MFC: r281562

File systems that do not use the buffer cache (such as ZFS) must
use VOP_FSYNC() to perform the NFS server's Commit operation.
This patch adds a mnt_kern_flag called MNTK_USES_BCACHE which
is set by file systems that use the buffer cache. If this flag
is not set, the NFS server always does a VOP_FSYNC().
This should be ok for old file system modules that do not set
MNTK_USES_BCACHE, since calling VOP_FSYNC() is correct, although
it might not be optimal for file systems that use the buffer cache.

7 files changed, 13 insertions, 3 deletions

diff --git a/sys/fs/ext2fs/ext2_vfsops.c b/sys/fs/ext2fs/ext2_vfsops.c
index d55bc56..ce943ea 100644
--- a/sys/fs/ext2fs/ext2_vfsops.c
+++ b/sys/fs/ext2fs/ext2_vfsops.c
@@ -661,7 +661,8 @@ ext2_mountfs(struct vnode *devvp, struct mount *mp)
 	 * Initialize filesystem stat information in mount struct.
 	 */
 	MNT_ILOCK(mp);
-	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED;
+	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED |
+	    MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	return (0);
 out:
diff --git a/sys/fs/fuse/fuse_vfsops.c b/sys/fs/fuse/fuse_vfsops.c
index c00a96c..0a33373 100644
--- a/sys/fs/fuse/fuse_vfsops.c
+++ b/sys/fs/fuse/fuse_vfsops.c
@@ -337,6 +337,7 @@ fuse_vfsop_mount(struct mount *mp)
 	MNT_ILOCK(mp);
 	mp->mnt_data = data;
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	/* We need this here as this slot is used by getnewvnode() */
 	mp->mnt_stat.f_iosize = PAGE_SIZE;
diff --git a/sys/fs/msdosfs/msdosfs_vfsops.c b/sys/fs/msdosfs/msdosfs_vfsops.c
index 1165934..7c6d3ed 100644
--- a/sys/fs/msdosfs/msdosfs_vfsops.c
+++ b/sys/fs/msdosfs/msdosfs_vfsops.c
@@ -759,6 +759,7 @@ mountmsdosfs(struct vnode *devvp, struct mount *mp)
 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 
 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
diff --git a/sys/fs/nandfs/nandfs_vfsops.c b/sys/fs/nandfs/nandfs_vfsops.c
index fd9b0c9..8585e6e 100644
--- a/sys/fs/nandfs/nandfs_vfsops.c
+++ b/sys/fs/nandfs/nandfs_vfsops.c
@@ -1385,6 +1385,7 @@ nandfs_mountfs(struct vnode *devvp, struct mount *mp)
 	nmp->nm_ronly = ronly;
 	MNT_ILOCK(mp);
 	mp->mnt_flag |= MNT_LOCAL;
+	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	nmp->nm_nandfsdev = nandfsdev;
 	/* Add our mountpoint */
diff --git a/sys/fs/nfsclient/nfs_clvfsops.c b/sys/fs/nfsclient/nfs_clvfsops.c
index 462d762..6ce469d 100644
--- a/sys/fs/nfsclient/nfs_clvfsops.c
+++ b/sys/fs/nfsclient/nfs_clvfsops.c
@@ -1193,7 +1193,8 @@ nfs_mount(struct mount *mp)
 out:
 	if (!error) {
 		MNT_ILOCK(mp);
-		mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_NO_IOPF;
+		mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_NO_IOPF |
+		    MNTK_USES_BCACHE;
 		MNT_IUNLOCK(mp);
 	}
 	return (error);
diff --git a/sys/fs/nfsserver/nfs_nfsdport.c b/sys/fs/nfsserver/nfs_nfsdport.c
index c94d425..cae2e9f 100644
--- a/sys/fs/nfsserver/nfs_nfsdport.c
+++ b/sys/fs/nfsserver/nfs_nfsdport.c
@@ -1270,8 +1270,11 @@ nfsvno_fsync(struct vnode *vp, u_int64_t off, int cnt, struct ucred *cred,
 	 * file is done.  At this time VOP_FSYNC does not accept offset and
 	 * byte count parameters so call VOP_FSYNC the whole file for now.
 	 * The same is true for NFSv4: RFC 3530 Sec. 14.2.3.
+	 * File systems that do not use the buffer cache (as indicated
+	 * by MNTK_USES_BCACHE not being set) must use VOP_FSYNC().
 	 */
-	if (cnt == 0 || cnt > MAX_COMMIT_COUNT) {
+	if (cnt == 0 || cnt > MAX_COMMIT_COUNT ||
+	    (vp->v_mount->mnt_kern_flag & MNTK_USES_BCACHE) == 0) {
 		/*
 		 * Give up and do the whole thing
 		 */
diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c
index 80824a5..64e1e29 100644
--- a/sys/fs/nullfs/null_vfsops.c
+++ b/sys/fs/nullfs/null_vfsops.c
@@ -198,6 +198,8 @@ nullfs_mount(struct mount *mp)
 		    MNTK_EXTENDED_SHARED);
 	}
 	mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT;
+	mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
+	    MNTK_USES_BCACHE;
 	MNT_IUNLOCK(mp);
 	mp->mnt_data = xmp;
 	vfs_getnewfsid(mp);