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authorBrian Foster <bfoster@redhat.com>2016-08-17 08:30:28 +1000
committerDave Chinner <david@fromorbit.com>2016-08-17 08:30:28 +1000
commit4dd3fd7197303739094183b139bae3142a3d55e6 (patch)
tree2b871419a3fe42b19cd3247da8402867f90f4077
parent694d0d0bb2030d2e36df73e2d23d5770511dbc8d (diff)
downloadop-kernel-dev-4dd3fd7197303739094183b139bae3142a3d55e6.zip
op-kernel-dev-4dd3fd7197303739094183b139bae3142a3d55e6.tar.gz
xfs: don't assert fail on non-async buffers on ioacct decrement
The buffer I/O accounting mechanism tracks async buffers under I/O. As an optimization, the buffer I/O count is incremented only once on the first async I/O for a given hold cycle of a buffer and decremented once the buffer is released to the LRU (or freed). xfs_buf_ioacct_dec() has an ASSERT() check for an XBF_ASYNC buffer, but we have one or two corner cases where a buffer can be submitted for I/O multiple times via different methods in a single hold cycle. If an async I/O occurs first, the I/O count is incremented. If a sync I/O occurs before the hold count drops, XBF_ASYNC is cleared by the time the I/O count is decremented. Remove the async assert check from xfs_buf_ioacct_dec() as this is a perfectly valid scenario. For the purposes of I/O accounting, we really only care about the buffer async state at I/O submission time. Discovered-and-analyzed-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
-rw-r--r--fs/xfs/xfs_buf.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 47a318c..607cc29 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -115,7 +115,6 @@ xfs_buf_ioacct_dec(
if (!(bp->b_flags & _XBF_IN_FLIGHT))
return;
- ASSERT(bp->b_flags & XBF_ASYNC);
bp->b_flags &= ~_XBF_IN_FLIGHT;
percpu_counter_dec(&bp->b_target->bt_io_count);
}
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