[PATCH 0/8] xfs: clean up unit usage in xfs_buf V2

[PATCH 0/8] xfs: clean up unit usage in xfs_buf V2

[Dave Chinner]

This series cleans up the buffer cache API to use daddr formats for
block numbers and basic blocks for lengths when trying to get or
read a buffer and from there cleans up the internal usage of the
same thing. Essentially we end up with tracking buffers by their
daddr blkno, and BB based length, including the length of the IO
needed to do out of the buffer. The b_offset field is still in
bytes, as that is mostly used as a byte offset into the allocated
memory that the buffer holds, rather than a disk based offset.

Version 2:
- new patch 1, fixes hang in log reading code when trying to find
  the head and IO dispatch returns EIO. Generic fix for the same
  problem for all IO dispatched via xfsbdstrat() and then waited on
  via xfs_buf_iowait().
- new patch 2, fixes EIO during IO dispatch reading uncached buffers
  when page size unaligned, subpage-sized multi-block buffers are
  incorrectly required to need multiple pages due to invalid
  b_offset. This was triggered by log recovery when finding the head
  of the log, and caused the hang fixed in patch 1. Problem was
  reliably triggered by patch 5, though there is no obvious reason
  that I can find for any of those changes to have tripped over this
  landmine.
- new patch 3, clean, noticed when trying to work out why b_offset
  wasn't zero find the problem fixed in patch 2.
- patch 4-7, updated according to Christoph's comments
- new patch 8, kills the xfs_buf_btoc (and related) macros as
  suggested by Christoph.

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[PATCH 1/8] xfs: check for buffer errors before waiting

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

If we call xfs_buf_iowait() on a buffer that failed dispatch due to
an IO error, it will wait forever for an Io that does not exist.
This is hndled in xfs_buf_read, but there is other code that calls
xfs_buf_iowait directly that doesn't.

Rather than make the call sites have to handle checking for dispatch
errors and then checking for completion errors, make
xfs_buf_iowait() check for dispatch errors on the buffer before
waiting. This means we handle both dispatch and completion errors
with one set of error handling at the caller sites.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c         |   22 ++++++++++------------
 fs/xfs/xfs_buf.h         |    2 +-
 fs/xfs/xfs_log_recover.c |    2 ++
 3 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index d65d972..2122b0f 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -623,17 +623,15 @@ _xfs_buf_read(
 	xfs_buf_t		*bp,
 	xfs_buf_flags_t		flags)
 {
-	int			status;
-
 	ASSERT(!(flags & XBF_WRITE));
 	ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
 
 	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);
 	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
 
-	status = xfs_buf_iorequest(bp);
-	if (status || bp->b_error || (flags & XBF_ASYNC))
-		return status;
+	xfs_buf_iorequest(bp);
+	if (flags & XBF_ASYNC)
+		return 0;
 	return xfs_buf_iowait(bp);
 }
 
@@ -718,7 +716,7 @@ xfs_buf_read_uncached(
 
 	xfsbdstrat(mp, bp);
 	error = xfs_buf_iowait(bp);
-	if (error || bp->b_error) {
+	if (error) {
 		xfs_buf_relse(bp);
 		return NULL;
 	}
@@ -1275,7 +1273,7 @@ next_chunk:
 	}
 }
 
-int
+void
 xfs_buf_iorequest(
 	xfs_buf_t		*bp)
 {
@@ -1296,13 +1294,12 @@ xfs_buf_iorequest(
 	_xfs_buf_ioend(bp, 0);
 
 	xfs_buf_rele(bp);
-	return 0;
 }
 
 /*
- *	Waits for I/O to complete on the buffer supplied.
- *	It returns immediately if no I/O is pending.
- *	It returns the I/O error code, if any, or 0 if there was no error.
+ * Waits for I/O to complete on the buffer supplied.  It returns immediately if
+ * no I/O is pending or there is already a pending error on the buffer.  It
+ * returns the I/O error code, if any, or 0 if there was no error.
  */
 int
 xfs_buf_iowait(
@@ -1310,7 +1307,8 @@ xfs_buf_iowait(
 {
 	trace_xfs_buf_iowait(bp, _RET_IP_);
 
-	wait_for_completion(&bp->b_iowait);
+	if (!bp->b_error)
+		wait_for_completion(&bp->b_iowait);
 
 	trace_xfs_buf_iowait_done(bp, _RET_IP_);
 	return bp->b_error;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index d4d1ee2..664fb4e 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -193,7 +193,7 @@ 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 void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
-extern int xfs_buf_iorequest(xfs_buf_t *);
+extern void 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);
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 396e3bf..64ed6ff 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -179,6 +179,7 @@ xlog_bread_noalign(
 	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
 	XFS_BUF_READ(bp);
 	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
+	bp->b_error = 0;
 
 	xfsbdstrat(log->l_mp, bp);
 	error = xfs_buf_iowait(bp);
@@ -266,6 +267,7 @@ xlog_bwrite(
 	xfs_buf_hold(bp);
 	xfs_buf_lock(bp);
 	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
+	bp->b_error = 0;
 
 	error = xfs_bwrite(bp);
 	if (error)
-- 
1.7.9

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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> If we call xfs_buf_iowait() on a buffer that failed dispatch due to
> an IO error, it will wait forever for an Io that does not exist.
> This is hndled in xfs_buf_read, but there is other code that calls
> xfs_buf_iowait directly that doesn't.
>
> Rather than make the call sites have to handle checking for dispatch
> errors and then checking for completion errors, make
> xfs_buf_iowait() check for dispatch errors on the buffer before
> waiting. This means we handle both dispatch and completion errors
> with one set of error handling at the caller sites.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---

> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 396e3bf..64ed6ff 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -179,6 +179,7 @@ xlog_bread_noalign(
>   	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
>   	XFS_BUF_READ(bp);
>   	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
> +	bp->b_error = 0;
>
>   	xfsbdstrat(log->l_mp, bp);
>   	error = xfs_buf_iowait(bp);
> @@ -266,6 +267,7 @@ xlog_bwrite(
>   	xfs_buf_hold(bp);
>   	xfs_buf_lock(bp);
>   	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
> +	bp->b_error = 0;
>
>   	error = xfs_bwrite(bp);
>   	if (error)

Just curious, were these needed for a particular reason?

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Dave Chinner]

On Thu, Mar 29, 2012 at 02:04:09PM -0500, Mark Tinguely wrote:
> On 03/29/12 07:23, Dave Chinner wrote:
> >From: Dave Chinner<dchinner@redhat.com>
> >
> >If we call xfs_buf_iowait() on a buffer that failed dispatch due to
> >an IO error, it will wait forever for an Io that does not exist.
> >This is hndled in xfs_buf_read, but there is other code that calls
> >xfs_buf_iowait directly that doesn't.
> >
> >Rather than make the call sites have to handle checking for dispatch
> >errors and then checking for completion errors, make
> >xfs_buf_iowait() check for dispatch errors on the buffer before
> >waiting. This means we handle both dispatch and completion errors
> >with one set of error handling at the caller sites.
> >
> >Signed-off-by: Dave Chinner<dchinner@redhat.com>
> >---
> 
> >diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> >index 396e3bf..64ed6ff 100644
> >--- a/fs/xfs/xfs_log_recover.c
> >+++ b/fs/xfs/xfs_log_recover.c
> >@@ -179,6 +179,7 @@ xlog_bread_noalign(
> >  	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
> >  	XFS_BUF_READ(bp);
> >  	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
> >+	bp->b_error = 0;
> >
> >  	xfsbdstrat(log->l_mp, bp);
> >  	error = xfs_buf_iowait(bp);
> >@@ -266,6 +267,7 @@ xlog_bwrite(
> >  	xfs_buf_hold(bp);
> >  	xfs_buf_lock(bp);
> >  	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
> >+	bp->b_error = 0;
> >
> >  	error = xfs_bwrite(bp);
> >  	if (error)
> 
> Just curious, were these needed for a particular reason?

If the previous user of the buffer got an error, it is not
guaranteed to be cleared because the buffer is not re-initialised.
i.e. it's an uncached buffer that we control completely and reuse
from IO to IO with just a reset of the bno and length. If b_error is
non zero here, then the IO can fail because nothing else clears the
error in the dispatch path....

Cheers,

Dave.
-- 
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david@fromorbit.com

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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Mark Tinguely]

On 03/29/12 16:10, Dave Chinner wrote:
> On Thu, Mar 29, 2012 at 02:04:09PM -0500, Mark Tinguely wrote:
>> On 03/29/12 07:23, Dave Chinner wrote:
>>> From: Dave Chinner<dchinner@redhat.com>
>>>
>>> If we call xfs_buf_iowait() on a buffer that failed dispatch due to
>>> an IO error, it will wait forever for an Io that does not exist.
>>> This is hndled in xfs_buf_read, but there is other code that calls
>>> xfs_buf_iowait directly that doesn't.
>>>
>>> Rather than make the call sites have to handle checking for dispatch
>>> errors and then checking for completion errors, make
>>> xfs_buf_iowait() check for dispatch errors on the buffer before
>>> waiting. This means we handle both dispatch and completion errors
>>> with one set of error handling at the caller sites.
>>>
>>> Signed-off-by: Dave Chinner<dchinner@redhat.com>
>>> ---
>>
>>> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
>>> index 396e3bf..64ed6ff 100644
>>> --- a/fs/xfs/xfs_log_recover.c
>>> +++ b/fs/xfs/xfs_log_recover.c
>>> @@ -179,6 +179,7 @@ xlog_bread_noalign(
>>>   	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
>>>   	XFS_BUF_READ(bp);
>>>   	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
>>> +	bp->b_error = 0;
>>>
>>>   	xfsbdstrat(log->l_mp, bp);
>>>   	error = xfs_buf_iowait(bp);
>>> @@ -266,6 +267,7 @@ xlog_bwrite(
>>>   	xfs_buf_hold(bp);
>>>   	xfs_buf_lock(bp);
>>>   	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
>>> +	bp->b_error = 0;
>>>
>>>   	error = xfs_bwrite(bp);
>>>   	if (error)
>>
>> Just curious, were these needed for a particular reason?
>
> If the previous user of the buffer got an error, it is not
> guaranteed to be cleared because the buffer is not re-initialised.
> i.e. it's an uncached buffer that we control completely and reuse
> from IO to IO with just a reset of the bno and length. If b_error is
> non zero here, then the IO can fail because nothing else clears the
> error in the dispatch path....
>
> Cheers,
>
> Dave.

