kernel - TMPFS - Add infrastructure to main kernel to help support TMPFS

[dragonfly.git] / 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.
 * 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: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $
 * $DragonFly: src/sys/sys/buf.h,v 1.54 2008/08/29 20:08:37 dillon Exp $
 */

#ifndef _SYS_BUF_H_
#define _SYS_BUF_H_

#if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)

#ifndef _SYS_QUEUE_H_
#include <sys/queue.h>
#endif
#ifndef _SYS_LOCK_H_
#include <sys/lock.h>
#endif
#ifndef _SYS_DEVICE_H_
#include <sys/device.h>
#endif

#ifndef _SYS_XIO_H_
#include <sys/xio.h>
#endif
#ifndef _SYS_TREE_H_
#include <sys/tree.h>
#endif
#ifndef _SYS_BIO_H_
#include <sys/bio.h>
#endif
#ifndef _SYS_SPINLOCK_H_
#include <sys/spinlock.h>
#endif

struct buf;
struct bio;
struct mount;
struct vnode;
struct xio;

#define NBUF_BIO        4

struct buf_rb_tree;
struct buf_rb_hash;
RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t);
RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t);

/*
 * To avoid including <ufs/ffs/softdep.h> 
 */   
LIST_HEAD(workhead, worklist);

#endif

typedef enum buf_cmd {
        BUF_CMD_DONE = 0,
        BUF_CMD_READ,
        BUF_CMD_WRITE,
        BUF_CMD_FREEBLKS,
        BUF_CMD_FORMAT,
        BUF_CMD_FLUSH
} buf_cmd_t;

#if defined(_KERNEL) || defined(_KERNEL_STRUCTURES)

/*
 * The buffer header describes an I/O operation in the kernel.
 *
 * NOTES:
 *      b_bufsize represents the filesystem block size (for this particular
 *      block) and/or the allocation size or original request size.  This
 *      field is NOT USED by lower device layers.  VNode and device
 *      strategy routines WILL NEVER ACCESS THIS FIELD.
 *
 *      b_bcount represents the I/O request size.  Unless B_NOBCLIP is set,
 *      the device chain is allowed to clip b_bcount to accomodate the device
 *      EOF.  Note that this is different from the byte oriented file EOF.
 *      If B_NOBCLIP is set, the device chain is required to generate an
 *      error if it would othrewise have to clip the request.  Buffers 
 *      obtained via getblk() automatically set B_NOBCLIP.  It is important
 *      to note that EOF clipping via b_bcount is different from EOF clipping
 *      via returning a b_actual < b_bcount.  B_NOBCLIP only effects block
 *      oriented EOF clipping (b_bcount modifications).
 *
 *      b_actual represents the number of bytes of I/O that actually occured,
 *      whether an error occured or not.  b_actual must be initialized to 0
 *      prior to initiating I/O as the device drivers will assume it to
 *      start at 0.
 *
 *      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_bio1 and b_bio2 represent the two primary I/O layers.  Additional
 *      I/O layers are allocated out of the object cache and may also exist.
 *
 *      b_bio1 is the logical layer and contains offset or block number 
 *      data for the primary vnode, b_vp.  I/O operations are almost
 *      universally initiated from the logical layer, so you will often
 *      see things like:  vn_strategy(bp->b_vp, &bp->b_bio1).
 *
 *      b_bio2 is the first physical layer (typically the slice-relative
 *      layer) and contains the translated offset or block number for
 *      the block device underlying a filesystem.   Filesystems such as UFS
 *      will maintain cached translations and you may see them initiate
 *      a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2).  BUT, 
 *      remember that the layering is relative to bp->b_vp, so the
 *      device-relative block numbers for buffer cache operations that occur
 *      directly on a block device will be in the first BIO layer.
 *
 *      b_ops - initialized if a buffer has a bio_ops
 *
 *      NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly.
 *      ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO
 *      PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE
 *      I/O DEEPER.  In particular, a vn_strategy() or dev_dstrategy()
 *      call should not ever access buf->b_vp as this vnode may be totally
 *      unrelated to the vnode/device whos strategy routine was called.
 */
struct buf {
        RB_ENTRY(buf) b_rbnode;         /* RB node in vnode clean/dirty tree */
        RB_ENTRY(buf) b_rbhash;         /* RB node in vnode hash tree */
        TAILQ_ENTRY(buf) b_freelist;    /* Free list position if not active. */
        struct buf *b_cluster_next;     /* Next buffer (cluster code) */
        struct vnode *b_vp;             /* (vp, loffset) index */
        struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */ 
        u_int32_t b_flags;              /* B_* flags. */
        unsigned short b_qindex;        /* buffer queue index */
        unsigned char b_act_count;      /* similar to vm_page act_count */
        unsigned char b_unused01;
        struct lock b_lock;             /* Buffer lock */
        buf_cmd_t b_cmd;                /* I/O command */
        int     b_bufsize;              /* Allocated buffer size. */
        int     b_runningbufspace;      /* when I/O is running, pipelining */
        int     b_bcount;               /* Valid bytes in buffer. */
        int     b_resid;                /* Remaining I/O */
        int     b_error;                /* Error return */
        caddr_t b_data;                 /* Memory, superblocks, indirect etc. */
        caddr_t b_kvabase;              /* base kva for buffer */
        int     b_kvasize;              /* size of kva for buffer */
        int     b_dirtyoff;             /* Offset in buffer of dirty region. */
        int     b_dirtyend;             /* Offset of end of dirty region. */
        struct  xio b_xio;              /* data buffer page list management */
        struct  bio_ops *b_ops;         /* bio_ops used w/ b_dep */
        struct  workhead b_dep;         /* List of filesystem dependencies. */
};

