diff mbox series

[V3,7/8] fs/ext4: Introduce DAX inode flag

Message ID 20200520055753.3733520-8-ira.weiny@intel.com
State Superseded
Headers show
Series Enable ext4 support for per-file/directory DAX operations | expand

Commit Message

Ira Weiny May 20, 2020, 5:57 a.m. UTC
From: Ira Weiny <ira.weiny@intel.com>

Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.

Set the flag to be user visible and changeable.  Set the flag to be
inherited.  Allow applications to change the flag at any time with the
exception of if VERITY or ENCRYPT is set.

Disallow setting VERITY or ENCRYPT if DAX is set.

Finally, on regular files, flag the inode to not be cached to facilitate
changing S_DAX on the next creation of the inode.

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

---
Change from V2:
	Add in making verity and DAX exclusive.
	'Squash' in making encryption and DAX exclusive.
	Add in EXT4_INODE_DAX flag definition to be compatible with
		ext4_[set|test]_inode_flag() bit operations
	Use ext4_[set|test]_inode_flag() bit operations to be consistent
		with other code.

Change from V0:
	Add FS_DAX_FL to include/uapi/linux/fs.h
		to be consistent
	Move ext4_dax_dontcache() to ext4_ioctl_setflags()
		This ensures that it is only set when the flags are going to be
		set and not if there is an error
		Also this sets don't cache in the FS_IOC_SETFLAGS case

Change from RFC:
	use new d_mark_dontcache()
	Allow caching if ALWAYS/NEVER is set
	Rebased to latest Linus master
	Change flag to unused 0x01000000
	update ext4_should_enable_dax()
---
 fs/ext4/ext4.h          | 14 ++++++++++----
 fs/ext4/inode.c         |  2 +-
 fs/ext4/ioctl.c         | 34 +++++++++++++++++++++++++++++++++-
 fs/ext4/super.c         |  3 +++
 fs/ext4/verity.c        |  2 +-
 include/uapi/linux/fs.h |  1 +
 6 files changed, 49 insertions(+), 7 deletions(-)

Comments

Jan Kara May 20, 2020, 2:11 p.m. UTC | #1
On Tue 19-05-20 22:57:52, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> 
> Set the flag to be user visible and changeable.  Set the flag to be
> inherited.  Allow applications to change the flag at any time with the
> exception of if VERITY or ENCRYPT is set.
> 
> Disallow setting VERITY or ENCRYPT if DAX is set.
> 
> Finally, on regular files, flag the inode to not be cached to facilitate
> changing S_DAX on the next creation of the inode.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

One comment below:

> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 5ba65eb0e2ef..be9713e898eb 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1323,6 +1323,9 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  	if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode)))
>  		return -EINVAL;

AFAIU this check is here so that fscrypt_inherit_context() is able call us
and we can clear S_DAX flag. So can't we rather move this below the
EXT4_INODE_DAX check and change this to

	IS_DAX(inode) && !(inode->i_flags & I_NEW)

? Because as I'm reading the code now, this should never trigger?

>  
> +	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX))
> +		return -EOPNOTSUPP;
> +

								Honza
Ira Weiny May 20, 2020, 6:34 p.m. UTC | #2
On Wed, May 20, 2020 at 04:11:38PM +0200, Jan Kara wrote:
> On Tue 19-05-20 22:57:52, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> > 
> > Set the flag to be user visible and changeable.  Set the flag to be
> > inherited.  Allow applications to change the flag at any time with the
> > exception of if VERITY or ENCRYPT is set.
> > 
> > Disallow setting VERITY or ENCRYPT if DAX is set.
> > 
> > Finally, on regular files, flag the inode to not be cached to facilitate
> > changing S_DAX on the next creation of the inode.
> > 
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> 
> The patch looks good to me. You can add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> 
> One comment below:
> 
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index 5ba65eb0e2ef..be9713e898eb 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -1323,6 +1323,9 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
> >  	if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode)))
> >  		return -EINVAL;
> 
> AFAIU this check is here so that fscrypt_inherit_context() is able call us
> and we can clear S_DAX flag.

Basically yes that is true.  It is IMO somewhat convoluted because I think ext4
probably could have prevented S_DAX from being set in __ext4_new_inode() in the
first place.  But that is a clean up I was not prepared to make last night.

> So can't we rather move this below the
> EXT4_INODE_DAX check and change this to
> 
> 	IS_DAX(inode) && !(inode->i_flags & I_NEW)
> 
> ? Because as I'm reading the code now, this should never trigger?