Thank-you for the explanation.

FYI: I am having problems with the patches applying. This patch 
complained at hunk at offset 623. Maybe I am using too new of kernel source.

--Mark.

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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Dave Chinner]

On Thu, Mar 29, 2012 at 04:48:11PM -0500, Mark Tinguely wrote:
> On 03/29/12 16:10, Dave Chinner wrote:
> >On Thu, Mar 29, 2012 at 02:04:09PM -0500, Mark Tinguely wrote:
> >If the previous user of the buffer got an error, it is not
> >guaranteed to be cleared because the buffer is not re-initialised.
> >i.e. it's an uncached buffer that we control completely and reuse
> >from IO to IO with just a reset of the bno and length. If b_error is
> >non zero here, then the IO can fail because nothing else clears the
> >error in the dispatch path....
> 
> Thank-you for the explanation.
> 
> FYI: I am having problems with the patches applying. This patch
> complained at hunk at offset 623. Maybe I am using too new of kernel
> source.

That's because they are based on top of a current TOT mainline and
Christoph's dio ilock and xfsbufd removal changes.

Cheers,

Dave.
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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Christoph Hellwig]

The actual fix looks good:


Reviewed-by: Christoph Hellwig <hch@lst.de>

But shou;dn't we move the setting of b_error to zero into common buffer
code instead of adding it to the callers?

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Re: [PATCH 1/8] xfs: check for buffer errors before waiting

[Dave Chinner]

On Thu, Mar 29, 2012 at 03:12:03PM -0400, Christoph Hellwig wrote:
> The actual fix looks good:
> 
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> But shou;dn't we move the setting of b_error to zero into common buffer
> code instead of adding it to the callers?

We generally do - in xfs_buf_iodone_callbacks() - which covers
pretty much all cached buffer IO.

However, for uncached buffers, it is only zeroed in xfs_buf_alloc().
For single use buffers, this is fine, but for multiple use buffers
like the log uses during recovery for log IO, it doesn't get reset
anywhere because the buffer doesn't go anywhere near common buffer
code between IOs.

Cheers,

Dave.
-- 
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[PATCH 2/8] xfs: fix incorrect b_offset initialisation

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Because we no longer use the page cache for buffering, there is no
direct block number to page offset relationship anymore.
xfs_buf_get_pages is still setting up b_offset as if there was some
relationship, and that is leading to incorrectly setting up
*uncached* buffers that don't overwrite b_offset once they've had
pages allocated.

For cached buffers, the first block of the buffer is always at offset
zero into the allocated memory. This is true for sub-page sized
buffers, as well as for multiple-page buffers.

For uncached buffers, b_offset is only non-zero when we are
associating specific memory to the buffers, and that is set
correctly by the code setting up the buffer.

Hence remove the setting of b_offset in xfs_buf_get_pages, because
it is now always the wrong thing to do.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 2122b0f..9063461 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -221,7 +221,6 @@ _xfs_buf_get_pages(
 {
 	/* Make sure that we have a page list */
 	if (bp->b_pages == NULL) {
-		bp->b_offset = xfs_buf_poff(bp->b_file_offset);
 		bp->b_page_count = page_count;
 		if (page_count <= XB_PAGES) {
 			bp->b_pages = bp->b_page_array;
-- 
1.7.9

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Re: [PATCH 2/8] xfs: fix incorrect b_offset initialisation

[Christoph Hellwig]

Looks good, and this might actually explain the weird corruption I saw
in some changes I'm working on the make use of b_offset.


Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH 2/8] xfs: fix incorrect b_offset initialisation

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> Because we no longer use the page cache for buffering, there is no
> direct block number to page offset relationship anymore.
> xfs_buf_get_pages is still setting up b_offset as if there was some
> relationship, and that is leading to incorrectly setting up
> *uncached* buffers that don't overwrite b_offset once they've had
> pages allocated.
>
> For cached buffers, the first block of the buffer is always at offset
> zero into the allocated memory. This is true for sub-page sized
> buffers, as well as for multiple-page buffers.
>
> For uncached buffers, b_offset is only non-zero when we are
> associating specific memory to the buffers, and that is set
> correctly by the code setting up the buffer.
>
> Hence remove the setting of b_offset in xfs_buf_get_pages, because
> it is now always the wrong thing to do.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 3/8] xfs: use kmem_zone_zalloc for buffers

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

To replace the alloc/memset pair.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 9063461..d1ba21d 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -172,7 +172,7 @@ xfs_buf_alloc(
 {
 	struct xfs_buf		*bp;
 
-	bp = kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags));
+	bp = kmem_zone_zalloc(xfs_buf_zone, xb_to_km(flags));
 	if (unlikely(!bp))
 		return NULL;
 
@@ -181,7 +181,6 @@ xfs_buf_alloc(
 	 */
 	flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
 
-	memset(bp, 0, sizeof(xfs_buf_t));
 	atomic_set(&bp->b_hold, 1);
 	atomic_set(&bp->b_lru_ref, 1);
 	init_completion(&bp->b_iowait);
-- 
1.7.9

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Re: [PATCH 3/8] xfs: use kmem_zone_zalloc for buffers

[Christoph Hellwig]

Looks good.

Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH 3/8] xfs: use kmem_zone_zalloc for buffers

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> To replace the alloc/memset pair.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---
>   fs/xfs/xfs_buf.c |    3 +--
>   1 files changed, 1 insertions(+), 2 deletions(-)
>

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 4/8] xfs: clean up buffer get/read call API

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

The xfs_buf_get/read API is not consistent in the units it uses, and
does not use appropriate or consistent units/types for the
variables.

Convert the API to use disk addresses and block counts for all
buffer get and read calls. Use consistent naming for all the
functions and their declarations, and convert the internal functions
to use disk addresses and block counts to avoid need to convert them
from one type to another and back again.

Fix all the callers to use disk addresses and block counts. In many
cases, this removes an additional conversion from the function call
as the callers already have a block count.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_buf.c         |   86 ++++++++++++++++++++++++---------------------
 fs/xfs/xfs_buf.h         |   38 +++++++++++---------
 fs/xfs/xfs_fsops.c       |    4 +-
 fs/xfs/xfs_log.c         |    6 ++--
 fs/xfs/xfs_log_recover.c |    2 +-
 fs/xfs/xfs_mount.c       |   12 +++---
 fs/xfs/xfs_rtalloc.c     |    8 ++--
 fs/xfs/xfs_vnodeops.c    |    2 +-
 8 files changed, 84 insertions(+), 74 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index d1ba21d..5a61ddc 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -166,8 +166,8 @@ xfs_buf_stale(
 struct xfs_buf *
 xfs_buf_alloc(
 	struct xfs_buftarg	*target,
-	xfs_off_t		range_base,
-	size_t			range_length,
+	xfs_daddr_t		blkno,
+	size_t			numblks,
 	xfs_buf_flags_t		flags)
 {
 	struct xfs_buf		*bp;
@@ -190,14 +190,21 @@ xfs_buf_alloc(
 	sema_init(&bp->b_sema, 0); /* held, no waiters */
 	XB_SET_OWNER(bp);
 	bp->b_target = target;
-	bp->b_file_offset = range_base;
+	bp->b_file_offset = blkno << BBSHIFT;
 	/*
 	 * Set buffer_length and count_desired to the same value initially.
 	 * I/O routines should use count_desired, which will be the same in
 	 * most cases but may be reset (e.g. XFS recovery).
 	 */
-	bp->b_buffer_length = bp->b_count_desired = range_length;
+	bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
 	bp->b_flags = flags;
+
+	/*
+	 * We do not set the block number here in the buffer because we have not
+	 * finished initialising the buffer. We insert the buffer into the cache
+	 * in this state, so this ensures that we are unable to do IO on a
+	 * buffer that hasn't been fully initialised.
+	 */
 	bp->b_bn = XFS_BUF_DADDR_NULL;
 	atomic_set(&bp->b_pin_count, 0);
 	init_waitqueue_head(&bp->b_waiters);
@@ -420,30 +427,30 @@ _xfs_buf_map_pages(
  */
 xfs_buf_t *
 _xfs_buf_find(
-	xfs_buftarg_t		*btp,	/* block device target		*/
-	xfs_off_t		ioff,	/* starting offset of range	*/
-	size_t			isize,	/* length of range		*/
+	struct xfs_buftarg	*btp,
+	xfs_daddr_t		blkno,
+	size_t			numblks,
 	xfs_buf_flags_t		flags,
 	xfs_buf_t		*new_bp)
 {
-	xfs_off_t		range_base;
-	size_t			range_length;
+	xfs_off_t		offset;
+	size_t			numbytes;
 	struct xfs_perag	*pag;
 	struct rb_node		**rbp;
 	struct rb_node		*parent;
 	xfs_buf_t		*bp;
 
