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Subject[PATCH 1/2] xfs: don't block on buffer read errors
Date
From: Dave Chinner <dchinner@redhat.com>

xfs_buf_read() fails to detect dispatch errors before attempting to
wait on sychronous IO. If there was an error, it will get stuck
forever, waiting for an I/O that was never started. Make sure the
error is detected correctly.

Further, such a failure can leave locked pages in the page cache
which will cause a later operation to hang on the page. Ensure that
we correctly process pages in the buffers when we get a dispatch
error.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/linux-2.6/xfs_buf.c | 15 +++++++++++++--
1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 76bb13c..ec79634 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -578,7 +578,7 @@ _xfs_buf_read(
XBF_READ_AHEAD | _XBF_RUN_QUEUES);

status = xfs_buf_iorequest(bp);
- if (!status && !(flags & XBF_ASYNC))
+ if (!(status || XFS_BUF_ISERROR(bp) || (flags & XBF_ASYNC)))
status = xfs_buf_iowait(bp);
return status;
}
@@ -1280,8 +1280,19 @@ submit_io:
if (size)
goto next_chunk;
} else {
- bio_put(bio);
+ /*
+ * if we get here, no pages were added to the bio. However,
+ * we can't just error out here - if the pages are locked then
+ * we have to unlock them otherwise we can hang on a later
+ * access to the page.
+ */
xfs_buf_ioerror(bp, EIO);
+ if (bp->b_flags & _XBF_PAGE_LOCKED) {
+ int i;
+ for (i = 0; i < bp->b_page_count; i++)
+ unlock_page(bp->b_pages[i]);
+ }
+ bio_put(bio);
}
}

--
1.7.1


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