[PATCH AUTOSEL 4.19 42/57] ext4: prohibit fstrim in norecovery mode

Sasha Levin
2019-03-30T01:30:26Z

From: "Darrick J. Wong" <darrick.wong@oracle.com>

[ Upstream commit 18915b5873f07e5030e6fb108a050fa7c71c59fb ]

The ext4 fstrim implementation uses the block bitmaps to find free space
that can be discarded. If we haven't replayed the journal, the bitmaps
will be stale and we absolutely *cannot* use stale metadata to zap the
underlying storage.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/ioctl.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 2e76fb55d94a..5f24fdc140ad 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -999,6 +999,13 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (!blk_queue_discard(q))
return -EOPNOTSUPP;

+ /*
+ * We haven't replayed the journal, so we cannot use our
+ * block-bitmap-guided storage zapping commands.
+ */
+ if (test_opt(sb, NOLOAD) && ext4_has_feature_journal(sb))
+ return -EROFS;
+
if (copy_from_user(&range, (struct fstrim_range __user *)arg,
sizeof(range)))
return -EFAULT;
--
2.19.1