[PATCH 3.12 39/50] ext4: fix error return from ext4_ext_handle_uninitialized_extents()

[Jiri Slaby]

From: Eric Whitney <enwlinux@xxxxxxxxx>

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

===============

commit ce37c42919608e96ade3748fe23c3062a0a966c5 upstream.

Commit 3779473246 breaks the return of error codes from
ext4_ext_handle_uninitialized_extents() in ext4_ext_map_blocks().  A
portion of the patch assigns that function's signed integer return
value to an unsigned int.  Consequently, negatively valued error codes
are lost and can be treated as a bogus allocated block count.

Signed-off-by: Eric Whitney <enwlinux@xxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 fs/ext4/extents.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e678549ec994..bd048b6addad 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4159,7 +4159,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	struct ext4_extent newex, *ex, *ex2;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	ext4_fsblk_t newblock = 0;
-	int free_on_err = 0, err = 0, depth;
+	int free_on_err = 0, err = 0, depth, ret;
 	unsigned int allocated = 0, offset = 0;
 	unsigned int allocated_clusters = 0;
 	struct ext4_allocation_request ar;
@@ -4220,9 +4220,13 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 			if (!ext4_ext_is_uninitialized(ex))
 				goto out;
 
-			allocated = ext4_ext_handle_uninitialized_extents(
+			ret = ext4_ext_handle_uninitialized_extents(
 				handle, inode, map, path, flags,
 				allocated, newblock);
+			if (ret < 0)
+				err = ret;
+			else
+				allocated = ret;
 			goto out3;
 		}
 	}
-- 
1.9.2

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