I agree this should never trigger.  But I don't see how the order of the checks
maters much.  But changing this to !new is probably worth doing to make it
clear what we really mean here.

I think that is a follow on patch.  In addition, if we don't set S_DAX at all
in __ext4_new_inode() this check could then be what I had originally with the warn on.

	if (WARN_ON_ONCE(IS_DAX(inode)))
		...

... because it would be considered a bug to be setting DAX on inodes which are
going to be encrypted..

Ira

Something like this:  (compiled only)

commit 6cd5aed3cd9e2c10e3fb7c6dd23918580532f256 (HEAD -> lck-4071-b13-v4)
Author: Ira Weiny <ira.weiny@intel.com>
Date:   Wed May 20 11:32:50 2020 -0700

    RFC: do not set S_DAX on an inode which is going to be encrypted

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 7941c140723f..be80cb639d74 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -844,6 +844,9 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
                return ERR_PTR(-ENOMEM);
        ei = EXT4_I(inode);
 
+       if (encrypt)
+               ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
+
        /*
         * Initialize owners and quota early so that we don't have to account
         * for quota initialization worst case in standard inode creating
@@ -1165,6 +1168,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
                err = fscrypt_inherit_context(dir, inode, handle, true);
                if (err)
                        goto fail_free_drop;
+               ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
        }
 
        if (!(ei->i_flags & EXT4_EA_INODE_FL)) {
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index be9713e898eb..099b87864f55 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1320,7 +1320,10 @@ 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)))
+       /* S_DAX should never be set here because encryption is not compatible
+        * with DAX
+        */
+       if (WARN_ON_ONCE(IS_DAX(inode)))
                return -EINVAL;
 
        if (ext4_test_inode_flag(inode, EXT4_INODE_DAX))
@@ -1337,22 +1340,11 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
         * being set on an existing inode in its own transaction.  Only in the
         * latter case should the "retry on ENOSPC" logic be used.
         */
-
        if (handle) {
                res = ext4_xattr_set_handle(handle, inode,
                                            EXT4_XATTR_INDEX_ENCRYPTION,
                                            EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
                                            ctx, len, 0);
-               if (!res) {
-                       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, false);
-               }
                return res;
        }
Andreas Dilger May 20, 2020, 7:26 p.m. UTC | #3
On May 19, 2020, at 11:57 PM, ira.weiny@intel.com wrote:
> 
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> 
> Set the flag to be user visible and changeable.  Set the flag to be
> inherited.  Allow applications to change the flag at any time with the
> exception of if VERITY or ENCRYPT is set.
> 
> Disallow setting VERITY or ENCRYPT if DAX is set.
> 
> Finally, on regular files, flag the inode to not be cached to facilitate
> changing S_DAX on the next creation of the inode.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> 
> ---
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 6235440e4c39..467c30a789b6 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -415,13 +415,16 @@ struct flex_groups {
> #define EXT4_VERITY_FL			0x00100000 /* Verity protected inode */
> #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
> /* 0x00400000 was formerly EXT4_EOFBLOCKS_FL */
> +
> +#define EXT4_DAX_FL			0x01000000 /* Inode is DAX */
> +
> #define EXT4_INLINE_DATA_FL		0x10000000 /* Inode has inline data. */
> #define EXT4_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> #define EXT4_CASEFOLD_FL		0x40000000 /* Casefolded file */
> #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */

Hi Ira,
This flag value conflicts with the reserved flag in e2fsprogs for snapshots:

#define EXT4_SNAPFILE_FL                0x01000000  /* Inode is a snapshot */

Please change EXT4_DAX_FL and FS_DAX_FL to use 0x02000000, which is not used
for anything in either case.

Cheers, Andreas


> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 379a612f8f1d..7c5f6eb51e2d 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -262,6 +262,7 @@ struct fsxattr {
> #define FS_EA_INODE_FL			0x00200000 /* Inode used for large EA */
> #define FS_EOFBLOCKS_FL			0x00400000 /* Reserved for ext4 */
> #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
> +#define FS_DAX_FL			0x01000000 /* Inode is DAX */
> #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
> #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> #define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */
> --
> 2.25.1
> 


