nilfs2: add nilfs_sufile_trim_fs to trim clean segs

Add nilfs_sufile_trim_fs(), which takes an 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@gmx.net>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 152 insertions, 0 deletions

diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
index 5628b99d454e..84e384dae663 100644
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -1001,6 +1001,158 @@ ssize_t nilfs_sufile_set_suinfo(struct inode *sufile, 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;
+
+        /*
+         * 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;
+
+        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