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Subject: Re: [PATCH V3 5/5] ext4: make fallocate retry when err is ENOSPC
To:     Wang Jianchao <jianchao.wan9@gmail.com>,
        linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     tytso@mit.edu, adilger.kernel@dilger.ca
References: <20210724074124.25731-1-jianchao.wan9@gmail.com>
 <20210724074124.25731-6-jianchao.wan9@gmail.com>
From:   Guoqing Jiang <guoqing.jiang@linux.dev>
Message-ID: <0ac551b1-6295-9117-757d-12bee70de588@linux.dev>
Date:   Mon, 26 Jul 2021 11:40:17 +0800
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Hi,

On 7/24/21 3:41 PM, Wang Jianchao wrote:
> From: Wang Jianchao <wangjianchao@kuaishou.com>
>
> The blocks may be waiting for journal commit to be freed back to
> mb buddy. Let fallocate wait and retry in that case.
>
> Signed-off-by: Wang Jianchao <wangjianchao@kuaishou.com>
> ---
>   fs/ext4/extents.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 92ad64b89d9b..ad0b874d3448 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4635,7 +4635,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
>   	struct inode *inode = file_inode(file);
>   	loff_t new_size = 0;
>   	unsigned int max_blocks;
> -	int ret = 0;
> +	int ret = 0, retries = 0;
>   	int flags;
>   	ext4_lblk_t lblk;
>   	unsigned int blkbits = inode->i_blkbits;
> @@ -4656,6 +4656,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
>   		     FALLOC_FL_INSERT_RANGE))
>   		return -EOPNOTSUPP;
>   
> +retry:
>   	ext4_fc_start_update(inode);
>   
>   	if (mode & FALLOC_FL_PUNCH_HOLE) {
> @@ -4722,6 +4723,9 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
>   	trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
>   exit:
>   	ext4_fc_stop_update(inode);
> +	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
> +		goto retry;
> +

Not sure if it is necessary since ext4_alloc_file_blocks already retries 
allocate.

Thanks,
Guoqing