From 0bd16cf2173695726f1ed2f9372c613003d80f9a Mon Sep 17 00:00:00 2001
From: Dave Jiang <dave.jiang@intel.com>
Date: Tue, 15 Jun 2010 18:41:53 -0700
Subject: create: Check with OROM limit before setting default chunk size

Make create check with the appropriate meta data handler and see what the
largest chunk size is supported. The current 512K default is not supported
by existing imsm OROM.

[dan.j.williams@intel.com: trim the upper limit to 512k for future oroms]
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 Create.c         |  8 ++++++--
 mdadm.h          |  2 ++
 platform-intel.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 super-intel.c    | 12 ++++++++++++
 4 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/Create.c b/Create.c
index b04388f..43e5f37 100644
--- a/Create.c
+++ b/Create.c
@@ -235,9 +235,13 @@ int Create(struct supertype *st, char *mddev,
 	case 6:
 	case 0:
 		if (chunk == 0) {
-			chunk = 512;
+			if (st && st->ss->default_chunk)
+				chunk = st->ss->default_chunk(st);
+
+			chunk = chunk ? : 512;
+
 			if (verbose > 0)
-				fprintf(stderr, Name ": chunk size defaults to 512K\n");
+				fprintf(stderr, Name ": chunk size defaults to %dK\n", chunk);
 		}
 		break;
 	case LEVEL_LINEAR:
diff --git a/mdadm.h b/mdadm.h
index 1bf5ac0..142868a 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -609,6 +609,8 @@ extern struct superswitch {
 	struct mdinfo *(*container_content)(struct supertype *st);
 	/* Allow a metadata handler to override mdadm's default layouts */
 	int (*default_layout)(int level); /* optional */
+	/* query the supertype for default chunk size */
+	int (*default_chunk)(struct supertype *st); /* optional */
 
 /* for mdmon */
 	int (*open_new)(struct supertype *c, struct active_array *a,
diff --git a/platform-intel.h b/platform-intel.h
index bbdc9f9..9088436 100644
--- a/platform-intel.h
+++ b/platform-intel.h
@@ -115,6 +115,55 @@ static inline int imsm_orom_has_chunk(const struct imsm_orom *orom, int chunk)
 	return !!(orom->sss & (1 << (fs - 1)));
 }
 
+/**
+ * fls - find last (most-significant) bit set
+ * @x: the word to search
+ * The funciton is borrowed from Linux kernel code
+ * include/asm-generic/bitops/fls.h
+ */
+static inline int fls(int x)
+{
+	int r = 32;
+
+	if (!x)
+		return 0;
+	if (!(x & 0xffff0000u)) {
+		x <<= 16;
+		r -= 16;
+	}
+	if (!(x & 0xff000000u)) {
+		x <<= 8;
+		r -= 8;
+	}
+	if (!(x & 0xf0000000u)) {
+		x <<= 4;
+		r -= 4;
+	}
+	if (!(x & 0xc0000000u)) {
+		x <<= 2;
+		r -= 2;
+	}
+	if (!(x & 0x80000000u)) {
+		x <<= 1;
+		r -= 1;
+	}
+	return r;
+}
+
+/**
+ * imsm_orom_default_chunk - return the largest chunk size supported via orom
+ * @orom: orom pointer from find_imsm_orom
+ */
+static inline int imsm_orom_default_chunk(const struct imsm_orom *orom)
+{
+	int fs = fls(orom->sss);
+
+	if (!fs)
+		return 0;
+
+	return min(512, (1 << fs));
+}
+
 struct sys_dev {
 	char *path;
 	struct sys_dev *next;
diff --git a/super-intel.c b/super-intel.c
index 394ace4..e212d9a 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -4003,6 +4003,17 @@ static int validate_geometry_imsm(struct supertype *st, int level, int layout,
 	close(cfd);
 	return 0;
 }
+
+static int default_chunk_imsm(struct supertype *st)
+{
+	struct intel_super *super = st->sb;
+
+	if (!super->orom)
+		return 0;
+
+	return imsm_orom_default_chunk(super->orom);
+}
+
 #endif /* MDASSEMBLE */
 
 static int is_rebuilding(struct imsm_dev *dev)
@@ -5240,6 +5251,7 @@ struct superswitch super_imsm = {
 	.brief_detail_super = brief_detail_super_imsm,
 	.write_init_super = write_init_super_imsm,
 	.validate_geometry = validate_geometry_imsm,
+	.default_chunk	= default_chunk_imsm,
 	.add_to_super	= add_to_super_imsm,
 	.detail_platform = detail_platform_imsm,
 #endif
-- 
cgit