FreeBSD-5.3/sys/sys/buf.h
/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)buf.h 8.9 (Berkeley) 3/30/95
* $FreeBSD: src/sys/sys/buf.h,v 1.167 2004/07/25 21:24:23 phk Exp $
*/
#ifndef _SYS_BUF_H_
#define _SYS_BUF_H_
#include <sys/queue.h>
#include <sys/lock.h>
#include <sys/lockmgr.h>
struct bio;
struct buf;
struct mount;
struct vnode;
/*
* To avoid including <ufs/ffs/softdep.h>
*/
LIST_HEAD(workhead, worklist);
/*
* These are currently used only by the soft dependency code, hence
* are stored once in a global variable. If other subsystems wanted
* to use these hooks, a pointer to a set of bio_ops could be added
* to each buffer.
*/
extern struct bio_ops {
int (*io_prewrite)(struct vnode *, struct buf *);
void (*io_start)(struct buf *);
void (*io_complete)(struct buf *);
void (*io_deallocate)(struct buf *);
void (*io_movedeps)(struct buf *, struct buf *);
int (*io_countdeps)(struct buf *, int);
} bioops;
struct buf_ops {
char *bop_name;
int (*bop_write)(struct buf *);
};
extern struct buf_ops buf_ops_bio;
struct vm_object;
typedef unsigned char b_xflags_t;
/*
* The buffer header describes an I/O operation in the kernel.
*
* NOTES:
* b_bufsize, b_bcount. b_bufsize is the allocation size of the
* buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
* originally requested buffer size and can serve as a bounds check
* against EOF. For most, but not all uses, b_bcount == b_bufsize.
*
* b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
* ranges of dirty data that need to be written to backing store.
* The range is typically clipped at b_bcount ( not b_bufsize ).
*
* b_resid. Number of bytes remaining in I/O. After an I/O operation
* completes, b_resid is usually 0 indicating 100% success.
*
* All fields are protected by the buffer lock except those marked:
* V - Protected by owning vnode lock
* Q - Protected by the buf queue lock
* D - Protected by an dependency implementation specific lock
*/
struct buf {
struct bio b_io; /* "Builtin" I/O request. */
#define b_bcount b_io.bio_bcount
#define b_caller1 b_io.bio_caller1
#define b_data b_io.bio_data
#define b_dev b_io.bio_dev
#define b_error b_io.bio_error
#define b_iocmd b_io.bio_cmd
#define b_ioflags b_io.bio_flags
#define b_iooffset b_io.bio_offset
#define b_resid b_io.bio_resid
struct buf_ops *b_op;
unsigned b_magic;
#define B_MAGIC_BIO 0x10b10b10
#define B_MAGIC_NFS 0x67238234
void (*b_iodone)(struct buf *);
daddr_t b_blkno; /* Underlying physical block number. */
off_t b_offset; /* Offset into file. */
TAILQ_ENTRY(buf) b_vnbufs; /* (V) Buffer's associated vnode. */
struct buf *b_left; /* (V) splay tree link */
struct buf *b_right; /* (V) splay tree link */
uint32_t b_vflags; /* (V) BV_* flags */
TAILQ_ENTRY(buf) b_freelist; /* (Q) Free list position inactive. */
unsigned short b_qindex; /* (Q) buffer queue index */
uint32_t b_flags; /* B_* flags. */
b_xflags_t b_xflags; /* extra flags */
struct lock b_lock; /* Buffer lock */
long b_bufsize; /* Allocated buffer size. */
long b_runningbufspace; /* when I/O is running, pipelining */
caddr_t b_kvabase; /* base kva for buffer */
int b_kvasize; /* size of kva for buffer */
daddr_t b_lblkno; /* Logical block number. */
struct vnode *b_vp; /* Device vnode. */
struct vm_object *b_object; /* Object for vp */
int b_dirtyoff; /* Offset in buffer of dirty region. */
int b_dirtyend; /* Offset of end of dirty region. */
struct ucred *b_rcred; /* Read credentials reference. */
struct ucred *b_wcred; /* Write credentials reference. */
void *b_saveaddr; /* Original b_addr for physio. */
union pager_info {
int pg_reqpage;
} b_pager;
union cluster_info {
TAILQ_HEAD(cluster_list_head, buf) cluster_head;
TAILQ_ENTRY(buf) cluster_entry;
} b_cluster;
struct vm_page *b_pages[btoc(MAXPHYS)];
int b_npages;
struct workhead b_dep; /* (D) List of filesystem dependencies. */
};
/*
* These flags are kept in b_flags.
*
* Notes:
*
* B_ASYNC VOP calls on bp's are usually async whether or not
* B_ASYNC is set, but some subsystems, such as NFS, like
* to know what is best for the caller so they can
* optimize the I/O.
*
* B_PAGING Indicates that bp is being used by the paging system or
* some paging system and that the bp is not linked into
* the b_vp's clean/dirty linked lists or ref counts.
* Buffer vp reassignments are illegal in this case.
*
* B_CACHE This may only be set if the buffer is entirely valid.
* The situation where B_DELWRI is set and B_CACHE is
* clear MUST be committed to disk by getblk() so
* B_DELWRI can also be cleared. See the comments for
* getblk() in kern/vfs_bio.c. If B_CACHE is clear,
* the caller is expected to clear BIO_ERROR and B_INVAL,
* set BIO_READ, and initiate an I/O.
*
* The 'entire buffer' is defined to be the range from
* 0 through b_bcount.
*
* B_MALLOC Request that the buffer be allocated from the malloc
* pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
*
* B_CLUSTEROK This flag is typically set for B_DELWRI buffers
* by filesystems that allow clustering when the buffer
* is fully dirty and indicates that it may be clustered
* with other adjacent dirty buffers. Note the clustering
* may not be used with the stage 1 data write under NFS
* but may be used for the commit rpc portion.
*
* B_VMIO Indicates that the buffer is tied into an VM object.
* The buffer's data is always PAGE_SIZE aligned even
* if b_bufsize and b_bcount are not. ( b_bufsize is
* always at least DEV_BSIZE aligned, though ).
*
* B_DIRECT Hint that we should attempt to completely free
* the pages underlying the buffer. B_DIRECT is
* sticky until the buffer is released and typically
* only has an effect when B_RELBUF is also set.
*
*/
#define B_AGE 0x00000001 /* Move to age queue when I/O done. */
#define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
#define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
#define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
#define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
#define B_CACHE 0x00000020 /* Bread found us in the cache. */
#define B_VALIDSUSPWRT 0x00000040 /* Valid write during suspension. */
#define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
#define B_00000100 0x00000100 /* Available flag. */
#define B_DONE 0x00000200 /* I/O completed. */
#define B_EINTR 0x00000400 /* I/O was interrupted */
#define B_00000800 0x00000800 /* Available flag. */
#define B_00001000 0x00001000 /* Available flag. */
#define B_INVAL 0x00002000 /* Does not contain valid info. */
#define B_00004000 0x00004000 /* Available flag. */
#define B_NOCACHE 0x00008000 /* Do not cache block after use. */
#define B_MALLOC 0x00010000 /* malloced b_data */
#define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
#define B_000400000 0x00040000 /* Available flag. */
#define B_000800000 0x00080000 /* Available flag. */
#define B_00100000 0x00100000 /* Available flag. */
#define B_DIRTY 0x00200000 /* Needs writing later (in EXT2FS). */
#define B_RELBUF 0x00400000 /* Release VMIO buffer. */
#define B_00800000 0x00800000 /* Available flag. */
#define B_WRITEINPROG 0x01000000 /* Write in progress. */
#define B_02000000 0x02000000 /* Available flag. */
#define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
#define B_08000000 0x08000000 /* Available flag. */
#define B_RAM 0x10000000 /* Read ahead mark (flag) */
#define B_VMIO 0x20000000 /* VMIO flag */
#define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
#define B_80000000 0x80000000 /* Available flag. */
#define PRINT_BUF_FLAGS "\20\40b31\37cluster\36vmio\35ram\34b27" \
"\33paging\32b25\31writeinprog\30b23\27relbuf\26dirty\25b20" \
"\24b19\23phys\22clusterok\21malloc\20nocache\17locked\16inval" \
"\15scanned\14nowdrain\13eintr\12done\11b8\10delwri\7validsuspwrt" \
"\6cache\5deferred\4direct\3async\2needcommit\1age"
/*
* These flags are kept in b_xflags.
*/
#define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
#define BX_VNCLEAN 0x00000002 /* On vnode clean list */
#define BX_BKGRDWRITE 0x00000010 /* Do writes in background */
#define BX_BKGRDMARKER 0x00000020 /* Mark buffer for splay tree */
#define BX_ALTDATA 0x00000040 /* Holds extended data */
#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
/*
* These flags are kept in b_vflags.
*/
#define BV_SCANNED 0x00000001 /* VOP_FSYNC funcs mark written bufs */
#define BV_BKGRDINPROG 0x00000002 /* Background write in progress */
#define BV_BKGRDWAIT 0x00000004 /* Background write waiting */
#ifdef _KERNEL
/*
* Buffer locking
*/
extern const char *buf_wmesg; /* Default buffer lock message */
#define BUF_WMESG "bufwait"
#include <sys/proc.h> /* XXX for curthread */
#include <sys/mutex.h>
/*
* Initialize a lock.
*/
#define BUF_LOCKINIT(bp) \
lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, 0)
/*
*
* Get a lock sleeping non-interruptably until it becomes available.
*/
static __inline int BUF_LOCK(struct buf *, int, struct mtx *);
static __inline int
BUF_LOCK(struct buf *bp, int locktype, struct mtx *interlock)
{
int s, ret;
s = splbio();
mtx_lock(bp->b_lock.lk_interlock);
locktype |= LK_INTERNAL;
bp->b_lock.lk_wmesg = buf_wmesg;
bp->b_lock.lk_prio = PRIBIO + 4;
ret = lockmgr(&(bp)->b_lock, locktype, interlock, curthread);
splx(s);
return ret;
}
/*
* Get a lock sleeping with specified interruptably and timeout.
*/
static __inline int BUF_TIMELOCK(struct buf *, int, struct mtx *,
char *, int, int);
static __inline int
BUF_TIMELOCK(struct buf *bp, int locktype, struct mtx *interlock,
char *wmesg, int catch, int timo)
{
int s, ret;
s = splbio();
mtx_lock(bp->b_lock.lk_interlock);
locktype |= LK_INTERNAL | LK_TIMELOCK;
bp->b_lock.lk_wmesg = wmesg;
bp->b_lock.lk_prio = (PRIBIO + 4) | catch;
bp->b_lock.lk_timo = timo;
ret = lockmgr(&(bp)->b_lock, (locktype), interlock, curthread);
splx(s);
return ret;
}
/*
* Release a lock. Only the acquiring process may free the lock unless
* it has been handed off to biodone.
*/
static __inline void BUF_UNLOCK(struct buf *);
static __inline void
BUF_UNLOCK(struct buf *bp)
{
int s;
s = splbio();
lockmgr(&(bp)->b_lock, LK_RELEASE, NULL, curthread);
splx(s);
}
/*
* Free a buffer lock.
*/
#define BUF_LOCKFREE(bp) \
do { \
if (BUF_REFCNT(bp) > 0) \
panic("free locked buf"); \
lockdestroy(&(bp)->b_lock); \
} while (0)
#ifdef _SYS_PROC_H_ /* Avoid #include <sys/proc.h> pollution */
/*
* When initiating asynchronous I/O, change ownership of the lock to the
* kernel. Once done, the lock may legally released by biodone. The
* original owning process can no longer acquire it recursively, but must
* wait until the I/O is completed and the lock has been freed by biodone.
*/
static __inline void BUF_KERNPROC(struct buf *);
static __inline void
BUF_KERNPROC(struct buf *bp)
{
struct thread *td = curthread;
if ((td != PCPU_GET(idlethread))
&& bp->b_lock.lk_lockholder == td)
td->td_locks--;
bp->b_lock.lk_lockholder = LK_KERNPROC;
}
#endif
/*
* Find out the number of references to a lock.
*/
static __inline int BUF_REFCNT(struct buf *);
static __inline int
BUF_REFCNT(struct buf *bp)
{
int s, ret;
/*
* When the system is panicing, the lock manager grants all lock
* requests whether or not the lock is available. To avoid "unlocked
* buffer" panics after a crash, we just claim that all buffers
* are locked when cleaning up after a system panic.
*/
if (panicstr != NULL)
return (1);
s = splbio();
ret = lockcount(&(bp)->b_lock);
splx(s);
return ret;
}
#endif /* _KERNEL */
struct buf_queue_head {
TAILQ_HEAD(buf_queue, buf) queue;
daddr_t last_pblkno;
struct buf *insert_point;
struct buf *switch_point;
};
/*
* This structure describes a clustered I/O. It is stored in the b_saveaddr
* field of the buffer on which I/O is done. At I/O completion, cluster
* callback uses the structure to parcel I/O's to individual buffers, and
* then free's this structure.
*/
struct cluster_save {
long bs_bcount; /* Saved b_bcount. */
long bs_bufsize; /* Saved b_bufsize. */
void *bs_saveaddr; /* Saved b_addr. */
int bs_nchildren; /* Number of associated buffers. */
struct buf **bs_children; /* List of associated buffers. */
};
#ifdef _KERNEL
static __inline int
buf_prewrite(struct vnode *vp, struct buf *bp)
{
if (bioops.io_prewrite)
return (*bioops.io_prewrite)(vp, bp);
else
return (0);
}
static __inline void
buf_start(struct buf *bp)
{
if (bioops.io_start)
(*bioops.io_start)(bp);
}
static __inline void
buf_complete(struct buf *bp)
{
if (bioops.io_complete)
(*bioops.io_complete)(bp);
}
static __inline void
buf_deallocate(struct buf *bp)
{
if (bioops.io_deallocate)
(*bioops.io_deallocate)(bp);
BUF_LOCKFREE(bp);
}
static __inline void
buf_movedeps(struct buf *bp, struct buf *bp2)
{
if (bioops.io_movedeps)
(*bioops.io_movedeps)(bp, bp2);
}
static __inline int
buf_countdeps(struct buf *bp, int i)
{
if (bioops.io_countdeps)
return ((*bioops.io_countdeps)(bp, i));
else
return (0);
}
#endif /* _KERNEL */
/*
* Zero out the buffer's data area.
*/
#define clrbuf(bp) { \
bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
(bp)->b_resid = 0; \
}
/*
* Flags for getblk's last parameter.
*/
#define GB_LOCK_NOWAIT 0x0001 /* Fail if we block on a buf lock. */
#define GB_NOCREAT 0x0002 /* Don't create a buf if not found. */
#ifdef _KERNEL
extern int nbuf; /* The number of buffer headers */
extern int maxswzone; /* Max KVA for swap structures */
extern int maxbcache; /* Max KVA for buffer cache */
extern int runningbufspace;
extern int buf_maxio; /* nominal maximum I/O for buffer */
extern struct buf *buf; /* The buffer headers. */
extern char *buffers; /* The buffer contents. */
extern int bufpages; /* Number of memory pages in the buffer pool. */
extern struct buf *swbuf; /* Swap I/O buffer headers. */
extern int nswbuf; /* Number of swap I/O buffer headers. */
struct uio;
caddr_t kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est);
void bufinit(void);
void bwillwrite(void);
int buf_dirty_count_severe(void);
void bremfree(struct buf *);
int bread(struct vnode *, daddr_t, int, struct ucred *, struct buf **);
int breadn(struct vnode *, daddr_t, int, daddr_t *, int *, int,
struct ucred *, struct buf **);
int bwrite(struct buf *);
void bdwrite(struct buf *);
void bawrite(struct buf *);
void bdirty(struct buf *);
void bundirty(struct buf *);
void brelse(struct buf *);
void bqrelse(struct buf *);
int vfs_bio_awrite(struct buf *);
struct buf * getpbuf(int *);
struct buf *incore(struct vnode *, daddr_t);
struct buf *gbincore(struct vnode *, daddr_t);
int inmem(struct vnode *, daddr_t);
struct buf *getblk(struct vnode *, daddr_t, int, int, int, int);
struct buf *geteblk(int);
int bufwait(struct buf *);
void bufdone(struct buf *);
void cluster_callback(struct buf *);
int cluster_read(struct vnode *, u_quad_t, daddr_t, long,
struct ucred *, long, int, struct buf **);
int cluster_wbuild(struct vnode *, long, daddr_t, int);
void cluster_write(struct buf *, u_quad_t, int);
void vfs_bio_set_validclean(struct buf *, int base, int size);
void vfs_bio_clrbuf(struct buf *);
void vfs_busy_pages(struct buf *, int clear_modify);
void vfs_unbusy_pages(struct buf *);
void vwakeup(struct buf *);
int vmapbuf(struct buf *);
void vunmapbuf(struct buf *);
void relpbuf(struct buf *, int *);
void brelvp(struct buf *);
void bgetvp(struct vnode *, struct buf *);
void pbgetvp(struct vnode *, struct buf *);
void pbrelvp(struct buf *);
int allocbuf(struct buf *bp, int size);
void reassignbuf(struct buf *);
struct buf *trypbuf(int *);
void bwait(struct buf *, u_char, const char *);
void bdone(struct buf *);
#endif /* _KERNEL */
#endif /* !_SYS_BUF_H_ */