Add UFS writesuspension mechanism, designed to allow userland processes

to modify on-disk metadata for filesystems mounted for write.

Reviewed by:	kib, mckusick
Sponsored by:	FreeBSD Foundation

1 files changed, 33 insertions, 10 deletions

diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index cc54ece..0a43d80 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -49,6 +49,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/buf.h>
 #include <sys/conf.h>
 #include <sys/fcntl.h>
+#include <sys/ioccom.h>
 #include <sys/malloc.h>
 #include <sys/mutex.h>
 
@@ -75,7 +76,6 @@ __FBSDID("$FreeBSD$");
 
 static uma_zone_t uma_inode, uma_ufs1, uma_ufs2;
 
-static int	ffs_reload(struct mount *, struct thread *);
 static int	ffs_mountfs(struct vnode *, struct mount *, struct thread *);
 static void	ffs_oldfscompat_read(struct fs *, struct ufsmount *,
 		    ufs2_daddr_t);
@@ -333,7 +333,7 @@ ffs_mount(struct mount *mp)
 			vfs_write_resume(mp);
 		}
 		if ((mp->mnt_flag & MNT_RELOAD) &&
-		    (error = ffs_reload(mp, td)) != 0)
+		    (error = ffs_reload(mp, td, 0)) != 0)
 			return (error);
 		if (fs->fs_ronly &&
 		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
@@ -595,8 +595,8 @@ ffs_cmount(struct mntarg *ma, void *data, uint64_t flags)
 
 /*
  * Reload all incore data for a filesystem (used after running fsck on
- * the root filesystem and finding things to fix). The filesystem must
- * be mounted read-only.
+ * the root filesystem and finding things to fix). If the 'force' flag
+ * is 0, the filesystem must be mounted read-only.
  *
  * Things to do to update the mount:
  *	1) invalidate all cached meta-data.
@@ -606,8 +606,8 @@ ffs_cmount(struct mntarg *ma, void *data, uint64_t flags)
  *	5) invalidate all cached file data.
  *	6) re-read inode data for all active vnodes.
  */
-static int
-ffs_reload(struct mount *mp, struct thread *td)
+int
+ffs_reload(struct mount *mp, struct thread *td, int force)
 {
 	struct vnode *vp, *mvp, *devvp;
 	struct inode *ip;
@@ -619,9 +619,15 @@ ffs_reload(struct mount *mp, struct thread *td)
 	int i, blks, size, error;
 	int32_t *lp;
 
-	if ((mp->mnt_flag & MNT_RDONLY) == 0)
-		return (EINVAL);
 	ump = VFSTOUFS(mp);
+
+	MNT_ILOCK(mp);
+	if ((mp->mnt_flag & MNT_RDONLY) == 0 && force == 0) {
+		MNT_IUNLOCK(mp);
+		return (EINVAL);
+	}
+	MNT_IUNLOCK(mp);
+	
 	/*
 	 * Step 1: invalidate all cached meta-data.
 	 */
@@ -655,8 +661,7 @@ ffs_reload(struct mount *mp, struct thread *td)
 	newfs->fs_maxcluster = fs->fs_maxcluster;
 	newfs->fs_contigdirs = fs->fs_contigdirs;
 	newfs->fs_active = fs->fs_active;
-	/* The file system is still read-only. */
-	newfs->fs_ronly = 1;
+	newfs->fs_ronly = fs->fs_ronly;
 	sblockloc = fs->fs_sblockloc;
 	bcopy(newfs, fs, (u_int)fs->fs_sbsize);
 	brelse(bp);
@@ -711,6 +716,13 @@ ffs_reload(struct mount *mp, struct thread *td)
 loop:
 	MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
 		/*
+		 * Skip syncer vnode.
+		 */
+		if (vp->v_type == VNON) {
+			VI_UNLOCK(vp);
+			continue;
+		}
+		/*
 		 * Step 4: invalidate all cached file data.
 		 */
 		if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td)) {
@@ -1834,6 +1846,7 @@ ffs_init(vfsp)
 	struct vfsconf *vfsp;
 {
 
+	ffs_susp_initialize();
 	softdep_initialize();
 	return (ufs_init(vfsp));
 }
@@ -1849,6 +1862,7 @@ ffs_uninit(vfsp)
 
 	ret = ufs_uninit(vfsp);
 	softdep_uninitialize();
+	ffs_susp_uninitialize();
 	return (ret);
 }
 
@@ -2198,6 +2212,15 @@ ffs_geom_strategy(struct bufobj *bo, struct buf *bp)
 	g_vfs_strategy(bo, bp);
 }
 
+int
+ffs_own_mount(const struct mount *mp)
+{
+
+	if (mp->mnt_op == &ufs_vfsops)
+		return (1);
+	return (0);
+}
+
 #ifdef	DDB
 
 static void