> On Jul 11, 2024, at 3:49 PM, Wengang Wang <wen.gang.wang@xxxxxxxxxx> wrote:
>
>
>
>> On Jul 9, 2024, at 2:57 PM, Darrick J. Wong <djwong@xxxxxxxxxx> wrote:
>>
>> 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.
>
> Nice!
>
>>
>>> @@ -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?
>
> Yes, good to know.
It seems that xfs_fsop_geom doesn’t know about reflink?
Thanks,
Wengang
>
>>
>>> + 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?)
>
> OK.
>
>>
>>> + 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).
>
> OK.
>
>> Or just ftruncate
>> scratch_fd to zero bytes? I think you have to do that for the EOF stuff
>> to work, right?
>>
>
> I’d truncate the UNSHARE range only in the loop.
> EOF stuff would be truncated on (O_TMPFILE) file close.
> The EOF stuff would be used for another purpose, see
> [PATCH 6/9] spaceman/defrag: workaround kernel
>
> Thanks,
> Wengang
>
>> --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)
