Re: [patch v2 1/1] md: Software Raid autodetect dev list not array

Randy Dunlap
2007-08-26T16:58:36Z

On Sun, 26 Aug 2007 04:51:24 -0700 Michael J. Evans wrote:

> From: Michael J. Evans <mjevans1983@gmail.com>
>
> In current release kernels the md module (Software RAID) uses a static array
> (dev_t[128]) to store partition/device info temporarily for autostart.
>
> This patch replaces that static array with a list.
>
> Signed-off-by: Michael J. Evans <mjevans1983@gmail.com>
> ---
> Version 2: Following Neil Brown's requests...
> using list_add_tail, and corrected missing i_passed++;.
> removed sections of code that would never be reached.
> - -
> The data/structures are only used within md.c, and very close together.
> However I wonder if the structural information shouldn't go in to...
> ../../include/linux/raid/md_k.h instead.
>
>
> 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.
>
> Subject: [patch 1/1] md: Software Raid autodetect dev list not array
>
> SOFTWARE RAID (Multiple Disks) SUPPORT
> P: Ingo Molnar
> M: mingo@redhat.com
> P: Neil Brown
> M: neilb@suse.de
> L: linux-raid@vger.kernel.org
> S: Supported
> Unless you have a reason NOT to do so, CC linux-kernel@vger.kernel.org.
>
> 12: Has been tested with CONFIG_PREEMPT, CONFIG_DEBUG_PREEMPT,
> CONFIG_DEBUG_SLAB, CONFIG_DEBUG_PAGEALLOC, CONFIG_DEBUG_MUTEXES,
> CONFIG_DEBUG_SPINLOCK, CONFIG_DEBUG_SPINLOCK_SLEEP all simultaneously
> enabled.
>
> It has been tested with CONFIG_SMP set and unset (Different x86_64 systems).
> It has been tested with CONFIG_PREEMPT set and unset (same system).
> CONFIG_LBD isn't even an option in my .config file.

It's not an option 64_BIT builds.

> Note: between 2.6.22 and 2.6.23-rc3-git5
> rdev = md_import_device(dev,0, 0);
> became
> rdev = md_import_device(dev,0, 90);
> So the patch has been edited to patch around that line. (might be fuzzy)
>
> Signed-off-by: Michael J. Evans <mjevans1983@gmail.com>
> =============================================================
> --- linux/drivers/md/md.c.orig 2007-08-21 03:19:42.511576248 -0700
> +++ linux/drivers/md/md.c 2007-08-21 04:30:09.775525710 -0700
> @@ -5752,13 +5754,24 @@ void md_autodetect_dev(dev_t dev)
> * 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: kzAlloc node failed, skipping device."
> + " : 0x%p.\n", node_detected_dev);

Is there any way to tell the user what device (or partition?) is
bein skipped? This printk should just print (confirm) that
node_detected_dev is NULL. Shouldn't it just print <dev> in
major:minor format?

> + }
> }
>
>
> @@ -5765,7 +5778,12 @@ static void autostart_arrays(int part)
> 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;
> + signed int i_found;

Drop "signed", like the surrounding code.
Leave a blank line between data declarations and beginning of code.

> + i_scanned = 0;
> + i_passed = 0;
>
> printk(KERN_INFO "md: Autodetecting RAID arrays.\n");
>
> @@ -5772,3 +5790,8 @@ static void autostart_arrays(int part)
> - for (i = 0; i < dev_cnt; i++) {
> - dev_t dev = detected_devices[i];
> -
> + /* FIXME: max 'int' #DEFINEd somewhere? not 0x7FFFFFFF ? */

include/linux/kernel.h has INT_MAX, UINT_MAX, LONG_MAX, ULONG_MAX,
LLONG_MAX, ULLONG_MAX.

> + while (!list_empty(&all_detected_devices) && i_scanned < 0x7FFFFFFF) {
> + 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);

---
~Randy
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