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, 14 insertions, 10 deletions

diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 0c5523ab16d4..83391126327a 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -225,16 +225,18 @@ struct vattr {
  * Flags for ioflag. (high 16 bits used to ask for read-ahead and
  * help with write clustering)
  */
-#define	IO_UNIT		0x01		/* do I/O as atomic unit */
-#define	IO_APPEND	0x02		/* append write to end */
-#define	IO_SYNC		0x04		/* do I/O synchronously */
-#define	IO_NODELOCKED	0x08		/* underlying node already locked */
-#define	IO_NDELAY	0x10		/* FNDELAY flag set in file table */
-#define	IO_VMIO		0x20		/* data already in VMIO space */
-#define	IO_INVAL	0x40		/* invalidate after I/O */
-#define	IO_ASYNC	0x80		/* bawrite rather then bdwrite */
-#define IO_DIRECT	0x100		/* attempt to bypass buffer cache */
-#define IO_NOWDRAIN	0x200		/* do not block on wdrain */
+#define	IO_UNIT		0x0001		/* do I/O as atomic unit */
+#define	IO_APPEND	0x0002		/* append write to end */
+#define	IO_SYNC		0x0004		/* do I/O synchronously */
+#define	IO_NODELOCKED	0x0008		/* underlying node already locked */
+#define	IO_NDELAY	0x0010		/* FNDELAY flag set in file table */
+#define	IO_VMIO		0x0020		/* data already in VMIO space */
+#define	IO_INVAL	0x0040		/* invalidate after I/O */
+#define	IO_ASYNC	0x0080		/* bawrite rather then bdwrite */
+#define	IO_DIRECT	0x0100		/* attempt to bypass buffer cache */
+#define	IO_NOWDRAIN	0x0200		/* do not block on wdrain */
+#define	IO_EXT		0x0400		/* operate on external attributes */
+#define	IO_NORMAL	0x0800		/* operate on regular data */
 
 /*
  *  Modes.  Some values same as Ixxx entries from inode.h for now.
@@ -281,6 +283,8 @@ extern int		vttoif_tab[];
 #define	WRITECLOSE	0x0004	/* vflush: only close writable files */
 #define	DOCLOSE		0x0008	/* vclean: close active files */
 #define	V_SAVE		0x0001	/* vinvalbuf: sync file first */
+#define	V_ALT		0x0002	/* vinvalbuf: invalidate only alternate bufs */
+#define	V_NORMAL	0x0004	/* vinvalbuf: invalidate only regular bufs */
 #define	REVOKEALL	0x0001	/* vop_revoke: revoke all aliases */
 #define	V_WAIT		0x0001	/* vn_start_write: sleep for suspend */
 #define	V_NOWAIT	0x0002	/* vn_start_write: don't sleep for suspend */