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root/fs/xfs/linux-2.6/xfs_buf.h

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INCLUDED FROM


DEFINITIONS

This source file includes following definitions.
  1. xfs_buf_iostrategy
  2. xfs_buf_geterror
  3. xfs_bawrite
  4. xfs_buf_relse
  5. XFS_bwrite
  6. xfs_bdwrite

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_BUF_H__
#define __XFS_BUF_H__

#include <linux/list.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <asm/system.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/uio.h>

/*
 *      Base types
 */

#define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))

#define xfs_buf_ctob(pp)        ((pp) * PAGE_CACHE_SIZE)
#define xfs_buf_btoc(dd)        (((dd) + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT)
#define xfs_buf_btoct(dd)       ((dd) >> PAGE_CACHE_SHIFT)
#define xfs_buf_poff(aa)        ((aa) & ~PAGE_CACHE_MASK)

typedef enum {
        XBRW_READ = 1,                  /* transfer into target memory */
        XBRW_WRITE = 2,                 /* transfer from target memory */
        XBRW_ZERO = 3,                  /* Zero target memory */
} xfs_buf_rw_t;

typedef enum {
        XBF_READ = (1 << 0),    /* buffer intended for reading from device */
        XBF_WRITE = (1 << 1),   /* buffer intended for writing to device   */
        XBF_MAPPED = (1 << 2),  /* buffer mapped (b_addr valid)            */
        XBF_ASYNC = (1 << 4),   /* initiator will not wait for completion  */
        XBF_DONE = (1 << 5),    /* all pages in the buffer uptodate        */
        XBF_DELWRI = (1 << 6),  /* buffer has dirty pages                  */
        XBF_STALE = (1 << 7),   /* buffer has been staled, do not find it  */
        XBF_FS_MANAGED = (1 << 8),  /* filesystem controls freeing memory  */
        XBF_ORDERED = (1 << 11),    /* use ordered writes                  */
        XBF_READ_AHEAD = (1 << 12), /* asynchronous read-ahead             */

        /* flags used only as arguments to access routines */
        XBF_LOCK = (1 << 14),       /* lock requested                      */
        XBF_TRYLOCK = (1 << 15),    /* lock requested, but do not wait     */
        XBF_DONT_BLOCK = (1 << 16), /* do not block in current thread      */

        /* flags used only internally */
        _XBF_PAGE_CACHE = (1 << 17),/* backed by pagecache                 */
        _XBF_PAGES = (1 << 18),     /* backed by refcounted pages          */
        _XBF_RUN_QUEUES = (1 << 19),/* run block device task queue         */
        _XBF_DELWRI_Q = (1 << 21),   /* buffer on delwri queue             */

        /*
         * Special flag for supporting metadata blocks smaller than a FSB.
         *
         * In this case we can have multiple xfs_buf_t on a single page and
         * need to lock out concurrent xfs_buf_t readers as they only
         * serialise access to the buffer.
         *
         * If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation
         * between reads of the page. Hence we can have one thread read the
         * page and modify it, but then race with another thread that thinks
         * the page is not up-to-date and hence reads it again.
         *
         * The result is that the first modifcation to the page is lost.
         * This sort of AGF/AGI reading race can happen when unlinking inodes
         * that require truncation and results in the AGI unlinked list
         * modifications being lost.
         */
        _XBF_PAGE_LOCKED = (1 << 22),

        /*
         * If we try a barrier write, but it fails we have to communicate
         * this to the upper layers.  Unfortunately b_error gets overwritten
         * when the buffer is re-issued so we have to add another flag to
         * keep this information.
         */
        _XFS_BARRIER_FAILED = (1 << 23),
} xfs_buf_flags_t;

typedef enum {
        XBT_FORCE_SLEEP = 0,
        XBT_FORCE_FLUSH = 1,
} xfs_buftarg_flags_t;

typedef struct xfs_bufhash {
        struct list_head        bh_list;
        spinlock_t              bh_lock;
} xfs_bufhash_t;

typedef struct xfs_buftarg {
        dev_t                   bt_dev;
        struct block_device     *bt_bdev;
        struct address_space    *bt_mapping;
        unsigned int            bt_bsize;
        unsigned int            bt_sshift;
        size_t                  bt_smask;

