Re: [PATCH v4 6/8] ext4: move inode extension checks out from ext4_iomap_alloc()

[Ritesh Harjani <riteshh@linux.ibm.com>]

On 10/3/19 5:04 PM, Matthew Bobrowski wrote:
> We lift the inode extension/orphan list handling logic out from
> ext4_iomap_alloc() and place it within the caller
> ext4_dax_write_iter().
> 
> Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>

This looks good. Should solve our previous lengthy discussion
about orphan handling :)

You may add:
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>


> ---
>   fs/ext4/file.c  | 17 +++++++++++++++++
>   fs/ext4/inode.c | 22 ----------------------
>   2 files changed, 17 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 2883711e8a33..f64da0c590b2 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -309,6 +309,7 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   	ssize_t ret;
>   	size_t count;
>   	loff_t offset;
> +	handle_t *handle;
>   	struct inode *inode = file_inode(iocb->ki_filp);
> 
>   	if (!inode_trylock(inode)) {
> @@ -328,6 +329,22 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
> 
>   	offset = iocb->ki_pos;
>   	count = iov_iter_count(from);
> +
> +	if (offset + count > EXT4_I(inode)->i_disksize) {
> +		handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
> +		if (IS_ERR(handle)) {
> +			ret = PTR_ERR(handle);
> +			goto out;
> +		}
> +
> +		ret = ext4_orphan_add(handle, inode);
> +		if (ret) {
> +			ext4_journal_stop(handle);
> +			goto out;
> +		}
> +		ext4_journal_stop(handle);
> +	}
> +
>   	ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
> 
>   	error = ext4_handle_inode_extension(inode, offset, ret, count);
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index d616062b603e..e133dda55063 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3508,7 +3508,6 @@ static int ext4_iomap_alloc(struct inode *inode,
>   			    struct ext4_map_blocks *map)
>   {
>   	handle_t *handle;
> -	u8 blkbits = inode->i_blkbits;
>   	int ret, dio_credits, retries = 0;
> 
>   	/*
> @@ -3530,28 +3529,7 @@ static int ext4_iomap_alloc(struct inode *inode,
>   		return PTR_ERR(handle);
> 
>   	ret = ext4_map_blocks(handle, inode, map, EXT4_GET_BLOCKS_CREATE_ZERO);
> -	if (ret < 0)
> -		goto journal_stop;
> 
> -	/*
> -	 * If we have allocated blocks beyond the EOF, we need to make
> -	 * sure that they get truncate if we crash before updating the
> -	 * inode size metadata in ext4_iomap_end(). For faults, we
> -	 * don't need to do that (and cannot due to the orphan list
> -	 * operations needing an inode_lock()). If we happen to
> -	 * instantiate blocks beyond EOF, it is because we race with a
> -	 * truncate operation, which already has added the inode onto
> -	 * the orphan list.
> -	 */
> -	if (!(flags & IOMAP_FAULT) && first_block + map->m_len >
> -	    (i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
> -		int err;
> -
> -		err = ext4_orphan_add(handle, inode);
> -		if (err < 0)
> -			ret = err;
> -	}
> -journal_stop:
>   	ext4_journal_stop(handle);
>   	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
>   		goto retry;
>