system/freebsd-src
system/freebsd-src
1
0
Fork 0
mirror of https://github.com/freebsd/freebsd-src synced 2024-10-20 15:24:25 +00:00
Code Issues Packages Projects Releases Wiki Activity
freebsd-src/sys/sys/buf.h
Matthew Dillon d331c5d43f Replace the global buffer hash table with per-vnode splay trees using a 
methodology similar to the vm_map_entry splay and the VM splay that Alan
Cox is working on.  Extensive testing has appeared to have shown no
increase in overhead.

Disadvantages
    Dirties more cache lines during lookups.

    Not as fast as a hash table lookup (but still N log N and optimal
    when there is locality of reference).

Advantages
    vnode->v_dirtyblkhd is now perfectly sorted, making fsync/sync/filesystem
    syncer operate more efficiently.

    I get to rip out all the old hacks (some of which were mine) that tried
    to keep the v_dirtyblkhd tailq sorted.

    The per-vnode splay tree should be easier to lock / SMPng pushdown on
    vnodes will be easier.

    This commit along with another that Alan is working on for the VM page
    global hash table will allow me to implement ranged fsync(), optimize
    server-side nfs commit rpcs, and implement partial syncs by the
    filesystem syncer (aka filesystem syncer would detect that someone is
    trying to get the vnode lock, remembers its place, and skip to the
    next vnode).

Note that the buffer cache splay is somewhat more complex then other splays
due to special handling of background bitmap writes (multiple buffers with
the same lblkno in the same vnode), and B_INVAL discontinuities between the
old hash table and the existence of the buffer on the v_cleanblkhd list.

Suggested by: alc
2002-07-10 17:02:32 +00:00

517 lines
17 KiB
C
Raw Blame History

/*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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
* $FreeBSD$
*/
#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 {
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.
*/
struct buf {
/* XXX: b_io must be the first element of struct buf for now /phk */
/* XXX: if you change this, fix BIOTOBUF macro below */
struct bio b_io; /* "Builtin" I/O request. */
#define BIOTOBUF(biop) ((struct buf *)(biop))
#define b_bcount b_io.bio_bcount
#define b_blkno b_io.bio_blkno
#define b_caller1 b_io.bio_caller1
#define b_data b_io.bio_data
#define b_dev b_io.bio_dev
#define b_driver1 b_io.bio_driver1
#define b_driver2 b_io.bio_driver2
#define b_error b_io.bio_error
#define b_iocmd b_io.bio_cmd
#define b_ioflags b_io.bio_flags
#define b_pblkno b_io.bio_pblkno
#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 *);
off_t b_offset; /* Offset into file. */
#ifdef USE_BUFHASH
LIST_ENTRY(buf) b_hash; /* Hash chain. */
#endif
TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
struct buf *b_left; /* splay tree link (V) */
struct buf *b_right; /* splay tree link (V) */
TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
long b_flags; /* B_* flags. */
unsigned short b_qindex; /* buffer queue index */
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 {
void *pg_spc;
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; /* List of filesystem dependencies. */
};
#define b_spc b_pager.pg_spc
/*
* 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.
*
* B_NOWDRAIN This flag should be set when a device (like MD)
* does a turn-around VOP_WRITE from its strategy
* routine. This flag prevents bwrite() from blocking
* in wdrain, avoiding a deadlock situation.
*/
#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_NOWDRAIN 0x00000800 /* Avoid wdrain deadlock */
#define B_SCANNED 0x00001000 /* VOP_FSYNC funcs mark written bufs */
#define B_INVAL 0x00002000 /* Does not contain valid info. */
#define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
#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_PHYS 0x00040000 /* I/O to user memory. */
#define B_00080000 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 0x00000004 /* Do writes in background */
#define BX_BKGRDINPROG 0x00000008 /* Background write in progress */
#define BX_BKGRDWAIT 0x00000010 /* Background write waiting */
#define BX_BKGRDMARKER 0x00000020 /* Mark buffer for splay tree */
#define NOOFFSET (-1LL) /* No buffer offset calculated yet */
#ifdef _KERNEL
/*
* Buffer locking
*/
extern struct mtx buftimelock; /* Interlock on setting prio and timo */
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);
static __inline int
BUF_LOCK(struct buf *bp, int locktype)
{
int s, ret;
s = splbio();
mtx_lock(&buftimelock);
locktype |= LK_INTERLOCK;
bp->b_lock.lk_wmesg = buf_wmesg;
bp->b_lock.lk_prio = PRIBIO + 4;
ret = lockmgr(&(bp)->b_lock, locktype, &buftimelock, curthread);
splx(s);
return ret;
}
/*
* Get a lock sleeping with specified interruptably and timeout.
*/
static __inline int BUF_TIMELOCK(struct buf *, int, char *, int, int);
static __inline int
BUF_TIMELOCK(struct buf *bp, int locktype, char *wmesg, int catch, int timo)
{
int s, ret;
s = splbio();
mtx_lock(&buftimelock);
locktype |= LK_INTERLOCK | 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), &buftimelock, 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_proc->p_pid)
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;
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
#define BUF_WRITE(bp) \
(bp)->b_op->bop_write(bp)
#define BUF_STRATEGY(bp) VOP_STRATEGY((bp)->b_vp, (bp))
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; \
}
#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, int 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);
struct buf *geteblk(int);
int bufwait(struct buf *);
void bufdone(struct buf *);
void bufdonebio(struct bio *);
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 *);
void 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 vnode *);
struct buf *trypbuf(int *);
#endif /* _KERNEL */
#endif /* !_SYS_BUF_H_ */
Reference in a new issue View git blame Copy permalink