-	range_base = (ioff << BBSHIFT);
-	range_length = (isize << BBSHIFT);
+	offset = blkno << BBSHIFT;
+	numbytes = numblks << BBSHIFT;
 
 	/* Check for IOs smaller than the sector size / not sector aligned */
-	ASSERT(!(range_length < (1 << btp->bt_sshift)));
-	ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
+	ASSERT(!(numbytes < (1 << btp->bt_sshift)));
+	ASSERT(!(offset & (xfs_off_t)btp->bt_smask));
 
 	/* get tree root */
 lookup_again:
 	pag = xfs_perag_get(btp->bt_mount,
-				xfs_daddr_to_agno(btp->bt_mount, ioff));
+				xfs_daddr_to_agno(btp->bt_mount, blkno));
 
 	/* walk tree */
 	spin_lock(&pag->pag_buf_lock);
@@ -454,9 +461,9 @@ lookup_again:
 		parent = *rbp;
 		bp = rb_entry(parent, struct xfs_buf, b_rbnode);
 
-		if (range_base < bp->b_file_offset)
+		if (offset < bp->b_file_offset)
 			rbp = &(*rbp)->rb_left;
-		else if (range_base > bp->b_file_offset)
+		else if (offset > bp->b_file_offset)
 			rbp = &(*rbp)->rb_right;
 		else {
 			/*
@@ -467,7 +474,7 @@ lookup_again:
 			 * reallocating a busy extent. Skip this buffer and
 			 * continue searching to the right for an exact match.
 			 */
-			if (bp->b_buffer_length != range_length) {
+			if (bp->b_buffer_length != numbytes) {
 				ASSERT(bp->b_flags & XBF_STALE);
 				rbp = &(*rbp)->rb_right;
 				continue;
@@ -545,25 +552,24 @@ found:
  */
 struct xfs_buf *
 xfs_buf_get(
-	xfs_buftarg_t		*target,/* target for buffer		*/
-	xfs_off_t		ioff,	/* starting offset of range	*/
-	size_t			isize,	/* length of range		*/
+	xfs_buftarg_t		*target,
+	xfs_daddr_t		blkno,
+	size_t			numblks,
 	xfs_buf_flags_t		flags)
 {
 	struct xfs_buf		*bp;
 	struct xfs_buf		*new_bp;
 	int			error = 0;
 
-	bp = _xfs_buf_find(target, ioff, isize, flags, NULL);
+	bp = _xfs_buf_find(target, blkno, numblks, flags, NULL);
 	if (likely(bp))
 		goto found;
 
-	new_bp = xfs_buf_alloc(target, ioff << BBSHIFT, isize << BBSHIFT,
-			       flags);
+	new_bp = xfs_buf_alloc(target, blkno, numblks, flags);
 	if (unlikely(!new_bp))
 		return NULL;
 
-	bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
+	bp = _xfs_buf_find(target, blkno, numblks, flags, new_bp);
 	if (!bp) {
 		kmem_zone_free(xfs_buf_zone, new_bp);
 		return NULL;
@@ -592,7 +598,7 @@ xfs_buf_get(
 	 * Now we have a workable buffer, fill in the block number so
 	 * that we can do IO on it.
 	 */
-	bp->b_bn = ioff;
+	bp->b_bn = blkno;
 	bp->b_count_desired = bp->b_buffer_length;
 
 found:
@@ -636,15 +642,15 @@ _xfs_buf_read(
 xfs_buf_t *
 xfs_buf_read(
 	xfs_buftarg_t		*target,
-	xfs_off_t		ioff,
-	size_t			isize,
+	xfs_daddr_t		blkno,
+	size_t			numblks,
 	xfs_buf_flags_t		flags)
 {
 	xfs_buf_t		*bp;
 
 	flags |= XBF_READ;
 
-	bp = xfs_buf_get(target, ioff, isize, flags);
+	bp = xfs_buf_get(target, blkno, numblks, flags);
 	if (bp) {
 		trace_xfs_buf_read(bp, flags, _RET_IP_);
 
@@ -679,13 +685,13 @@ xfs_buf_read(
 void
 xfs_buf_readahead(
 	xfs_buftarg_t		*target,
-	xfs_off_t		ioff,
-	size_t			isize)
+	xfs_daddr_t		blkno,
+	size_t			numblks)
 {
 	if (bdi_read_congested(target->bt_bdi))
 		return;
 
-	xfs_buf_read(target, ioff, isize,
+	xfs_buf_read(target, blkno, numblks,
 		     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
 }
 
@@ -695,16 +701,15 @@ xfs_buf_readahead(
  */
 struct xfs_buf *
 xfs_buf_read_uncached(
-	struct xfs_mount	*mp,
 	struct xfs_buftarg	*target,
 	xfs_daddr_t		daddr,
-	size_t			length,
+	size_t			numblks,
 	int			flags)
 {
 	xfs_buf_t		*bp;
 	int			error;
 
-	bp = xfs_buf_get_uncached(target, length, flags);
+	bp = xfs_buf_get_uncached(target, numblks, flags);
 	if (!bp)
 		return NULL;
 
@@ -712,7 +717,7 @@ xfs_buf_read_uncached(
 	XFS_BUF_SET_ADDR(bp, daddr);
 	XFS_BUF_READ(bp);
 
-	xfsbdstrat(mp, bp);
+	xfsbdstrat(target->bt_mount, bp);
 	error = xfs_buf_iowait(bp);
 	if (error) {
 		xfs_buf_relse(bp);
@@ -728,7 +733,7 @@ xfs_buf_read_uncached(
 void
 xfs_buf_set_empty(
 	struct xfs_buf		*bp,
-	size_t			len)
+	size_t			numblks)
 {
 	if (bp->b_pages)
 		_xfs_buf_free_pages(bp);
@@ -737,7 +742,7 @@ xfs_buf_set_empty(
 	bp->b_page_count = 0;
 	bp->b_addr = NULL;
 	bp->b_file_offset = 0;
-	bp->b_buffer_length = bp->b_count_desired = len;
+	bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
 	bp->b_bn = XFS_BUF_DADDR_NULL;
 	bp->b_flags &= ~XBF_MAPPED;
 }
@@ -799,17 +804,18 @@ xfs_buf_associate_memory(
 xfs_buf_t *
 xfs_buf_get_uncached(
 	struct xfs_buftarg	*target,
-	size_t			len,
+	size_t			numblks,
 	int			flags)
 {
-	unsigned long		page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
+	unsigned long		page_count;
 	int			error, i;
 	xfs_buf_t		*bp;
 
-	bp = xfs_buf_alloc(target, 0, len, 0);
+	bp = xfs_buf_alloc(target, 0, numblks, 0);
 	if (unlikely(bp == NULL))
 		goto fail;
 
+	page_count = PAGE_ALIGN(numblks << BBSHIFT) >> PAGE_SHIFT;
 	error = _xfs_buf_get_pages(bp, page_count, 0);
 	if (error)
 		goto fail_free_buf;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 664fb4e..43163bf 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -152,26 +152,30 @@ typedef struct xfs_buf {
 
 
 /* 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 *);
+struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target, xfs_daddr_t blkno,
+				size_t numblks, xfs_buf_flags_t flags,
+				struct xfs_buf *new_bp);
 #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);
-
-struct xfs_buf *xfs_buf_alloc(struct xfs_buftarg *, xfs_off_t, size_t,
-			      xfs_buf_flags_t);
-extern void xfs_buf_set_empty(struct xfs_buf *bp, size_t len);
-extern xfs_buf_t *xfs_buf_get_uncached(struct xfs_buftarg *, size_t, int);
-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);
-struct xfs_buf *xfs_buf_read_uncached(struct xfs_mount *mp,
-				struct xfs_buftarg *target,
-				xfs_daddr_t daddr, size_t length, int flags);
+struct xfs_buf *xfs_buf_get(struct xfs_buftarg *target, xfs_daddr_t blkno,
+				size_t numblks, xfs_buf_flags_t flags);
+struct xfs_buf *xfs_buf_read(struct xfs_buftarg *target, xfs_daddr_t blkno,
+				size_t numblks, xfs_buf_flags_t flags);
+void xfs_buf_readahead(struct xfs_buftarg *target, xfs_daddr_t blkno,
+				size_t numblks);
+
+struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
+struct xfs_buf *xfs_buf_alloc(struct xfs_buftarg *target, xfs_daddr_t blkno,
+				size_t numblks, xfs_buf_flags_t flags);
+void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
+int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
+
+struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
+				int flags);
+struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
+				xfs_daddr_t daddr, size_t numblks, int flags);
+void xfs_buf_hold(struct xfs_buf *bp);
 
