diff options
| author | Brian Foster <bfoster@redhat.com> | 2016-05-18 10:56:41 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2016-05-18 10:56:41 +1000 |
| commit | 9bdd9bd69b826875531bb1b2efb6aeb8d70e6f72 (patch) | |
| tree | 8cf9acecfa7280e4c3e43e116dc1f592665fa14b /fs/xfs/xfs_buf.c | |
| parent | f55532a0c0b8bb6148f4e07853b876ef73bc69ca (diff) | |
| download | linux-9bdd9bd69b826875531bb1b2efb6aeb8d70e6f72.tar.gz | |
xfs: buffer ->bi_end_io function requires irq-safe lock
Reports have surfaced of a lockdep splat complaining about an irq-safe -> irq-unsafe locking order in the xfs_buf_bio_end_io() bio completion handler. This only occurs when I/O errors are present because bp->b_lock is only acquired in this context to protect setting an error on the buffer. The problem is that this lock can be acquired with the (request_queue) q->queue_lock held. See scsi_end_request() or ata_qc_schedule_eh(), for example. Replace the locked test/set of b_io_error with a cmpxchg() call. This eliminates the need for the lock and thus the lock ordering problem goes away. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
Diffstat (limited to 'fs/xfs/xfs_buf.c')
| -rw-r--r-- | fs/xfs/xfs_buf.c | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 9a2191b91137..e71cfbd5acb3 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1100,22 +1100,18 @@ xfs_bwrite( return error; } -STATIC void +static void xfs_buf_bio_end_io( struct bio *bio) { - xfs_buf_t *bp = (xfs_buf_t *)bio->bi_private; + struct xfs_buf *bp = (struct xfs_buf *)bio->bi_private; /* * don't overwrite existing errors - otherwise we can lose errors on * buffers that require multiple bios to complete. */ - if (bio->bi_error) { - spin_lock(&bp->b_lock); - if (!bp->b_io_error) - bp->b_io_error = bio->bi_error; - spin_unlock(&bp->b_lock); - } + if (bio->bi_error) + cmpxchg(&bp->b_io_error, 0, bio->bi_error); if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ)) invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp)); |