From: Christoph Hellwig hch@lst.de
mainline inclusion from mainline-v5.13-rc1 commit 85c8c3c1f8d9e31f626c93435dd91c2f85603e07 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8O6NL CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Split out a self contained helper to find a free minor for the md "unit" number.
Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Song Liu song@kernel.org Signed-off-by: Li Lingfeng lilingfeng3@huawei.com --- drivers/md/md.c | 47 +++++++++++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 20 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index b9065f26d3d2..572925c215fc 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -723,6 +723,27 @@ static struct mddev *mddev_find_locked(dev_t unit) return NULL; }
+/* find an unused unit number */ +static dev_t mddev_alloc_unit(void) +{ + static int next_minor = 512; + int start = next_minor; + bool is_free = 0; + dev_t dev = 0; + + while (!is_free) { + dev = MKDEV(MD_MAJOR, next_minor); + next_minor++; + if (next_minor > MINORMASK) + next_minor = 0; + if (next_minor == start) + return 0; /* Oh dear, all in use. */ + is_free = !mddev_find_locked(dev); + } + + return dev; +} + static struct mddev *mddev_find(dev_t unit) { struct mddev *mddev; @@ -765,27 +786,13 @@ static struct mddev *mddev_find_or_alloc(dev_t unit) return new; } } else if (new) { - /* find an unused unit number */ - static int next_minor = 512; - int start = next_minor; - int is_free = 0; - int dev = 0; - while (!is_free) { - dev = MKDEV(MD_MAJOR, next_minor); - next_minor++; - if (next_minor > MINORMASK) - next_minor = 0; - if (next_minor == start) { - /* Oh dear, all in use. */ - spin_unlock(&all_mddevs_lock); - kfree(new); - return NULL; - } - - is_free = !mddev_find_locked(dev); + new->unit = mddev_alloc_unit(); + if (!new->unit) { + spin_unlock(&all_mddevs_lock); + kfree(new); + return NULL; } - new->unit = dev; - new->md_minor = MINOR(dev); + new->md_minor = MINOR(new->unit); new->hold_active = UNTIL_STOP; list_add(&new->all_mddevs, &all_mddevs); spin_unlock(&all_mddevs_lock);