 /* Releasing Buffers */
 extern void xfs_buf_free(xfs_buf_t *);
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index 1c6fdeb..019ba5c 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -147,9 +147,9 @@ xfs_growfs_data_private(
 	if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
 		return error;
 	dpct = pct - mp->m_sb.sb_imax_pct;
-	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+	bp = xfs_buf_read_uncached(mp->m_ddev_targp,
 				XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
-				BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
+				XFS_FSS_TO_BB(mp, 1), 0);
 	if (!bp)
 		return EIO;
 	xfs_buf_relse(bp);
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 418d5d7..8990012 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1187,7 +1187,7 @@ xlog_alloc_log(xfs_mount_t	*mp,
 	xlog_get_iclog_buffer_size(mp, log);
 
 	error = ENOMEM;
-	bp = xfs_buf_alloc(mp->m_logdev_targp, 0, log->l_iclog_size, 0);
+	bp = xfs_buf_alloc(mp->m_logdev_targp, 0, BTOBB(log->l_iclog_size), 0);
 	if (!bp)
 		goto out_free_log;
 	bp->b_iodone = xlog_iodone;
@@ -1219,7 +1219,7 @@ xlog_alloc_log(xfs_mount_t	*mp,
 		prev_iclog = iclog;
 
 		bp = xfs_buf_get_uncached(mp->m_logdev_targp,
-						log->l_iclog_size, 0);
+						BTOBB(log->l_iclog_size), 0);
 		if (!bp)
 			goto out_free_iclog;
 
@@ -1588,7 +1588,7 @@ xlog_dealloc_log(xlog_t *log)
 	 * always need to ensure that the extra buffer does not point to memory
 	 * owned by another log buffer before we free it.
 	 */
-	xfs_buf_set_empty(log->l_xbuf, log->l_iclog_size);
+	xfs_buf_set_empty(log->l_xbuf, BTOBB(log->l_iclog_size));
 	xfs_buf_free(log->l_xbuf);
 
 	iclog = log->l_iclog;
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 64ed6ff..d94ed40 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -120,7 +120,7 @@ xlog_get_bp(
 		nbblks += log->l_sectBBsize;
 	nbblks = round_up(nbblks, log->l_sectBBsize);
 
-	bp = xfs_buf_get_uncached(log->l_mp->m_logdev_targp, BBTOB(nbblks), 0);
+	bp = xfs_buf_get_uncached(log->l_mp->m_logdev_targp, nbblks, 0);
 	if (bp)
 		xfs_buf_unlock(bp);
 	return bp;
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 385a3b1..89be5ff 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -684,8 +684,8 @@ xfs_readsb(xfs_mount_t *mp, int flags)
 	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
 
 reread:
-	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
-					XFS_SB_DADDR, sector_size, 0);
+	bp = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
+					BTOBB(sector_size), 0);
 	if (!bp) {
 		if (loud)
 			xfs_warn(mp, "SB buffer read failed");
@@ -1033,9 +1033,9 @@ xfs_check_sizes(xfs_mount_t *mp)
 		xfs_warn(mp, "filesystem size mismatch detected");
 		return XFS_ERROR(EFBIG);
 	}
-	bp = xfs_buf_read_uncached(mp, mp->m_ddev_targp,
+	bp = xfs_buf_read_uncached(mp->m_ddev_targp,
 					d - XFS_FSS_TO_BB(mp, 1),
-					BBTOB(XFS_FSS_TO_BB(mp, 1)), 0);
+					XFS_FSS_TO_BB(mp, 1), 0);
 	if (!bp) {
 		xfs_warn(mp, "last sector read failed");
 		return EIO;
@@ -1048,9 +1048,9 @@ xfs_check_sizes(xfs_mount_t *mp)
 			xfs_warn(mp, "log size mismatch detected");
 			return XFS_ERROR(EFBIG);
 		}
-		bp = xfs_buf_read_uncached(mp, mp->m_logdev_targp,
+		bp = xfs_buf_read_uncached(mp->m_logdev_targp,
 					d - XFS_FSB_TO_BB(mp, 1),
-					XFS_FSB_TO_B(mp, 1), 0);
+					XFS_FSB_TO_BB(mp, 1), 0);
 		if (!bp) {
 			xfs_warn(mp, "log device read failed");
 			return EIO;
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index ca4f315..7434d3f 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -1872,9 +1872,9 @@ xfs_growfs_rt(
 	/*
 	 * Read in the last block of the device, make sure it exists.
 	 */
-	bp = xfs_buf_read_uncached(mp, mp->m_rtdev_targp,
+	bp = xfs_buf_read_uncached(mp->m_rtdev_targp,
 				XFS_FSB_TO_BB(mp, nrblocks - 1),
-				XFS_FSB_TO_B(mp, 1), 0);
+				XFS_FSB_TO_BB(mp, 1), 0);
 	if (!bp)
 		return EIO;
 	xfs_buf_relse(bp);
@@ -2219,9 +2219,9 @@ xfs_rtmount_init(
 			(unsigned long long) mp->m_sb.sb_rblocks);
 		return XFS_ERROR(EFBIG);
 	}
-	bp = xfs_buf_read_uncached(mp, mp->m_rtdev_targp,
+	bp = xfs_buf_read_uncached(mp->m_rtdev_targp,
 					d - XFS_FSB_TO_BB(mp, 1),
-					XFS_FSB_TO_B(mp, 1), 0);
+					XFS_FSB_TO_BB(mp, 1), 0);
 	if (!bp) {
 		xfs_warn(mp, "realtime device size check failed");
 		return EIO;
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 64981d7..445c224 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -1966,7 +1966,7 @@ xfs_zero_remaining_bytes(
 
 	bp = xfs_buf_get_uncached(XFS_IS_REALTIME_INODE(ip) ?
 					mp->m_rtdev_targp : mp->m_ddev_targp,
-				mp->m_sb.sb_blocksize, XBF_DONT_BLOCK);
+				BTOBB(mp->m_sb.sb_blocksize), XBF_DONT_BLOCK);
 	if (!bp)
 		return XFS_ERROR(ENOMEM);
 
-- 
1.7.9

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Re: [PATCH 4/8] xfs: clean up buffer get/read call API

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> The xfs_buf_get/read API is not consistent in the units it uses, and
> does not use appropriate or consistent units/types for the
> variables.
>
> Convert the API to use disk addresses and block counts for all
> buffer get and read calls. Use consistent naming for all the
> functions and their declarations, and convert the internal functions
> to use disk addresses and block counts to avoid need to convert them
> from one type to another and back again.
>
> Fix all the callers to use disk addresses and block counts. In many
> cases, this removes an additional conversion from the function call
> as the callers already have a block count.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig<hch@lst.de>
> ---

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 5/8] xfs: kill b_file_offset

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Seeing as we pass block numbers around everywhere in the buffer
cache now, it makes no sense to index everything by byte offset.
Replace all the byte offset indexing with block number based
indexing, and replace all uses of the byte offset with direct
conversion from the block index.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_buf.c |   17 +++++++----------
 fs/xfs/xfs_buf.h |    5 +----
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 5a61ddc..19266cf 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -190,7 +190,7 @@ xfs_buf_alloc(
 	sema_init(&bp->b_sema, 0); /* held, no waiters */
 	XB_SET_OWNER(bp);
 	bp->b_target = target;
-	bp->b_file_offset = blkno << BBSHIFT;
+
 	/*
 	 * Set buffer_length and count_desired to the same value initially.
 	 * I/O routines should use count_desired, which will be the same in
@@ -331,8 +331,8 @@ xfs_buf_allocate_memory(
 	}
 
 use_alloc_page:
-	end = bp->b_file_offset + bp->b_buffer_length;
-	page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
+	end = BBTOB(bp->b_bn) + bp->b_buffer_length;
+	page_count = xfs_buf_btoc(end) - xfs_buf_btoct(BBTOB(bp->b_bn));
 	error = _xfs_buf_get_pages(bp, page_count, flags);
 	if (unlikely(error))
 		return error;
@@ -433,19 +433,17 @@ _xfs_buf_find(
 	xfs_buf_flags_t		flags,
 	xfs_buf_t		*new_bp)
 {
-	xfs_off_t		offset;
 	size_t			numbytes;
 	struct xfs_perag	*pag;
 	struct rb_node		**rbp;
 	struct rb_node		*parent;
 	xfs_buf_t		*bp;
 
-	offset = blkno << BBSHIFT;
 	numbytes = numblks << BBSHIFT;
 
 	/* Check for IOs smaller than the sector size / not sector aligned */
 	ASSERT(!(numbytes < (1 << btp->bt_sshift)));
-	ASSERT(!(offset & (xfs_off_t)btp->bt_smask));
+	ASSERT(!(BBTOB(blkno) & (xfs_off_t)btp->bt_smask));
 
 	/* get tree root */
 lookup_again:
@@ -461,13 +459,13 @@ lookup_again:
 		parent = *rbp;
 		bp = rb_entry(parent, struct xfs_buf, b_rbnode);
 
-		if (offset < bp->b_file_offset)
+		if (blkno < bp->b_bn)
 			rbp = &(*rbp)->rb_left;
-		else if (offset > bp->b_file_offset)
+		else if (blkno > bp->b_bn)
 			rbp = &(*rbp)->rb_right;
 		else {
 			/*
-			 * found a block offset match. If the range doesn't
+			 * found a block number match. If the range doesn't
 			 * match, the only way this is allowed is if the buffer
 			 * in the cache is stale and the transaction that made
 			 * it stale has not yet committed. i.e. we are
@@ -741,7 +739,6 @@ xfs_buf_set_empty(
 	bp->b_pages = NULL;
 	bp->b_page_count = 0;
 	bp->b_addr = NULL;
-	bp->b_file_offset = 0;
 	bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
 	bp->b_bn = XFS_BUF_DADDR_NULL;
 	bp->b_flags &= ~XBF_MAPPED;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 43163bf..4cda900 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -118,7 +118,7 @@ typedef struct xfs_buf {
 	 * fast-path on locking.
 	 */
 	struct rb_node		b_rbnode;	/* rbtree node */
-	xfs_off_t		b_file_offset;	/* offset in file */
+	xfs_daddr_t		b_bn;		/* block number for I/O */
 	size_t			b_buffer_length;/* size of buffer in bytes */
 	atomic_t		b_hold;		/* reference count */
 	atomic_t		b_lru_ref;	/* lru reclaim ref count */
@@ -130,7 +130,6 @@ typedef struct xfs_buf {
 	struct list_head	b_list;
 	struct xfs_perag	*b_pag;		/* contains rbtree root */
 	xfs_buftarg_t		*b_target;	/* buffer target (device) */
-	xfs_daddr_t		b_bn;		/* block number for I/O */
 	size_t			b_count_desired;/* desired transfer size */
 	void			*b_addr;	/* virtual address of buffer */
 	struct work_struct	b_iodone_work;
@@ -247,8 +246,6 @@ void xfs_buf_stale(struct xfs_buf *bp);
 
