Re: [PATCH V1 8/9] fs/ext4: Introduce DAX inode flag

Jan Kara
2020-05-14T11:06:23Z

On Wed 13-05-20 23:53:14, 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.
>
> 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>

Honza

>
> ---
> 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 | 13 +++++++++----
> fs/ext4/inode.c | 4 +++-
> fs/ext4/ioctl.c | 24 +++++++++++++++++++++++-
> include/uapi/linux/fs.h | 1 +
> 4 files changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 01d1de838896..715f8f2029b2 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 |\
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 140b1930e2f4..105cf04f7940 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4400,6 +4400,8 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
>
> static bool ext4_should_enable_dax(struct inode *inode)
> {
> + unsigned int flags = EXT4_I(inode)->i_flags;
> +
> if (test_opt2(inode->i_sb, DAX_NEVER))
> return false;
> if (!S_ISREG(inode->i_mode))
> @@ -4418,7 +4420,7 @@ static bool ext4_should_enable_dax(struct inode *inode)
> if (test_opt(inode->i_sb, DAX_ALWAYS))
> return true;
>
> - return false;
> + return flags & EXT4_DAX_FL;
> }
>
> void ext4_set_inode_flags(struct inode *inode, bool init)
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 145083e8cd1e..d6d018ea8e94 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)
> {
> @@ -369,6 +384,8 @@ 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 +545,15 @@ 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 +572,8 @@ 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/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
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR