xfs: split metadata and log buffer completion to separate workqueues
XFS traditionally sends all buffer I/O completion work to a single
workqueue. This includes metadata buffer completion and log buffer
completion. The log buffer completion requires a high priority queue to
prevent stalls due to log forces getting stuck behind other queued work.
Rather than continue to prioritize all buffer I/O completion due to the
needs of log completion, split log buffer completion off to
m_log_workqueue and move the high priority flag from m_buf_workqueue to
m_log_workqueue.
Add a b_ioend_wq wq pointer to xfs_buf to allow completion workqueue
customization on a per-buffer basis. Initialize b_ioend_wq to
m_buf_workqueue by default in the generic buffer I/O submission path.
Finally, override the default wq with the high priority m_log_workqueue
in the log buffer I/O submission path.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index d083889..945bea9 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1041,7 +1041,7 @@
struct work_struct *work)
{
struct xfs_buf *bp =
- container_of(work, xfs_buf_t, b_iodone_work);
+ container_of(work, xfs_buf_t, b_ioend_work);
xfs_buf_ioend(bp);
}
@@ -1050,8 +1050,8 @@
xfs_buf_ioend_async(
struct xfs_buf *bp)
{
- INIT_WORK(&bp->b_iodone_work, xfs_buf_ioend_work);
- queue_work(bp->b_target->bt_mount->m_buf_workqueue, &bp->b_iodone_work);
+ INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
+ queue_work(bp->b_ioend_wq, &bp->b_ioend_work);
}
void
@@ -1220,6 +1220,13 @@
*/
bp->b_error = 0;
+ /*
+ * Initialize the I/O completion workqueue if we haven't yet or the
+ * submitter has not opted to specify a custom one.
+ */
+ if (!bp->b_ioend_wq)
+ bp->b_ioend_wq = bp->b_target->bt_mount->m_buf_workqueue;
+
if (bp->b_flags & XBF_WRITE) {
if (bp->b_flags & XBF_SYNCIO)
rw = WRITE_SYNC;
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 82002c0..75ff5d5 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -164,7 +164,8 @@
struct xfs_perag *b_pag; /* contains rbtree root */
xfs_buftarg_t *b_target; /* buffer target (device) */
void *b_addr; /* virtual address of buffer */
- struct work_struct b_iodone_work;
+ struct work_struct b_ioend_work;
+ struct workqueue_struct *b_ioend_wq; /* I/O completion wq */
xfs_buf_iodone_t b_iodone; /* I/O completion function */
struct completion b_iowait; /* queue for I/O waiters */
void *b_fspriv;
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index e810e9d..d508a65 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1808,6 +1808,8 @@
XFS_BUF_ZEROFLAGS(bp);
XFS_BUF_ASYNC(bp);
bp->b_flags |= XBF_SYNCIO;
+ /* use high priority completion wq */
+ bp->b_ioend_wq = log->l_mp->m_log_workqueue;
if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {
bp->b_flags |= XBF_FUA;
@@ -1856,6 +1858,8 @@
bp->b_flags |= XBF_SYNCIO;
if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
bp->b_flags |= XBF_FUA;
+ /* use high priority completion wq */
+ bp->b_ioend_wq = log->l_mp->m_log_workqueue;
ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 45fa5b5..b5aacfc 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -842,8 +842,7 @@
struct xfs_mount *mp)
{
mp->m_buf_workqueue = alloc_workqueue("xfs-buf/%s",
- WQ_MEM_RECLAIM|WQ_HIGHPRI|WQ_FREEZABLE, 1,
- mp->m_fsname);
+ WQ_MEM_RECLAIM|WQ_FREEZABLE, 1, mp->m_fsname);
if (!mp->m_buf_workqueue)
goto out;
@@ -868,7 +867,7 @@
goto out_destroy_cil;
mp->m_log_workqueue = alloc_workqueue("xfs-log/%s",
- WQ_FREEZABLE, 0, mp->m_fsname);
+ WQ_FREEZABLE|WQ_HIGHPRI, 0, mp->m_fsname);
if (!mp->m_log_workqueue)
goto out_destroy_reclaim;