 #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)
-- 
1.7.9

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Re: [PATCH 5/8] xfs: kill b_file_offset

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> Seeing as we pass block numbers around everywhere in the buffer
> cache now, it makes no sense to index everything by byte offset.
> Replace all the byte offset indexing with block number based
> indexing, and replace all uses of the byte offset with direct
> conversion from the block index.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig<hch@lst.de>
> ---


Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 6/8] xfs: use blocks for counting length of buffers

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

Now that we pass block counts everywhere, and index buffers by block
number, track the length of the buffer in units of blocks rather
than bytes. Convert the code to use block counts, and those that
need byte counts get converted at the time of use.

Also, remove the XFS_BUF_{SET_}SIZE() macros that are just wrappers
around the buffer length. They onyl serve to make the code shouty
loud and don't actually add any real value.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_attr.c        |   15 +++++++++------
 fs/xfs/xfs_buf.c         |   22 ++++++++++++----------
 fs/xfs/xfs_buf.h         |    4 +---
 fs/xfs/xfs_log.c         |    5 +----
 fs/xfs/xfs_log_recover.c |    8 ++++----
 fs/xfs/xfs_trace.h       |   14 +++++++-------
 6 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/fs/xfs/xfs_attr.c b/fs/xfs/xfs_attr.c
index 65d61b9..6e9bd7e 100644
--- a/fs/xfs/xfs_attr.c
+++ b/fs/xfs/xfs_attr.c
@@ -1993,8 +1993,7 @@ xfs_attr_rmtval_get(xfs_da_args_t *args)
 			if (error)
 				return(error);
 
-			tmp = (valuelen < XFS_BUF_SIZE(bp))
-				? valuelen : XFS_BUF_SIZE(bp);
+			tmp = min_t(int, valuelen, BBTOB(bp->b_length));
 			xfs_buf_iomove(bp, 0, tmp, dst, XBRW_READ);
 			xfs_buf_relse(bp);
 			dst += tmp;
@@ -2097,6 +2096,8 @@ xfs_attr_rmtval_set(xfs_da_args_t *args)
 	lblkno = args->rmtblkno;
 	valuelen = args->valuelen;
 	while (valuelen > 0) {
+		int buflen;
+
 		/*
 		 * Try to remember where we decided to put the value.
 		 */
@@ -2118,11 +2119,13 @@ xfs_attr_rmtval_set(xfs_da_args_t *args)
 				 XBF_LOCK | XBF_DONT_BLOCK);
 		if (!bp)
 			return ENOMEM;
-		tmp = (valuelen < XFS_BUF_SIZE(bp)) ? valuelen :
-							XFS_BUF_SIZE(bp);
+
+		buflen = BBTOB(bp->b_length);
+		tmp = min_t(int, valuelen, buflen);
 		xfs_buf_iomove(bp, 0, tmp, src, XBRW_WRITE);
-		if (tmp < XFS_BUF_SIZE(bp))
-			xfs_buf_zero(bp, tmp, XFS_BUF_SIZE(bp) - tmp);
+		if (tmp < buflen)
+			xfs_buf_zero(bp, tmp, buflen - tmp);
+
 		error = xfs_bwrite(bp);	/* GROT: NOTE: synchronous write */
 		xfs_buf_relse(bp);
 		if (error)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 19266cf..e128575 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -192,11 +192,12 @@ xfs_buf_alloc(
 	bp->b_target = target;
 
 	/*
-	 * Set buffer_length and count_desired to the same value initially.
+	 * Set length and count_desired to the same value initially.
 	 * I/O routines should use count_desired, which will be the same in
 	 * most cases but may be reset (e.g. XFS recovery).
 	 */
-	bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
+	bp->b_length = numblks;
+	bp->b_count_desired = numblks << BBSHIFT;
 	bp->b_flags = flags;
 
 	/*
@@ -307,14 +308,14 @@ xfs_buf_allocate_memory(
 	 * the memory from the heap - there's no need for the complexity of
 	 * page arrays to keep allocation down to order 0.
 	 */
-	if (bp->b_buffer_length < PAGE_SIZE) {
-		bp->b_addr = kmem_alloc(bp->b_buffer_length, xb_to_km(flags));
+	if (bp->b_length < BTOBB(PAGE_SIZE)) {
+		bp->b_addr = kmem_alloc(BBTOB(bp->b_length), xb_to_km(flags));
 		if (!bp->b_addr) {
 			/* low memory - use alloc_page loop instead */
 			goto use_alloc_page;
 		}
 
-		if (((unsigned long)(bp->b_addr + bp->b_buffer_length - 1) &
+		if (((unsigned long)(bp->b_addr + BBTOB(bp->b_length) - 1) &
 								PAGE_MASK) !=
 		    ((unsigned long)bp->b_addr & PAGE_MASK)) {
 			/* b_addr spans two pages - use alloc_page instead */
@@ -331,7 +332,7 @@ xfs_buf_allocate_memory(
 	}
 
 use_alloc_page:
-	end = BBTOB(bp->b_bn) + bp->b_buffer_length;
+	end = BBTOB(bp->b_bn + bp->b_length);
 	page_count = xfs_buf_btoc(end) - xfs_buf_btoct(BBTOB(bp->b_bn));
 	error = _xfs_buf_get_pages(bp, page_count, flags);
 	if (unlikely(error))
@@ -472,7 +473,7 @@ lookup_again:
 			 * reallocating a busy extent. Skip this buffer and
 			 * continue searching to the right for an exact match.
 			 */
-			if (bp->b_buffer_length != numbytes) {
+			if (bp->b_length != numblks) {
 				ASSERT(bp->b_flags & XBF_STALE);
 				rbp = &(*rbp)->rb_right;
 				continue;
@@ -597,7 +598,7 @@ xfs_buf_get(
 	 * that we can do IO on it.
 	 */
 	bp->b_bn = blkno;
-	bp->b_count_desired = bp->b_buffer_length;
+	bp->b_count_desired = BBTOB(bp->b_length);
 
 found:
 	if (!(bp->b_flags & XBF_MAPPED)) {
@@ -739,7 +740,8 @@ xfs_buf_set_empty(
 	bp->b_pages = NULL;
 	bp->b_page_count = 0;
 	bp->b_addr = NULL;
-	bp->b_buffer_length = bp->b_count_desired = numblks << BBSHIFT;
+	bp->b_length = numblks;
+	bp->b_count_desired = numblks << BBSHIFT;
 	bp->b_bn = XFS_BUF_DADDR_NULL;
 	bp->b_flags &= ~XBF_MAPPED;
 }
@@ -792,7 +794,7 @@ xfs_buf_associate_memory(
 	}
 
 	bp->b_count_desired = len;
-	bp->b_buffer_length = buflen;
+	bp->b_length = BTOBB(buflen);
 	bp->b_flags |= XBF_MAPPED;
 
 	return 0;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4cda900..df1814c 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -119,7 +119,7 @@ typedef struct xfs_buf {
 	 */
 	struct rb_node		b_rbnode;	/* rbtree node */
 	xfs_daddr_t		b_bn;		/* block number for I/O */
-	size_t			b_buffer_length;/* size of buffer in bytes */
+	int			b_length;	/* size of buffer in BBs */
 	atomic_t		b_hold;		/* reference count */
 	atomic_t		b_lru_ref;	/* lru reclaim ref count */
 	xfs_buf_flags_t		b_flags;	/* status flags */
@@ -248,8 +248,6 @@ void xfs_buf_stale(struct xfs_buf *bp);
 #define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_bn = (xfs_daddr_t)(bno))
 #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))
 
 static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 {
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 8990012..f9d8355 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1197,9 +1197,6 @@ xlog_alloc_log(xfs_mount_t	*mp,
 	spin_lock_init(&log->l_icloglock);
 	init_waitqueue_head(&log->l_flush_wait);
 
-	/* log record size must be multiple of BBSIZE; see xlog_rec_header_t */
-	ASSERT((XFS_BUF_SIZE(bp) & BBMASK) == 0);
-
 	iclogp = &log->l_iclog;
 	/*
 	 * The amount of memory to allocate for the iclog structure is
@@ -1239,7 +1236,7 @@ xlog_alloc_log(xfs_mount_t	*mp,
 		head->h_fmt = cpu_to_be32(XLOG_FMT);
 		memcpy(&head->h_fs_uuid, &mp->m_sb.sb_uuid, sizeof(uuid_t));
 
