2020-05-21 19:15:18

by Ira Weiny

Subject: [PATCH V4 1/8] fs/ext4: Narrow scope of DAX check in setflags

From: Ira Weiny <[email protected]>

When preventing DAX and journaling on an inode. Use the effective DAX
check rather than the mount option.

This will be required to support per inode DAX flags.

Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Ira Weiny <[email protected]>
---
fs/ext4/ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index bfc1281fc4cb..5813e5e73eab 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -393,9 +393,9 @@ static int ext4_ioctl_setflags(struct inode *inode,
if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) {
/*
* Changes to the journaling mode can cause unsafe changes to
- * S_DAX if we are using the DAX mount option.
+ * S_DAX if the inode is DAX
*/
- if (test_opt(inode->i_sb, DAX)) {
+ if (IS_DAX(inode)) {
err = -EBUSY;
goto flags_out;
}
--
2.25.1

2020-05-22 07:59:04

by Jan Kara

Subject: Re: [PATCH V4 1/8] fs/ext4: Narrow scope of DAX check in setflags

On Thu 21-05-20 12:13:06, [email protected] wrote:
> From: Ira Weiny <[email protected]>
>
> When preventing DAX and journaling on an inode. Use the effective DAX
> check rather than the mount option.
>
> This will be required to support per inode DAX flags.
>
> Reviewed-by: Jan Kara <[email protected]>
> Signed-off-by: Ira Weiny <[email protected]>
...
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index bfc1281fc4cb..5813e5e73eab 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -393,9 +393,9 @@ static int ext4_ioctl_setflags(struct inode *inode,
> if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) {
> /*
> * Changes to the journaling mode can cause unsafe changes to
> - * S_DAX if we are using the DAX mount option.
> + * S_DAX if the inode is DAX
> */
> - if (test_opt(inode->i_sb, DAX)) {
> + if (IS_DAX(inode)) {
> err = -EBUSY;
> goto flags_out;
> }

Now one problem popped up in my mind: We should also make EXT4_JOURNAL_DATA_FL
and EXT4_DAX_FL exclusive so that both cannot be turned on at the same
time. And IS_DAX() check isn't enough for that. Sorry for not noticing
earlier... it's like peeling an onion...

Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR