nilfs2: issue discard request after cleaning segments

This adds a function to send discard requests for given array of
segment numbers, and calls the function when garbage collection
succeeded.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

diff --git a/Documentation/filesystems/nilfs2.txt b/Documentation/filesystems/nilfs2.txt
index 839efd8..cf6d0d8 100644 (file)
--- 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 105b508..9280b0f 100644 (file)
--- 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 8173fae..3f88401 100644 (file)
--- 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 6241e17..92733d5 100644 (file)
--- 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 589786e..fd057f8 100644 (file)
--- 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 3fe02cf..640702e 100644 (file)
--- 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 */
 
 
 /**