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From: ira.weiny@intel.com
To: linux-ext4@vger.kernel.org,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>
Cc: Ira Weiny <ira.weiny@intel.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH V1 3/9] fs/ext4: Disallow encryption if inode is DAX
Date: Wed, 13 May 2020 23:53:09 -0700	[thread overview]
Message-ID: <20200514065316.2500078-4-ira.weiny@intel.com> (raw)
In-Reply-To: <20200514065316.2500078-1-ira.weiny@intel.com>

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

Furthermore, clarify the documentation of the exclusivity and how that
will work.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
	remove WARN_ON_ONCE
	Add documentation to the encrypt doc WRT DAX
---
 Documentation/filesystems/fscrypt.rst |  4 +++-
 fs/ext4/super.c                       | 10 +---------
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
index aa072112cfff..1475b8d52fef 100644
--- a/Documentation/filesystems/fscrypt.rst
+++ b/Documentation/filesystems/fscrypt.rst
@@ -1038,7 +1038,9 @@ astute users may notice some differences in behavior:
 - The ext4 filesystem does not support data journaling with encrypted
   regular files.  It will fall back to ordered data mode instead.
 
-- DAX (Direct Access) is not supported on encrypted files.
+- DAX (Direct Access) is not supported on encrypted files.  Attempts to enable
+  DAX on an encrypted file will fail.  Mount options will _not_ enable DAX on
+  encrypted files.
 
 - The st_size of an encrypted symlink will not necessarily give the
   length of the symlink target as required by POSIX.  It will actually
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index bf5fcb477f66..9873ab27e3fa 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1320,7 +1320,7 @@ 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 (IS_DAX(inode))
 		return -EINVAL;
 
 	res = ext4_convert_inline_data(inode);
@@ -1344,10 +1344,6 @@ 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;
@@ -1371,10 +1367,6 @@ 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


  parent reply	other threads:[~2020-05-14  6:53 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14  6:53 [PATCH V1 0/9] Enable ext4 support for per-file/directory DAX operations ira.weiny
2020-05-14  6:53 ` [PATCH V1 1/9] fs/ext4: Narrow scope of DAX check in setflags ira.weiny
2020-05-14  6:53 ` [PATCH V1 2/9] fs/ext4: Disallow verity if inode is DAX ira.weiny
2020-05-14 10:21   ` Jan Kara
2020-05-14  6:53 ` ira.weiny [this message]
2020-05-14 10:23   ` [PATCH V1 3/9] fs/ext4: Disallow encryption " Jan Kara
2020-05-14  6:53 ` [PATCH V1 4/9] fs/ext4: Change EXT4_MOUNT_DAX to EXT4_MOUNT_DAX_ALWAYS ira.weiny
2020-05-14  6:53 ` [PATCH V1 5/9] fs/ext4: Update ext4_should_use_dax() ira.weiny
2020-05-14  6:53 ` [PATCH V1 6/9] fs/ext4: Only change S_DAX on inode load ira.weiny
2020-05-14  6:53 ` [PATCH V1 7/9] fs/ext4: Make DAX mount option a tri-state ira.weiny
2020-05-14 11:25   ` Jan Kara
2020-05-14 14:27     ` Ira Weiny
2020-05-14 15:08   ` Darrick J. Wong
2020-05-15  3:38     ` Ira Weiny
2020-05-14  6:53 ` [PATCH V1 8/9] fs/ext4: Introduce DAX inode flag ira.weiny
2020-05-14 11:06   ` Jan Kara
2020-05-14  6:53 ` [PATCH V1 9/9] Documentation/dax: Update DAX enablement for ext4 ira.weiny
2020-05-14 11:15   ` Jan Kara

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