diff options
| author | Dave Chinner <dchinner@redhat.com> | 2014-10-02 09:04:31 +1000 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2014-10-02 09:04:31 +1000 |
| commit | 61be9c529a4a715ab8679e9ca82bc3790c7ab66c (patch) | |
| tree | 3e8d1c757133eb7c844cd4ba8815f4a6bc0218cb | |
| parent | e8aaba9a783c8e5d2c58ebe69650ea31b91bb745 (diff) | |
xfs: rework xfs_buf_bio_endio error handling
Currently the report of a bio error from completion
immediately marks the buffer with an error. The issue is that this
is racy w.r.t. synchronous IO - the submitter can see b_error being
set before the IO is complete, and hence we cannot differentiate
between submission failures and completion failures.
Add an internal b_io_error field protected by the b_lock to catch IO
completion errors, and only propagate that to the buffer during
final IO completion handling. Hence we can tell in xfs_buf_iorequest
if we've had a submission failure bey checking bp->b_error before
dropping our b_io_remaining reference - that reference will prevent
b_io_error values from being propagated to b_error in the event that
completion races with submission.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
| -rw-r--r-- | fs/xfs/xfs_buf.c | 18 | ||||
| -rw-r--r-- | fs/xfs/xfs_buf.h | 1 |
2 files changed, 17 insertions, 2 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index a046149e6099..170d6c0afe71 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1008,6 +1008,13 @@ xfs_buf_ioend( bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD); + /* + * Pull in IO completion errors now. We are guaranteed to be running + * single threaded, so we don't need the lock to read b_io_error. + */ + if (!bp->b_error && bp->b_io_error) + xfs_buf_ioerror(bp, bp->b_io_error); + /* Only validate buffers that were read without errors */ if (read && !bp->b_error && bp->b_ops) { ASSERT(!bp->b_iodone); @@ -1192,8 +1199,12 @@ xfs_buf_bio_end_io( * don't overwrite existing errors - otherwise we can lose errors on * buffers that require multiple bios to complete. */ - if (!bp->b_error) - xfs_buf_ioerror(bp, error); + if (error) { + spin_lock(&bp->b_lock); + if (!bp->b_io_error) + bp->b_io_error = error; + spin_unlock(&bp->b_lock); + } 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)); @@ -1379,6 +1390,9 @@ xfs_buf_iorequest( if (bp->b_flags & XBF_WRITE) xfs_buf_wait_unpin(bp); + /* clear the internal error state to avoid spurious errors */ + bp->b_io_error = 0; + /* * Take references to the buffer. For XBF_ASYNC buffers, holding a * reference for as long as submission takes is all that is necessary diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h index 4585c1595a98..44db8cd67bda 100644 --- a/fs/xfs/xfs_buf.h +++ b/fs/xfs/xfs_buf.h @@ -158,6 +158,7 @@ typedef struct xfs_buf { struct list_head b_lru; /* lru list */ spinlock_t b_lock; /* internal state lock */ unsigned int b_state; /* internal state flags */ + int b_io_error; /* internal IO error state */ wait_queue_head_t b_waiters; /* unpin waiters */ struct list_head b_list; struct xfs_perag *b_pag; /* contains rbtree root */ |