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Date: Fri, 22 May 2020 13:48:48 +0200 From: Jan Kara <jack@...e.cz> To: ira.weiny@...el.com Cc: linux-ext4@...r.kernel.org, Andreas Dilger <adilger.kernel@...ger.ca>, "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>, Eric Biggers <ebiggers@...nel.org>, Al Viro <viro@...iv.linux.org.uk>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@....de>, Jeff Moyer <jmoyer@...hat.com>, "Darrick J. Wong" <darrick.wong@...cle.com>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH V4 7/8] fs/ext4: Introduce DAX inode flag On Thu 21-05-20 12:13:12, ira.weiny@...el.com wrote: > From: Ira Weiny <ira.weiny@...el.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@...el.com> ... > @@ -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; > + } > + } The way this check is implemented wouldn't IMO do what we need... It doesn't check the flags that are being set but just the current inode state. I think it should rather be: if ((flags ^ oldflags) & EXT4_INODE_DAX_FL) { ... } And perhaps move this to a place in ext4_ioctl_setflags() where we check other similar conflicts. And then we should check conflicts with the journal flag as well, as I mentioned in reply to the first patch. There it is more complicated by the fact that we should disallow setting of both EXT4_INODE_DAX_FL and EXT4_JOURNAL_DATA_FL at the same time so the checks will be somewhat more complicated. Honza > + > /* Is it quota file? Do not allow user to mess with it */ > if (ext4_is_quota_file(inode)) > goto flags_out; -- Jan Kara <jack@...e.com> SUSE Labs, CR
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