[01/10] btrfs: create a mount option for dax
diff mbox series

Message ID 20181205122835.19290-2-rgoldwyn@suse.de
State New
Headers show
Series
  • btrfs: Support for DAX devices
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Commit Message

Goldwyn Rodrigues Dec. 5, 2018, 12:28 p.m. UTC
From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Also, set the inode->i_flags to S_DAX

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/ctree.h |  1 +
 fs/btrfs/ioctl.c |  5 ++++-
 fs/btrfs/super.c | 15 +++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

Comments

Johannes Thumshirn Dec. 5, 2018, 12:42 p.m. UTC | #1
On 05/12/2018 13:28, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Also, set the inode->i_flags to S_DAX
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
> ---
>  fs/btrfs/ctree.h |  1 +
>  fs/btrfs/ioctl.c |  5 ++++-
>  fs/btrfs/super.c | 15 +++++++++++++++
>  3 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 68f322f600a0..5cc470fa6a40 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1353,6 +1353,7 @@ static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info)
>  #define BTRFS_MOUNT_FREE_SPACE_TREE	(1 << 26)
>  #define BTRFS_MOUNT_NOLOGREPLAY		(1 << 27)
>  #define BTRFS_MOUNT_REF_VERIFY		(1 << 28)
> +#define BTRFS_MOUNT_DAX			(1 << 29)

Just as a heads up, this will collide with the patch called '[RFC PATCH
02/17] btrfs: add mount definition BTRFS_MOUNT_PRIORITY_USAGE' from Su Yue.

[...]

> +#ifdef CONFIG_FS_DAX
> +		case Opt_dax:
> +			if (btrfs_super_num_devices(info->super_copy) > 1) {
> +				btrfs_info(info,
> +					   "dax not supported for multi-device btrfs partition\n");
> +				ret = -EOPNOTSUPP;
> +				goto out;
> +			}
> +			btrfs_set_opt(info->mount_opt, DAX);
> +			break;
> +#endif

Can you please explain why we can't enable DAX on a multi device FS in
the changelog? It's (for me at least) not obvious.

Thanks,
	Johannes
Nikolay Borisov Dec. 5, 2018, 12:43 p.m. UTC | #2
On 5.12.18 г. 14:28 ч., Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@suse.com>
> 
> Also, set the inode->i_flags to S_DAX
> 
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

One question below though .

> ---
>  fs/btrfs/ctree.h |  1 +
>  fs/btrfs/ioctl.c |  5 ++++-
>  fs/btrfs/super.c | 15 +++++++++++++++
>  3 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 68f322f600a0..5cc470fa6a40 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1353,6 +1353,7 @@ static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info)
>  #define BTRFS_MOUNT_FREE_SPACE_TREE	(1 << 26)
>  #define BTRFS_MOUNT_NOLOGREPLAY		(1 << 27)
>  #define BTRFS_MOUNT_REF_VERIFY		(1 << 28)
> +#define BTRFS_MOUNT_DAX			(1 << 29)
>  
>  #define BTRFS_DEFAULT_COMMIT_INTERVAL	(30)
>  #define BTRFS_DEFAULT_MAX_INLINE	(2048)
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 802a628e9f7d..e9146c157816 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -149,8 +149,11 @@ void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
>  	if (binode->flags & BTRFS_INODE_DIRSYNC)
>  		new_fl |= S_DIRSYNC;
>  
> +	if ((btrfs_test_opt(btrfs_sb(inode->i_sb), DAX)) && S_ISREG(inode->i_mode))
> +		new_fl |= S_DAX;
> +
>  	set_mask_bits(&inode->i_flags,
> -		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC,
> +		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC | S_DAX,
>  		      new_fl);
>  }
>  
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 645fc81e2a94..035263b61cf5 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -326,6 +326,7 @@ enum {
>  	Opt_treelog, Opt_notreelog,
>  	Opt_usebackuproot,
>  	Opt_user_subvol_rm_allowed,
> +	Opt_dax,
>  
>  	/* Deprecated options */
>  	Opt_alloc_start,
> @@ -393,6 +394,7 @@ static const match_table_t tokens = {
>  	{Opt_notreelog, "notreelog"},
>  	{Opt_usebackuproot, "usebackuproot"},
>  	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
> +	{Opt_dax, "dax"},
>  
>  	/* Deprecated options */
>  	{Opt_alloc_start, "alloc_start=%s"},
> @@ -739,6 +741,17 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
>  		case Opt_user_subvol_rm_allowed:
>  			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
>  			break;
> +#ifdef CONFIG_FS_DAX
> +		case Opt_dax:
> +			if (btrfs_super_num_devices(info->super_copy) > 1) {
> +				btrfs_info(info,
> +					   "dax not supported for multi-device btrfs partition\n");

What prevents supporting dax for multiple devices so long as all devices
are dax?

