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md: refactor mddev_find_or_alloc

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Allocate the new mddev first speculatively, which greatly simplifies
the code flow.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
This commit is contained in:
Christoph Hellwig 2021-04-12 10:05:29 +02:00 committed by Song Liu
parent 85c8c3c1f8
commit d144fe6ff1
1 changed files with 31 additions and 43 deletions
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74
drivers/md/md.c
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@ -784,57 +784,45 @@ static struct mddev *mddev_find(dev_t unit)
static struct mddev *mddev_find_or_alloc(dev_t unit)
{
struct mddev *mddev, *new = NULL;
struct mddev *mddev = NULL, *new;
if (unit && MAJOR(unit) != MD_MAJOR)
unit &= ~((1<<MdpMinorShift)-1);
retry:
spin_lock(&all_mddevs_lock);
if (unit) {
mddev = mddev_find_locked(unit);
if (mddev) {
mddev_get(mddev);
spin_unlock(&all_mddevs_lock);
kfree(new);
return mddev;
}
if (new) {
list_add(&new->all_mddevs, &all_mddevs);
spin_unlock(&all_mddevs_lock);
new->hold_active = UNTIL_IOCTL;
return new;
}
} else if (new) {
new->unit = mddev_alloc_unit();
if (!new->unit) {
spin_unlock(&all_mddevs_lock);
kfree(new);
return NULL;
}
new->md_minor = MINOR(new->unit);
new->hold_active = UNTIL_STOP;
list_add(&new->all_mddevs, &all_mddevs);
spin_unlock(&all_mddevs_lock);
return new;
}
spin_unlock(&all_mddevs_lock);
unit &= ~((1 << MdpMinorShift) - 1);
new = kzalloc(sizeof(*new), GFP_KERNEL);
if (!new)
return NULL;
new->unit = unit;
if (MAJOR(unit) == MD_MAJOR)
new->md_minor = MINOR(unit);
else
new->md_minor = MINOR(unit) >> MdpMinorShift;
mddev_init(new);
goto retry;
spin_lock(&all_mddevs_lock);
if (unit) {
mddev = mddev_find_locked(unit);
if (mddev) {
mddev_get(mddev);
goto out_free_new;
}
new->unit = unit;
if (MAJOR(unit) == MD_MAJOR)
new->md_minor = MINOR(unit);
else
new->md_minor = MINOR(unit) >> MdpMinorShift;
new->hold_active = UNTIL_IOCTL;
} else {
new->unit = mddev_alloc_unit();
if (!new->unit)
goto out_free_new;
new->md_minor = MINOR(new->unit);
new->hold_active = UNTIL_STOP;
}
list_add(&new->all_mddevs, &all_mddevs);
spin_unlock(&all_mddevs_lock);
return new;
out_free_new:
spin_unlock(&all_mddevs_lock);
kfree(new);
return mddev;
}
static struct attribute_group md_redundancy_group;