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Convert the vnode clean/dirty attached buffer lists from LISTs to TAILQs.

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Add a new flags field (we get this for free because of struct packing)
for cleaner management of tailq membership.
We had two spare b_flags slots, but they are a precious resource and may
be needed for other things that are related to other b_flags bits.  The two
new flags are convenient to use in a seperate location.

Reviewed (in principle) by: dg
Obtained from: John Dyson's old work-in-progress
This commit is contained in:
Peter Wemm 1998-10-31 14:05:11 +00:00
parent 3ab1f0562c
commit 630ff66320
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=40786
3 changed files with 22 additions and 14 deletions
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16
sys/sys/bio.h
View File

@ -36,7 +36,7 @@
* SUCH DAMAGE.
*
* @(#)buf.h 8.9 (Berkeley) 3/30/95
* $Id: buf.h,v 1.58 1998/09/25 17:34:49 peter Exp $
* $Id: buf.h,v 1.59 1998/10/03 16:19:27 bde Exp $
*/
#ifndef _SYS_BUF_H_
@ -44,8 +44,6 @@
#include <sys/queue.h>
#define NOLIST ((struct buf *)0x87654321)
struct buf;
struct mount;
struct vnode;
@ -83,13 +81,14 @@ struct iodone_chain {
*/
struct buf {
LIST_ENTRY(buf) b_hash; /* Hash chain. */
LIST_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
TAILQ_ENTRY(buf) b_act; /* Device driver queue when active. *new* */
struct proc *b_proc; /* Associated proc; NULL if kernel. */
long b_flags; /* B_* flags. */
unsigned short b_qindex; /* buffer queue index */
unsigned char b_usecount; /* buffer use count */
unsigned char b_xflags; /* extra flags */
int b_error; /* Errno value. */
long b_bufsize; /* Allocated buffer size. */
long b_bcount; /* Valid bytes in buffer. */
@ -170,6 +169,12 @@ struct buf {
"\17locked\16inval\15avail2\14error\13eintr\12done\11freebuf" \
"\10delwri\7call\6cache\5busy\4bad\3async\2needcommit\1age"
/*
* These flags are kept in b_xflags.
*/
#define B_VNDIRTY 0x01 /* On vnode dirty list */
#define B_VNCLEAN 0x02 /* On vnode clean list */
#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
struct buf_queue_head {
@ -217,9 +222,8 @@ bufq_remove(struct buf_queue_head *head, struct buf *bp)
head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
if (head->insert_point == NULL)
head->last_pblkno = 0;
} else if (bp == TAILQ_FIRST(&head->queue)) {
} else if (bp == TAILQ_FIRST(&head->queue))
head->last_pblkno = bp->b_pblkno;
}
TAILQ_REMOVE(&head->queue, bp, b_act);
if (TAILQ_FIRST(&head->queue) == head->switch_point)
head->switch_point = NULL;

16
sys/sys/buf.h
View File

@ -36,7 +36,7 @@
* SUCH DAMAGE.
*
* @(#)buf.h 8.9 (Berkeley) 3/30/95
* $Id: buf.h,v 1.58 1998/09/25 17:34:49 peter Exp $
* $Id: buf.h,v 1.59 1998/10/03 16:19:27 bde Exp $
*/
#ifndef _SYS_BUF_H_
@ -44,8 +44,6 @@
#include <sys/queue.h>
#define NOLIST ((struct buf *)0x87654321)
struct buf;
struct mount;
struct vnode;
@ -83,13 +81,14 @@ struct iodone_chain {
*/
struct buf {
LIST_ENTRY(buf) b_hash; /* Hash chain. */
LIST_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
TAILQ_ENTRY(buf) b_act; /* Device driver queue when active. *new* */
struct proc *b_proc; /* Associated proc; NULL if kernel. */
long b_flags; /* B_* flags. */
unsigned short b_qindex; /* buffer queue index */
unsigned char b_usecount; /* buffer use count */
unsigned char b_xflags; /* extra flags */
int b_error; /* Errno value. */
long b_bufsize; /* Allocated buffer size. */
long b_bcount; /* Valid bytes in buffer. */
@ -170,6 +169,12 @@ struct buf {
"\17locked\16inval\15avail2\14error\13eintr\12done\11freebuf" \
"\10delwri\7call\6cache\5busy\4bad\3async\2needcommit\1age"
/*
* These flags are kept in b_xflags.
*/
#define B_VNDIRTY 0x01 /* On vnode dirty list */
#define B_VNCLEAN 0x02 /* On vnode clean list */
#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
struct buf_queue_head {
@ -217,9 +222,8 @@ bufq_remove(struct buf_queue_head *head, struct buf *bp)
head->insert_point = TAILQ_PREV(bp, buf_queue, b_act);
if (head->insert_point == NULL)
head->last_pblkno = 0;
} else if (bp == TAILQ_FIRST(&head->queue)) {
} else if (bp == TAILQ_FIRST(&head->queue))
head->last_pblkno = bp->b_pblkno;
}
TAILQ_REMOVE(&head->queue, bp, b_act);
if (TAILQ_FIRST(&head->queue) == head->switch_point)
head->switch_point = NULL;

4
sys/sys/vnode.h
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)vnode.h 8.7 (Berkeley) 2/4/94
* $Id: vnode.h,v 1.75 1998/10/16 03:55:01 peter Exp $
* $Id: vnode.h,v 1.76 1998/10/29 09:51:28 peter Exp $
*/
#ifndef _SYS_VNODE_H_
@ -69,7 +69,7 @@ enum vtagtype {
* Each underlying filesystem allocates its own private area and hangs
* it from v_data. If non-null, this area is freed in getnewvnode().
*/
LIST_HEAD(buflists, buf);
TAILQ_HEAD(buflists, buf);
typedef int vop_t __P((void *));
struct namecache;