-		iclog->ic_size = XFS_BUF_SIZE(bp) - log->l_iclog_hsize;
+		iclog->ic_size = BBTOB(bp->b_length) - log->l_iclog_hsize;
 		iclog->ic_state = XLOG_STATE_ACTIVE;
 		iclog->ic_log = log;
 		atomic_set(&iclog->ic_refcnt, 0);
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index d94ed40..15b7470 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -146,7 +146,7 @@ xlog_align(
 {
 	xfs_daddr_t	offset = blk_no & ((xfs_daddr_t)log->l_sectBBsize - 1);
 
-	ASSERT(BBTOB(offset + nbblks) <= XFS_BUF_SIZE(bp));
+	ASSERT(offset + nbblks <= bp->b_length);
 	return bp->b_addr + BBTOB(offset);
 }
 
@@ -174,7 +174,7 @@ xlog_bread_noalign(
 	nbblks = round_up(nbblks, log->l_sectBBsize);
 
 	ASSERT(nbblks > 0);
-	ASSERT(BBTOB(nbblks) <= XFS_BUF_SIZE(bp));
+	ASSERT(nbblks <= bp->b_length);
 
 	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
 	XFS_BUF_READ(bp);
@@ -219,7 +219,7 @@ xlog_bread_offset(
 	xfs_caddr_t	offset)
 {
 	xfs_caddr_t	orig_offset = bp->b_addr;
-	int		orig_len = bp->b_buffer_length;
+	int		orig_len = BBTOB(bp->b_length);
 	int		error, error2;
 
 	error = xfs_buf_associate_memory(bp, offset, BBTOB(nbblks));
@@ -260,7 +260,7 @@ xlog_bwrite(
 	nbblks = round_up(nbblks, log->l_sectBBsize);
 
 	ASSERT(nbblks > 0);
-	ASSERT(BBTOB(nbblks) <= XFS_BUF_SIZE(bp));
+	ASSERT(nbblks <= bp->b_length);
 
 	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
 	XFS_BUF_ZEROFLAGS(bp);
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 7d37440..895e0ff 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -281,7 +281,7 @@ DECLARE_EVENT_CLASS(xfs_buf_class,
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(xfs_daddr_t, bno)
-		__field(size_t, buffer_length)
+		__field(int, nblks)
 		__field(int, hold)
 		__field(int, pincount)
 		__field(unsigned, lockval)
@@ -291,18 +291,18 @@ DECLARE_EVENT_CLASS(xfs_buf_class,
 	TP_fast_assign(
 		__entry->dev = bp->b_target->bt_dev;
 		__entry->bno = bp->b_bn;
-		__entry->buffer_length = bp->b_buffer_length;
+		__entry->nblks = bp->b_length;
 		__entry->hold = atomic_read(&bp->b_hold);
 		__entry->pincount = atomic_read(&bp->b_pin_count);
 		__entry->lockval = bp->b_sema.count;
 		__entry->flags = bp->b_flags;
 		__entry->caller_ip = caller_ip;
 	),
-	TP_printk("dev %d:%d bno 0x%llx len 0x%zx hold %d pincount %d "
+	TP_printk("dev %d:%d bno 0x%llx nblks 0x%x hold %d pincount %d "
 		  "lock %d flags %s caller %pf",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),
 		  (unsigned long long)__entry->bno,
-		  __entry->buffer_length,
+		  __entry->nblks,
 		  __entry->hold,
 		  __entry->pincount,
 		  __entry->lockval,
@@ -362,7 +362,7 @@ DECLARE_EVENT_CLASS(xfs_buf_flags_class,
 	TP_fast_assign(
 		__entry->dev = bp->b_target->bt_dev;
 		__entry->bno = bp->b_bn;
-		__entry->buffer_length = bp->b_buffer_length;
+		__entry->buffer_length = BBTOB(bp->b_length);
 		__entry->flags = flags;
 		__entry->hold = atomic_read(&bp->b_hold);
 		__entry->pincount = atomic_read(&bp->b_pin_count);
@@ -408,7 +408,7 @@ TRACE_EVENT(xfs_buf_ioerror,
 	TP_fast_assign(
 		__entry->dev = bp->b_target->bt_dev;
 		__entry->bno = bp->b_bn;
-		__entry->buffer_length = bp->b_buffer_length;
+		__entry->buffer_length = BBTOB(bp->b_length);
 		__entry->hold = atomic_read(&bp->b_hold);
 		__entry->pincount = atomic_read(&bp->b_pin_count);
 		__entry->lockval = bp->b_sema.count;
@@ -452,7 +452,7 @@ DECLARE_EVENT_CLASS(xfs_buf_item_class,
 		__entry->bli_recur = bip->bli_recur;
 		__entry->bli_refcount = atomic_read(&bip->bli_refcount);
 		__entry->buf_bno = bip->bli_buf->b_bn;
-		__entry->buf_len = bip->bli_buf->b_buffer_length;
+		__entry->buf_len = BBTOB(bip->bli_buf->b_length);
 		__entry->buf_flags = bip->bli_buf->b_flags;
 		__entry->buf_hold = atomic_read(&bip->bli_buf->b_hold);
 		__entry->buf_pincount = atomic_read(&bip->bli_buf->b_pin_count);
-- 
1.7.9

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Re: [PATCH 6/8] xfs: use blocks for counting length of buffers

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH 6/8] xfs: use blocks for counting length of buffers

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> Now that we pass block counts everywhere, and index buffers by block
> number, track the length of the buffer in units of blocks rather
> than bytes. Convert the code to use block counts, and those that
> need byte counts get converted at the time of use.
>
> Also, remove the XFS_BUF_{SET_}SIZE() macros that are just wrappers
> around the buffer length. They onyl serve to make the code shouty
> loud and don't actually add any real value.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---


Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 7/8] xfs: use blocks for storing the desired IO size

[Dave Chinner]

Now that we pass block counts everywhere, and index buffers by block
number and length in units of blocks, convert the desired IO size
into block counts rather than bytes. Convert the code to use block
counts, and those that need byte counts get converted at the time of
use.

Rename the b_desired_count variable to something closer to it's
purpose - b_io_length - as it is only used to specify the length of
an IO for a subset of the buffer.  The only time this is used is for
log IO - both writing iclogs and during log recovery. In all other
cases, the b_io_length matches b_length, and hence a lot of code
confuses the two. e.g. the buf item code uses the io count
exclusively when it should be using the buffer length. Fix these
apprpriately as they are found.

Also, remove the XFS_BUF_{SET_}COUNT() macros that are just wrappers
around the desired IO length. They only serve to make the code
shouty loud, don't actually add any real value, and are often used
incorrectly.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_buf.c         |   26 +++++++++++++-------------
 fs/xfs/xfs_buf.h         |    4 +---
 fs/xfs/xfs_buf_item.c    |   15 ++++++++-------
 fs/xfs/xfs_da_btree.c    |   16 ++++++++--------
 fs/xfs/xfs_log.c         |    2 +-
 fs/xfs/xfs_log_recover.c |   15 ++++++++-------
 fs/xfs/xfs_trans_buf.c   |    4 ++--
 7 files changed, 41 insertions(+), 41 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e128575..aad217c 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -192,12 +192,12 @@ xfs_buf_alloc(
 	bp->b_target = target;
 
 	/*
-	 * Set length and count_desired to the same value initially.
-	 * I/O routines should use count_desired, which will be the same in
+	 * Set length and io_length to the same value initially.
+	 * I/O routines should use io_length, which will be the same in
 	 * most cases but may be reset (e.g. XFS recovery).
 	 */
 	bp->b_length = numblks;
-	bp->b_count_desired = numblks << BBSHIFT;
+	bp->b_io_length = numblks;
 	bp->b_flags = flags;
 
 	/*
@@ -296,7 +296,7 @@ xfs_buf_allocate_memory(
 	xfs_buf_t		*bp,
 	uint			flags)
 {
-	size_t			size = bp->b_count_desired;
+	size_t			size;
 	size_t			nbytes, offset;
 	gfp_t			gfp_mask = xb_to_gfp(flags);
 	unsigned short		page_count, i;
@@ -339,6 +339,7 @@ use_alloc_page:
 		return error;
 
 	offset = bp->b_offset;
+	size = BBTOB(bp->b_length);
 	bp->b_flags |= _XBF_PAGES;
 
 	for (i = 0; i < bp->b_page_count; i++) {
@@ -598,7 +599,7 @@ xfs_buf_get(
 	 * that we can do IO on it.
 	 */
 	bp->b_bn = blkno;
-	bp->b_count_desired = BBTOB(bp->b_length);
+	bp->b_io_length = bp->b_length;
 
 found:
 	if (!(bp->b_flags & XBF_MAPPED)) {
@@ -741,7 +742,7 @@ xfs_buf_set_empty(
 	bp->b_page_count = 0;
 	bp->b_addr = NULL;
 	bp->b_length = numblks;
-	bp->b_count_desired = numblks << BBSHIFT;
+	bp->b_io_length = numblks;
 	bp->b_bn = XFS_BUF_DADDR_NULL;
 	bp->b_flags &= ~XBF_MAPPED;
 }
@@ -793,7 +794,7 @@ xfs_buf_associate_memory(
 		pageaddr += PAGE_SIZE;
 	}
 
-	bp->b_count_desired = len;
+	bp->b_io_length = BTOBB(len);
 	bp->b_length = BTOBB(buflen);
 	bp->b_flags |= XBF_MAPPED;
 
