Instead of passing a kernel pointer to vfs_stat by relying on the
implicit set_fs(KERNEL_DS) in md_setup_drive, just open code the
trivial getattr, and use the opportunity to move a little bit more
code from the caller into the new helper.

Signed-off-by: Christoph Hellwig <[email protected]>
---
 drivers/md/md-autodetect.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/md/md-autodetect.c b/drivers/md/md-autodetect.c
index 14b6e86814c061..1e8f1df257a112 100644
--- a/drivers/md/md-autodetect.c
+++ b/drivers/md/md-autodetect.c
@@ -8,6 +8,7 @@
 #include <linux/raid/detect.h>
 #include <linux/raid/md_u.h>
 #include <linux/raid/md_p.h>
+#include <linux/namei.h>
 #include "md.h"
 
 /*
@@ -119,6 +120,23 @@ static int __init md_setup(char *str)
        return 1;
 }
 
+static void __init md_lookup_dev(const char *devname, dev_t *dev)
+{
+       struct kstat stat;
+       struct path path;
+       char filename[64];
+
+       if (strncmp(devname, "/dev/", 5) == 0)
+               devname += 5;
+       snprintf(filename, 63, "/dev/%s", devname);
+
+       if (!kern_path(filename, LOOKUP_FOLLOW, &path) &&
+           !vfs_getattr(&path, &stat, STATX_BASIC_STATS, AT_NO_AUTOMOUNT) &&
+           S_ISBLK(stat.mode))
+               *dev = new_decode_dev(stat.rdev);
+       path_put(&path);
+}
+
 static void __init md_setup_drive(struct md_setup_args *args)
 {
        char *devname = args->device_names;
@@ -138,21 +156,14 @@ static void __init md_setup_drive(struct md_setup_args 
*args)
        }
 
        for (i = 0; i < MD_SB_DISKS && devname != NULL; i++) {
-               struct kstat stat;
-               char *p;
-               char comp_name[64];
                dev_t dev;
+               char *p;
 
                p = strchr(devname, ',');
                if (p)
                        *p++ = 0;
-
                dev = name_to_dev_t(devname);
-               if (strncmp(devname, "/dev/", 5) == 0)
-                       devname += 5;
-               snprintf(comp_name, 63, "/dev/%s", devname);
-               if (vfs_stat(comp_name, &stat) == 0 && S_ISBLK(stat.mode))
-                       dev = new_decode_dev(stat.rdev);
+               md_lookup_dev(devname, &dev);
                if (!dev) {
                        pr_warn("md: Unknown device name: %s\n", devname);
                        break;
-- 
2.27.0

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