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authorDave Chinner <dchinner@redhat.com>2013-12-12 16:34:38 +1100
committerBen Myers <bpm@sgi.com>2013-12-17 09:40:23 -0600
commitac8809f9ab01a73de1a47b5a37bd8dcca8712fb3 (patch)
tree69be412f26ab598149abe559fc1541a14b151a07 /fs/xfs/xfs_buf_item.c
parent33177f05364c6cd13b06d0f3500dad07cf4647c2 (diff)
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xfs: abort metadata writeback on permanent errors
If we are doing aysnc writeback of metadata, we can get write errors but have nobody to report them to. At the moment, we simply attempt to reissue the write from io completion in the hope that it's a transient error. When it's not a transient error, the buffer is stuck forever in this loop, and we cannot break out of it. Eventually, unmount will hang because the AIL cannot be emptied and everything goes downhill from them. To solve this problem, only retry the write IO once before aborting it. We don't throw the buffer away because some transient errors can last minutes (e.g. FC path failover) or even hours (thin provisioned devices that have run out of backing space) before they go away. Hence we really want to keep trying until we can't try any more. Because the buffer was not cleaned, however, it does not get removed from the AIL and hence the next pass across the AIL will start IO on it again. As such, we still get the "retry forever" semantics that we currently have, but we allow other access to the buffer in the mean time. Meanwhile the filesystem can continue to modify the buffer and relog it, so the IO errors won't hang the log or the filesystem. Now when we are pushing the AIL, we can see all these "permanent IO error" buffers and we can issue a warning about failures before we retry the IO. We can also catch these buffers when unmounting an issue a corruption warning, too. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_buf_item.c')
-rw-r--r--fs/xfs/xfs_buf_item.c21
1 files changed, 19 insertions, 2 deletions
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index a64f67ba25d3..2227b9b050bb 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -496,6 +496,14 @@ xfs_buf_item_unpin(
}
}
+/*
+ * Buffer IO error rate limiting. Limit it to no more than 10 messages per 30
+ * seconds so as to not spam logs too much on repeated detection of the same
+ * buffer being bad..
+ */
+
+DEFINE_RATELIMIT_STATE(xfs_buf_write_fail_rl_state, 30 * HZ, 10);
+
STATIC uint
xfs_buf_item_push(
struct xfs_log_item *lip,
@@ -524,6 +532,14 @@ xfs_buf_item_push(
trace_xfs_buf_item_push(bip);
+ /* has a previous flush failed due to IO errors? */
+ if ((bp->b_flags & XBF_WRITE_FAIL) &&
+ ___ratelimit(&xfs_buf_write_fail_rl_state, "XFS:")) {
+ xfs_warn(bp->b_target->bt_mount,
+"Detected failing async write on buffer block 0x%llx. Retrying async write.\n",
+ (long long)bp->b_bn);
+ }
+
if (!xfs_buf_delwri_queue(bp, buffer_list))
rval = XFS_ITEM_FLUSHING;
xfs_buf_unlock(bp);
@@ -1096,8 +1112,9 @@ xfs_buf_iodone_callbacks(
xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
- if (!XFS_BUF_ISSTALE(bp)) {
- bp->b_flags |= XBF_WRITE | XBF_ASYNC | XBF_DONE;
+ if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
+ bp->b_flags |= XBF_WRITE | XBF_ASYNC |
+ XBF_DONE | XBF_WRITE_FAIL;
xfs_buf_iorequest(bp);
} else {
xfs_buf_relse(bp);