@@ -1035,9 +1036,8 @@ xfs_buf_ioerror_alert(
 	const char		*func)
 {
 	xfs_alert(bp->b_target->bt_mount,
-"metadata I/O error: block 0x%llx (\"%s\") error %d buf count %zd",
-		(__uint64_t)XFS_BUF_ADDR(bp), func,
-		bp->b_error, XFS_BUF_COUNT(bp));
+"metadata I/O error: block 0x%llx (\"%s\") error %d numblks %d",
+		(__uint64_t)XFS_BUF_ADDR(bp), func, bp->b_error, bp->b_length);
 }
 
 int
@@ -1209,7 +1209,7 @@ _xfs_buf_ioapply(
 	int			rw, map_i, total_nr_pages, nr_pages;
 	struct bio		*bio;
 	int			offset = bp->b_offset;
-	int			size = bp->b_count_desired;
+	int			size = BBTOB(bp->b_io_length);
 	sector_t		sector = bp->b_bn;
 
 	total_nr_pages = bp->b_page_count;
@@ -1257,7 +1257,7 @@ next_chunk:
 			break;
 
 		offset = 0;
-		sector += nbytes >> BBSHIFT;
+		sector += BTOBB(nbytes);
 		size -= nbytes;
 		total_nr_pages--;
 	}
@@ -1351,7 +1351,7 @@ xfs_buf_iomove(
 		page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
 		cpoff = xfs_buf_poff(boff + bp->b_offset);
 		csize = min_t(size_t,
-			      PAGE_SIZE-cpoff, bp->b_count_desired-boff);
+			      PAGE_SIZE - cpoff, BBTOB(bp->b_io_length) - boff);
 
 		ASSERT(((csize + cpoff) <= PAGE_SIZE));
 
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index df1814c..57d3e7a 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -130,7 +130,6 @@ typedef struct xfs_buf {
 	struct list_head	b_list;
 	struct xfs_perag	*b_pag;		/* contains rbtree root */
 	xfs_buftarg_t		*b_target;	/* buffer target (device) */
-	size_t			b_count_desired;/* desired transfer size */
 	void			*b_addr;	/* virtual address of buffer */
 	struct work_struct	b_iodone_work;
 	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
@@ -139,6 +138,7 @@ typedef struct xfs_buf {
 	struct xfs_trans	*b_transp;
 	struct page		**b_pages;	/* array of page pointers */
 	struct page		*b_page_array[XB_PAGES]; /* inline pages */
+	int			b_io_length;	/* IO size in BBs */
 	atomic_t		b_pin_count;	/* pin count */
 	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
 	unsigned int		b_page_count;	/* size of page array */
@@ -246,8 +246,6 @@ void xfs_buf_stale(struct xfs_buf *bp);
 
 #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_COUNT(bp)		((bp)->b_count_desired)
-#define XFS_BUF_SET_COUNT(bp, cnt)	((bp)->b_count_desired = (cnt))
 
 static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 {
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 7f0abea..a25206c 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -123,11 +123,11 @@ xfs_buf_item_log_check(
 	ASSERT(bip->bli_logged != NULL);
 
 	bp = bip->bli_buf;
-	ASSERT(XFS_BUF_COUNT(bp) > 0);
+	ASSERT(bp->b_length > 0);
 	ASSERT(bp->b_addr != NULL);
 	orig = bip->bli_orig;
 	buffer = bp->b_addr;
-	for (x = 0; x < XFS_BUF_COUNT(bp); x++) {
+	for (x = 0; x < BBTOB(bp->b_length); x++) {
 		if (orig[x] != buffer[x] && !btst(bip->bli_logged, x)) {
 			xfs_emerg(bp->b_mount,
 				"%s: bip %x buffer %x orig %x index %d",
@@ -657,7 +657,8 @@ xfs_buf_item_init(
 	 * truncate any pieces.  map_size is the size of the
 	 * bitmap needed to describe the chunks of the buffer.
 	 */
-	chunks = (int)((XFS_BUF_COUNT(bp) + (XFS_BLF_CHUNK - 1)) >> XFS_BLF_SHIFT);
+	chunks = (int)((BBTOB(bp->b_length) + (XFS_BLF_CHUNK - 1)) >>
+								XFS_BLF_SHIFT);
 	map_size = (int)((chunks + NBWORD) >> BIT_TO_WORD_SHIFT);
 
 	bip = (xfs_buf_log_item_t*)kmem_zone_zalloc(xfs_buf_item_zone,
@@ -667,7 +668,7 @@ xfs_buf_item_init(
 	xfs_buf_hold(bp);
 	bip->bli_format.blf_type = XFS_LI_BUF;
 	bip->bli_format.blf_blkno = (__int64_t)XFS_BUF_ADDR(bp);
-	bip->bli_format.blf_len = (ushort)BTOBB(XFS_BUF_COUNT(bp));
+	bip->bli_format.blf_len = (ushort)bp->b_length;
 	bip->bli_format.blf_map_size = map_size;
 
 #ifdef XFS_TRANS_DEBUG
@@ -679,9 +680,9 @@ xfs_buf_item_init(
 	 * the buffer to indicate which bytes the callers have asked
 	 * to have logged.
 	 */
-	bip->bli_orig = (char *)kmem_alloc(XFS_BUF_COUNT(bp), KM_SLEEP);
-	memcpy(bip->bli_orig, bp->b_addr, XFS_BUF_COUNT(bp));
-	bip->bli_logged = (char *)kmem_zalloc(XFS_BUF_COUNT(bp) / NBBY, KM_SLEEP);
+	bip->bli_orig = kmem_alloc(BBTOB(bp->b_length), KM_SLEEP);
+	memcpy(bip->bli_orig, bp->b_addr, BBTOB(bp->b_length));
+	bip->bli_logged = kmem_zalloc(BBTOB(bp->b_length) / NBBY, KM_SLEEP);
 #endif
 
 	/*
diff --git a/fs/xfs/xfs_da_btree.c b/fs/xfs/xfs_da_btree.c
index 7f1a6f5..b8adc79 100644
--- a/fs/xfs/xfs_da_btree.c
+++ b/fs/xfs/xfs_da_btree.c
@@ -2277,20 +2277,20 @@ xfs_da_buf_make(int nbuf, xfs_buf_t **bps)
 	if (nbuf == 1) {
 		dabuf->nbuf = 1;
 		bp = bps[0];
-		dabuf->bbcount = (short)BTOBB(XFS_BUF_COUNT(bp));
+		dabuf->bbcount = bp->b_length;
 		dabuf->data = bp->b_addr;
 		dabuf->bps[0] = bp;
 	} else {
 		dabuf->nbuf = nbuf;
 		for (i = 0, dabuf->bbcount = 0; i < nbuf; i++) {
 			dabuf->bps[i] = bp = bps[i];
-			dabuf->bbcount += BTOBB(XFS_BUF_COUNT(bp));
+			dabuf->bbcount += bp->b_length;
 		}
 		dabuf->data = kmem_alloc(BBTOB(dabuf->bbcount), KM_SLEEP);
-		for (i = off = 0; i < nbuf; i++, off += XFS_BUF_COUNT(bp)) {
+		for (i = off = 0; i < nbuf; i++, off += BBTOB(bp->b_length)) {
 			bp = bps[i];
 			memcpy((char *)dabuf->data + off, bp->b_addr,
-				XFS_BUF_COUNT(bp));
+				BBTOB(bp->b_length));
 		}
 	}
 	return dabuf;
@@ -2310,10 +2310,10 @@ xfs_da_buf_clean(xfs_dabuf_t *dabuf)
 		ASSERT(dabuf->nbuf > 1);
 		dabuf->dirty = 0;
 		for (i = off = 0; i < dabuf->nbuf;
-				i++, off += XFS_BUF_COUNT(bp)) {
+				i++, off += BBTOB(bp->b_length)) {
 			bp = dabuf->bps[i];
 			memcpy(bp->b_addr, dabuf->data + off,
-						XFS_BUF_COUNT(bp));
+						BBTOB(bp->b_length));
 		}
 	}
 }
@@ -2356,10 +2356,10 @@ xfs_da_log_buf(xfs_trans_t *tp, xfs_dabuf_t *dabuf, uint first, uint last)
 	}
 	dabuf->dirty = 1;
 	ASSERT(first <= last);
-	for (i = off = 0; i < dabuf->nbuf; i++, off += XFS_BUF_COUNT(bp)) {
+	for (i = off = 0; i < dabuf->nbuf; i++, off += BBTOB(bp->b_length)) {
 		bp = dabuf->bps[i];
 		f = off;
-		l = f + XFS_BUF_COUNT(bp) - 1;
+		l = f + BBTOB(bp->b_length) - 1;
 		if (f < first)
 			f = first;
 		if (l > last)
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index f9d8355..5e2aa52 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1487,7 +1487,7 @@ xlog_sync(xlog_t		*log,
 	} else {
 		iclog->ic_bwritecnt = 1;
 	}
-	XFS_BUF_SET_COUNT(bp, count);
+	bp->b_io_length = BTOBB(count);
 	bp->b_fspriv = iclog;
 	XFS_BUF_ZEROFLAGS(bp);
 	XFS_BUF_ASYNC(bp);
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 15b7470..0872d71 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -178,7 +178,7 @@ xlog_bread_noalign(
 
 	XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
 	XFS_BUF_READ(bp);
-	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
+	bp->b_io_length = nbblks;
 	bp->b_error = 0;
 
 	xfsbdstrat(log->l_mp, bp);
@@ -266,7 +266,7 @@ xlog_bwrite(
 	XFS_BUF_ZEROFLAGS(bp);
 	xfs_buf_hold(bp);
 	xfs_buf_lock(bp);
-	XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
+	bp->b_io_length = nbblks;
 	bp->b_error = 0;
 
 	error = xfs_bwrite(bp);
@@ -1774,7 +1774,7 @@ xlog_recover_do_inode_buffer(
 
 	trace_xfs_log_recover_buf_inode_buf(mp->m_log, buf_f);
 
