On Tue, Jul 09, 2024 at 12:10:22PM -0700, Wengang Wang wrote:
> For each segment, the following steps are done trying to defrag it:
>
> 1. share the segment with a temporary file
> 2. unshare the segment in the target file. kernel simulates Cow on the whole
> segment complete the unshare (defrag).
> 3. release blocks from the tempoary file.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
> ---
> spaceman/defrag.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 114 insertions(+)
>
> diff --git a/spaceman/defrag.c b/spaceman/defrag.c
> index 175cf461..9f11e36b 100644
> --- a/spaceman/defrag.c
> +++ b/spaceman/defrag.c
> @@ -263,6 +263,40 @@ add_ext:
> return ret;
> }
>
> +/*
> + * check if the segment exceeds EoF.
> + * fix up the clone range and return true if EoF happens,
> + * return false otherwise.
> + */
> +static bool
> +defrag_clone_eof(struct file_clone_range *clone)
> +{
> + off_t delta;
> +
> + delta = clone->src_offset + clone->src_length - g_defrag_file_size;
> + if (delta > 0) {
> + clone->src_length = 0; // to the end
> + return true;
> + }
> + return false;
> +}
> +
> +/*
> + * get the time delta since pre_time in ms.
> + * pre_time should contains values fetched by gettimeofday()
> + * cur_time is used to store current time by gettimeofday()
> + */
> +static long long
> +get_time_delta_us(struct timeval *pre_time, struct timeval *cur_time)
> +{
> + long long us;
> +
> + gettimeofday(cur_time, NULL);
> + us = (cur_time->tv_sec - pre_time->tv_sec) * 1000000;
> + us += (cur_time->tv_usec - pre_time->tv_usec);
> + return us;
> +}
> +
> /*
> * defragment a file
> * return 0 if successfully done, 1 otherwise
> @@ -273,6 +307,7 @@ defrag_xfs_defrag(char *file_path) {
> long nr_seg_defrag = 0, nr_ext_defrag = 0;
> int scratch_fd = -1, defrag_fd = -1;
> char tmp_file_path[PATH_MAX+1];
> + struct file_clone_range clone;
> char *defrag_dir;
> struct fsxattr fsx;
> int ret = 0;
Now that I see this, you might want to straighten up the lines:
struct fsxattr fsx = { };
long nr_seg_defrag = 0, nr_ext_defrag = 0;
etc. Note the "= { }" bit that means you don't have to memset them to
zero explicitly.
> @@ -296,6 +331,8 @@ defrag_xfs_defrag(char *file_path) {
> goto out;
> }
>
> + clone.src_fd = defrag_fd;
> +
> defrag_dir = dirname(file_path);
> snprintf(tmp_file_path, PATH_MAX, "%s/.xfsdefrag_%d", defrag_dir,
> getpid());
> @@ -309,7 +346,11 @@ defrag_xfs_defrag(char *file_path) {
> }
>
> do {
> + struct timeval t_clone, t_unshare, t_punch_hole;
> struct defrag_segment segment;
> + long long seg_size, seg_off;
> + int time_delta;
> + bool stop;
>
> ret = defrag_get_next_segment(defrag_fd, &segment);
> /* no more segments, we are done */
> @@ -322,6 +363,79 @@ defrag_xfs_defrag(char *file_path) {
> ret = 1;
> break;
> }
> +
> + /* we are done if the segment contains only 1 extent */
> + if (segment.ds_nr < 2)
> + continue;
> +
> + /* to bytes */
> + seg_off = segment.ds_offset * 512;
> + seg_size = segment.ds_length * 512;
> +
> + clone.src_offset = seg_off;
> + clone.src_length = seg_size;
> + clone.dest_offset = seg_off;
> +
> + /* checks for EoF and fix up clone */
> + stop = defrag_clone_eof(&clone);
> + gettimeofday(&t_clone, NULL);
> + ret = ioctl(scratch_fd, FICLONERANGE, &clone);
Hm, should the top-level defrag_f function check in the
filetable[i].fsgeom structure that the fs supports reflink?
> + if (ret != 0) {
> + fprintf(stderr, "FICLONERANGE failed %s\n",
> + strerror(errno));
Might be useful to include the file_path in the error message:
/opt/a: FICLONERANGE failed Software caused connection abort
(maybe also put a semicolon before the strerror message?)
> + break;
> + }
> +
> + /* for time stats */
> + time_delta = get_time_delta_us(&t_clone, &t_unshare);
> + if (time_delta > max_clone_us)
> + max_clone_us = time_delta;
> +
> + /* for defrag stats */
> + nr_ext_defrag += segment.ds_nr;
> +
> + /*
> + * For the shared range to be unshared via a copy-on-write
> + * operation in the file to be defragged. This causes the
> + * file needing to be defragged to have new extents allocated
> + * and the data to be copied over and written out.
> + */
> + ret = fallocate(defrag_fd, FALLOC_FL_UNSHARE_RANGE, seg_off,
> + seg_size);
> + if (ret != 0) {
> + fprintf(stderr, "UNSHARE_RANGE failed %s\n",
> + strerror(errno));
> + break;
> + }
> +
> + /* for time stats */
> + time_delta = get_time_delta_us(&t_unshare, &t_punch_hole);
> + if (time_delta > max_unshare_us)
> + max_unshare_us = time_delta;
> +
> + /*
> + * Punch out the original extents we shared to the
> + * scratch file so they are returned to free space.
> + */
> + ret = fallocate(scratch_fd,
> + FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, seg_off,
> + seg_size);
Indentation here (two tabs for a continuation). Or just ftruncate
scratch_fd to zero bytes? I think you have to do that for the EOF stuff
to work, right?
--D
> + if (ret != 0) {
> + fprintf(stderr, "PUNCH_HOLE failed %s\n",
> + strerror(errno));
> + break;
> + }
> +
> + /* for defrag stats */
> + nr_seg_defrag += 1;
> +
> + /* for time stats */
> + time_delta = get_time_delta_us(&t_punch_hole, &t_clone);
> + if (time_delta > max_punch_us)
> + max_punch_us = time_delta;
> +
> + if (stop)
> + break;
> } while (true);
> out:
> if (scratch_fd != -1) {
> --
> 2.39.3 (Apple Git-146)
>
>
