ToeiRei
Veteran
Joined: 03 Jan 2005
Posts: 1191
Location: Austria
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 Posted: Fri Oct 10, 2008 8:31 am Post subject: Kernel 2.6.27 - XFS Fix |
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The new kernel is out now and there is a problem with the xfs barrier handling which you might notify by watching your syslog / dmesg. The message is "xlog_iodone: Barriers are no longer supported"
| Code: | | Oct 9 07:50:44 pavilion Filesystem "sda9": xlog_iodone: Barriers are no longer supported by device. Disabling barriers |
Barriers are for ensuring that the data is written in the correct order.
In the new 2.6.27 kernel, barriers are disabled as soon as a log buffer in xlog_iodone does not find the XBF_ORDERED flag. This sounds simple, but leads to problems as this is also the case on a split log write in case of a log wraparound. The disabled barriers can easily lead to directory corruption on unclean shutdowns and some problems with deleting directories.
Patch:
| Code: | Index: 2.6.x-xfs-quilt/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- 2.6.x-xfs-quilt.orig/fs/xfs/linux-2.6/xfs_buf.c 2008-09-19
13:47:36.000000000 +1000
+++ 2.6.x-xfs-quilt/fs/xfs/linux-2.6/xfs_buf.c 2008-10-10 15:07:51.316145158
+1100
@@ -1001,12 +1001,13 @@ xfs_buf_iodone_work(
* We can get an EOPNOTSUPP to ordered writes. Here we clear the
* ordered flag and reissue them. Because we can't tell the higher
* layers directly that they should not issue ordered I/O anymore, they
- * need to check if the ordered flag was cleared during I/O completion.
+ * need to check if the _XFS_BARRIER_FAILED flag was set during I/O
completion.
*/
if ((bp->b_error == EOPNOTSUPP) &&
(bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC))
{
XB_TRACE(bp, "ordered_retry", bp->b_iodone);
bp->b_flags &= ~XBF_ORDERED;
+ bp->b_flags |= _XFS_BARRIER_FAILED;
xfs_buf_iorequest(bp);
} else if (bp->b_iodone)
(*(bp->b_iodone))(bp);
Index: 2.6.x-xfs-quilt/fs/xfs/linux-2.6/xfs_buf.h
===================================================================
--- 2.6.x-xfs-quilt.orig/fs/xfs/linux-2.6/xfs_buf.h 2008-09-19
13:47:36.000000000 +1000
+++ 2.6.x-xfs-quilt/fs/xfs/linux-2.6/xfs_buf.h 2008-10-10 11:54:23.269373217
+1100
@@ -85,6 +85,14 @@ typedef enum {
* modifications being lost.
*/
_XBF_PAGE_LOCKED = (1 << 22),
+
+ /*
+ * If we try a barrier write, but it fails we have to communicate
+ * this to the upper layers. Unfortunately b_error gets overwritten
+ * when the buffer is re-issued so we have to add another flag to
+ * keep this information.
+ */
+ _XFS_BARRIER_FAILED = (1 << 23),
} xfs_buf_flags_t;
typedef enum {
Index: 2.6.x-xfs-quilt/fs/xfs/xfs_log.c
===================================================================
--- 2.6.x-xfs-quilt.orig/fs/xfs/xfs_log.c 2008-09-22 11:54:19.000000000
+1000
+++ 2.6.x-xfs-quilt/fs/xfs/xfs_log.c 2008-10-10 15:09:56.967725107 +1100
@@ -1033,11 +1033,12 @@ xlog_iodone(xfs_buf_t *bp)
l = iclog->ic_log;
/*
- * If the ordered flag has been removed by a lower
- * layer, it means the underlyin device no longer supports
+ * If the _XFS_BARRIER_FAILED flag was set by a lower
+ * layer, it means the underlying device no longer supports
* barrier I/O. Warn loudly and turn off barriers.
*/
- if ((l->l_mp->m_flags & XFS_MOUNT_BARRIER) && !XFS_BUF_ISORDERED(bp)) {
+ if (bp->b_flags & _XFS_BARRIER_FAILED) {
+ bp->b_flags &= ~_XFS_BARRIER_FAILED;
l->l_mp->m_flags &= ~XFS_MOUNT_BARRIER;
xfs_fs_cmn_err(CE_WARN, l->l_mp,
"xlog_iodone: Barriers are no longer supported" |
Reference: http://oss.sgi.com/archives/xfs/2008-10/msg00183.html
Rei
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