Add snapshots to the fast filesystem. Most of the changes support

the gating of system calls that cause modifications to the underlying
filesystem. The gating can be enabled by any filesystem that needs
to consistently suspend operations by adding the vop_stdgetwritemount
to their set of vnops. Once gating is enabled, the function
vfs_write_suspend stops all new write operations to a filesystem,
allows any filesystem modifying system calls already in progress
to complete, then sync's the filesystem to disk and returns. The
function vfs_write_resume allows the suspended write operations to
begin again. Gating is not added by default for all filesystems as
for SMP systems it adds two extra locks to such critical kernel
paths as the write system call. Thus, gating should only be added
as needed.

Details on the use and current status of snapshots in FFS can be
found in /sys/ufs/ffs/README.snapshot so for brevity and timelyness
is not included here. Unless and until you create a snapshot file,
these changes should have no effect on your system (famous last words).

1 files changed, 113 insertions, 1 deletions

diff --git a/sys/nfs/nfs_serv.c b/sys/nfs/nfs_serv.c
index 06ce9ed..0334f74 100644
--- a/sys/nfs/nfs_serv.c
+++ b/sys/nfs/nfs_serv.c
@@ -325,10 +325,18 @@ nfsrv_setattr(nfsd, slp, procp, mrq)
 	struct mbuf *mb, *mb2, *mreq;
 	u_quad_t frev;
 	struct timespec guard;
+	struct mount *mp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	VATTR_NULL(vap);
 	if (v3) {
 		nfsm_srvsattr(vap);
@@ -440,6 +448,7 @@ out:
 nfsmout:
 	if (vp)
 		vput(vp);
+	vn_finished_write(mp);
 	return(error);
 }
 
@@ -1039,6 +1048,7 @@ nfsrv_write(nfsd, slp, procp, mrq)
 	struct uio io, *uiop = &io;
 	off_t off;
 	u_quad_t frev;
+	struct mount *mntp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	if (mrep == NULL) {
@@ -1048,6 +1058,13 @@ nfsrv_write(nfsd, slp, procp, mrq)
 	}
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mntp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mntp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mntp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	if (v3) {
 		nfsm_dissect(tl, u_int32_t *, 5 * NFSX_UNSIGNED);
 		off = fxdr_hyper(tl);
@@ -1205,6 +1222,7 @@ nfsrv_write(nfsd, slp, procp, mrq)
 nfsmout:
 	if (vp)
 		vput(vp);
+	vn_finished_write(mntp);
 	return(error);
 }
 
@@ -1241,6 +1259,7 @@ nfsrv_writegather(ndp, slp, procp, mrq)
 	struct vnode *vp = NULL;
 	struct uio io, *uiop = &io;
 	u_quad_t frev, cur_usec;
+	struct mount *mntp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 #ifndef nolint
@@ -1444,8 +1463,16 @@ loop1:
 			mp = mp->m_next;
 		    }
 		    if (!error) {
+			if (vn_start_write(vp, &mntp, V_NOWAIT) != 0) {
+			    VOP_UNLOCK(vp, 0, procp);
+			    error = vn_start_write(NULL, &mntp, V_WAIT);
+			    vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, procp);
+			}
+		    }
+		    if (!error) {
 			error = VOP_WRITE(vp, uiop, ioflags, cred);
 			nfsstats.srvvop_writes++;
+			vn_finished_write(mntp);
 		    }
 		    FREE((caddr_t)iov, M_TEMP);
 		}
@@ -1620,6 +1647,8 @@ nfsrv_create(nfsd, slp, procp, mrq)
 	fhandle_t *fhp;
 	u_quad_t frev, tempsize;
 	u_char cverf[NFSX_V3CREATEVERF];
+	struct mount *mp = NULL;
+	struct vnode *vp;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 #ifndef nolint
@@ -1629,6 +1658,12 @@ nfsrv_create(nfsd, slp, procp, mrq)
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
 	nfsm_srvnamesiz(len);
 
 	nd.ni_cnd.cn_cred = cred;
@@ -1869,6 +1904,7 @@ nfsmout:
 	}
 	if (nd.ni_vp)
 		vput(nd.ni_vp);
+	vn_finished_write(mp);
 	return (error);
 }
 
@@ -1901,12 +1937,20 @@ nfsrv_mknod(nfsd, slp, procp, mrq)
 	nfsfh_t nfh;
 	fhandle_t *fhp;
 	u_quad_t frev;
+	struct mount *mp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 
 	nd.ni_cnd.cn_cred = cred;
@@ -2030,6 +2074,7 @@ out:
 		nfsm_srvpostop_attr(0, vap);
 	}
 	nfsm_srvwcc_data(dirfor_ret, &dirfor, diraft_ret, &diraft);
+	vn_finished_write(mp);
 	return (0);
 nfsmout:
 	if (dirp)
@@ -2045,6 +2090,7 @@ nfsmout:
 	}
 	if (nd.ni_vp)
 		vput(nd.ni_vp);
+	vn_finished_write(mp);
 	return (error);
 }
 
