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linux/fs/xfs/linux-2.6/xfs_buf.h
Christoph Hellwig a9759f2de3 [XFS] kill superflous buffer locking (2nd attempt) 
There is no need to lock any page in xfs_buf.c because we operate on our
own address_space and all locking is covered by the buffer semaphore. If
we ever switch back to main blockdeive address_space as suggested e.g. for
fsblock with a similar scheme the locking will have to be totally revised
anyway because the current scheme is neither correct nor coherent with
itself.

SGI-PV: 971186
SGI-Modid: xfs-linux-melb:xfs-kern:30156a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
2008-02-07 18:18:50 +11:00

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/*
* 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 */
} 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 semaphore b_iodonesema; /* Semaphore 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_V_IODONESEMA(bp) up(&bp->b_iodonesema);
#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;
}
static inline int xfs_bdwrite(void *mp, xfs_buf_t *bp)
{
bp->b_strat = xfs_bdstrat_cb;
bp->b_fspriv3 = mp;
return 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 *, int);
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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