[PATCH 02/19] drm/i915/gemfs: enable THP

[Matthew Auld]

Enable transparent-huge-pages through gemfs by mounting with
huge=within_size.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gemfs.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gemfs.c b/drivers/gpu/drm/i915/i915_gemfs.c
index 62b266d1d36d..8dc6e577a5c4 100644
--- a/drivers/gpu/drm/i915/i915_gemfs.c
+++ b/drivers/gpu/drm/i915/i915_gemfs.c
@@ -25,6 +25,7 @@
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/mount.h>
+#include <linux/pagemap.h>
 
 #include "i915_drv.h"
 #include "i915_gemfs.h"
@@ -46,6 +47,21 @@ int i915_gemfs_init(struct drm_i915_private *i915)
 	if (IS_ERR(gemfs))
 		return PTR_ERR(gemfs);
 
+	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
+	    has_transparent_hugepage()) {
+		struct super_block *sb = gemfs->mnt_sb;
+		char options[] = "huge=within_size";
+		int flags = 0;
+
+		/* We don't consider failure to remount fatal, since this should
+		 * only ever attempt to modify the mount options of the sb, and
+		 * so should always leave us with a working mount upon failure.
+		 * Hence decoupling this from the actual kern_mount is probably
+		 * advisable.
+		 */
+		WARN_ON(sb->s_op->remount_fs(sb, &flags, options));
+	}
+
 	i915->gemfs = gemfs;
 
 	return 0;
-- 
2.9.4