linux-kernel - [PATCH RFC 3/8] fs/ext4: Disallow encryption if inode is DAX

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Message-Id: <20200414040030.1802884-4-ira.weiny@intel.com>
Date:   Mon, 13 Apr 2020 21:00:25 -0700
From:   ira.weiny@...el.com
To:     linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>
Cc:     Ira Weiny <ira.weiny@...el.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>,
        Christoph Hellwig <hch@....de>,
        "Theodore Y. Ts'o" <tytso@....edu>, Jeff Moyer <jmoyer@...hat.com>,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH RFC 3/8] fs/ext4: Disallow encryption if inode is DAX

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

Encryption and DAX are incompatible.  Changing the DAX mode due to a
change in Encryption mode is wrong without a corresponding
address_space_operations update.

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

Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
 fs/ext4/super.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0c7c4adb664e..b14863058115 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1325,7 +1325,7 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	if (inode->i_ino == EXT4_ROOT_INO)
 		return -EPERM;
 
-	if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode)))
+	if (WARN_ON_ONCE(IS_DAX(inode)))
 		return -EINVAL;
 
 	res = ext4_convert_inline_data(inode);
@@ -1349,10 +1349,6 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 			ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
 			ext4_clear_inode_state(inode,
 					EXT4_STATE_MAY_INLINE_DATA);
-			/*
-			 * Update inode->i_flags - S_ENCRYPTED will be enabled,
-			 * S_DAX may be disabled
-			 */
 			ext4_set_inode_flags(inode);
 		}
 		return res;
@@ -1376,10 +1372,6 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 				    ctx, len, 0);
 	if (!res) {
 		ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
-		/*
-		 * Update inode->i_flags - S_ENCRYPTED will be enabled,
-		 * S_DAX may be disabled
-		 */
 		ext4_set_inode_flags(inode);
 		res = ext4_mark_inode_dirty(handle, inode);
 		if (res)
-- 
2.25.1