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linux/fs/xfs/linux-2.6/xfs_buf.h
Dave Chinner d808f617ad xfs: Don't issue buffer IO direct from AIL push V2 
All buffers logged into the AIL are marked as delayed write.
When the AIL needs to push the buffer out, it issues an async write of the
buffer. This means that IO patterns are dependent on the order of
buffers in the AIL.

Instead of flushing the buffer, promote the buffer in the delayed
write list so that the next time the xfsbufd is run the buffer will
be flushed by the xfsbufd. Return the state to the xfsaild that the
buffer was promoted so that the xfsaild knows that it needs to cause
the xfsbufd to run to flush the buffers that were promoted.

Using the xfsbufd for issuing the IO allows us to dispatch all
buffer IO from the one queue. This means that we can make much more
enlightened decisions on what order to flush buffers to disk as
we don't have multiple places issuing IO. Optimisations to xfsbufd
will be in a future patch.

Version 2
- kill XFS_ITEM_FLUSHING as it is now unused.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2010-02-02 10:13:42 +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 */
XBF_LOG_BUFFER = (1 << 13), /* this is a buffer used for the log */
/* 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;
#define XFS_BUF_FLAGS \
{ XBF_READ, "READ" }, \
{ XBF_WRITE, "WRITE" }, \
{ XBF_MAPPED, "MAPPED" }, \
{ XBF_ASYNC, "ASYNC" }, \
{ XBF_DONE, "DONE" }, \
{ XBF_DELWRI, "DELWRI" }, \
{ XBF_STALE, "STALE" }, \
{ XBF_FS_MANAGED, "FS_MANAGED" }, \
{ XBF_ORDERED, "ORDERED" }, \
{ XBF_READ_AHEAD, "READ_AHEAD" }, \
{ XBF_LOCK, "LOCK" }, /* should never be set */\
{ XBF_TRYLOCK, "TRYLOCK" }, /* ditto */\
{ XBF_DONT_BLOCK, "DONT_BLOCK" }, /* ditto */\
{ _XBF_PAGE_CACHE, "PAGE_CACHE" }, \
{ _XBF_PAGES, "PAGES" }, \
{ _XBF_RUN_QUEUES, "RUN_QUEUES" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
{ _XBF_PAGE_LOCKED, "PAGE_LOCKED" }, \
{ _XFS_BARRIER_FAILED, "BARRIER_FAILED" }
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;
struct xfs_mount *b_mount;
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(xfs_buftarg_t *, xfs_off_t, size_t,
xfs_buf_flags_t);
extern xfs_buf_t *xfs_buf_read(xfs_buftarg_t *, xfs_off_t, size_t,
xfs_buf_flags_t);
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 int xfs_bwrite(struct xfs_mount *mp, struct xfs_buf *bp);
extern int xfs_bawrite(void *mp, xfs_buf_t *bp);
extern void xfs_bdwrite(void *mp, xfs_buf_t *bp);
extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
extern int xfs_bdstrat_cb(struct xfs_buf *);
extern void xfs_buf_ioend(xfs_buf_t *, int);
extern void xfs_buf_ioerror(xfs_buf_t *, int);
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, void *,
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 *);
extern void xfs_buf_delwri_promote(xfs_buf_t *);
/* Buffer Daemon Setup Routines */
extern int xfs_buf_init(void);
extern void xfs_buf_terminate(void);
#define xfs_buf_target_name(target) \
({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })
#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 |= XBF_STALE)
#define XFS_BUF_UNSTALE(bp) ((bp)->b_flags &= ~XBF_STALE)
#define XFS_BUF_ISSTALE(bp) ((bp)->b_flags & XBF_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_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_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_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 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_biodone(bp) xfs_buf_ioend(bp, 0)
#define xfs_biomove(bp, off, len, data, rw) \
xfs_buf_iomove((bp), (off), (len), (data), \
((rw) == XBF_WRITE) ? XBRW_WRITE : XBRW_READ)
#define xfs_biozero(bp, off, len) \
xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
#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(struct xfs_mount *, struct xfs_buftarg *);
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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