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, 3 insertions, 3 deletions

diff --git a/sys/ufs/ffs/softdep.h b/sys/ufs/ffs/softdep.h
index 1908a3e..cf9cac8 100644
--- a/sys/ufs/ffs/softdep.h
+++ b/sys/ufs/ffs/softdep.h
@@ -382,7 +382,7 @@ struct freefrag {
 	struct	worklist ff_list;	/* id_inowait or delayed worklist */
 #	define	ff_state ff_list.wk_state /* owning user; should be uid_t */
 	struct	vnode *ff_devvp;	/* filesystem device vnode */
-	struct	fs *ff_fs;		/* addr of superblock */
+	struct	mount *ff_mnt;		/* associated mount point */
 	ufs_daddr_t ff_blkno;		/* fragment physical block number */
 	long	ff_fragsize;		/* size of fragment being deleted */
 	ino_t	ff_inum;		/* owning inode number */
@@ -398,7 +398,7 @@ struct freeblks {
 	struct	worklist fb_list;	/* id_inowait or delayed worklist */
 	ino_t	fb_previousinum;	/* inode of previous owner of blocks */
 	struct	vnode *fb_devvp;	/* filesystem device vnode */
-	struct	fs *fb_fs;		/* addr of superblock */
+	struct	mount *fb_mnt;		/* associated mount point */
 	off_t	fb_oldsize;		/* previous file size */
 	off_t	fb_newsize;		/* new file size */
 	int	fb_chkcnt;		/* used to check cnt of blks released */
@@ -418,7 +418,7 @@ struct freefile {
 	mode_t	fx_mode;		/* mode of inode */
 	ino_t	fx_oldinum;		/* inum of the unlinked file */
 	struct	vnode *fx_devvp;	/* filesystem device vnode */
-	struct	fs *fx_fs;		/* addr of superblock */
+	struct	mount *fx_mnt;		/* associated mount point */
 };
 
 /*