ext4: let the block device know when unused blocks can be discarded

Let the block device know when unused blocks can be discarded, using
the new sb_issue_discard() interface.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index bd9b011941a2..815a22ea6078 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2653,6 +2653,7 @@ ext4_mb_free_committed_blocks(struct super_block *sb)
         struct ext4_sb_info *sbi = EXT4_SB(sb);
         int err, count = 0, count2 = 0;
         struct ext4_free_data *entry;
+        ext4_fsblk_t discard_block;
 
         if (list_empty(&sbi->s_committed_transaction))
                 return;
@@ -2696,6 +2697,12 @@ ext4_mb_free_committed_blocks(struct super_block *sb)
                         page_cache_release(e4b.bd_bitmap_page);
                 }
                 ext4_unlock_group(sb, entry->group);
+                discard_block = (ext4_fsblk_t) entry->group * EXT4_BLOCKS_PER_GROUP(sb)
+                        + entry->start_blk
+                        + le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
+                trace_mark(ext4_discard_blocks, "dev %s blk %llu count %u", sb->s_id,
+                           (unsigned long long) discard_block, entry->count);
+                sb_issue_discard(sb, discard_block, entry->count);
 
                 kmem_cache_free(ext4_free_ext_cachep, entry);
                 ext4_mb_release_desc(&e4b);