        /* per device buffer hash table */
        uint                    bt_hashmask;
        uint                    bt_hashshift;
        xfs_bufhash_t           *bt_hash;

        /* per device delwri queue */
        struct task_struct      *bt_task;
        struct list_head        bt_list;
        struct list_head        bt_delwrite_queue;
        spinlock_t              bt_delwrite_lock;
        unsigned long           bt_flags;
} xfs_buftarg_t;

/*
 *      xfs_buf_t:  Buffer structure for pagecache-based buffers
 *
 * This buffer structure is used by the pagecache buffer management routines
 * to refer to an assembly of pages forming a logical buffer.
 *
 * The buffer structure is used on a temporary basis only, and discarded when
 * released.  The real data storage is recorded in the pagecache. Buffers are
 * hashed to the block device on which the file system resides.
 */

struct xfs_buf;
typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
typedef void (*xfs_buf_relse_t)(struct xfs_buf *);
typedef int (*xfs_buf_bdstrat_t)(struct xfs_buf *);

#define XB_PAGES        2

typedef struct xfs_buf {
        struct semaphore        b_sema;         /* semaphore for lockables */
        unsigned long           b_queuetime;    /* time buffer was queued */
        atomic_t                b_pin_count;    /* pin count */
        wait_queue_head_t       b_waiters;      /* unpin waiters */
        struct list_head        b_list;
        xfs_buf_flags_t         b_flags;        /* status flags */
        struct list_head        b_hash_list;    /* hash table list */
        xfs_bufhash_t           *b_hash;        /* hash table list start */
        xfs_buftarg_t           *b_target;      /* buffer target (device) */
        atomic_t                b_hold;         /* reference count */
        xfs_daddr_t             b_bn;           /* block number for I/O */
        xfs_off_t               b_file_offset;  /* offset in file */
        size_t                  b_buffer_length;/* size of buffer in bytes */
        size_t                  b_count_desired;/* desired transfer size */
        void                    *b_addr;        /* virtual address of buffer */
        struct work_struct      b_iodone_work;
        atomic_t                b_io_remaining; /* #outstanding I/O requests */
        xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
        xfs_buf_relse_t         b_relse;        /* releasing function */
        xfs_buf_bdstrat_t       b_strat;        /* pre-write function */
        struct completion       b_iowait;       /* queue for I/O waiters */
        void                    *b_fspriv;
        void                    *b_fspriv2;
        void                    *b_fspriv3;
        unsigned short          b_error;        /* error code on I/O */
        unsigned int            b_page_count;   /* size of page array */
        unsigned int            b_offset;       /* page offset in first page */
        struct page             **b_pages;      /* array of page pointers */
        struct page             *b_page_array[XB_PAGES]; /* inline pages */
#ifdef XFS_BUF_LOCK_TRACKING
        int                     b_last_holder;
#endif
} xfs_buf_t;


/* Finding and Reading Buffers */
extern xfs_buf_t *_xfs_buf_find(xfs_buftarg_t *, xfs_off_t, size_t,
                                xfs_buf_flags_t, xfs_buf_t *);
#define xfs_incore(buftarg,blkno,len,lockit) \
        _xfs_buf_find(buftarg, blkno ,len, lockit, NULL)

extern xfs_buf_t *xfs_buf_get_flags(xfs_buftarg_t *, xfs_off_t, size_t,
                                xfs_buf_flags_t);
#define xfs_buf_get(target, blkno, len, flags) \
        xfs_buf_get_flags((target), (blkno), (len), XBF_LOCK | XBF_MAPPED)

extern xfs_buf_t *xfs_buf_read_flags(xfs_buftarg_t *, xfs_off_t, size_t,
                                xfs_buf_flags_t);
#define xfs_buf_read(target, blkno, len, flags) \
        xfs_buf_read_flags((target), (blkno), (len), XBF_LOCK | XBF_MAPPED)

extern xfs_buf_t *xfs_buf_get_empty(size_t, xfs_buftarg_t *);
extern xfs_buf_t *xfs_buf_get_noaddr(size_t, xfs_buftarg_t *);
extern int xfs_buf_associate_memory(xfs_buf_t *, void *, size_t);
extern void xfs_buf_hold(xfs_buf_t *);
extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t,
                                xfs_buf_flags_t);

