On Fri, 21 Feb 2014 15:56:50 +0100, Andreas Rohner wrote:
> This patch adds the nilfs_sufile_trim_fs function, which takes a
> fstrim_range structure and calls blkdev_issue_discard for every
> clean segment in the specified range. The range is truncated to
> file system block boundaries.
>
> Signed-off-by: Andreas Rohner <andreas.rohner@xxxxxxx>
> ---
> fs/nilfs2/sufile.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/nilfs2/sufile.h | 1 +
> 2 files changed, 148 insertions(+)
>
> diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
> index 3127e9f..6c3b350 100644
> --- a/fs/nilfs2/sufile.c
> +++ b/fs/nilfs2/sufile.c
> @@ -870,6 +870,153 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
> }
>
> /**
> + * nilfs_sufile_trim_fs() - trim ioctl handle function
> + * @sufile: inode of segment usage file
> + * @range: fstrim_range structure
> + *
> + * start: First Byte to trim
> + * len: number of Bytes to trim from start
> + * minlen: minimum extent length in Bytes
> + *
> + * Decription: nilfs_sufile_trim_fs goes through all segments containing bytes
> + * from start to start+len. start is rounded up to the next block boundary
> + * and start+len is rounded down. For each clean segment blkdev_issue_discard
> + * function is invoked.
> + *
> + * Return Value: On success, 0 is returned or negative error code, otherwise.
> + */
> +int nilfs_sufile_trim_fs(struct inode *sufile, struct fstrim_range *range)
> +{
> + struct the_nilfs *nilfs = sufile->i_sb->s_fs_info;
> + struct buffer_head *su_bh;
> + struct nilfs_segment_usage *su;
> + void *kaddr;
> + size_t n, i, susz = NILFS_MDT(sufile)->mi_entry_size;
> + sector_t seg_start, seg_end, start_block, end_block;
> + sector_t start = 0, nblocks = 0;
> + u64 segnum, segnum_end, minlen, len, max_blocks, ndiscarded = 0;
> + int ret = 0;
> + unsigned int sects_per_block;
> +
> + sects_per_block = (1 << nilfs->ns_blocksize_bits) /
> + bdev_logical_block_size(nilfs->ns_bdev);
> + len = range->len >> nilfs->ns_blocksize_bits;
> + minlen = range->minlen >> nilfs->ns_blocksize_bits;
> + max_blocks = ((u64)nilfs->ns_nsegments * nilfs->ns_blocks_per_segment);
> +
> + if (!len || range->start >= max_blocks << nilfs->ns_blocksize_bits)
> + return -EINVAL;
> +
> + start_block = (range->start + nilfs->ns_blocksize - 1) >>
> + nilfs->ns_blocksize_bits;
> +
> + if (max_blocks - start_block < len)
> + end_block = max_blocks - 1;
> + else
> + end_block = start_block + len - 1;
This patch looks good to me. When you resubmit this series, please
add a comment to clarify why we do not simplify this as follows:
end_block = min_t(sector_t, max_blocks, start_block + len) - 1;
For example,
/*
* range->len can be very large (actually, it is set to
* ULLONG_MAX by default) - truncate upper end of the range
* carefully so as not to overflow.
*/
if (max_blocks - start_block < len)
end_block = max_blocks - 1;
else
end_block = start_block + len - 1;
Regards,
Ryusuke Konishi
> +
> + segnum = nilfs_get_segnum_of_block(nilfs, start_block);
> + segnum_end = nilfs_get_segnum_of_block(nilfs, end_block);
> +
> + down_read(&NILFS_MDT(sufile)->mi_sem);
> +
> + while (segnum <= segnum_end) {
> + n = nilfs_sufile_segment_usages_in_block(sufile, segnum,
> + segnum_end);
> +
> + ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0,
> + &su_bh);
> + if (ret < 0) {
> + if (ret != -ENOENT)
> + goto out_sem;
> + /* hole */
> + segnum += n;
> + continue;
> + }
> +
> + kaddr = kmap_atomic(su_bh->b_page);
> + su = nilfs_sufile_block_get_segment_usage(sufile, segnum,
> + su_bh, kaddr);
> + for (i = 0; i < n; ++i, ++segnum, su = (void *)su + susz) {
> + if (!nilfs_segment_usage_clean(su))
> + continue;
> +
> + nilfs_get_segment_range(nilfs, segnum, &seg_start,
> + &seg_end);
> +
> + if (!nblocks) {
> + /* start new extent */
> + start = seg_start;
> + nblocks = seg_end - seg_start + 1;
> + continue;
> + }
> +
> + if (start + nblocks == seg_start) {
> + /* add to previous extent */
> + nblocks += seg_end - seg_start + 1;
> + continue;
> + }
> +
> + /* discard previous extent */
> + if (start < start_block) {
> + nblocks -= start_block - start;
> + start = start_block;
> + }
> +
> + if (nblocks >= minlen) {
> + kunmap_atomic(kaddr);
> +
> + ret = blkdev_issue_discard(nilfs->ns_bdev,
> + start * sects_per_block,
> + nblocks * sects_per_block,
> + GFP_NOFS, 0);
> + if (ret < 0) {
> + put_bh(su_bh);
> + goto out_sem;
> + }
> +
> + ndiscarded += nblocks;
> + kaddr = kmap_atomic(su_bh->b_page);
> + su = nilfs_sufile_block_get_segment_usage(
> + sufile, segnum, su_bh, kaddr);
> + }
> +
> + /* start new extent */
> + start = seg_start;
> + nblocks = seg_end - seg_start + 1;
> + }
> + kunmap_atomic(kaddr);
> + put_bh(su_bh);
> + }
> +
> +
> + if (nblocks) {
> + /* discard last extent */
> + if (start < start_block) {
> + nblocks -= start_block - start;
> + start = start_block;
> + }
> + if (start + nblocks > end_block + 1)
> + nblocks = end_block - start + 1;
> +
> + if (nblocks >= minlen) {
> + ret = blkdev_issue_discard(nilfs->ns_bdev,
> + start * sects_per_block,
> + nblocks * sects_per_block,
> + GFP_NOFS, 0);
> + if (!ret)
> + ndiscarded += nblocks;
> + }
> + }
> +
> +out_sem:
> + up_read(&NILFS_MDT(sufile)->mi_sem);
> +
> + range->len = ndiscarded << nilfs->ns_blocksize_bits;
> + return ret;
> +}
> +
> +/**
> * nilfs_sufile_read - read or get sufile inode
> * @sb: super block instance
> * @susize: size of a segment usage entry
> diff --git a/fs/nilfs2/sufile.h b/fs/nilfs2/sufile.h
> index e84bc5b..2434abd 100644
> --- a/fs/nilfs2/sufile.h
> +++ b/fs/nilfs2/sufile.h
> @@ -65,6 +65,7 @@ void nilfs_sufile_do_set_error(struct inode *, __u64, struct buffer_head *,
> int nilfs_sufile_resize(struct inode *sufile, __u64 newnsegs);
> int nilfs_sufile_read(struct super_block *sb, size_t susize,
> struct nilfs_inode *raw_inode, struct inode **inodep);
> +int nilfs_sufile_trim_fs(struct inode *sufile, struct fstrim_range *range);
>
> /**
> * nilfs_sufile_scrap - make a segment garbage
> --
> 1.9.0
>
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