fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation

Execution of get_anon_bdev concurrently and preemptive kernel all
could bring race condition, it isn't enough to check dev against
its upper limitation with equality operator only.

This patch fix it.

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/super.c b/fs/super.c
index 928c20f47af9..b61372354f2b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -842,7 +842,7 @@ int get_anon_bdev(dev_t *p)
         else if (error)
                 return -EAGAIN;
 
-        if (dev == (1 << MINORBITS)) {
+        if (dev >= (1 << MINORBITS)) {
                 spin_lock(&unnamed_dev_lock);
                 ida_remove(&unnamed_dev_ida, dev);
                 if (unnamed_dev_start > dev)