[PATCH 086/102] xfs: Properly exclude IO type flags from buffer flags

Dave Chinner
2012-08-23T05:04:33Z

From: Dave Chinner <dchinner@redhat.com>

Upstream commit: 12bcb3f7d4371f74bd25372e98e0d2da978e82b2

Recent event tracing during a debugging session showed that flags
that define the IO type for a buffer are leaking into the flags on
the buffer incorrectly. Fix the flag exclusion mask in
xfs_buf_alloc() to avoid problems that may be caused by such
leakage.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
---
fs/xfs/linux-2.6/xfs_buf.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 522ab83..a87b93a 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -175,9 +175,11 @@ xfs_buf_alloc(
return NULL;

/*
- * We don't want certain flags to appear in b_flags.
+ * We don't want certain flags to appear in b_flags unless they are
+ * specifically set by later operations on the buffer.
*/
- flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
+ flags &= ~(XBF_LOCK | XBF_MAPPED | XBF_DONT_BLOCK |
+ XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);

atomic_set(&bp->b_hold, 1);
atomic_set(&bp->b_lru_ref, 1);