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[v2,12/17] btrfs: turn on inlinecrypt mount option for encrypt

Message ID 303b721e0c738ebb8ee3ada3d4b867a07d6d5bfb.1689564024.git.sweettea-kernel@dorminy.me (mailing list archive)
State Superseded
Headers show
Series btrfs: add encryption feature | expand

Commit Message

Sweet Tea Dorminy July 17, 2023, 3:52 a.m. UTC
fscrypt's extent encryption requires the use of inline encryption or the
software fallback that the block layer provides; it is rather
complicated to allow software encryption with extent encryption due to
the timing of memory allocations. Thus, if btrfs has ever had a
encrypted file, or when encryption is enabled on a directory, update the
mount flags to include inlinecrypt.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 fs/btrfs/ioctl.c |  4 ++++
 fs/btrfs/super.c | 10 ++++++++++
 2 files changed, 14 insertions(+)

Comments

Luis Henriques July 17, 2023, 3:34 p.m. UTC | #1
Sweet Tea Dorminy <sweettea-kernel@dorminy.me> writes:

> fscrypt's extent encryption requires the use of inline encryption or the
> software fallback that the block layer provides; it is rather
> complicated to allow software encryption with extent encryption due to
> the timing of memory allocations. Thus, if btrfs has ever had a
> encrypted file, or when encryption is enabled on a directory, update the
> mount flags to include inlinecrypt.
>
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> ---
>  fs/btrfs/ioctl.c |  4 ++++
>  fs/btrfs/super.c | 10 ++++++++++
>  2 files changed, 14 insertions(+)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 91ad59519900..11866a88e33f 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -4574,6 +4574,10 @@ long btrfs_ioctl(struct file *file, unsigned int
>  		 * state persists.
>  		 */
>  		btrfs_set_fs_incompat(fs_info, ENCRYPT);
> +		if (!(inode->i_sb->s_flags & SB_INLINECRYPT)) {
> +			inode->i_sb->s_flags |= SB_INLINECRYPT;
> +			mb();

I've no idea this mb() is needed here, but I know it's usually a good
practice to document why it is needed.

Cheers,
Josef Bacik July 17, 2023, 5:55 p.m. UTC | #2
On Sun, Jul 16, 2023 at 11:52:43PM -0400, Sweet Tea Dorminy wrote:
> fscrypt's extent encryption requires the use of inline encryption or the
> software fallback that the block layer provides; it is rather
> complicated to allow software encryption with extent encryption due to
> the timing of memory allocations. Thus, if btrfs has ever had a
> encrypted file, or when encryption is enabled on a directory, update the
> mount flags to include inlinecrypt.
> 
> Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
> ---
>  fs/btrfs/ioctl.c |  4 ++++
>  fs/btrfs/super.c | 10 ++++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 91ad59519900..11866a88e33f 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -4574,6 +4574,10 @@ long btrfs_ioctl(struct file *file, unsigned int
>  		 * state persists.
>  		 */
>  		btrfs_set_fs_incompat(fs_info, ENCRYPT);
> +		if (!(inode->i_sb->s_flags & SB_INLINECRYPT)) {
> +			inode->i_sb->s_flags |= SB_INLINECRYPT;
> +			mb();

Extraneous mb().  Thanks,

Josef
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Patch

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 91ad59519900..11866a88e33f 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4574,6 +4574,10 @@  long btrfs_ioctl(struct file *file, unsigned int
 		 * state persists.
 		 */
 		btrfs_set_fs_incompat(fs_info, ENCRYPT);
+		if (!(inode->i_sb->s_flags & SB_INLINECRYPT)) {
+			inode->i_sb->s_flags |= SB_INLINECRYPT;
+			mb();
+		}
 		return fscrypt_ioctl_set_policy(file, (const void __user *)arg);
 	}
 	case FS_IOC_GET_ENCRYPTION_POLICY:
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 0cc9c2909f64..1e9a93c6750a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1165,6 +1165,16 @@  static int btrfs_fill_super(struct super_block *sb,
 		return err;
 	}
 
+	if (btrfs_fs_incompat(fs_info, ENCRYPT)) {
+		if (IS_ENABLED(CONFIG_FS_ENCRYPTION_INLINE_CRYPT)) {
+			sb->s_flags |= SB_INLINECRYPT;
+		} else {
+			btrfs_err(fs_info, "encryption not supported");
+			err = -EINVAL;
+			goto fail_close;
+		}
+	}
+
 	inode = btrfs_iget(sb, BTRFS_FIRST_FREE_OBJECTID, fs_info->fs_root);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);