On Tue 19-05-20 22:57:49, ira.weiny@xxxxxxxxx wrote: > From: Ira Weiny <ira.weiny@xxxxxxxxx> > > S_DAX should only be enabled when the underlying block device supports > dax. > > Change ext4_should_use_dax() to check for device support prior to the > over riding mount option. > > While we are at it change the function to ext4_should_enable_dax() as > this better reflects the ask as well as matches xfs. > > Reviewed-by: Jan Kara <jack@xxxxxxx> > Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx> ... > @@ -4412,7 +4410,13 @@ static bool ext4_should_use_dax(struct inode *inode) > return false; > if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY)) > return false; > - return true; > + if (!bdev_dax_supported(inode->i_sb->s_bdev, > + inode->i_sb->s_blocksize)) > + return false; > + if (test_opt(inode->i_sb, DAX_ALWAYS)) > + return true; > + > + return false; > } Now that I think about it - shouldn't we rather cache the result of bdev_dax_supported() in sb on mount and then just check the flag here? Because bdev_dax_supported() isn't exactly cheap (it does a lot of checks and mappings, tries to read from the pmem, ...). Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
