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Date:   Wed, 13 May 2020 13:33:28 +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>,
        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 6/9] fs/ext4: Only change S_DAX on inode load

On Tue 12-05-20 22:43:21, ira.weiny@...el.com wrote:
> From: Ira Weiny <ira.weiny@...el.com>
> 
> To prevent complications with in memory inodes we only set S_DAX on
> inode load.  FS_XFLAG_DAX can be changed at any time and S_DAX will
> change after inode eviction and reload.
> 
> Add init bool to ext4_set_inode_flags() to indicate if the inode is
> being newly initialized.
> 
> Assert that S_DAX is not set on an inode which is just being loaded.
> 
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza


> 
> ---
> Changes from RFC:
> 	Change J_ASSERT() to WARN_ON_ONCE()
> 	Fix bug which would clear S_DAX incorrectly
> ---
>  fs/ext4/ext4.h   |  2 +-
>  fs/ext4/ialloc.c |  2 +-
>  fs/ext4/inode.c  | 13 ++++++++++---
>  fs/ext4/ioctl.c  |  3 ++-
>  fs/ext4/super.c  |  4 ++--
>  fs/ext4/verity.c |  2 +-
>  6 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 1a3daf2d18ef..86a0994332ce 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -2692,7 +2692,7 @@ extern int ext4_can_truncate(struct inode *inode);
>  extern int ext4_truncate(struct inode *);
>  extern int ext4_break_layouts(struct inode *);
>  extern int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length);
> -extern void ext4_set_inode_flags(struct inode *);
> +extern void ext4_set_inode_flags(struct inode *, bool init);
>  extern int ext4_alloc_da_blocks(struct inode *inode);
>  extern void ext4_set_aops(struct inode *inode);
>  extern int ext4_writepage_trans_blocks(struct inode *);
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index 4b8c9a9bdf0c..7941c140723f 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -1116,7 +1116,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
>  	ei->i_block_group = group;
>  	ei->i_last_alloc_group = ~0;
>  
> -	ext4_set_inode_flags(inode);
> +	ext4_set_inode_flags(inode, true);
>  	if (IS_DIRSYNC(inode))
>  		ext4_handle_sync(handle);
>  	if (insert_inode_locked(inode) < 0) {
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d3a4c2ed7a1c..23e42a223235 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4419,11 +4419,13 @@ static bool ext4_should_enable_dax(struct inode *inode)
>  	return false;
>  }
>  
> -void ext4_set_inode_flags(struct inode *inode)
> +void ext4_set_inode_flags(struct inode *inode, bool init)
>  {
>  	unsigned int flags = EXT4_I(inode)->i_flags;
>  	unsigned int new_fl = 0;
>  
> +	WARN_ON_ONCE(IS_DAX(inode) && init);
> +
>  	if (flags & EXT4_SYNC_FL)
>  		new_fl |= S_SYNC;
>  	if (flags & EXT4_APPEND_FL)
> @@ -4434,8 +4436,13 @@ void ext4_set_inode_flags(struct inode *inode)
>  		new_fl |= S_NOATIME;
>  	if (flags & EXT4_DIRSYNC_FL)
>  		new_fl |= S_DIRSYNC;
> -	if (ext4_should_enable_dax(inode))
> +
> +	/* Because of the way inode_set_flags() works we must preserve S_DAX
> +	 * here if already set. */
> +	new_fl |= (inode->i_flags & S_DAX);
> +	if (init && ext4_should_enable_dax(inode))
>  		new_fl |= S_DAX;
> +
>  	if (flags & EXT4_ENCRYPT_FL)
>  		new_fl |= S_ENCRYPTED;
>  	if (flags & EXT4_CASEFOLD_FL)
> @@ -4649,7 +4656,7 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
>  		 * not initialized on a new filesystem. */
>  	}
>  	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
> -	ext4_set_inode_flags(inode);
> +	ext4_set_inode_flags(inode, true);
>  	inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
>  	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
>  	if (ext4_has_feature_64bit(sb))
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 5813e5e73eab..145083e8cd1e 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -381,7 +381,8 @@ static int ext4_ioctl_setflags(struct inode *inode,
>  			ext4_clear_inode_flag(inode, i);
>  	}
>  
> -	ext4_set_inode_flags(inode);
> +	ext4_set_inode_flags(inode, false);
> +
>  	inode->i_ctime = current_time(inode);
>  
>  	err = ext4_mark_iloc_dirty(handle, inode, &iloc);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index d0434b513919..5ec900fdf73c 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1344,7 +1344,7 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  			ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
>  			ext4_clear_inode_state(inode,
>  					EXT4_STATE_MAY_INLINE_DATA);
> -			ext4_set_inode_flags(inode);
> +			ext4_set_inode_flags(inode, false);
>  		}
>  		return res;
>  	}
> @@ -1367,7 +1367,7 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  				    ctx, len, 0);
>  	if (!res) {
>  		ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
> -		ext4_set_inode_flags(inode);
> +		ext4_set_inode_flags(inode, false);
>  		res = ext4_mark_inode_dirty(handle, inode);
>  		if (res)
>  			EXT4_ERROR_INODE(inode, "Failed to mark inode dirty");
> diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
> index f05a09fb2ae4..89a155ece323 100644
> --- a/fs/ext4/verity.c
> +++ b/fs/ext4/verity.c
> @@ -244,7 +244,7 @@ static int ext4_end_enable_verity(struct file *filp, const void *desc,
>  		if (err)
>  			goto out_stop;
>  		ext4_set_inode_flag(inode, EXT4_INODE_VERITY);
> -		ext4_set_inode_flags(inode);
> +		ext4_set_inode_flags(inode, false);
>  		err = ext4_mark_iloc_dirty(handle, inode, &iloc);
>  	}
>  out_stop:
> -- 
> 2.25.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR

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