/*
 * XXX temporary
 */
#define b_bio1          b_bio_array[0]  /* logical layer */
#define b_bio2          b_bio_array[1]  /* (typically) the disk layer */
#define b_loffset       b_bio1.bio_offset


/*
 * Flags passed to getblk()
 *
 * GETBLK_PCATCH - Allow signals to be caught.  getblk() is allowed to return
 *                 NULL if this flag is passed.
 *
 * GETBLK_BHEAVY - This is a heavy weight buffer, meaning that resolving
 *                 writes can require additional buffers.
 *
 * GETBLK_SZMATCH- blksize must match pre-existing b_bcount.  getblk() can
 *                 return NULL.
 *
 * GETBLK_NOWAIT - Do not use a blocking lock.  getblk() can return NULL.
 */
#define GETBLK_PCATCH   0x0001  /* catch signals */
#define GETBLK_BHEAVY   0x0002  /* heavy weight buffer */
#define GETBLK_SZMATCH  0x0004  /* pre-existing buffer must match */
#define GETBLK_NOWAIT   0x0008  /* non-blocking */

#define FINDBLK_TEST    0x0010  /* test only, do not lock */
#define FINDBLK_NBLOCK  0x0020  /* use non-blocking lock, can return NULL */

/*
 * These flags are kept in b_flags.
 *
 * Notes:
 *
 *      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 B_ERROR|B_INVAL,
 *                      set BUF_CMD_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_LOCKED        The buffer will be released to the locked queue
 *                      regardless of its current state.  Note that
 *                      if B_DELWRI is set, no I/O occurs until the caller
 *                      acquires the buffer, clears B_LOCKED, then releases
 *                      it again.
 *
 *      B_AGE           When allocating a new buffer any buffer encountered
 *                      with B_AGE set will be reallocated more quickly then
 *                      buffers encountered without it set.  B_AGE is set
 *                      as part of the loop so idle buffers should eventually
 *                      wind up with B_AGE set.  B_AGE explicitly does NOT
 *                      cause the buffer to be instantly reallocated for
 *                      other purposes.
 *
 *                      Standard buffer flushing routines leave B_AGE intact
 *                      through the DIRTY queue and into the CLEAN queue.
 *                      Setting B_AGE on a dirty buffer will not cause it
 *                      to be flushed more quickly but will cause it to be
 *                      reallocated more quickly after having been flushed.
 *
 *      B_NOCACHE       Request that the buffer and backing store be
 *                      destroyed on completion.  If B_DELWRI is set and the
 *                      write fails, the buffer remains intact.
 *
 *      B_NOTMETA       May be set on block device buffers representing
 *                      file data (i.e. which aren't really meta-data),
 *                      which will cause the buffer cache to set PG_NOTMETA
 *                      in the VM pages when releasing them and the
 *                      swapcache to not try to cache them.
 */

