Re: [PATCH v2] ceph: fix copy_file_range error path in short copies

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2020-02-06 at 10:38 +0000, Luis Henriques wrote:
> When there's an error in the copying loop but some bytes have already been
> copied into the destination file, it is necessary to dirty the caps and
> eventually update the MDS with the file metadata (timestamps, size).  This
> patch fixes this error path.
> 
> Another issue this patch fixes is the destination file size being reported
> to the MDS.  If we're on the error path but the amount of bytes written
> has already changed the destination file size, the offset to use is
> dst_off and not endoff.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Luis Henriques <lhenriques@suse.com>
> ---
>  fs/ceph/file.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 11929d2bb594..f7f8cb6c243f 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -2104,9 +2104,16 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
>  			CEPH_OSD_OP_FLAG_FADVISE_DONTNEED, 0);
>  		if (err) {
>  			dout("ceph_osdc_copy_from returned %d\n", err);
> -			if (!ret)
> +			/*
> +			 * If we haven't done any copy yet, just exit with the
> +			 * error code; otherwise, return the number of bytes
> +			 * already copied, update metadata and dirty caps.
> +			 */
> +			if (!ret) {
>  				ret = err;
> -			goto out_caps;
> +				goto out_caps;
> +			}
> +			goto update_dst_inode;
>  		}
>  		len -= object_size;
>  		src_off += object_size;
> @@ -2118,16 +2125,17 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off,
>  		/* We still need one final local copy */
>  		do_final_copy = true;
>  
> +update_dst_inode:
>  	file_update_time(dst_file);
>  	inode_inc_iversion_raw(dst_inode);
>  
> -	if (endoff > size) {
> +	if (dst_off > size) {
>  		int caps_flags = 0;
>  
>  		/* Let the MDS know about dst file size change */
> -		if (ceph_quota_is_max_bytes_approaching(dst_inode, endoff))
> +		if (ceph_quota_is_max_bytes_approaching(dst_inode, dst_off))
>  			caps_flags |= CHECK_CAPS_NODELAY;
> -		if (ceph_inode_set_size(dst_inode, endoff))
> +		if (ceph_inode_set_size(dst_inode, dst_off))
>  			caps_flags |= CHECK_CAPS_AUTHONLY;
>  		if (caps_flags)
>  			ceph_check_caps(dst_ci, caps_flags, NULL);

Looks good to me. Merged into ceph-client/testing. We'll see about
getting it in before 5.6 ships.

Thanks,
-- 
Jeff Layton <jlayton@kernel.org>