[src/trunk]: src/sys/sys - shuffle members of struct buf to distinguish buffe...

[yamt <yamt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b6b71ca6387d
branches:  trunk
changeset: 555920:b6b71ca6387d
user:      yamt <yamt%NetBSD.org@localhost>
date:      Thu Dec 04 15:00:32 2003 +0000

description:
- shuffle members of struct buf to distinguish buffer cache only ones.
- put b_private and b_dcookie into a union as they're never used
  simultaneously.
- note who can use b_private.

diffstat:

 sys/sys/buf.h |  35 +++++++++++++++++++++++++----------
 1 files changed, 25 insertions(+), 10 deletions(-)

diffs (66 lines):

diff -r fcd8bfb13e4a -r b6b71ca6387d sys/sys/buf.h
--- a/sys/sys/buf.h     Thu Dec 04 14:57:47 2003 +0000
+++ b/sys/sys/buf.h     Thu Dec 04 15:00:32 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: buf.h,v 1.64 2003/08/07 16:33:59 agc Exp $     */
+/*     $NetBSD: buf.h,v 1.65 2003/12/04 15:00:32 yamt Exp $    */
 
 /*-
  * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
@@ -149,13 +149,9 @@
  * The buffer header describes an I/O operation in the kernel.
  */
 struct buf {
-       LIST_ENTRY(buf) b_hash;         /* Hash chain. */
-       LIST_ENTRY(buf) b_vnbufs;       /* Buffer's associated vnode. */
-       TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
        TAILQ_ENTRY(buf) b_actq;        /* Device driver queue when active. */
-       struct  proc *b_proc;           /* Associated proc if B_PHYS set. */
+       struct simplelock b_interlock;  /* Lock for b_flags changes */
        volatile long   b_flags;        /* B_* flags. */
-       struct simplelock b_interlock;  /* Lock for b_flags changes */
        int     b_error;                /* Errno value. */
        long    b_bufsize;              /* Allocated buffer size. */
        long    b_bcount;               /* Valid bytes in buffer. */
@@ -164,18 +160,37 @@
        struct {
                caddr_t b_addr;         /* Memory, superblocks, indirect etc. */
        } b_un;
-       void    *b_saveaddr;            /* Original b_addr for physio. */
-       daddr_t b_lblkno;               /* Logical block number. */
        daddr_t b_blkno;                /* Underlying physical block number
                                           (partition relative) */
        daddr_t b_rawblkno;             /* Raw underlying physical block
                                           number (not partition relative) */
                                        /* Function to call upon completion. */
        void    (*b_iodone) __P((struct buf *));
+       struct  proc *b_proc;           /* Associated proc if B_PHYS set. */
        struct  vnode *b_vp;            /* File vnode. */
-       void    *b_private;             /* Private data for owner */
-       off_t   b_dcookie;              /* Offset cookie if dir block */
        struct  workhead b_dep;         /* List of filesystem dependencies. */
+       void    *b_saveaddr;            /* Original b_addr for physio. */
+
+       /*
+        * private data for owner.
+        *  - buffer cache buffers are owned by corresponding filesystem.
+        *  - non-buffer cache buffers are owned by subsystem which
+        *    allocated them. (filesystem, disk driver, etc)
+        */
+       union {
+               void *bf_private;
+               off_t bf_dcookie;       /* NFS: Offset cookie if dir block */
+       } b_fspriv;
+#define        b_private       b_fspriv.bf_private
+#define        b_dcookie       b_fspriv.bf_dcookie
+
+       /*
+        * buffer cache specific data
+        */
+       LIST_ENTRY(buf) b_hash;         /* Hash chain. */
+       LIST_ENTRY(buf) b_vnbufs;       /* Buffer's associated vnode. */
+       TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
+       daddr_t b_lblkno;               /* Logical block number. */
 };
 
 #define        BUF_INIT(bp)                                                    \