Hi guys,
Friendly ping. Just checking in on this patch since I haven't heard back so far
and this is a blocker in some scenarios where we're using btrfs.
Thanks!
Christian
On Fri, Mar 24, 2017 at 04:00:57PM +0100, Christian Brauner wrote:
> The old check here tried to ensure that empty streams are not considered
> valid.
> The old check however, will always fail when only one run through the while(1)
> loop is needed and honor_end_cmd is set. So this:
>
> btrfs send /some/subvol | btrfs receive -e /some/
>
> will consistently fail because -e causes honor_cmd_to be set and
> btrfs_read_and_process_send_stream() to correctly return 1. So the command
> will
> be successful but btrfs receive will error out because the send - receive
> concluded in one run through the while(1) loop.
>
> If we want to exclude empty streams we need a way to tell the difference
> between
> btrfs_read_and_process_send_stream() returning 1 because read_buf() did not
> detect any data and read_and_process_cmd() returning 1 because honor_end_cmd
> was
> set. Without introducing too many changes the best way to me seems to have
> btrfs_read_and_process_send_stream() return -ENODATA in the first case. The
> rest
> stays the same. We can then check for -ENODATA in do_receive() and report a
> proper error in this case. This should also be backwards compatible to
> previous
> versions of btrfs receive. They will fail on empty streams because a negative
> value is returned. The only thing that they will lack is a nice error message.
>
> Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
> ---
> cmds-receive.c | 13 +++++--------
> send-stream.c | 2 +-
> 2 files changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/cmds-receive.c b/cmds-receive.c
> index 6cf22637..b59f00e4 100644
> --- a/cmds-receive.c
> +++ b/cmds-receive.c
> @@ -1091,7 +1091,6 @@ static int do_receive(struct btrfs_receive *rctx, const
> char *tomnt,
> char *dest_dir_full_path;
> char root_subvol_path[PATH_MAX];
> int end = 0;
> - int count;
>
> dest_dir_full_path = realpath(tomnt, NULL);
> if (!dest_dir_full_path) {
> @@ -1186,7 +1185,6 @@ static int do_receive(struct btrfs_receive *rctx, const
> char *tomnt,
> if (ret < 0)
> goto out;
>
> - count = 0;
> while (!end) {
> if (rctx->cached_capabilities_len) {
> if (g_verbose >= 3)
> @@ -1200,16 +1198,15 @@ static int do_receive(struct btrfs_receive *rctx,
> const char *tomnt,
> rctx,
> rctx->honor_end_cmd,
> max_errors);
> - if (ret < 0)
> - goto out;
> - /* Empty stream is invalid */
> - if (ret && count == 0) {
> + if (ret < 0 && ret == -ENODATA) {
> + /* Empty stream is invalid */
> error("empty stream is not considered valid");
> ret = -EINVAL;
> goto out;
> + } else if (ret < 0) {
> + goto out;
> }
> - count++;
> - if (ret)
> + if (ret > 0)
> end = 1;
>
> close_inode_for_write(rctx);
> diff --git a/send-stream.c b/send-stream.c
> index 5a028cd9..78f2571a 100644
> --- a/send-stream.c
> +++ b/send-stream.c
> @@ -492,7 +492,7 @@ int btrfs_read_and_process_send_stream(int fd,
> if (ret < 0)
> goto out;
> if (ret) {
> - ret = 1;
> + ret = -ENODATA;
> goto out;
> }
>
> --
> 2.11.0
>
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