Cheers, Andreas
Ira Weiny May 20, 2020, 8:02 p.m. UTC | #4
On Wed, May 20, 2020 at 01:26:44PM -0600, Andreas Dilger wrote:
> On May 19, 2020, at 11:57 PM, ira.weiny@intel.com wrote:
> > 
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> > 
> > Set the flag to be user visible and changeable.  Set the flag to be
> > inherited.  Allow applications to change the flag at any time with the
> > exception of if VERITY or ENCRYPT is set.
> > 
> > Disallow setting VERITY or ENCRYPT if DAX is set.
> > 
> > Finally, on regular files, flag the inode to not be cached to facilitate
> > changing S_DAX on the next creation of the inode.
> > 
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > 
> > ---
> > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> > index 6235440e4c39..467c30a789b6 100644
> > --- a/fs/ext4/ext4.h
> > +++ b/fs/ext4/ext4.h
> > @@ -415,13 +415,16 @@ struct flex_groups {
> > #define EXT4_VERITY_FL			0x00100000 /* Verity protected inode */
> > #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
> > /* 0x00400000 was formerly EXT4_EOFBLOCKS_FL */
> > +
> > +#define EXT4_DAX_FL			0x01000000 /* Inode is DAX */
> > +
> > #define EXT4_INLINE_DATA_FL		0x10000000 /* Inode has inline data. */
> > #define EXT4_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> > #define EXT4_CASEFOLD_FL		0x40000000 /* Casefolded file */
> > #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
> 
> Hi Ira,
> This flag value conflicts with the reserved flag in e2fsprogs for snapshots:
> 
> #define EXT4_SNAPFILE_FL                0x01000000  /* Inode is a snapshot */

Sure NP but is that new?  I'm building off of 5.7-rc4.

Just curious if I completely missed something.

> 
> Please change EXT4_DAX_FL and FS_DAX_FL to use 0x02000000, which is not used
> for anything in either case.

NP, thanks!
Ira

> 
> Cheers, Andreas
> 
> 
> > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> > index 379a612f8f1d..7c5f6eb51e2d 100644
> > --- a/include/uapi/linux/fs.h
> > +++ b/include/uapi/linux/fs.h
> > @@ -262,6 +262,7 @@ struct fsxattr {
> > #define FS_EA_INODE_FL			0x00200000 /* Inode used for large EA */
> > #define FS_EOFBLOCKS_FL			0x00400000 /* Reserved for ext4 */
> > #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
> > +#define FS_DAX_FL			0x01000000 /* Inode is DAX */
> > #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
> > #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> > #define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */
> > --
> > 2.25.1
> > 
> 
> 
> Cheers, Andreas
> 
> 
> 
> 
>
Darrick J. Wong May 20, 2020, 8:55 p.m. UTC | #5
On Wed, May 20, 2020 at 01:02:42PM -0700, Ira Weiny wrote:
> On Wed, May 20, 2020 at 01:26:44PM -0600, Andreas Dilger wrote:
> > On May 19, 2020, at 11:57 PM, ira.weiny@intel.com wrote:
> > > 
> > > From: Ira Weiny <ira.weiny@intel.com>
> > > 
> > > Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> > > 
> > > Set the flag to be user visible and changeable.  Set the flag to be
> > > inherited.  Allow applications to change the flag at any time with the
> > > exception of if VERITY or ENCRYPT is set.
> > > 
> > > Disallow setting VERITY or ENCRYPT if DAX is set.
> > > 
> > > Finally, on regular files, flag the inode to not be cached to facilitate
> > > changing S_DAX on the next creation of the inode.
> > > 
> > > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > > 
> > > ---
> > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> > > index 6235440e4c39..467c30a789b6 100644
> > > --- a/fs/ext4/ext4.h
> > > +++ b/fs/ext4/ext4.h
> > > @@ -415,13 +415,16 @@ struct flex_groups {
> > > #define EXT4_VERITY_FL			0x00100000 /* Verity protected inode */
> > > #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
> > > /* 0x00400000 was formerly EXT4_EOFBLOCKS_FL */
> > > +
> > > +#define EXT4_DAX_FL			0x01000000 /* Inode is DAX */
> > > +
> > > #define EXT4_INLINE_DATA_FL		0x10000000 /* Inode has inline data. */
> > > #define EXT4_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> > > #define EXT4_CASEFOLD_FL		0x40000000 /* Casefolded file */
> > > #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
> > 
> > Hi Ira,
> > This flag value conflicts with the reserved flag in e2fsprogs for snapshots:
> > 
> > #define EXT4_SNAPFILE_FL                0x01000000  /* Inode is a snapshot */
> 
> Sure NP but is that new?  I'm building off of 5.7-rc4.
> 
> Just curious if I completely missed something.

