Add support to UFS2 to provide storage for extended attributes.

As this code is not actually used by any of the existing
interfaces, it seems unlikely to break anything (famous
last words).

The internal kernel interface to manipulate these attributes
is invoked using two new IO_ flags: IO_NORMAL and IO_EXT.
These flags may be specified in the ioflags word of VOP_READ,
VOP_WRITE, and VOP_TRUNCATE. Specifying IO_NORMAL means that
you want to do I/O to the normal data part of the file and
IO_EXT means that you want to do I/O to the extended attributes
part of the file. IO_NORMAL and IO_EXT are mutually exclusive
for VOP_READ and VOP_WRITE, but may be specified individually
or together in the case of VOP_TRUNCATE. For example, when
removing a file, VOP_TRUNCATE is called with both IO_NORMAL
and IO_EXT set. For backward compatibility, if neither IO_NORMAL
nor IO_EXT is set, then IO_NORMAL is assumed.

Note that the BA_ and IO_ flags have been `merged' so that they
may both be used in the same flags word. This merger is possible
by assigning the IO_ flags to the low sixteen bits and the BA_
flags the high sixteen bits. This works because the high sixteen
bits of the IO_ word is reserved for read-ahead and help with
write clustering so will never be used for flags. This merge
lets us get away from code of the form:

        if (ioflags & IO_SYNC)
                flags |= BA_SYNC;

For the future, I have considered adding a new field to the
vattr structure, va_extsize. This addition could then be
exported through the stat structure to allow applications to
find out the size of the extended attribute storage and also
would provide a more standard interface for truncating them
(via VOP_SETATTR rather than VOP_TRUNCATE).

I am also contemplating adding a pathconf parameter (for
concreteness, lets call it _PC_MAX_EXTSIZE) which would
let an application determine the maximum size of the extended
atribute storage.

Sponsored by:	DARPA & NAI Labs.

1 files changed, 5 insertions, 3 deletions

diff --git a/sys/ufs/ffs/ffs_extern.h b/sys/ufs/ffs/ffs_extern.h
index ae59ca380ffb..c2972c8f2305 100644
--- a/sys/ufs/ffs/ffs_extern.h
+++ b/sys/ufs/ffs/ffs_extern.h
@@ -79,8 +79,8 @@ int	ffs_mountroot(void);
 int	ffs_mount(struct mount *, char *, caddr_t, struct nameidata *,
 	    struct thread *);
 int	ffs_reallocblks(struct vop_reallocblks_args *);
-int	ffs_realloccg(struct inode *,
-	    ufs2_daddr_t, ufs2_daddr_t, int, int, struct ucred *, struct buf **);
+int	ffs_realloccg(struct inode *, ufs2_daddr_t, ufs2_daddr_t,
+	    ufs2_daddr_t, int, int, struct ucred *, struct buf **);
 void	ffs_setblock(struct fs *, u_char *, ufs1_daddr_t);
 int	ffs_snapblkfree(struct fs *, struct vnode *, ufs2_daddr_t, long, ino_t);
 void	ffs_snapremove(struct vnode *vp);
@@ -115,11 +115,13 @@ void	softdep_update_inodeblock(struct inode *, struct buf *, int);
 void	softdep_load_inodeblock(struct inode *);
 void	softdep_freefile(struct vnode *, ino_t, int);
 int	softdep_request_cleanup(struct fs *, struct vnode *);
-void	softdep_setup_freeblocks(struct inode *, off_t);
+void	softdep_setup_freeblocks(struct inode *, off_t, int);
 void	softdep_setup_inomapdep(struct buf *, struct inode *, ino_t);
 void	softdep_setup_blkmapdep(struct buf *, struct fs *, ufs2_daddr_t);
 void	softdep_setup_allocdirect(struct inode *, ufs_lbn_t, ufs2_daddr_t,
 	    ufs2_daddr_t, long, long, struct buf *);
+void	softdep_setup_allocext(struct inode *, ufs_lbn_t, ufs2_daddr_t,
+	    ufs2_daddr_t, long, long, struct buf *);
 void	softdep_setup_allocindir_meta(struct buf *, struct inode *,
 	    struct buf *, int, ufs2_daddr_t);
 void	softdep_setup_allocindir_page(struct inode *, ufs_lbn_t,