[PATCH 5/5] ext4 crypto: fix bugs in ext4_encrypted_zeroout()

[Theodore Ts'o <tytso@mit.edu>]

Fix multiple bugs in ext4_encrypted_zeroout(), including one that
could cause us to write an encrypted zero page to the wrong location
on disk, potentially causing data and file system corruption.
Fortunately, this tends to only show up in stress tests, but even with
these fixes, we are seeing some test failures with generic/127 --- but
these are now caused by data failures instead of metadata corruption.

Since ext4_encrypted_zeroout() is only used for some optimizations to
keep the extent tree from being too fragmented, and
ext4_encrypted_zeroout() itself isn't all that optimized from a time
or IOPS perspective, disable the extent tree optimization for
encrypted inodes for now.  This prevents the data corruption issues
reported by generic/127 until we can figure out what's going wrong.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
---
 fs/ext4/crypto.c  | 23 +++++++++++++++++++----
 fs/ext4/extents.c |  3 +++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 879cb15..af06830 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -392,7 +392,13 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 	ext4_lblk_t		lblk = ex->ee_block;
 	ext4_fsblk_t		pblk = ext4_ext_pblock(ex);
 	unsigned int		len = ext4_ext_get_actual_len(ex);
-	int			err = 0;
+	int			ret, err = 0;
+
+#if 0
+	ext4_msg(inode->i_sb, KERN_CRIT,
+		 "ext4_encrypted_zeroout ino %lu lblk %u len %u",
+		 (unsigned long) inode->i_ino, lblk, len);
+#endif
 
 	BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
 
@@ -418,17 +424,26 @@ int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
 			goto errout;
 		}
 		bio->bi_bdev = inode->i_sb->s_bdev;
-		bio->bi_iter.bi_sector = pblk;
-		err = bio_add_page(bio, ciphertext_page,
+		bio->bi_iter.bi_sector =
+			pblk << (inode->i_sb->s_blocksize_bits - 9);
+		ret = bio_add_page(bio, ciphertext_page,
 				   inode->i_sb->s_blocksize, 0);
-		if (err) {
+		if (ret != inode->i_sb->s_blocksize) {
+			/* should never happen! */
+			ext4_msg(inode->i_sb, KERN_ERR,
+				 "bio_add_page failed: %d", ret);
+			WARN_ON(1);
 			bio_put(bio);
+			err = -EIO;
 			goto errout;
 		}
 		err = submit_bio_wait(WRITE, bio);
+		if ((err == 0) && bio->bi_error)
+			err = -EIO;
 		bio_put(bio);
 		if (err)
 			goto errout;
+		lblk++; pblk++;
 	}
 	err = 0;
 errout:
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 2553aa8..7f486e3 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3558,6 +3558,9 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 		max_zeroout = sbi->s_extent_max_zeroout_kb >>
 			(inode->i_sb->s_blocksize_bits - 10);
 
+	if (ext4_encrypted_inode(inode))
+		max_zeroout = 0;
+
 	/* If extent is less than s_max_zeroout_kb, zeroout directly */
 	if (max_zeroout && (ee_len <= max_zeroout)) {
 		err = ext4_ext_zeroout(inode, ex);
-- 
2.5.0