6 files changed, 60 insertions, 1 deletions

diff --git a/Documentation/filesystems/nilfs2.txt b/Documentation/filesystems/nilfs2.txt
index 839efd8a8a8c..cf6d0d85ca82 100644
--- a/Documentation/filesystems/nilfs2.txt
+++ b/Documentation/filesystems/nilfs2.txt
@@ -74,6 +74,9 @@ norecovery		Disable recovery of the filesystem on mount.
                         This disables every write access on the device for
                         read-only mounts or snapshots.  This option will fail
                         for r/w mounts on an unclean volume.
+discard                 Issue discard/TRIM commands to the underlying block
+                        device when blocks are freed.  This is useful for SSD
+                        devices and sparse/thinly-provisioned LUNs.
 
 NILFS2 usage
 ============
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 105b508b47a8..9280b0f10792 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -2560,6 +2560,16 @@ int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
                 set_current_state(TASK_INTERRUPTIBLE);
                 schedule_timeout(sci->sc_interval);
         }
+        if (nilfs_test_opt(sbi, DISCARD)) {
+                int ret = nilfs_discard_segments(nilfs, sci->sc_freesegs,
+                                                 sci->sc_nfreesegs);
+                if (ret) {
+                        printk(KERN_WARNING
+                               "NILFS warning: error %d on discard request, "
+                               "turning discards off for the device\n", ret);
+                        nilfs_clear_opt(sbi, DISCARD);
+                }
+        }
 
  out_unlock:
         sci->sc_freesegs = NULL;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 8173faee31e6..3f88401a375b 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -481,6 +481,8 @@ static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
                 seq_printf(seq, ",order=strict");
         if (nilfs_test_opt(sbi, NORECOVERY))
                 seq_printf(seq, ",norecovery");
+        if (nilfs_test_opt(sbi, DISCARD))
+                seq_printf(seq, ",discard");
 
         return 0;
 }
@@ -550,7 +552,7 @@ static const struct export_operations nilfs_export_ops = {
 enum {
         Opt_err_cont, Opt_err_panic, Opt_err_ro,
         Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
-        Opt_err,
+        Opt_discard, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -561,6 +563,7 @@ static match_table_t tokens = {
         {Opt_snapshot, "cp=%u"},
         {Opt_order, "order=%s"},
         {Opt_norecovery, "norecovery"},
+        {Opt_discard, "discard"},
         {Opt_err, NULL}
 };
 
@@ -614,6 +617,9 @@ static int parse_options(char *options, struct super_block *sb)
                 case Opt_norecovery:
                         nilfs_set_opt(sbi, NORECOVERY);
                         break;
+                case Opt_discard:
+                        nilfs_set_opt(sbi, DISCARD);
+                        break;
                 default:
                         printk(KERN_ERR
                                "NILFS: Unrecognized mount option \"%s\"\n", p);
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 6241e1722efc..92733d5651d2 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -646,6 +646,44 @@ int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
         goto out;
 }
 
+int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
+                            size_t nsegs)
+{
+        sector_t seg_start, seg_end;
+        sector_t start = 0, nblocks = 0;
+        unsigned int sects_per_block;
+        __u64 *sn;
+        int ret = 0;
+
+        sects_per_block = (1 << nilfs->ns_blocksize_bits) /
+                bdev_logical_block_size(nilfs->ns_bdev);
+        for (sn = segnump; sn < segnump + nsegs; sn++) {
+                nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
+
+                if (!nblocks) {
+                        start = seg_start;
+                        nblocks = seg_end - seg_start + 1;
+                } else if (start + nblocks == seg_start) {
+                        nblocks += seg_end - seg_start + 1;
+                } else {
+                        ret = blkdev_issue_discard(nilfs->ns_bdev,
+                                                   start * sects_per_block,
+                                                   nblocks * sects_per_block,
+                                                   GFP_NOFS,
+                                                   DISCARD_FL_BARRIER);
+                        if (ret < 0)
+                                return ret;
+                        nblocks = 0;
+                }
+        }
+        if (nblocks)
+                ret = blkdev_issue_discard(nilfs->ns_bdev,
+                                           start * sects_per_block,
+                                           nblocks * sects_per_block,
+                                           GFP_NOFS, DISCARD_FL_BARRIER);
+        return ret;
+}
+
 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
 {
         struct inode *dat = nilfs_dat_inode(nilfs);
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 589786e33464..fd057f8ad439 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -221,6 +221,7 @@ struct the_nilfs *find_or_create_nilfs(struct block_device *);
 void put_nilfs(struct the_nilfs *);
 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
+int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 3fe02cf8b65a..640702e97457 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -153,6 +153,7 @@ struct nilfs_super_root {
                                                    semantics also for data */
 #define NILFS_MOUNT_NORECOVERY          0x4000  /* Disable write access during
                                                    mount-time recovery */
+#define NILFS_MOUNT_DISCARD             0x8000  /* Issue DISCARD requests */
 
 
 /**