[PATCH 4.8 136/138] ubi: fastmap: Fix add_vol() return value test in ubi_attach_fastmap()

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>

commit 40b6e61ac72e99672e47cdb99c8d7d226004169b upstream.

Commit e96a8a3bb671 ("UBI: Fastmap: Do not add vol if it already
exists") introduced a bug by changing the possible error codes returned
by add_vol():
- this function no longer returns NULL in case of allocation failure
  but return ERR_PTR(-ENOMEM)
- when a duplicate entry in the volume RB tree is found it returns
  ERR_PTR(-EEXIST) instead of ERR_PTR(-EINVAL)

Fix the tests done on add_vol() return val to match this new behavior.

Fixes: e96a8a3bb671 ("UBI: Fastmap: Do not add vol if it already exists")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
Acked-by: Sheng Yong <shengyong1@xxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mtd/ubi/fastmap.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -751,11 +751,11 @@ static int ubi_attach_fastmap(struct ubi
 			     fmvhdr->vol_type,
 			     be32_to_cpu(fmvhdr->last_eb_bytes));
 
-		if (!av)
-			goto fail_bad;
-		if (PTR_ERR(av) == -EINVAL) {
-			ubi_err(ubi, "volume (ID %i) already exists",
-				fmvhdr->vol_id);
+		if (IS_ERR(av)) {
+			if (PTR_ERR(av) == -EEXIST)
+				ubi_err(ubi, "volume (ID %i) already exists",
+					fmvhdr->vol_id);
+
 			goto fail_bad;
 		}