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xfs: kill the b_strat callback in xfs_buf

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The b_strat callback is used by xfs_buf_iostrategy to perform additional
checks before submitting a buffer.  It is used in xfs_bwrite and when
writing out delayed buffers.  In xfs_bwrite it we can de-virtualize the
call easily as b_strat is set a few lines above the call to
xfs_buf_iostrategy.  For the delayed buffers the rationale is a bit
more complicated:

 - there are three callers of xfs_buf_delwri_queue, which places buffers
   on the delwri list:
    (1) xfs_bdwrite - this sets up b_strat, so it's fine
    (2) xfs_buf_iorequest.  None of the callers can have XBF_DELWRI set:
	- xlog_bdstrat is only used for log buffers, which are never delwri
	- _xfs_buf_read explicitly clears the delwri flag
	- xfs_buf_iodone_work retries log buffers only
	- xfsbdstrat - only used for reads, superblock writes without the
	  delwri flag, log I/O and file zeroing with explicitly allocated
	  buffers.
	- xfs_buf_iostrategy - only calls xfs_buf_iorequest if b_strat is
	  not set
    (3) xfs_buf_unlock
	- only puts the buffer on the delwri list if the DELWRI flag is
	  already set.  The DELWRI flag is only ever set in xfs_bwrite,
	  xfs_buf_iodone_callbacks, or xfs_trans_log_buf.  For
	  xfs_buf_iodone_callbacks and xfs_trans_log_buf we require
	  an initialized buf item, which means b_strat was set to
	  xfs_bdstrat_cb in xfs_buf_item_init.

Conclusion: we can just get rid of the callback and replace it with
explicit calls to xfs_bdstrat_cb.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Christoph Hellwig 2010-07-20 17:51:16 +10:00 committed by Alex Elder
parent a64afb057b
commit 939d723b72
4 changed files with 3 additions and 17 deletions
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10
fs/xfs/linux-2.6/xfs_buf.c
View file

@ -987,13 +987,12 @@ xfs_bwrite(
{
int error;
bp->b_strat = xfs_bdstrat_cb;
bp->b_mount = mp;
bp->b_flags |= XBF_WRITE;
bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
xfs_buf_delwri_dequeue(bp);
xfs_buf_iostrategy(bp);
xfs_bdstrat_cb(bp);
error = xfs_buf_iowait(bp);
if (error)
@ -1009,7 +1008,6 @@ xfs_bdwrite(
{
trace_xfs_buf_bdwrite(bp, _RET_IP_);
bp->b_strat = xfs_bdstrat_cb;
bp->b_mount = mp;
bp->b_flags &= ~XBF_READ;
@ -1044,7 +1042,6 @@ xfs_bioerror(
XFS_BUF_UNDONE(bp);
XFS_BUF_STALE(bp);
XFS_BUF_CLR_BDSTRAT_FUNC(bp);
xfs_biodone(bp);
return EIO;
@ -1074,7 +1071,6 @@ xfs_bioerror_relse(
XFS_BUF_DONE(bp);
XFS_BUF_STALE(bp);
XFS_BUF_CLR_IODONE_FUNC(bp);
XFS_BUF_CLR_BDSTRAT_FUNC(bp);
if (!(fl & XBF_ASYNC)) {
/*
* Mark b_error and B_ERROR _both_.
@ -1869,7 +1865,7 @@ xfsbufd(
struct xfs_buf *bp;
bp = list_first_entry(&tmp, struct xfs_buf, b_list);
list_del_init(&bp->b_list);
xfs_buf_iostrategy(bp);
xfs_bdstrat_cb(bp);
count++;
}
if (count)
@ -1916,7 +1912,7 @@ xfs_flush_buftarg(
bp->b_flags &= ~XBF_ASYNC;
list_add(&bp->b_list, &wait_list);
}
xfs_buf_iostrategy(bp);
xfs_bdstrat_cb(bp);
}
if (wait) {

8
fs/xfs/linux-2.6/xfs_buf.h
View file

@ -187,7 +187,6 @@ typedef struct xfs_buf {
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;
@ -245,11 +244,6 @@ 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;
@ -321,8 +315,6 @@ extern void xfs_buf_terminate(void);
#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))

1
fs/xfs/xfs_buf_item.c
View file

@ -694,7 +694,6 @@ xfs_buf_item_init(
*/
if (bp->b_mount != mp)
bp->b_mount = mp;
XFS_BUF_SET_BDSTRAT_FUNC(bp, xfs_bdstrat_cb);
if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
if (lip->li_type == XFS_LI_BUF) {

1
fs/xfs/xfs_inode.c
View file

@ -2719,7 +2719,6 @@ xfs_iflush_cluster(
* mark it as stale and brelse.
*/
if (XFS_BUF_IODONE_FUNC(bp)) {
XFS_BUF_CLR_BDSTRAT_FUNC(bp);
XFS_BUF_UNDONE(bp);
XFS_BUF_STALE(bp);
XFS_BUF_ERROR(bp,EIO);