Yeah, you missed that ... for some reason the kernel ext4 driver is
missing flags that are in e2fsprogs.  (huh??)

I would say you could probably just take over the flag because the 2010s
called and they don't want next3 back.  I guess that leaves 0x02000000
as the sole unclaimed bit, but this seriously needs some cleaning.

--D

> > 
> > Please change EXT4_DAX_FL and FS_DAX_FL to use 0x02000000, which is not used
> > for anything in either case.
> 
> NP, thanks!
> Ira
> 
> > 
> > Cheers, Andreas
> > 
> > 
> > > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> > > index 379a612f8f1d..7c5f6eb51e2d 100644
> > > --- a/include/uapi/linux/fs.h
> > > +++ b/include/uapi/linux/fs.h
> > > @@ -262,6 +262,7 @@ struct fsxattr {
> > > #define FS_EA_INODE_FL			0x00200000 /* Inode used for large EA */
> > > #define FS_EOFBLOCKS_FL			0x00400000 /* Reserved for ext4 */
> > > #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
> > > +#define FS_DAX_FL			0x01000000 /* Inode is DAX */
> > > #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
> > > #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
> > > #define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */
> > > --
> > > 2.25.1
> > > 
> > 
> > 
> > Cheers, Andreas
> > 
> > 
> > 
> > 
> > 
> 
>
Andreas Dilger May 21, 2020, 12:57 a.m. UTC | #6
On May 20, 2020, at 2:55 PM, Darrick J. Wong <darrick.wong@oracle.com> wrote:
> On Wed, May 20, 2020 at 01:02:42PM -0700, Ira Weiny wrote:
>> On Wed, May 20, 2020 at 01:26:44PM -0600, Andreas Dilger wrote:
>>> On May 19, 2020, at 11:57 PM, ira.weiny@intel.com wrote:
>>>> 
>>>> From: Ira Weiny <ira.weiny@intel.com>
>>>> 
>>>> Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
>>>> 
>>>> Set the flag to be user visible and changeable.  Set the flag to be
>>>> inherited.  Allow applications to change the flag at any time with the
>>>> exception of if VERITY or ENCRYPT is set.
>>>> 
>>>> Disallow setting VERITY or ENCRYPT if DAX is set.
>>>> 
>>>> Finally, on regular files, flag the inode to not be cached to facilitate
>>>> changing S_DAX on the next creation of the inode.
>>>> 
>>>> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>>>> 
>>>> ---
>>>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>>>> index 6235440e4c39..467c30a789b6 100644
>>>> --- a/fs/ext4/ext4.h
>>>> +++ b/fs/ext4/ext4.h
>>>> @@ -415,13 +415,16 @@ struct flex_groups {
>>>> #define EXT4_VERITY_FL			0x00100000 /* Verity protected inode */
>>>> #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
>>>> /* 0x00400000 was formerly EXT4_EOFBLOCKS_FL */
>>>> +
>>>> +#define EXT4_DAX_FL			0x01000000 /* Inode is DAX */
>>>> +
>>>> #define EXT4_INLINE_DATA_FL		0x10000000 /* Inode has inline data. */
>>>> #define EXT4_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
>>>> #define EXT4_CASEFOLD_FL		0x40000000 /* Casefolded file */
>>>> #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
>>> 
>>> Hi Ira,
>>> This flag value conflicts with the reserved flag in e2fsprogs for snapshots:
>>> 
>>> #define EXT4_SNAPFILE_FL                0x01000000  /* Inode is a snapshot */
>> 
>> Sure NP but is that new?  I'm building off of 5.7-rc4.
>> 
>> Just curious if I completely missed something.
> 
> Yeah, you missed that ... for some reason the kernel ext4 driver is
> missing flags that are in e2fsprogs.  (huh??)

It's no different than ext2 not having the full set of bits defined or
in use.

> I would say you could probably just take over the flag because the 2010s
> called and they don't want next3 back.  I guess that leaves 0x02000000
> as the sole unclaimed bit, but this seriously needs some cleaning.

Darrick,
we are in the process of updating the snapshot code for ext4, so need to
keep the 0x01000000 bit for snapshots.  Since 0x02000000 has never been
used for anything, there is no reason not to use it instead.

