[PATCH V4 2/8] fs/ext4: Disallow verity if inode is DAX

ira.weiny
2020-05-21T19:13:31Z

From: Ira Weiny <ira.weiny@intel.com>

Verity and DAX are incompatible. Changing the DAX mode due to a verity
flag change is wrong without a corresponding address_space_operations
update.

Make the 2 options mutually exclusive by returning an error if DAX was
set first.

(Setting DAX is already disabled if Verity is set first.)

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V2:
Remove Section title 'Verity and DAX'

Changes:
remove WARN_ON_ONCE
Add documentation for DAX/Verity exclusivity
---
Documentation/filesystems/ext4/verity.rst | 3 +++
fs/ext4/verity.c | 3 +++
2 files changed, 6 insertions(+)

diff --git a/Documentation/filesystems/ext4/verity.rst b/Documentation/filesystems/ext4/verity.rst
index 3e4c0ee0e068..e99ff3fd09f7 100644
--- a/Documentation/filesystems/ext4/verity.rst
+++ b/Documentation/filesystems/ext4/verity.rst
@@ -39,3 +39,6 @@ is encrypted as well as the data itself.

Verity files cannot have blocks allocated past the end of the verity
metadata.
+
+Verity and DAX are not compatible and attempts to set both of these flags
+on a file will fail.
diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index dc5ec724d889..f05a09fb2ae4 100644
--- a/fs/ext4/verity.c
+++ b/fs/ext4/verity.c
@@ -113,6 +113,9 @@ static int ext4_begin_enable_verity(struct file *filp)
handle_t *handle;
int err;

+ if (IS_DAX(inode))
+ return -EINVAL;
+
if (ext4_verity_in_progress(inode))
return -EBUSY;

--
2.25.1