[PATCH 08/21] xfs: enable xlog users to toggle atomic extent swapping

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Plumb the necessary bits into the xlog code so that higher level callers
can enable the atomic extent swapping feature and have it clear
automatically when possible.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/xfs_log.c      |   13 +++++++++++++
 fs/xfs/xfs_log.h      |    1 +
 fs/xfs/xfs_log_priv.h |    1 +
 3 files changed, 15 insertions(+)


diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index a0ef09addc84..37e85c1bb913 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1501,11 +1501,17 @@ xlog_clear_incompat(
 	if (down_write_trylock(&log->l_incompat_xattrs))
 		incompat_mask |= XFS_SB_FEAT_INCOMPAT_LOG_XATTRS;
 
+	if (down_write_trylock(&log->l_incompat_swapext))
+		incompat_mask |= XFS_SB_FEAT_INCOMPAT_LOG_SWAPEXT;
+
 	if (!incompat_mask)
 		return;
 
 	xfs_clear_incompat_log_features(mp, incompat_mask);
 
+	if (incompat_mask & XFS_SB_FEAT_INCOMPAT_LOG_SWAPEXT)
+		up_write(&log->l_incompat_swapext);
+
 	if (incompat_mask & XFS_SB_FEAT_INCOMPAT_LOG_XATTRS)
 		up_write(&log->l_incompat_xattrs);
 }
@@ -1625,6 +1631,7 @@ xlog_alloc_log(
 	log->l_sectBBsize = 1 << log2_size;
 
 	init_rwsem(&log->l_incompat_xattrs);
+	init_rwsem(&log->l_incompat_swapext);
 
 	xlog_get_iclog_buffer_size(mp, log);
 
@@ -3922,6 +3929,9 @@ xlog_use_incompat_feat(
 	case XLOG_INCOMPAT_FEAT_XATTRS:
 		down_read(&log->l_incompat_xattrs);
 		break;
+	case XLOG_INCOMPAT_FEAT_SWAPEXT:
+		down_read(&log->l_incompat_swapext);
+		break;
 	}
 }
 
@@ -3935,5 +3945,8 @@ xlog_drop_incompat_feat(
 	case XLOG_INCOMPAT_FEAT_XATTRS:
 		up_read(&log->l_incompat_xattrs);
 		break;
+	case XLOG_INCOMPAT_FEAT_SWAPEXT:
+		up_read(&log->l_incompat_swapext);
+		break;
 	}
 }
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index d187f6445909..30bdbf8ee25c 100644
--- a/fs/xfs/xfs_log.h
+++ b/fs/xfs/xfs_log.h
@@ -161,6 +161,7 @@ bool	  xlog_force_shutdown(struct xlog *log, uint32_t shutdown_flags);
 
 enum xlog_incompat_feat {
 	XLOG_INCOMPAT_FEAT_XATTRS = XFS_SB_FEAT_INCOMPAT_LOG_XATTRS,
+	XLOG_INCOMPAT_FEAT_SWAPEXT = XFS_SB_FEAT_INCOMPAT_LOG_SWAPEXT
 };
 
 void xlog_use_incompat_feat(struct xlog *log, enum xlog_incompat_feat what);
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index a13b5b6b744d..6cbee6996de5 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -448,6 +448,7 @@ struct xlog {
 
 	/* Users of log incompat features should take a read lock. */
 	struct rw_semaphore	l_incompat_xattrs;
+	struct rw_semaphore	l_incompat_swapext;
 };
 
 /*