If we need to reclaim flags, it would be better to look at "COMPR" flags:

/* Reserved for compression usage... */
#define FS_COMPR_FL           0x00000004 /* Compress file */
#define FS_DIRTY_FL           0x00000100
#define FS_COMPRBLK_FL        0x00000200 /* One or more compressed clusters */
#define FS_NOCOMP_FL          0x00000400 /* Don't compress */

since I don't think they have ever been used.  I don't think we need 4x
on-disk state flags for that, especially not as part of the API.  It is
enough to have FS_COMPR_FL for the API, and then handle internal state
separately (e.g. compress into a separate on-disk extent and then swap
extents atomically instead of storing transient state on disk).

Cheers, Andreas
diff mbox series

Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 6235440e4c39..467c30a789b6 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -415,13 +415,16 @@  struct flex_groups {
 #define EXT4_VERITY_FL			0x00100000 /* Verity protected inode */
 #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
 /* 0x00400000 was formerly EXT4_EOFBLOCKS_FL */
+
+#define EXT4_DAX_FL			0x01000000 /* Inode is DAX */
+
 #define EXT4_INLINE_DATA_FL		0x10000000 /* Inode has inline data. */
 #define EXT4_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
 #define EXT4_CASEFOLD_FL		0x40000000 /* Casefolded file */
 #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
 
-#define EXT4_FL_USER_VISIBLE		0x705BDFFF /* User visible flags */
-#define EXT4_FL_USER_MODIFIABLE		0x604BC0FF /* User modifiable flags */
+#define EXT4_FL_USER_VISIBLE		0x715BDFFF /* User visible flags */
+#define EXT4_FL_USER_MODIFIABLE		0x614BC0FF /* User modifiable flags */
 
 /* Flags we can manipulate with through EXT4_IOC_FSSETXATTR */
 #define EXT4_FL_XFLAG_VISIBLE		(EXT4_SYNC_FL | \
@@ -429,14 +432,16 @@  struct flex_groups {
 					 EXT4_APPEND_FL | \
 					 EXT4_NODUMP_FL | \
 					 EXT4_NOATIME_FL | \
-					 EXT4_PROJINHERIT_FL)
+					 EXT4_PROJINHERIT_FL | \
+					 EXT4_DAX_FL)
 
 /* Flags that should be inherited by new inodes from their parent. */
 #define EXT4_FL_INHERITED (EXT4_SECRM_FL | EXT4_UNRM_FL | EXT4_COMPR_FL |\
 			   EXT4_SYNC_FL | EXT4_NODUMP_FL | EXT4_NOATIME_FL |\
 			   EXT4_NOCOMPR_FL | EXT4_JOURNAL_DATA_FL |\
 			   EXT4_NOTAIL_FL | EXT4_DIRSYNC_FL |\
-			   EXT4_PROJINHERIT_FL | EXT4_CASEFOLD_FL)
+			   EXT4_PROJINHERIT_FL | EXT4_CASEFOLD_FL |\
+			   EXT4_DAX_FL)
 
 /* Flags that are appropriate for regular files (all but dir-specific ones). */
 #define EXT4_REG_FLMASK (~(EXT4_DIRSYNC_FL | EXT4_TOPDIR_FL | EXT4_CASEFOLD_FL |\
@@ -488,6 +493,7 @@  enum {
 	EXT4_INODE_VERITY	= 20,	/* Verity protected inode */
 	EXT4_INODE_EA_INODE	= 21,	/* Inode used for large EA */
 /* 22 was formerly EXT4_INODE_EOFBLOCKS */
+	EXT4_INODE_DAX		= 24,	/* Inode is DAX */
 	EXT4_INODE_INLINE_DATA	= 28,	/* Data in inode. */
 	EXT4_INODE_PROJINHERIT	= 29,	/* Create with parents projid */
 	EXT4_INODE_RESERVED	= 31,	/* reserved for ext4 lib */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 140b1930e2f4..ae61db8b8bae 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4418,7 +4418,7 @@  static bool ext4_should_enable_dax(struct inode *inode)
 	if (test_opt(inode->i_sb, DAX_ALWAYS))
 		return true;
 
-	return false;
+	return ext4_test_inode_flag(inode, EXT4_INODE_DAX);
 }
 
 void ext4_set_inode_flags(struct inode *inode, bool init)
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 145083e8cd1e..668b8c17d6eb 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -292,6 +292,21 @@  static int ext4_ioctl_check_immutable(struct inode *inode, __u32 new_projid,
 	return 0;
 }
 