#define B_AGE           0x00000001      /* Reuse more quickly */
#define B_NEEDCOMMIT    0x00000002      /* Append-write in progress. */
#define B_NOTMETA       0x00000004      /* This really isn't metadata */
#define B_DIRECT        0x00000008      /* direct I/O flag (pls free vmio) */
#define B_DEFERRED      0x00000010      /* vfs-controlled deferment */
#define B_CACHE         0x00000020      /* Bread found us in the cache. */
#define B_HASHED        0x00000040      /* Indexed via v_rbhash_tree */
#define B_DELWRI        0x00000080      /* Delay I/O until buffer reused. */
#define B_BNOCLIP       0x00000100      /* EOF clipping b_bcount not allowed */
#define B_UNUSED9       0x00000200
#define B_EINTR         0x00000400      /* I/O was interrupted */
#define B_ERROR         0x00000800      /* I/O error occurred. */
#define B_UNUSED12      0x00001000      /* Unused */
#define B_INVAL         0x00002000      /* Does not contain valid info. */
#define B_LOCKED        0x00004000      /* Locked in core (not reusable). */
#define B_NOCACHE       0x00008000      /* Destroy buffer AND backing store */
#define B_MALLOC        0x00010000      /* malloced b_data */
#define B_CLUSTEROK     0x00020000      /* Pagein op, so swap() can count it. */
#define B_UNUSED18      0x00040000
#define B_RAW           0x00080000      /* Set by physio for raw transfers. */
#define B_HEAVY         0x00100000      /* Heavy-weight buffer */
#define B_DIRTY         0x00200000      /* Needs writing later. */
#define B_RELBUF        0x00400000      /* Release VMIO buffer. */
#define B_UNUSED23      0x00800000      /* Request wakeup on done */
#define B_VNCLEAN       0x01000000      /* On vnode clean list */
#define B_VNDIRTY       0x02000000      /* On vnode dirty list */
#define B_PAGING        0x04000000      /* volatile paging I/O -- bypass VMIO */
#define B_ORDERED       0x08000000      /* Must guarantee I/O ordering */
#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_VFSFLAG1      0x80000000      /* VFSs can set this flag */

#define PRINT_BUF_FLAGS "\20"   \
        "\40unused31\37cluster\36vmio\35ram\34ordered" \
        "\33paging\32vndirty\31vnclean\30unused23\27relbuf\26dirty" \
        "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \
        "\17locked\16inval\15unused12\14error\13eintr\12unused9\11bnoclip" \
        "\10delwri\7hashed\6cache\5deferred\4direct\3unused2\2needcommit\1age"

#define NOOFFSET        (-1LL)          /* No buffer offset calculated yet */

#ifdef _KERNEL
/*
 * Buffer locking.  See sys/buf2.h for inline functions.
 */
extern char *buf_wmesg;                 /* Default buffer lock message */
#define BUF_WMESG "bufwait"

#endif /* _KERNEL */

struct bio_queue_head {
        TAILQ_HEAD(bio_queue, bio) queue;
        off_t   off_unused;
        int     reorder;
        struct  bio *transition;
        struct  bio *bio_unused;
};

/*
 * This structure describes a clustered I/O.
 */
struct cluster_save {
        int     bs_nchildren;           /* Number of associated buffers. */
        struct buf **bs_children;       /* List of associated buffers. */
};

