From 24e17b5fb99d4d1b47fe0847a3a801e36d431ff6 Mon Sep 17 00:00:00 2001
From: Nathan Scott <nathans@sgi.com>
Date: Thu, 5 May 2005 13:33:20 -0700
Subject: [XFS] Use the right offset when ensuring a delayed allocate
 conversion has covered the offset originally requested.  Can cause data
 corruption when multiple processes are performing writeout on different areas
 of the same file.  Quite difficult to hit though.

SGI Modid: xfs-linux:xfs-kern:22377a

Signed-off-by: Nathan Scott <nathans@sgi.com>
Signed-off-by: Christoph Hellwig <hch@sgi.com>
.
---
 fs/xfs/linux-2.6/xfs_aops.c | 68 ++++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 29 deletions(-)

(limited to 'fs/xfs/linux-2.6/xfs_aops.c')

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 1edd3b69433..9278e9aba9b 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -558,7 +558,8 @@ xfs_submit_page(
 	int			i;
 
 	BUG_ON(PageWriteback(page));
-	set_page_writeback(page);
+	if (bh_count)
+		set_page_writeback(page);
 	if (clear_dirty)
 		clear_page_dirty(page);
 	unlock_page(page);
@@ -578,9 +579,6 @@ xfs_submit_page(
 
 		if (probed_page && clear_dirty)
 			wbc->nr_to_write--;	/* Wrote an "extra" page */
-	} else {
-		end_page_writeback(page);
-		wbc->pages_skipped++;	/* We didn't write this page */
 	}
 }
 
@@ -602,21 +600,26 @@ xfs_convert_page(
 {
 	struct buffer_head	*bh_arr[MAX_BUF_PER_PAGE], *bh, *head;
 	xfs_iomap_t		*mp = iomapp, *tmp;
-	unsigned long		end, offset;
-	pgoff_t			end_index;
-	int			i = 0, index = 0;
+	unsigned long		offset, end_offset;
+	int			index = 0;
 	int			bbits = inode->i_blkbits;
+	int			len, page_dirty;
 
-	end_index = i_size_read(inode) >> PAGE_CACHE_SHIFT;
-	if (page->index < end_index) {
-		end = PAGE_CACHE_SIZE;
-	} else {
-		end = i_size_read(inode) & (PAGE_CACHE_SIZE-1);
-	}
+	end_offset = (i_size_read(inode) & (PAGE_CACHE_SIZE - 1));
+
+	/*
+	 * page_dirty is initially a count of buffers on the page before
+	 * EOF and is decrememted as we move each into a cleanable state.
+	 */
+	len = 1 << inode->i_blkbits;
+	end_offset = max(end_offset, PAGE_CACHE_SIZE);
+	end_offset = roundup(end_offset, len);
+	page_dirty = end_offset / len;
+
+	offset = 0;
 	bh = head = page_buffers(page);
 	do {
-		offset = i << bbits;
-		if (offset >= end)
+		if (offset >= end_offset)
 			break;
 		if (!(PageUptodate(page) || buffer_uptodate(bh)))
 			continue;
@@ -625,6 +628,7 @@ xfs_convert_page(
 			if (startio) {
 				lock_buffer(bh);
 				bh_arr[index++] = bh;
+				page_dirty--;
 			}
 			continue;
 		}
@@ -657,10 +661,11 @@ xfs_convert_page(
 			unlock_buffer(bh);
 			mark_buffer_dirty(bh);
 		}
-	} while (i++, (bh = bh->b_this_page) != head);
+		page_dirty--;
+	} while (offset += len, (bh = bh->b_this_page) != head);
 
-	if (startio) {
-		xfs_submit_page(page, wbc, bh_arr, index, 1, index == i);
+	if (startio && index) {
+		xfs_submit_page(page, wbc, bh_arr, index, 1, !page_dirty);
 	} else {
 		unlock_page(page);
 	}
@@ -743,19 +748,22 @@ xfs_page_state_convert(
 		}
 	}
 
-	offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
 	end_offset = min_t(unsigned long long,
-			offset + PAGE_CACHE_SIZE, i_size_read(inode));
-
-	bh = head = page_buffers(page);
-	iomp = NULL;
+			(loff_t)(page->index + 1) << PAGE_CACHE_SHIFT, offset);
+	offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
 
 	/*
-	 * page_dirty is initially a count of buffers on the page and
-	 * is decrememted as we move each into a cleanable state.
+	 * page_dirty is initially a count of buffers on the page before
+	 * EOF and is decrememted as we move each into a cleanable state.
 	 */
-	len = bh->b_size;
-	page_dirty = PAGE_CACHE_SIZE / len;
+	len = 1 << inode->i_blkbits;
+	p_offset = max(p_offset, PAGE_CACHE_SIZE);
+	p_offset = roundup(p_offset, len);
+	page_dirty = p_offset / len;
+
+	iomp = NULL;
+	p_offset = 0;
+	bh = head = page_buffers(page);
 
 	do {
 		if (offset >= end_offset)
@@ -877,8 +885,10 @@ xfs_page_state_convert(
 	if (uptodate && bh == head)
 		SetPageUptodate(page);
 
-	if (startio)
-		xfs_submit_page(page, wbc, bh_arr, cnt, 0, 1);
+	if (startio) {
+		WARN_ON(page_dirty);
+		xfs_submit_page(page, wbc, bh_arr, cnt, 0, !page_dirty);
+	}
 
 	if (iomp) {
 		offset = (iomp->iomap_offset + iomp->iomap_bsize - 1) >>
-- 
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