[PATCH 28/41] xfs: replace barriers with explicit flush / FUA usage

From: Tejun Heo
Date: Fri Sep 03 2010 - 06:34:58 EST


From: Christoph Hellwig <hch@xxxxxxxxxxxxx>

Switch to the WRITE_FLUSH_FUA flag for log writes and remove the EOPNOTSUPP
detection for barriers.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
---
fs/xfs/linux-2.6/xfs_buf.c | 16 ++--------------
fs/xfs/linux-2.6/xfs_buf.h | 11 +----------
fs/xfs/linux-2.6/xfs_trace.h | 1 -
fs/xfs/xfs_log.c | 13 -------------
4 files changed, 3 insertions(+), 38 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index ea79072..b93ea33 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -929,19 +929,7 @@ xfs_buf_iodone_work(
xfs_buf_t *bp =
container_of(work, xfs_buf_t, b_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 _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)) {
- trace_xfs_buf_ordered_retry(bp, _RET_IP_);
- bp->b_flags &= ~XBF_ORDERED;
- bp->b_flags |= _XFS_BARRIER_FAILED;
- xfs_buf_iorequest(bp);
- } else if (bp->b_iodone)
+ if (bp->b_iodone)
(*(bp->b_iodone))(bp);
else if (bp->b_flags & XBF_ASYNC)
xfs_buf_relse(bp);
@@ -1200,7 +1188,7 @@ _xfs_buf_ioapply(

if (bp->b_flags & XBF_ORDERED) {
ASSERT(!(bp->b_flags & XBF_READ));
- rw = WRITE_BARRIER;
+ rw = WRITE_FLUSH_FUA;
} else if (bp->b_flags & XBF_LOG_BUFFER) {
ASSERT(!(bp->b_flags & XBF_READ_AHEAD));
bp->b_flags &= ~_XBF_RUN_QUEUES;
diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index d072e5f..d533d64 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -86,14 +86,6 @@ typedef enum {
*/
#define _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.
- */
-#define _XFS_BARRIER_FAILED (1 << 23)
-
typedef unsigned int xfs_buf_flags_t;

#define XFS_BUF_FLAGS \
@@ -114,8 +106,7 @@ typedef unsigned int xfs_buf_flags_t;
{ _XBF_PAGES, "PAGES" }, \
{ _XBF_RUN_QUEUES, "RUN_QUEUES" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
- { _XBF_PAGE_LOCKED, "PAGE_LOCKED" }, \
- { _XFS_BARRIER_FAILED, "BARRIER_FAILED" }
+ { _XBF_PAGE_LOCKED, "PAGE_LOCKED" }


typedef enum {
diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h
index be5dffd..8fe311a 100644
--- a/fs/xfs/linux-2.6/xfs_trace.h
+++ b/fs/xfs/linux-2.6/xfs_trace.h
@@ -325,7 +325,6 @@ DEFINE_BUF_EVENT(xfs_buf_lock);
DEFINE_BUF_EVENT(xfs_buf_lock_done);
DEFINE_BUF_EVENT(xfs_buf_cond_lock);
DEFINE_BUF_EVENT(xfs_buf_unlock);
-DEFINE_BUF_EVENT(xfs_buf_ordered_retry);
DEFINE_BUF_EVENT(xfs_buf_iowait);
DEFINE_BUF_EVENT(xfs_buf_iowait_done);
DEFINE_BUF_EVENT(xfs_buf_delwri_queue);
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 33f718f..ba8e36e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -917,19 +917,6 @@ xlog_iodone(xfs_buf_t *bp)
l = iclog->ic_log;

/*
- * 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 (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"
- " by device. Disabling barriers\n");
- }
-
- /*
* Race to shutdown the filesystem if we see an error.
*/
if (XFS_TEST_ERROR((XFS_BUF_GETERROR(bp)), l->l_mp,
--
1.7.1

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