/* Releasing Buffers */
extern void xfs_buf_free(xfs_buf_t *);
extern void xfs_buf_rele(xfs_buf_t *);

/* Locking and Unlocking Buffers */
extern int xfs_buf_cond_lock(xfs_buf_t *);
extern int xfs_buf_lock_value(xfs_buf_t *);
extern void xfs_buf_lock(xfs_buf_t *);
extern void xfs_buf_unlock(xfs_buf_t *);

/* Buffer Read and Write Routines */
extern void xfs_buf_ioend(xfs_buf_t *,  int);
extern void xfs_buf_ioerror(xfs_buf_t *, int);
extern int xfs_buf_iostart(xfs_buf_t *, xfs_buf_flags_t);
extern int xfs_buf_iorequest(xfs_buf_t *);
extern int xfs_buf_iowait(xfs_buf_t *);
extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, xfs_caddr_t,
                                xfs_buf_rw_t);

static inline int xfs_buf_iostrategy(xfs_buf_t *bp)
{
        return bp->b_strat ? bp->b_strat(bp) : xfs_buf_iorequest(bp);
}

static inline int xfs_buf_geterror(xfs_buf_t *bp)
{
        return bp ? bp->b_error : ENOMEM;
}

/* Buffer Utility Routines */
extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);

/* Pinning Buffer Storage in Memory */
extern void xfs_buf_pin(xfs_buf_t *);
extern void xfs_buf_unpin(xfs_buf_t *);
extern int xfs_buf_ispin(xfs_buf_t *);

/* Delayed Write Buffer Routines */
extern void xfs_buf_delwri_dequeue(xfs_buf_t *);

/* Buffer Daemon Setup Routines */
extern int xfs_buf_init(void);
extern void xfs_buf_terminate(void);

#ifdef XFS_BUF_TRACE
extern ktrace_t *xfs_buf_trace_buf;
extern void xfs_buf_trace(xfs_buf_t *, char *, void *, void *);
#else
#define xfs_buf_trace(bp,id,ptr,ra)     do { } while (0)
#endif

#define xfs_buf_target_name(target)     \
        ({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })


#define XFS_B_ASYNC             XBF_ASYNC
#define XFS_B_DELWRI            XBF_DELWRI
#define XFS_B_READ              XBF_READ
#define XFS_B_WRITE             XBF_WRITE
#define XFS_B_STALE             XBF_STALE

#define XFS_BUF_TRYLOCK         XBF_TRYLOCK
#define XFS_INCORE_TRYLOCK      XBF_TRYLOCK
#define XFS_BUF_LOCK            XBF_LOCK
#define XFS_BUF_MAPPED          XBF_MAPPED

#define BUF_BUSY                XBF_DONT_BLOCK

#define XFS_BUF_BFLAGS(bp)      ((bp)->b_flags)
#define XFS_BUF_ZEROFLAGS(bp)   ((bp)->b_flags &= \
                ~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI|XBF_ORDERED))

#define XFS_BUF_STALE(bp)       ((bp)->b_flags |= XFS_B_STALE)
#define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XFS_B_STALE)
#define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XFS_B_STALE)
#define XFS_BUF_SUPER_STALE(bp) do {                            \
                                        XFS_BUF_STALE(bp);      \
                                        xfs_buf_delwri_dequeue(bp);     \
                                        XFS_BUF_DONE(bp);       \
                                } while (0)

#define XFS_BUF_MANAGE          XBF_FS_MANAGED
#define XFS_BUF_UNMANAGE(bp)    ((bp)->b_flags &= ~XBF_FS_MANAGED)

#define XFS_BUF_DELAYWRITE(bp)          ((bp)->b_flags |= XBF_DELWRI)
#define XFS_BUF_UNDELAYWRITE(bp)        xfs_buf_delwri_dequeue(bp)
#define XFS_BUF_ISDELAYWRITE(bp)        ((bp)->b_flags & XBF_DELWRI)

