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Date:      Mon, 13 May 2019 23:30:06 +0000 (UTC)
From:      Alan Somers <asomers@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject:   svn commit: r347554 - projects/fuse2/sys/fs/fuse
Message-ID:  <201905132330.x4DNU63x003357@repo.freebsd.org>
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Author: asomers
Date: Mon May 13 23:30:06 2019
New Revision: 347554
URL: https://svnweb.freebsd.org/changeset/base/347554

Log:
  fusefs: eliminate superfluous FUSE_GETATTR when filesize=0
  
  fuse_vnode_refreshsize was using 0 as a flag value for filesize meaning
  "uninitialized" (thanks to the malloc(...M_ZERO) in fuse_vnode_alloc.  But
  this led to unnecessary getattr operations when the filesize legitimately
  happened to be zero.  Fix by adding a distinct flag value.
  
  Sponsored by:	The FreeBSD Foundation

Modified:
  projects/fuse2/sys/fs/fuse/fuse_node.c
  projects/fuse2/sys/fs/fuse/fuse_node.h

Modified: projects/fuse2/sys/fs/fuse/fuse_node.c
==============================================================================
--- projects/fuse2/sys/fs/fuse/fuse_node.c	Mon May 13 22:17:11 2019	(r347553)
+++ projects/fuse2/sys/fs/fuse/fuse_node.c	Mon May 13 23:30:06 2019	(r347554)
@@ -143,6 +143,7 @@ fuse_vnode_init(struct vnode *vp, struct fuse_vnode_da
 	fvdat->nid = nodeid;
 	LIST_INIT(&fvdat->handles);
 	vattr_null(&fvdat->cached_attrs);
+	fvdat->filesize = FUSE_FILESIZE_UNINITIALIZED;
 	if (nodeid == FUSE_ROOT_ID) {
 		vp->v_vflag |= VV_ROOT;
 	}
@@ -388,15 +389,10 @@ fuse_vnode_refreshsize(struct vnode *vp, struct ucred 
 
 	if ((fvdat->flag & FN_SIZECHANGE) != 0 ||
 	    fuse_data_cache_mode == FUSE_CACHE_UC ||
-	    fvdat->filesize != 0)
+	    fvdat->filesize != FUSE_FILESIZE_UNINITIALIZED)
 		return 0;
 
-	/*
-	 * TODO: replace VOP_GETATTR with fuse_internal_getattr to use the
-	 * cached attributes.  Better yet, replace fvdat->filesize with
-	 * attrs->va_size
-	 */
-	err = VOP_GETATTR(vp, &va, cred);
+	err = fuse_internal_getattr(vp, &va, cred, curthread);
 	SDT_PROBE2(fusefs, , node, trace, 1, "refreshed file size");
 	return err;
 }

Modified: projects/fuse2/sys/fs/fuse/fuse_node.h
==============================================================================
--- projects/fuse2/sys/fs/fuse/fuse_node.h	Mon May 13 22:17:11 2019	(r347553)
+++ projects/fuse2/sys/fs/fuse/fuse_node.h	Mon May 13 23:30:06 2019	(r347554)
@@ -71,6 +71,8 @@
 #define FN_SIZECHANGE        0x00000100
 #define FN_DIRECTIO          0x00000200
 
+#define FUSE_FILESIZE_UNINITIALIZED	-1
+
 struct fuse_vnode_data {
 	/** self **/
 	uint64_t	nid;
@@ -89,7 +91,11 @@ struct fuse_vnode_data {
 	/* The monotonic time after which the attr cache is invalid */
 	struct bintime	attr_cache_timeout;
 	struct vattr	cached_attrs;
-	/* TODO: use cached_attrs.size instead */
+	/*
+	 * File size according to the kernel, not the daemon.
+	 * May differ from cached_attrs.st_size due to write caching.  Unlike
+	 * cached_attrs.st_size, filesize never expires.
+	 */
 	off_t		filesize;
 	uint64_t	nlookup;
 	enum vtype	vtype;

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