_inode_get_aux(const void *cookie_netfs_data,
-					   void *buffer, uint16_t bufmax)
-{
-	struct ceph_aux_inode aux;
-	const struct ceph_inode_info* ci = cookie_netfs_data;
-	const struct inode* inode = &ci->vfs_inode;
-
-	memset(&aux, 0, sizeof(aux));
-	aux.version = ci->i_version;
-	aux.mtime = inode->i_mtime;
-	aux.size = i_size_read(inode);
-
-	memcpy(buffer, &aux, sizeof(aux));
-
-	return sizeof(aux);
-}
-
 static void ceph_fscache_inode_get_attr(const void *cookie_netfs_data,
 					uint64_t *size)
 {
@@ -197,9 +149,7 @@ static enum fscache_checkaux ceph_fscache_inode_check_aux(
 static const struct fscache_cookie_def ceph_fscache_inode_object_def = {
 	.name		= "CEPH.inode",
 	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.get_key	= ceph_fscache_inode_get_key,
 	.get_attr	= ceph_fscache_inode_get_attr,
-	.get_aux	= ceph_fscache_inode_get_aux,
 	.check_aux	= ceph_fscache_inode_check_aux,
 };
 
@@ -207,6 +157,7 @@ void ceph_fscache_register_inode_cookie(struct inode *inode)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
+	struct ceph_aux_inode aux;
 
 	/* No caching for filesystem */
 	if (!fsc->fscache)
@@ -218,9 +169,15 @@ void ceph_fscache_register_inode_cookie(struct inode *inode)
 
 	inode_lock_nested(inode, I_MUTEX_CHILD);
 	if (!ci->fscache) {
+		memset(&aux, 0, sizeof(aux));
+		aux.version = ci->i_version;
+		aux.mtime = inode->i_mtime;
+		aux.size = i_size_read(inode);
 		ci->fscache = fscache_acquire_cookie(fsc->fscache,
-					&ceph_fscache_inode_object_def,
-					ci, false);
+						     &ceph_fscache_inode_object_def,
+						     &ci->i_vino, sizeof(ci->i_vino),
+						     &aux, sizeof(aux),
+						     ci, false);
 	}
 	inode_unlock(inode);
 }
@@ -235,7 +192,7 @@ void ceph_fscache_unregister_inode_cookie(struct ceph_inode_info* ci)
 	ci->fscache = NULL;
 
 	fscache_uncache_all_inode_pages(cookie, &ci->vfs_inode);
-	fscache_relinquish_cookie(cookie, 0);
+	fscache_relinquish_cookie(cookie, &ci->i_vino, false);
 }
 
 static bool ceph_fscache_can_enable(void *data)
@@ -254,11 +211,11 @@ void ceph_fscache_file_set_cookie(struct inode *inode, struct file *filp)
 	if (inode_is_open_for_write(inode)) {
 		dout("fscache_file_set_cookie %p %p disabling cache\n",
 		     inode, filp);
-		fscache_disable_cookie(ci->fscache, false);
+		fscache_disable_cookie(ci->fscache, &ci->i_vino, false);
 		fscache_uncache_all_inode_pages(ci->fscache, inode);
 	} else {
-		fscache_enable_cookie(ci->fscache, ceph_fscache_can_enable,
-				inode);
+		fscache_enable_cookie(ci->fscache, &ci->i_vino,
+				      ceph_fscache_can_enable, inode);
 		if (fscache_cookie_enabled(ci->fscache)) {
 			dout("fscache_file_set_cookie %p %p enabling cache\n",
 			     inode, filp);
@@ -385,7 +342,7 @@ void ceph_fscache_unregister_fs(struct ceph_fs_client* fsc)
 		WARN_ON_ONCE(!found);
 		mutex_unlock(&ceph_fscache_lock);
 
-		__fscache_relinquish_cookie(fsc->fscache, 0);
+		__fscache_relinquish_cookie(fsc->fscache, NULL, false);
 	}
 	fsc->fscache = NULL;
 }
@@ -402,7 +359,7 @@ void ceph_fscache_revalidate_cookie(struct ceph_inode_info *ci)
 	 * truncate while the caller holds CEPH_CAP_FILE_RD */
 	mutex_lock(&ci->i_truncate_mutex);
 	if (!cache_valid(ci)) {
-		if (fscache_check_consistency(ci->fscache))
+		if (fscache_check_consistency(ci->fscache, &ci->i_vino))
 			fscache_invalidate(ci->fscache);
 		spin_lock(&ci->i_ceph_lock);
 		ci->i_fscache_gen = ci->i_rdcache_gen;