fuse/md-cache: add support for the 'fopen-keep-cache' mount option

fopen-keep-cache disables unconditional page-cache invalidations
on file open in fuse (via FOPEN_KEEP_CACHE) and replaces that
behavior with detection of remote changes and explicit
invalidations from mount/fuse. This option improves local caching
through the page cache and native client.

This change defines a new 'invalidate' translator callback to
identify when an inode's cache mapping has been determined to be
invalid. md-cache implements the policy to detect and invoke
inode invalidations. fuse-bridge and io-cache implement
invalidate handlers to invalidate the respective caches (page
cache in the case of fuse).

BUG: 833564
Change-Id: I99818da5777eaf06276c1c0b194669f5bab92d48
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.com/3584
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

4 files changed, 55 insertions, 0 deletions

diff --git a/libglusterfs/src/glusterfs.h b/libglusterfs/src/glusterfs.h
index 780353d29a8..357284e27b4 100644
--- a/libglusterfs/src/glusterfs.h
+++ b/libglusterfs/src/glusterfs.h
@@ -285,6 +285,7 @@ struct _cmd_args {
         int              selinux;
         int              worm;
         int              mac_compat;
+	int		 fopen_keep_cache;
 	struct list_head xlator_options;  /* list of xlator_option_t */
 
 	/* fuse options */
diff --git a/libglusterfs/src/inode.c b/libglusterfs/src/inode.c
index e32eddb5d1c..a0088c03c55 100644
--- a/libglusterfs/src/inode.c
+++ b/libglusterfs/src/inode.c
@@ -950,6 +950,54 @@ inode_forget (inode_t *inode, uint64_t nlookup)
         return 0;
 }
 
+/*
+ * Invalidate an inode. This is invoked when a translator decides that an inode's
+ * cache is no longer valid. Any translator interested in taking action in this
+ * situation can define the invalidate callback.
+ */
+int
+inode_invalidate(inode_t *inode)
+{
+	int ret = 0;
+	xlator_t *xl = NULL;
+	xlator_t *old_THIS = NULL;
+
+	if (!inode) {
+		gf_log_callingfn(THIS->name, GF_LOG_WARNING, "inode not found");
+		return -1;
+	}
+
+	/*
+	 * The master xlator is not in the graph but it can define an invalidate
+	 * handler.
+	 */
+	xl = inode->table->xl->ctx->master;
+	if (xl && xl->cbks->invalidate) {
+		old_THIS = THIS;
+		THIS = xl;
+		ret = xl->cbks->invalidate(xl, inode);
+		THIS = old_THIS;
+		if (ret)
+			return ret;
+	}
+
+	xl = inode->table->xl->graph->first;
+	while (xl) {
+		old_THIS = THIS;
+		THIS = xl;
+		if (xl->cbks->invalidate)
+			ret = xl->cbks->invalidate(xl, inode);
+		THIS = old_THIS;
+
+		if (ret)
+			break;
+
+		xl = xl->next;
+	}
+
+	return ret;
+}
+
 
 static void
 __inode_unlink (inode_t *inode, inode_t *parent, const char *name)
diff --git a/libglusterfs/src/inode.h b/libglusterfs/src/inode.h
index 41003df71ca..20e28f6820d 100644
--- a/libglusterfs/src/inode.h
+++ b/libglusterfs/src/inode.h
@@ -131,6 +131,9 @@ int
 inode_forget (inode_t *inode, uint64_t nlookup);
 
 int
+inode_invalidate(inode_t *inode);
+
+int
 inode_rename (inode_table_t *table, inode_t *olddir, const char *oldname,
 	      inode_t *newdir, const char *newname,
 	      inode_t *inode, struct iatt *stbuf);
diff --git a/libglusterfs/src/xlator.h b/libglusterfs/src/xlator.h
index 2fce7dc474a..5162d20e500 100644
--- a/libglusterfs/src/xlator.h
+++ b/libglusterfs/src/xlator.h
@@ -730,10 +730,13 @@ typedef int32_t (*cbk_forget_t) (xlator_t *this,
 typedef int32_t (*cbk_release_t) (xlator_t *this,
                                   fd_t *fd);
 
+typedef int32_t (*cbk_invalidate_t)(xlator_t *this, inode_t *inode);
+
 struct xlator_cbks {
         cbk_forget_t    forget;
         cbk_release_t   release;
         cbk_release_t   releasedir;
+	cbk_invalidate_t invalidate;
 };
 
 typedef int32_t (*dumpop_priv_t) (xlator_t *this);