+static void ext4_dax_dontcache(struct inode *inode, unsigned int flags)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	if (S_ISDIR(inode->i_mode))
+		return;
+
+	if (test_opt2(inode->i_sb, DAX_NEVER) ||
+	    test_opt(inode->i_sb, DAX_ALWAYS))
+		return;
+
+	if ((ei->i_flags ^ flags) & EXT4_DAX_FL)
+		d_mark_dontcache(inode);
+}
+
 static int ext4_ioctl_setflags(struct inode *inode,
 			       unsigned int flags)
 {
@@ -303,6 +318,16 @@  static int ext4_ioctl_setflags(struct inode *inode,
 	unsigned int jflag;
 	struct super_block *sb = inode->i_sb;
 
+	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX)) {
+		if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY) ||
+		    ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT) ||
+		    ext4_test_inode_state(inode,
+					  EXT4_STATE_VERITY_IN_PROGRESS)) {
+			err = -EOPNOTSUPP;
+			goto flags_out;
+		}
+	}
+
 	/* Is it quota file? Do not allow user to mess with it */
 	if (ext4_is_quota_file(inode))
 		goto flags_out;
@@ -369,6 +394,8 @@  static int ext4_ioctl_setflags(struct inode *inode,
 	if (err)
 		goto flags_err;
 
+	ext4_dax_dontcache(inode, flags);
+
 	for (i = 0, mask = 1; i < 32; i++, mask <<= 1) {
 		if (!(mask & EXT4_FL_USER_MODIFIABLE))
 			continue;
@@ -528,12 +555,15 @@  static inline __u32 ext4_iflags_to_xflags(unsigned long iflags)
 		xflags |= FS_XFLAG_NOATIME;
 	if (iflags & EXT4_PROJINHERIT_FL)
 		xflags |= FS_XFLAG_PROJINHERIT;
+	if (iflags & EXT4_DAX_FL)
+		xflags |= FS_XFLAG_DAX;
 	return xflags;
 }
 
 #define EXT4_SUPPORTED_FS_XFLAGS (FS_XFLAG_SYNC | FS_XFLAG_IMMUTABLE | \
 				  FS_XFLAG_APPEND | FS_XFLAG_NODUMP | \
-				  FS_XFLAG_NOATIME | FS_XFLAG_PROJINHERIT)
+				  FS_XFLAG_NOATIME | FS_XFLAG_PROJINHERIT | \
+				  FS_XFLAG_DAX)
 
 /* Transfer xflags flags to internal */
 static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
@@ -552,6 +582,8 @@  static inline unsigned long ext4_xflags_to_iflags(__u32 xflags)
 		iflags |= EXT4_NOATIME_FL;
 	if (xflags & FS_XFLAG_PROJINHERIT)
 		iflags |= EXT4_PROJINHERIT_FL;
+	if (xflags & FS_XFLAG_DAX)
+		iflags |= EXT4_DAX_FL;
 
 	return iflags;
 }
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5ba65eb0e2ef..be9713e898eb 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1323,6 +1323,9 @@  static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
 	if (WARN_ON_ONCE(IS_DAX(inode) && i_size_read(inode)))
 		return -EINVAL;
 
+	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX))
+		return -EOPNOTSUPP;
+
 	res = ext4_convert_inline_data(inode);
 	if (res)
 		return res;
diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index 89a155ece323..4fecb3e4e338 100644
--- a/fs/ext4/verity.c
+++ b/fs/ext4/verity.c
@@ -113,7 +113,7 @@  static int ext4_begin_enable_verity(struct file *filp)
 	handle_t *handle;
 	int err;
 
-	if (IS_DAX(inode))
+	if (IS_DAX(inode) || ext4_test_inode_flag(inode, EXT4_INODE_DAX))
 		return -EINVAL;
 
 	if (ext4_verity_in_progress(inode))
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 379a612f8f1d..7c5f6eb51e2d 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -262,6 +262,7 @@  struct fsxattr {
 #define FS_EA_INODE_FL			0x00200000 /* Inode used for large EA */
 #define FS_EOFBLOCKS_FL			0x00400000 /* Reserved for ext4 */
 #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
+#define FS_DAX_FL			0x01000000 /* Inode is DAX */
 #define FS_INLINE_DATA_FL		0x10000000 /* Reserved for ext4 */
 #define FS_PROJINHERIT_FL		0x20000000 /* Create with parents projid */
 #define FS_CASEFOLD_FL			0x40000000 /* Folder is case insensitive */