@@ -2075,12 +2121,21 @@ nfsrv_remove(nfsd, slp, procp, mrq)
 	nfsfh_t nfh;
 	fhandle_t *fhp;
 	u_quad_t frev;
+	struct mount *mp = NULL;
+	struct vnode *vp;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 
 	nd.ni_cnd.cn_cred = cred;
@@ -2137,6 +2192,7 @@ nfsmout:
 	}
 	if (nd.ni_vp)
 		vput(nd.ni_vp);
+	vn_finished_write(mp);
 	return(error);
 }
 
@@ -2170,6 +2226,8 @@ nfsrv_rename(nfsd, slp, procp, mrq)
 	fhandle_t *ffhp, *tfhp;
 	u_quad_t frev;
 	uid_t saved_uid;
+	struct mount *mp = NULL;
+	struct vnode *vp;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 #ifndef nolint
@@ -2186,6 +2244,13 @@ nfsrv_rename(nfsd, slp, procp, mrq)
 	ndclear(&tond);
 
 	nfsm_srvmtofh(ffhp);
+	if ((mp = vfs_getvfs(&ffhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &ffhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 	/*
 	 * Remember our original uid so that we can reset cr_uid before
@@ -2360,6 +2425,7 @@ nfsmout:
 	if (fromnd.ni_vp)
 		vrele(fromnd.ni_vp);
 
+	vn_finished_write(mp);
 	return (error);
 }
 
@@ -2390,6 +2456,7 @@ nfsrv_link(nfsd, slp, procp, mrq)
 	nfsfh_t nfh, dnfh;
 	fhandle_t *fhp, *dfhp;
 	u_quad_t frev;
+	struct mount *mp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
@@ -2397,6 +2464,13 @@ nfsrv_link(nfsd, slp, procp, mrq)
 	fhp = &nfh.fh_generic;
 	dfhp = &dnfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvmtofh(dfhp);
 	nfsm_srvnamesiz(len);
 
@@ -2475,6 +2549,7 @@ nfsmout:
 	}
 	if (nd.ni_vp)
 		vrele(nd.ni_vp);
+	vn_finished_write(mp);
 	return(error);
 }
 
@@ -2508,12 +2583,21 @@ nfsrv_symlink(nfsd, slp, procp, mrq)
 	nfsfh_t nfh;
 	fhandle_t *fhp;
 	u_quad_t frev;
+	struct mount *mp = NULL;
+	struct vnode *vp;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 	nd.ni_cnd.cn_cred = cred;
 	nd.ni_cnd.cn_nameiop = CREATE;
@@ -2651,6 +2735,7 @@ nfsmout:
 	if (pathcp)
 		FREE(pathcp, M_TEMP);
 
+	vn_finished_write(mp);
 	return (error);
 }
 
@@ -2685,12 +2770,21 @@ nfsrv_mkdir(nfsd, slp, procp, mrq)
 	nfsfh_t nfh;
 	fhandle_t *fhp;
 	u_quad_t frev;
+	struct mount *mp = NULL;
+	struct vnode *vp;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 	nd.ni_cnd.cn_cred = cred;
 	nd.ni_cnd.cn_nameiop = CREATE;
@@ -2787,6 +2881,7 @@ nfsmout:
 		else
 			vrele(nd.ni_vp);
 	}
+	vn_finished_write(mp);
 	return (error);
 }
 
@@ -2817,12 +2912,20 @@ nfsrv_rmdir(nfsd, slp, procp, mrq)
 	fhandle_t *fhp;
 	struct nameidata nd;
 	u_quad_t frev;
+	struct mount *mp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 	ndclear(&nd);
 
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_srvnamesiz(len);
 	nd.ni_cnd.cn_cred = cred;
 	nd.ni_cnd.cn_nameiop = DELETE;
@@ -2895,6 +2998,7 @@ nfsmout:
 	if (nd.ni_vp)
 		vput(nd.ni_vp);
 
+	vn_finished_write(mp);
 	return(error);
 }
 
@@ -3588,6 +3692,7 @@ nfsrv_commit(nfsd, slp, procp, mrq)
 	char *cp2;
 	struct mbuf *mb, *mb2, *mreq;
 	u_quad_t frev, off;
+	struct mount *mp = NULL;
 
 	nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
 #ifndef nolint
@@ -3595,6 +3700,13 @@ nfsrv_commit(nfsd, slp, procp, mrq)
 #endif
 	fhp = &nfh.fh_generic;
 	nfsm_srvmtofh(fhp);
+	if ((mp = vfs_getvfs(&fhp->fh_fsid)) == NULL)
+		return (ESTALE);
+	if ((error = VFS_FHTOVP(mp, &fhp->fh_fid, &vp)) != NULL)
+		return (error);
+	(void) vn_start_write(vp, &mp, V_WAIT);
+	vput(vp);
+	vp = NULL;
 	nfsm_dissect(tl, u_int32_t *, 3 * NFSX_UNSIGNED);
 
 	/*
@@ -3697,6 +3809,7 @@ nfsrv_commit(nfsd, slp, procp, mrq)
 nfsmout:
 	if (vp)
 		vput(vp);
+	vn_finished_write(mp);
 	return(error);
 }
 
@@ -4065,4 +4178,3 @@ nfsrv_access(vp, flags, cred, rdonly, p, override)
 	return error;
 }
 #endif /* NFS_NOSERVER */
-