Re: [PATCH] ext4: don't free the tmp_inode tree after a partial migration swap

[Jan Kara]

On Fri 18-09-26 18:12:40, Yichong Chen wrote:
> ext4_ext_migrate() cleans up the temporary inode when
> ext4_ext_swap_inode_data() fails:
> 
> 	retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
> 	if (retval)
> 		free_ext_block(handle, tmp_inode);
> 
> ext4_ext_swap_inode_data() switches the inode to extents and copies the
> tree root into it before it frees the old indirect block map, so it can
> return an error after the swap has already happened.  The copied root
> points at index blocks that tmp_inode allocated, and free_ext_block()
> walks that same tree and frees them, leaving the migrated inode with a
> tree node that the block bitmap considers free.
> 
> Only free the tmp_inode tree when the inode has not been switched to
> extents, which is exactly the case where the swap did not happen.
> 
> Fixes: c14c6fd5c56a ("ext4: Add EXT4_IOC_MIGRATE ioctl")
> Signed-off-by: Yichong Chen <chenyichong@xxxxxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/migrate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
> index 2ce587043945..e588b4157604 100644
> --- a/fs/ext4/migrate.c
> +++ b/fs/ext4/migrate.c
> @@ -562,7 +562,7 @@ int ext4_ext_migrate(struct inode *inode)
>  		free_ext_block(handle, tmp_inode);
>  	else {
>  		retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
> -		if (retval)
> +		if (retval && !ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
>  			/*
>  			 * if we fail to swap inode data free the extent
>  			 * details of the tmp inode
> -- 
> 2.51.0
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR