APPLIED: [PATCH] [Unstable] ext4: properly check for dirty state in ext4_inode_datasync_dirty()

[Andrea Righi]

On Thu, Oct 29, 2020 at 07:32:22PM +0100, Andrea Righi wrote:
> ext4_inode_datasync_dirty() needs to return 'true' if the inode is
> dirty, 'false' otherwise, but the logic seems to be incorrectly changed
> by commit aa75f4d3daae ("ext4: main fast-commit commit path").
> 
> This introduces a problem with swap files that are always failing to be
> activated, showing this error in dmesg:
> 
>  [   34.406479] swapon: file is not committed
> 
> Simple test case to reproduce the problem:
> 
>   # fallocate -l 8G swapfile
>   # chmod 0600 swapfile
>   # mkswap swapfile
>   # swapon swapfile
> 
> Fix the logic to return the proper state of the inode.
> 
> Link: https://lore.kernel.org/lkml/20201024131333.GA32124@xps-13-7390
> Fixes: aa75f4d3daae ("ext4: main fast-commit commit path")
> Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar at gmail.com>
> (cherry picked from commit a316082fa331d086dd8dea9d1e10c7fac3cbbad6 https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git)
> Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
> ---
>  fs/ext4/inode.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 03c2253005f0..520a0209451e 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3307,10 +3307,12 @@ static bool ext4_inode_datasync_dirty(struct inode *inode)
>  
>  	if (journal) {
>  		if (jbd2_transaction_committed(journal,
> -					EXT4_I(inode)->i_datasync_tid))
> -			return true;
> -		return atomic_read(&EXT4_SB(inode->i_sb)->s_fc_subtid) >=
> -			EXT4_I(inode)->i_fc_committed_subtid;
> +			EXT4_I(inode)->i_datasync_tid))
> +			return false;
> +		if (test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT))
> +			return atomic_read(&EXT4_SB(inode->i_sb)->s_fc_subtid) <
> +				EXT4_I(inode)->i_fc_committed_subtid;
> +		return true;
>  	}
>  
>  	/* Any metadata buffers to write? */
> -- 
> 2.27.0
>