/*
 * Zero out the buffer's data area.
 */
#define clrbuf(bp) {                                                    \
        bzero((bp)->b_data, (u_int)(bp)->b_bcount);                     \
        (bp)->b_resid = 0;                                              \
}

/*
 * Flags to low-level bitmap allocation routines (balloc).
 *
 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count
 * to 127.
 */
#define B_SEQMASK       0x7F000000      /* Sequential heuristic mask. */
#define B_SEQSHIFT      24              /* Sequential heuristic shift. */
#define B_SEQMAX        0x7F
#define B_CLRBUF        0x01            /* Cleared invalid areas of buffer. */
#define B_SYNC          0x02            /* Do all allocations synchronously. */

#ifdef _KERNEL
extern int      nbuf;                   /* The number of buffer headers */
extern long     maxswzone;              /* Max KVA for swap structures */
extern long     maxbcache;              /* Max KVA for buffer cache */
extern int      runningbufspace;
extern int      runningbufcount;
extern int      hidirtybufspace;
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. */
extern int      bioq_reorder_burst_interval;
extern int      bioq_reorder_burst_bytes;
extern int      bioq_reorder_minor_interval;
extern int      bioq_reorder_minor_bytes;

struct uio;

void    bufinit (void);
int     bd_heatup (void);
void    bd_wait (int count);
int     buf_dirty_count_severe (void);
int     buf_runningbufspace_severe (void);
void    initbufbio(struct buf *);
void    reinitbufbio(struct buf *);
void    clearbiocache(struct bio *);
void    bremfree (struct buf *);
int     bread (struct vnode *, off_t, int, struct buf **);
int     breadn (struct vnode *, off_t, int, off_t *, int *, int,
            struct buf **);
int     bwrite (struct buf *);
void    bdwrite (struct buf *);
void    buwrite (struct buf *);
void    bawrite (struct buf *);
void    bdirty (struct buf *);
void    bheavy (struct buf *);
void    bundirty (struct buf *);
int     bowrite (struct buf *);
void    brelse (struct buf *);
void    bqrelse (struct buf *);
int     vfs_bio_awrite (struct buf *);
struct buf *getpbuf (int *);
int     inmem (struct vnode *, off_t);
struct buf *findblk (struct vnode *, off_t, int);
struct buf *getblk (struct vnode *, off_t, int, int, int);
struct buf *getcacheblk (struct vnode *, off_t);
struct buf *geteblk (int);
void regetblk(struct buf *bp);
struct bio *push_bio(struct bio *);
struct bio *pop_bio(struct bio *);
int     biowait (struct bio *, const char *);
int     biowait_timeout (struct bio *, const char *, int);
void    bpdone (struct buf *, int);
void    biodone (struct bio *);
void    biodone_sync (struct bio *);

void    cluster_append(struct bio *, struct buf *);
int     cluster_read (struct vnode *, off_t, off_t, int,
            size_t, int, struct buf **);
int     cluster_wbuild (struct vnode *, int, off_t, int);
void    cluster_write (struct buf *, off_t, int, int);
int     physread (struct dev_read_args *);
int     physwrite (struct dev_write_args *);
void    vfs_bio_clrbuf (struct buf *);
void    vfs_busy_pages (struct vnode *, struct buf *);
void    vfs_unbusy_pages (struct buf *);
int     vmapbuf (struct buf *, caddr_t, int);
void    vunmapbuf (struct buf *);
void    relpbuf (struct buf *, int *);
void    brelvp (struct buf *);
int     bgetvp (struct vnode *, struct buf *);
int     allocbuf (struct buf *bp, int size);
int     scan_all_buffers (int (*)(struct buf *, void *), void *);
void    reassignbuf (struct buf *);
struct  buf *trypbuf (int *);
void    bio_ops_sync(struct mount *mp);
void    vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to);
void    vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to);

#endif  /* _KERNEL */
#endif  /* _KERNEL || _KERNEL_STRUCTURES */
#endif  /* !_SYS_BUF_H_ */