From: Michael J. Evans <mjevans1983@gmail.com>
Date: Wed, 17 Oct 2007 06:30:52 +0000 (-0700)
Subject: md: software Raid autodetect dev list not array
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=4d936ec1fdc1541cd6d59d21ddb8b9386e2fcc4c;p=openwrt%2Fstaging%2Fblogic.git

md: software Raid autodetect dev list not array

In current release kernels the md module (Software RAID) uses a static
array (dev_t[128]) to store partition/device info temporarily for
autostart.

I discovered this (and that the devices are added as disks/partitions are
discovered at boot) while I was debugging why only one of my MD arrays would
come up whole, while all the others were short a disk.

I eventually discovered that it was enumerating through all of 9 of my 11 hds
(2 had only 4 partitions apiece) while the other 9 have 15 partitions (I
wanted 64 per drive...).  The last partition of the 8th drive in my 9 drive
raid 5 sets wasn't added, thus making the final md array short both a parity
and data disk, and it was started later, elsewhere.

This patch replaces that static array with a list.

[akpm@linux-foundation.org: removed unused var]
Signed-off-by: Michael J. Evans <mjevans1983@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 0dc563d76b39..f173ace1f8fb 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5770,26 +5770,47 @@ static int __init md_init(void)
  * Searches all registered partitions for autorun RAID arrays
  * at boot time.
  */
-static dev_t detected_devices[128];
-static int dev_cnt;
+
+static LIST_HEAD(all_detected_devices);
+struct detected_devices_node {
+	struct list_head list;
+	dev_t dev;
+};
 
 void md_autodetect_dev(dev_t dev)
 {
-	if (dev_cnt >= 0 && dev_cnt < 127)
-		detected_devices[dev_cnt++] = dev;
+	struct detected_devices_node *node_detected_dev;
+
+	node_detected_dev = kzalloc(sizeof(*node_detected_dev), GFP_KERNEL);
+	if (node_detected_dev) {
+		node_detected_dev->dev = dev;
+		list_add_tail(&node_detected_dev->list, &all_detected_devices);
+	} else {
+		printk(KERN_CRIT "md: md_autodetect_dev: kzalloc failed"
+			", skipping dev(%d,%d)\n", MAJOR(dev), MINOR(dev));
+	}
 }
 
 
 static void autostart_arrays(int part)
 {
 	mdk_rdev_t *rdev;
-	int i;
+	struct detected_devices_node *node_detected_dev;
+	dev_t dev;
+	int i_scanned, i_passed;
 
-	printk(KERN_INFO "md: Autodetecting RAID arrays.\n");
+	i_scanned = 0;
+	i_passed = 0;
 
-	for (i = 0; i < dev_cnt; i++) {
-		dev_t dev = detected_devices[i];
+	printk(KERN_INFO "md: Autodetecting RAID arrays.\n");
 
+	while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
+		i_scanned++;
+		node_detected_dev = list_entry(all_detected_devices.next,
+					struct detected_devices_node, list);
+		list_del(&node_detected_dev->list);
+		dev = node_detected_dev->dev;
+		kfree(node_detected_dev);
 		rdev = md_import_device(dev,0, 90);
 		if (IS_ERR(rdev))
 			continue;
@@ -5799,8 +5820,11 @@ static void autostart_arrays(int part)
 			continue;
 		}
 		list_add(&rdev->same_set, &pending_raid_disks);
+		i_passed++;
 	}
-	dev_cnt = 0;
+
+	printk(KERN_INFO "md: Scanned %d and added %d devices.\n",
+						i_scanned, i_passed);
 
 	autorun_devices(part);
 }