xfs_vm_writepage and xfs_page_convert set a page uptodate if it is determined
that all of the buffer_heads attached to that page are uptodate.
Currently we use the flag variable 'uptodate'. The flag is initially set = 1
and it is cleared if a !buffer_uptodate buffer is encountered. In addition we
check that bh == head in order to ensure that all of the buffer_heads have been
checked. However, it is possible to break out of the buffer_head loop early
having processed only the first buffer. This leaves uptodate == 1 and bh ==
head, so the uptodate bit can be set on a page even if not all of the buffers
have been checked. This can lead to data corruption on platforms with > 1
buffer per page.
SGI-PV: 1014173
Signed-off-by: Ben Myers <bpm@xxxxxxx>
---
fs/xfs/linux-2.6/xfs_aops.c | 16 ++++++++--------
1 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 52dbd14..c961f35 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -686,7 +686,7 @@ xfs_convert_page(
unsigned long p_offset;
unsigned int type;
int len, page_dirty;
- int count = 0, done = 0, uptodate = 1;
+ int count = 0, done = 0, uptodate = 0;
xfs_off_t offset = page_offset(page);
if (page->index != tindex)
@@ -727,8 +727,8 @@ xfs_convert_page(
do {
if (offset >= end_offset)
break;
- if (!buffer_uptodate(bh))
- uptodate = 0;
+ if (buffer_uptodate(bh))
+ uptodate++;
if (!(PageUptodate(page) || buffer_uptodate(bh))) {
done = 1;
continue;
@@ -761,7 +761,7 @@ xfs_convert_page(
}
} while (offset += len, (bh = bh->b_this_page) != head);
- if (uptodate && bh == head)
+ if (uptodate == (PAGE_CACHE_SIZE / len))
SetPageUptodate(page);
if (count) {
@@ -915,7 +915,7 @@ xfs_vm_writepage(
__uint64_t end_offset;
pgoff_t end_index, last_index;
ssize_t len;
- int err, imap_valid = 0, uptodate = 1;
+ int err, imap_valid = 0, uptodate = 0;
int count = 0;
int nonblocking = 0;
@@ -978,8 +978,8 @@ xfs_vm_writepage(
if (offset >= end_offset)
break;
- if (!buffer_uptodate(bh))
- uptodate = 0;
+ if (buffer_uptodate(bh))
+ uptodate++;
/*
* set_page_dirty dirties all buffers in a page, independent
@@ -1047,7 +1047,7 @@ xfs_vm_writepage(
} while (offset += len, ((bh = bh->b_this_page) != head));
- if (uptodate && bh == head)
+ if (uptodate == (PAGE_CACHE_SIZE / len))
SetPageUptodate(page);
xfs_start_page_writeback(page, 1, count);
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