Re: [PATCH] cleanup gendisk handling

From: Arjan van de Ven (arjanv@redhat.com)
Date: Mon Sep 03 2001 - 13:36:13 EST


Christoph Hellwig wrote:
> diff -uNr -X../current/dontdiff ../master/linux-2.4.10-pre4/drivers/block/genhd.c linux/drivers/block/genhd.c
> --- ../master/linux-2.4.10-pre4/drivers/block/genhd.c Fri Jul 20 02:48:15 2001
> +++ linux/drivers/block/genhd.c Mon Sep 3 19:38:50 2001
> @@ -17,6 +17,75 @@
> #include <linux/blk.h>
> #include <linux/init.h>
>
> +
> +struct gendisk *gendisk_head;
> +
> +void
> +add_gendisk(struct gendisk *gp)
> +{
> + gp->next = gendisk_head;
> + gendisk_head = gp;
> +}
> +
> +void
> +del_gendisk(struct gendisk *gp)
> +{
> + struct gendisk **gpp;
> +
> + for (gpp = &gendisk_head; *gpp; gpp = &((*gpp)->next))
> + if (*gpp == gp)
> + break;
> + if (*gpp)
> + *gpp = (*gpp)->next;
> +}
> +
> +struct gendisk *
> +get_gendisk(kdev_t dev)
> +{
> + struct gendisk *gp = NULL;
> + int maj = MAJOR(dev);
> +
> + for (gp = gendisk_head; gp; gp = gp->next)
> + if (gp->major == maj)
> + return gp;
> + return NULL;
> +}
> +
> +#ifdef CONFIG_PROC_FS
> +int
> +get_partition_list(char *page, char **start, off_t offset, int count)
> +{
> + struct gendisk *gp;
> + char buf[64];
> + int len, n;
> +
> + len = sprintf(page, "major minor #blocks name\n\n");
> + for (gp = gendisk_head; gp; gp = gp->next) {
> + for (n = 0; n < (gp->nr_real << gp->minor_shift); n++) {
> + if (gp->part[n].nr_sects == 0)
> + continue;
> +
> + len += snprintf(page + len, 63,
> + "%4d %4d %10d %s\n",
> + gp->major, n, gp->sizes[n],
> + disk_name(gp, n, buf));
> + if (len < offset)
> + offset -= len, len = 0;
> + else if (len >= offset + count)
> + goto out;
> + }
> + }
> +
> +out:
> + *start = page + offset;
> + len -= offset;
> + if (len < 0)
> + len = 0;
> + return len > count ? count : len;
> +}
> +#endif
> +
> +
> extern int blk_dev_init(void);
> #ifdef CONFIG_BLK_DEV_DAC960
> extern void DAC960_Initialize(void);

Hi,

I had a patch similar to this one a while ago (and it got dropped); One
difference is that your patch doesn't
seem to lock the linked list... so the operation is SMP unsafe (it was
before, but fixing that would be a
good sideeffect of this patch)

Greetings,
   Arjan van de Ven
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