[PATCH 03/11] xfs: remove ->b_offset handling for page backed buffers

[Christoph Hellwig <hch@xxxxxx>]

->b_offset can only be non-zero for SLAB backed buffers, so remove all
code dealing with it for page backed buffers.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_buf.c | 15 +++++----------
 fs/xfs/xfs_buf.h |  3 ++-
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index ac85ec6f0a2fab..392b85d059bff5 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -79,7 +79,7 @@ static inline int
 xfs_buf_vmap_len(
 	struct xfs_buf	*bp)
 {
-	return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
+	return (bp->b_page_count * PAGE_SIZE);
 }
 
 /*
@@ -329,8 +329,7 @@ xfs_buf_free(
 		uint		i;
 
 		if (xfs_buf_is_vmapped(bp))
-			vm_unmap_ram(bp->b_addr - bp->b_offset,
-					bp->b_page_count);
+			vm_unmap_ram(bp->b_addr, bp->b_page_count);
 
 		for (i = 0; i < bp->b_page_count; i++) {
 			struct page	*page = bp->b_pages[i];
@@ -386,7 +385,7 @@ xfs_buf_alloc_pages(
 	uint			flags)
 {
 	size_t			size;
-	size_t			nbytes, offset;
+	size_t			nbytes;
 	gfp_t			gfp_mask = xb_to_gfp(flags);
 	unsigned short		page_count, i;
 	xfs_off_t		start, end;
@@ -407,7 +406,6 @@ xfs_buf_alloc_pages(
 	if (unlikely(error))
 		return error;
 
-	offset = bp->b_offset;
 	bp->b_flags |= _XBF_PAGES;
 
 	for (i = 0; i < bp->b_page_count; i++) {
@@ -441,10 +439,9 @@ xfs_buf_alloc_pages(
 
 		XFS_STATS_INC(bp->b_mount, xb_page_found);
 
-		nbytes = min_t(size_t, size, PAGE_SIZE - offset);
+		nbytes = min_t(size_t, size, PAGE_SIZE);
 		size -= nbytes;
 		bp->b_pages[i] = page;
-		offset = 0;
 	}
 	return 0;
 
@@ -466,7 +463,7 @@ _xfs_buf_map_pages(
 	ASSERT(bp->b_flags & _XBF_PAGES);
 	if (bp->b_page_count == 1) {
 		/* A single page buffer is always mappable */
-		bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
+		bp->b_addr = page_address(bp->b_pages[0]);
 	} else if (flags & XBF_UNMAPPED) {
 		bp->b_addr = NULL;
 	} else {
@@ -493,7 +490,6 @@ _xfs_buf_map_pages(
 
 		if (!bp->b_addr)
 			return -ENOMEM;
-		bp->b_addr += bp->b_offset;
 	}
 
 	return 0;
@@ -1726,7 +1722,6 @@ xfs_buf_offset(
 	if (bp->b_addr)
 		return bp->b_addr + offset;
 
-	offset += bp->b_offset;
 	page = bp->b_pages[offset >> PAGE_SHIFT];
 	return page_address(page) + (offset & (PAGE_SIZE-1));
 }
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 459ca34f26f588..21b4c58fd2fa87 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -167,7 +167,8 @@ struct xfs_buf {
 	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 */
-	unsigned int		b_offset;	/* page offset in first page */
+	unsigned int		b_offset;	/* page offset in first page,
+						   only used for SLAB buffers */
 	int			b_error;	/* error code on I/O */
 
 	/*
-- 
2.30.2