#define XFS_BUF_ERROR(bp,no)    xfs_buf_ioerror(bp,no)
#define XFS_BUF_GETERROR(bp)    xfs_buf_geterror(bp)
#define XFS_BUF_ISERROR(bp)     (xfs_buf_geterror(bp) ? 1 : 0)

#define XFS_BUF_DONE(bp)        ((bp)->b_flags |= XBF_DONE)
#define XFS_BUF_UNDONE(bp)      ((bp)->b_flags &= ~XBF_DONE)
#define XFS_BUF_ISDONE(bp)      ((bp)->b_flags & XBF_DONE)

#define XFS_BUF_BUSY(bp)        do { } while (0)
#define XFS_BUF_UNBUSY(bp)      do { } while (0)
#define XFS_BUF_ISBUSY(bp)      (1)

#define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
#define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
#define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)

#define XFS_BUF_ORDERED(bp)     ((bp)->b_flags |= XBF_ORDERED)
#define XFS_BUF_UNORDERED(bp)   ((bp)->b_flags &= ~XBF_ORDERED)
#define XFS_BUF_ISORDERED(bp)   ((bp)->b_flags & XBF_ORDERED)

#define XFS_BUF_SHUT(bp)        do { } while (0)
#define XFS_BUF_UNSHUT(bp)      do { } while (0)
#define XFS_BUF_ISSHUT(bp)      (0)

#define XFS_BUF_HOLD(bp)        xfs_buf_hold(bp)
#define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
#define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
#define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)

#define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
#define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
#define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)

#define XFS_BUF_IODONE_FUNC(bp)                 ((bp)->b_iodone)
#define XFS_BUF_SET_IODONE_FUNC(bp, func)       ((bp)->b_iodone = (func))
#define XFS_BUF_CLR_IODONE_FUNC(bp)             ((bp)->b_iodone = NULL)
#define XFS_BUF_SET_BDSTRAT_FUNC(bp, func)      ((bp)->b_strat = (func))
#define XFS_BUF_CLR_BDSTRAT_FUNC(bp)            ((bp)->b_strat = NULL)

#define XFS_BUF_FSPRIVATE(bp, type)             ((type)(bp)->b_fspriv)
#define XFS_BUF_SET_FSPRIVATE(bp, val)          ((bp)->b_fspriv = (void*)(val))
#define XFS_BUF_FSPRIVATE2(bp, type)            ((type)(bp)->b_fspriv2)
#define XFS_BUF_SET_FSPRIVATE2(bp, val)         ((bp)->b_fspriv2 = (void*)(val))
#define XFS_BUF_FSPRIVATE3(bp, type)            ((type)(bp)->b_fspriv3)
#define XFS_BUF_SET_FSPRIVATE3(bp, val)         ((bp)->b_fspriv3 = (void*)(val))
#define XFS_BUF_SET_START(bp)                   do { } while (0)
#define XFS_BUF_SET_BRELSE_FUNC(bp, func)       ((bp)->b_relse = (func))

#define XFS_BUF_PTR(bp)                 (xfs_caddr_t)((bp)->b_addr)
#define XFS_BUF_SET_PTR(bp, val, cnt)   xfs_buf_associate_memory(bp, val, cnt)
#define XFS_BUF_ADDR(bp)                ((bp)->b_bn)
#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_bn = (xfs_daddr_t)(bno))
#define XFS_BUF_OFFSET(bp)              ((bp)->b_file_offset)
#define XFS_BUF_SET_OFFSET(bp, off)     ((bp)->b_file_offset = (off))
#define XFS_BUF_COUNT(bp)               ((bp)->b_count_desired)
#define XFS_BUF_SET_COUNT(bp, cnt)      ((bp)->b_count_desired = (cnt))
#define XFS_BUF_SIZE(bp)                ((bp)->b_buffer_length)
#define XFS_BUF_SET_SIZE(bp, cnt)       ((bp)->b_buffer_length = (cnt))

