xfs: add the zoned space allocator

For zoned RT devices space is always allocated at the write pointer, that
is right after the last written block and only recorded on I/O completion.

Because the actual allocation algorithm is very simple and just involves
picking a good zone - preferably the one used for the last write to the
inode.  As the number of zones that can written at the same time is
usually limited by the hardware, selecting a zone is done as late as
possible from the iomap dio and buffered writeback bio submissions
helpers just before submitting the bio.

Given that the writers already took a reservation before acquiring the
iolock, space will always be readily available if an open zone slot is
available.  A new structure is used to track these open zones, and
pointed to by the xfs_rtgroup.  Because zoned file systems don't have
a rsum cache the space for that pointer can be reused.

Allocations are only recorded at I/O completion time.  The scheme used
for that is very similar to the reflink COW end I/O path.

Co-developed-by: Hans Holmberg <hans.holmberg@wdc.com>
Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index f8851ff835de..6493bdb57351 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -20,6 +20,7 @@
 #include "xfs_sysfs.h"
 #include "xfs_sb.h"
 #include "xfs_health.h"
+#include "xfs_zone_alloc.h"
 
 struct kmem_cache	*xfs_log_ticket_cache;
 
@@ -3540,6 +3541,9 @@ xlog_force_shutdown(
 	spin_unlock(&log->l_icloglock);
 
 	wake_up_var(&log->l_opstate);
+	if (IS_ENABLED(CONFIG_XFS_RT) && xfs_has_zoned(log->l_mp))
+		xfs_zoned_wake_all(log->l_mp);
+
 	return log_error;
 }