-	inodes_per_buf = XFS_BUF_COUNT(bp) >> mp->m_sb.sb_inodelog;
+	inodes_per_buf = BBTOB(bp->b_io_length) >> mp->m_sb.sb_inodelog;
 	for (i = 0; i < inodes_per_buf; i++) {
 		next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
 			offsetof(xfs_dinode_t, di_next_unlinked);
@@ -1816,7 +1816,8 @@ xlog_recover_do_inode_buffer(
 
 		ASSERT(item->ri_buf[item_index].i_addr != NULL);
 		ASSERT((item->ri_buf[item_index].i_len % XFS_BLF_CHUNK) == 0);
-		ASSERT((reg_buf_offset + reg_buf_bytes) <= XFS_BUF_COUNT(bp));
+		ASSERT((reg_buf_offset + reg_buf_bytes) <=
+							BBTOB(bp->b_io_length));
 
 		/*
 		 * The current logged region contains a copy of the
@@ -1875,8 +1876,8 @@ xlog_recover_do_reg_buffer(
 		ASSERT(nbits > 0);
 		ASSERT(item->ri_buf[i].i_addr != NULL);
 		ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
-		ASSERT(XFS_BUF_COUNT(bp) >=
-		       ((uint)bit << XFS_BLF_SHIFT)+(nbits<<XFS_BLF_SHIFT));
+		ASSERT(BBTOB(bp->b_io_length) >=
+		       ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));
 
 		/*
 		 * Do a sanity check if this is a dquot buffer. Just checking
@@ -2169,7 +2170,7 @@ xlog_recover_buffer_pass2(
 	 */
 	if (XFS_DINODE_MAGIC ==
 	    be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
-	    (XFS_BUF_COUNT(bp) != MAX(log->l_mp->m_sb.sb_blocksize,
+	    (BBTOB(bp->b_io_length) != MAX(log->l_mp->m_sb.sb_blocksize,
 			(__uint32_t)XFS_INODE_CLUSTER_SIZE(log->l_mp)))) {
 		xfs_buf_stale(bp);
 		error = xfs_bwrite(bp);
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 9132d16..2ec196b 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -56,7 +56,7 @@ xfs_trans_buf_item_match(
 		if (blip->bli_item.li_type == XFS_LI_BUF &&
 		    blip->bli_buf->b_target == target &&
 		    XFS_BUF_ADDR(blip->bli_buf) == blkno &&
-		    XFS_BUF_COUNT(blip->bli_buf) == len)
+		    BBTOB(blip->bli_buf->b_length) == len)
 			return blip->bli_buf;
 	}
 
@@ -585,7 +585,7 @@ xfs_trans_log_buf(xfs_trans_t	*tp,
 
 	ASSERT(bp->b_transp == tp);
 	ASSERT(bip != NULL);
-	ASSERT((first <= last) && (last < XFS_BUF_COUNT(bp)));
+	ASSERT(first <= last && last < BBTOB(bp->b_length));
 	ASSERT(bp->b_iodone == NULL ||
 	       bp->b_iodone == xfs_buf_iodone_callbacks);
 
-- 
1.7.9

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Re: [PATCH 7/8] xfs: use blocks for storing the desired IO size

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> Now that we pass block counts everywhere, and index buffers by block
> number and length in units of blocks, convert the desired IO size
> into block counts rather than bytes. Convert the code to use block
> counts, and those that need byte counts get converted at the time of
> use.
>
> Rename the b_desired_count variable to something closer to it's
> purpose - b_io_length - as it is only used to specify the length of
> an IO for a subset of the buffer.  The only time this is used is for
> log IO - both writing iclogs and during log recovery. In all other
> cases, the b_io_length matches b_length, and hence a lot of code
> confuses the two. e.g. the buf item code uses the io count
> exclusively when it should be using the buffer length. Fix these
> apprpriately as they are found.
>
> Also, remove the XFS_BUF_{SET_}COUNT() macros that are just wrappers
> around the desired IO length. They only serve to make the code
> shouty loud, don't actually add any real value, and are often used
> incorrectly.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig<hch@lst.de>
> ---

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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[PATCH 8/8] xfs: kill xfs_buf_btoc

[Dave Chinner]

From: Dave Chinner <dchinner@redhat.com>

xfs_buf_btoc and friends are simple macros that do basic block
to page index conversion and vice versa. These aren't widely used,
and we use open coded masking and shifting everywhere else. Hence
remove themacros and open code the work they do.

Also, use of PAGE_CACHE_{SIZE|SHIFT|MASK} for these macros is now
incorrect - we are using pages directly and not the page cache, so
use PAGE_{SIZE|MASK|SHIFT} instead.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_buf.c |   39 +++++++++++++++++++++------------------
 fs/xfs/xfs_buf.h |    5 -----
 2 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index aad217c..3dd0f4e 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -300,7 +300,7 @@ xfs_buf_allocate_memory(
 	size_t			nbytes, offset;
 	gfp_t			gfp_mask = xb_to_gfp(flags);
 	unsigned short		page_count, i;
-	xfs_off_t		end;
+	xfs_off_t		start, end;
 	int			error;
 
 	/*
@@ -308,15 +308,15 @@ xfs_buf_allocate_memory(
 	 * the memory from the heap - there's no need for the complexity of
 	 * page arrays to keep allocation down to order 0.
 	 */
-	if (bp->b_length < BTOBB(PAGE_SIZE)) {
-		bp->b_addr = kmem_alloc(BBTOB(bp->b_length), xb_to_km(flags));
+	size = BBTOB(bp->b_length);
+	if (size < PAGE_SIZE) {
+		bp->b_addr = kmem_alloc(size, xb_to_km(flags));
 		if (!bp->b_addr) {
 			/* low memory - use alloc_page loop instead */
 			goto use_alloc_page;
 		}
 
-		if (((unsigned long)(bp->b_addr + BBTOB(bp->b_length) - 1) &
-								PAGE_MASK) !=
+		if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
 		    ((unsigned long)bp->b_addr & PAGE_MASK)) {
 			/* b_addr spans two pages - use alloc_page instead */
 			kmem_free(bp->b_addr);
@@ -332,14 +332,14 @@ xfs_buf_allocate_memory(
 	}
 
 use_alloc_page:
-	end = BBTOB(bp->b_bn + bp->b_length);
-	page_count = xfs_buf_btoc(end) - xfs_buf_btoct(BBTOB(bp->b_bn));
+	start = BBTOB(bp->b_bn) >> PAGE_SHIFT;
+	end = (BBTOB(bp->b_bn + bp->b_length) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	page_count = end - start;
 	error = _xfs_buf_get_pages(bp, page_count, flags);
 	if (unlikely(error))
 		return error;
 
 	offset = bp->b_offset;
-	size = BBTOB(bp->b_length);
 	bp->b_flags |= _XBF_PAGES;
 
 	for (i = 0; i < bp->b_page_count; i++) {
@@ -1343,27 +1343,30 @@ xfs_buf_iomove(
 	void			*data,	/* data address			*/
 	xfs_buf_rw_t		mode)	/* read/write/zero flag		*/
 {
-	size_t			bend, cpoff, csize;
-	struct page		*page;
+	size_t			bend;
 
 	bend = boff + bsize;
 	while (boff < bend) {
-		page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
-		cpoff = xfs_buf_poff(boff + bp->b_offset);
-		csize = min_t(size_t,
-			      PAGE_SIZE - cpoff, BBTOB(bp->b_io_length) - boff);
+		struct page	*page;
+		int		page_index, page_offset, csize;
+
+		page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
+		page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
+		page = bp->b_pages[page_index];
+		csize = min_t(size_t, PAGE_SIZE - page_offset,
+				      BBTOB(bp->b_io_length) - boff);
 
-		ASSERT(((csize + cpoff) <= PAGE_SIZE));
+		ASSERT((csize + page_offset) <= PAGE_SIZE);
 
 		switch (mode) {
 		case XBRW_ZERO:
-			memset(page_address(page) + cpoff, 0, csize);
+			memset(page_address(page) + page_offset, 0, csize);
 			break;
 		case XBRW_READ:
-			memcpy(data, page_address(page) + cpoff, csize);
+			memcpy(data, page_address(page) + page_offset, csize);
 			break;
 		case XBRW_WRITE:
-			memcpy(page_address(page) + cpoff, data, csize);
+			memcpy(page_address(page) + page_offset, data, csize);
 		}
 
 		boff += csize;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 57d3e7a..a99d2c9 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -32,11 +32,6 @@
 
 #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 */
-- 
1.7.9

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Re: [PATCH 8/8] xfs: kill xfs_buf_btoc

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

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Re: [PATCH 8/8] xfs: kill xfs_buf_btoc

[Mark Tinguely]

On 03/29/12 07:23, Dave Chinner wrote:
> From: Dave Chinner<dchinner@redhat.com>
>
> xfs_buf_btoc and friends are simple macros that do basic block
> to page index conversion and vice versa. These aren't widely used,
> and we use open coded masking and shifting everywhere else. Hence
> remove themacros and open code the work they do.
>
> Also, use of PAGE_CACHE_{SIZE|SHIFT|MASK} for these macros is now
> incorrect - we are using pages directly and not the page cache, so
> use PAGE_{SIZE|MASK|SHIFT} instead.
>
> Signed-off-by: Dave Chinner<dchinner@redhat.com>
> ---


Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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