#define XFS_BUF_SET_VTYPE_REF(bp, type, ref)    do { } while (0)
#define XFS_BUF_SET_VTYPE(bp, type)             do { } while (0)
#define XFS_BUF_SET_REF(bp, ref)                do { } while (0)

#define XFS_BUF_ISPINNED(bp)    xfs_buf_ispin(bp)

#define XFS_BUF_VALUSEMA(bp)    xfs_buf_lock_value(bp)
#define XFS_BUF_CPSEMA(bp)      (xfs_buf_cond_lock(bp) == 0)
#define XFS_BUF_VSEMA(bp)       xfs_buf_unlock(bp)
#define XFS_BUF_PSEMA(bp,x)     xfs_buf_lock(bp)
#define XFS_BUF_FINISH_IOWAIT(bp)       complete(&bp->b_iowait);

#define XFS_BUF_SET_TARGET(bp, target)  ((bp)->b_target = (target))
#define XFS_BUF_TARGET(bp)              ((bp)->b_target)
#define XFS_BUFTARG_NAME(target)        xfs_buf_target_name(target)

static inline int xfs_bawrite(void *mp, xfs_buf_t *bp)
{
        bp->b_fspriv3 = mp;
        bp->b_strat = xfs_bdstrat_cb;
        xfs_buf_delwri_dequeue(bp);
        return xfs_buf_iostart(bp, XBF_WRITE | XBF_ASYNC | _XBF_RUN_QUEUES);
}

static inline void xfs_buf_relse(xfs_buf_t *bp)
{
        if (!bp->b_relse)
                xfs_buf_unlock(bp);
        xfs_buf_rele(bp);
}

#define xfs_bpin(bp)            xfs_buf_pin(bp)
#define xfs_bunpin(bp)          xfs_buf_unpin(bp)

#define xfs_buftrace(id, bp)    \
            xfs_buf_trace(bp, id, NULL, (void *)__builtin_return_address(0))

#define xfs_biodone(bp)         xfs_buf_ioend(bp, 0)

#define xfs_biomove(bp, off, len, data, rw) \
            xfs_buf_iomove((bp), (off), (len), (data), \
                ((rw) == XFS_B_WRITE) ? XBRW_WRITE : XBRW_READ)

#define xfs_biozero(bp, off, len) \
            xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)


static inline int XFS_bwrite(xfs_buf_t *bp)
{
        int     iowait = (bp->b_flags & XBF_ASYNC) == 0;
        int     error = 0;

        if (!iowait)
                bp->b_flags |= _XBF_RUN_QUEUES;

        xfs_buf_delwri_dequeue(bp);
        xfs_buf_iostrategy(bp);
        if (iowait) {
                error = xfs_buf_iowait(bp);
                xfs_buf_relse(bp);
        }
        return error;
}

/*
 * No error can be returned from xfs_buf_iostart for delwri
 * buffers as they are queued and no I/O is issued.
 */
static inline void xfs_bdwrite(void *mp, xfs_buf_t *bp)
{
        bp->b_strat = xfs_bdstrat_cb;
        bp->b_fspriv3 = mp;
        (void)xfs_buf_iostart(bp, XBF_DELWRI | XBF_ASYNC);
}

#define XFS_bdstrat(bp) xfs_buf_iorequest(bp)

#define xfs_iowait(bp)  xfs_buf_iowait(bp)

#define xfs_baread(target, rablkno, ralen)  \
        xfs_buf_readahead((target), (rablkno), (ralen), XBF_DONT_BLOCK)


/*
 *      Handling of buftargs.
 */
extern xfs_buftarg_t *xfs_alloc_buftarg(struct block_device *, int);
extern void xfs_free_buftarg(xfs_buftarg_t *);
extern void xfs_wait_buftarg(xfs_buftarg_t *);
extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
extern int xfs_flush_buftarg(xfs_buftarg_t *, int);
#ifdef CONFIG_KDB_MODULES
extern struct list_head *xfs_get_buftarg_list(void);
#endif

#define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)

#define xfs_binval(buftarg)             xfs_flush_buftarg(buftarg, 1)
#define XFS_bflush(buftarg)             xfs_flush_buftarg(buftarg, 1)

#endif  /* __XFS_BUF_H__ */

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