<snip>

>
Adam Borowski Dec. 5, 2018, 2:59 p.m. UTC | #3
On Wed, Dec 05, 2018 at 02:43:03PM +0200, Nikolay Borisov wrote:
> One question below though .
> 
> > +++ b/fs/btrfs/super.c
> > @@ -739,6 +741,17 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
> >  		case Opt_user_subvol_rm_allowed:
> >  			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
> >  			break;
> > +#ifdef CONFIG_FS_DAX
> > +		case Opt_dax:
> > +			if (btrfs_super_num_devices(info->super_copy) > 1) {
> > +				btrfs_info(info,
> > +					   "dax not supported for multi-device btrfs partition\n");
> 
> What prevents supporting dax for multiple devices so long as all devices
> are dax?

As I mentioned in a separate mail, most profiles are either redundant
(RAID0), require hardware support (RAID1, DUP) or are impossible (RAID5,
RAID6).

But, "single" profile multi-device would be useful and actually provide
something other dax-supporting filesystems don't have: combining multiple
devices into one logical piece.

On the other hand, DUP profiles need to be banned.  In particular, the
filesystem you mount might have existing DUP block groups.


Meow!

Patch
diff mbox series

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 68f322f600a0..5cc470fa6a40 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1353,6 +1353,7 @@  static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info)
 #define BTRFS_MOUNT_FREE_SPACE_TREE	(1 << 26)
 #define BTRFS_MOUNT_NOLOGREPLAY		(1 << 27)
 #define BTRFS_MOUNT_REF_VERIFY		(1 << 28)
+#define BTRFS_MOUNT_DAX			(1 << 29)
 
 #define BTRFS_DEFAULT_COMMIT_INTERVAL	(30)
 #define BTRFS_DEFAULT_MAX_INLINE	(2048)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 802a628e9f7d..e9146c157816 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -149,8 +149,11 @@  void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
 	if (binode->flags & BTRFS_INODE_DIRSYNC)
 		new_fl |= S_DIRSYNC;
 
+	if ((btrfs_test_opt(btrfs_sb(inode->i_sb), DAX)) && S_ISREG(inode->i_mode))
+		new_fl |= S_DAX;
+
 	set_mask_bits(&inode->i_flags,
-		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC,
+		      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC | S_DAX,
 		      new_fl);
 }
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 645fc81e2a94..035263b61cf5 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -326,6 +326,7 @@  enum {
 	Opt_treelog, Opt_notreelog,
 	Opt_usebackuproot,
 	Opt_user_subvol_rm_allowed,
+	Opt_dax,
 
 	/* Deprecated options */
 	Opt_alloc_start,
@@ -393,6 +394,7 @@  static const match_table_t tokens = {
 	{Opt_notreelog, "notreelog"},
 	{Opt_usebackuproot, "usebackuproot"},
 	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
+	{Opt_dax, "dax"},
 
 	/* Deprecated options */
 	{Opt_alloc_start, "alloc_start=%s"},
@@ -739,6 +741,17 @@  int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 		case Opt_user_subvol_rm_allowed:
 			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
 			break;
+#ifdef CONFIG_FS_DAX
+		case Opt_dax:
+			if (btrfs_super_num_devices(info->super_copy) > 1) {
+				btrfs_info(info,
+					   "dax not supported for multi-device btrfs partition\n");
+				ret = -EOPNOTSUPP;
+				goto out;
+			}
+			btrfs_set_opt(info->mount_opt, DAX);
+			break;
+#endif
 		case Opt_enospc_debug:
 			btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
 			break;
@@ -1329,6 +1342,8 @@  static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_puts(seq, ",clear_cache");
 	if (btrfs_test_opt(info, USER_SUBVOL_RM_ALLOWED))
 		seq_puts(seq, ",user_subvol_rm_allowed");
+	if (btrfs_test_opt(info, DAX))
+		seq_puts(seq, ",dax");
 	if (btrfs_test_opt(info, ENOSPC_DEBUG))
 		seq_puts(seq, ",enospc_debug");
 	if (btrfs_test_opt(info, AUTO_DEFRAG))