nilfs2: add iterator for segment buffers

This adds a few iterator functions for segment buffers to make it easy
to handle multiple series of logs.

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

3 files changed, 66 insertions, 48 deletions

diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
index 636590c92c8b..d856d62bf886 100644
--- a/fs/nilfs2/segbuf.c
+++ b/fs/nilfs2/segbuf.c
@@ -234,7 +234,7 @@ void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
         raw_sum->ss_datasum = cpu_to_le32(crc);
 }
 
-void nilfs_release_buffers(struct list_head *list)
+static void nilfs_release_buffers(struct list_head *list)
 {
         struct buffer_head *bh, *n;
 
@@ -256,6 +256,49 @@ void nilfs_release_buffers(struct list_head *list)
         }
 }
 
+static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
+{
+        nilfs_release_buffers(&segbuf->sb_segsum_buffers);
+        nilfs_release_buffers(&segbuf->sb_payload_buffers);
+}
+
+/*
+ * Iterators for segment buffers
+ */
+void nilfs_clear_logs(struct list_head *logs)
+{
+        struct nilfs_segment_buffer *segbuf;
+
+        list_for_each_entry(segbuf, logs, sb_list)
+                nilfs_segbuf_clear(segbuf);
+}
+
+void nilfs_truncate_logs(struct list_head *logs,
+                         struct nilfs_segment_buffer *last)
+{
+        struct nilfs_segment_buffer *n, *segbuf;
+
+        segbuf = list_prepare_entry(last, logs, sb_list);
+        list_for_each_entry_safe_continue(segbuf, n, logs, sb_list) {
+                list_del_init(&segbuf->sb_list);
+                nilfs_segbuf_clear(segbuf);
+                nilfs_segbuf_free(segbuf);
+        }
+}
+
+int nilfs_wait_on_logs(struct list_head *logs)
+{
+        struct nilfs_segment_buffer *segbuf;
+        int err;
+
+        list_for_each_entry(segbuf, logs, sb_list) {
+                err = nilfs_segbuf_wait(segbuf);
+                if (err)
+                        return err;
+        }
+        return 0;
+}
+
 /*
  * BIO operations
  */
diff --git a/fs/nilfs2/segbuf.h b/fs/nilfs2/segbuf.h
index 241a00dc4988..7fbaf5eee016 100644
--- a/fs/nilfs2/segbuf.h
+++ b/fs/nilfs2/segbuf.h
@@ -164,16 +164,18 @@ nilfs_segbuf_add_file_buffer(struct nilfs_segment_buffer *segbuf,
         segbuf->sb_sum.nfileblk++;
 }
 
-void nilfs_release_buffers(struct list_head *);
-
-static inline void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
-{
-        nilfs_release_buffers(&segbuf->sb_segsum_buffers);
-        nilfs_release_buffers(&segbuf->sb_payload_buffers);
-}
-
 int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
                        struct the_nilfs *nilfs);
 int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);
 
+void nilfs_clear_logs(struct list_head *logs);
+void nilfs_truncate_logs(struct list_head *logs,
+                         struct nilfs_segment_buffer *last);
+int nilfs_wait_on_logs(struct list_head *logs);
+
+static inline void nilfs_destroy_logs(struct list_head *logs)
+{
+        nilfs_truncate_logs(logs, NULL);
+}
+
 #endif /* _NILFS_SEGBUF_H */
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 4422cdae112a..689deb9d41d1 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -1276,7 +1276,7 @@ static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
 static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
                                             struct the_nilfs *nilfs)
 {
-        struct nilfs_segment_buffer *segbuf, *n;
+        struct nilfs_segment_buffer *segbuf;
         __u64 nextnum;
         int err;
 
@@ -1313,18 +1313,14 @@ static int nilfs_segctor_begin_construction(struct nilfs_sc_info *sci,
         nilfs_segbuf_set_next_segnum(segbuf, nextnum, nilfs);
 
         /* truncating segment buffers */
-        list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
-                                          sb_list) {
-                list_del_init(&segbuf->sb_list);
-                nilfs_segbuf_free(segbuf);
-        }
+        nilfs_truncate_logs(&sci->sc_segbufs, segbuf);
         return 0;
 }
 
 static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
                                          struct the_nilfs *nilfs, int nadd)
 {
-        struct nilfs_segment_buffer *segbuf, *prev, *n;
+        struct nilfs_segment_buffer *segbuf, *prev;
         struct inode *sufile = nilfs->ns_sufile;
         __u64 nextnextnum;
         LIST_HEAD(list);
@@ -1369,12 +1365,11 @@ static int nilfs_segctor_extend_segments(struct nilfs_sc_info *sci,
  failed_segbuf:
         nilfs_segbuf_free(segbuf);
  failed:
-        list_for_each_entry_safe(segbuf, n, &list, sb_list) {
+        list_for_each_entry(segbuf, &list, sb_list) {
                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
                 WARN_ON(ret); /* never fails */
-                list_del_init(&segbuf->sb_list);
-                nilfs_segbuf_free(segbuf);
         }
+        nilfs_destroy_logs(&list);
         return err;
 }
 
@@ -1411,27 +1406,6 @@ static void nilfs_segctor_free_incomplete_segments(struct nilfs_sc_info *sci,
         }
 }
 
-static void nilfs_segctor_clear_segment_buffers(struct nilfs_sc_info *sci)
-{
-        struct nilfs_segment_buffer *segbuf;
-
-        list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list)
-                nilfs_segbuf_clear(segbuf);
-        sci->sc_super_root = NULL;
-}
-
-static void nilfs_segctor_destroy_segment_buffers(struct nilfs_sc_info *sci)
-{
-        struct nilfs_segment_buffer *segbuf;
-
-        while (!list_empty(&sci->sc_segbufs)) {
-                segbuf = NILFS_FIRST_SEGBUF(&sci->sc_segbufs);
-                list_del_init(&segbuf->sb_list);
-                nilfs_segbuf_free(segbuf);
-        }
-        /* sci->sc_curseg = NULL; */
-}
-
 static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
                                            struct the_nilfs *nilfs, int err)
 {
@@ -1447,7 +1421,8 @@ static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
                         WARN_ON(ret); /* do not happen */
                 }
         }
-        nilfs_segctor_clear_segment_buffers(sci);
+        nilfs_clear_logs(&sci->sc_segbufs);
+        sci->sc_super_root = NULL;
 }
 
 static void nilfs_segctor_update_segusage(struct nilfs_sc_info *sci,
@@ -1490,17 +1465,15 @@ static void nilfs_segctor_truncate_segments(struct nilfs_sc_info *sci,
                                             struct nilfs_segment_buffer *last,
                                             struct inode *sufile)
 {
-        struct nilfs_segment_buffer *segbuf = last, *n;
+        struct nilfs_segment_buffer *segbuf = last;
         int ret;
 
-        list_for_each_entry_safe_continue(segbuf, n, &sci->sc_segbufs,
-                                          sb_list) {
-                list_del_init(&segbuf->sb_list);
+        list_for_each_entry_continue(segbuf, &sci->sc_segbufs, sb_list) {
                 sci->sc_segbuf_nblocks -= segbuf->sb_rest_blocks;
                 ret = nilfs_sufile_free(sufile, segbuf->sb_nextnum);
                 WARN_ON(ret);
-                nilfs_segbuf_free(segbuf);
         }
+        nilfs_truncate_logs(&sci->sc_segbufs, last);
 }
 
 
@@ -1539,7 +1512,7 @@ static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
                                                         NULL);
                         WARN_ON(err); /* do not happen */
                 }
-                nilfs_segctor_clear_segment_buffers(sci);
+                nilfs_clear_logs(&sci->sc_segbufs);
 
                 err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
                 if (unlikely(err))
@@ -2179,7 +2152,7 @@ static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
         } while (sci->sc_stage.scnt != NILFS_ST_DONE);
 
  out:
-        nilfs_segctor_destroy_segment_buffers(sci);
+        nilfs_destroy_logs(&sci->sc_segbufs);
         nilfs_segctor_check_out_files(sci, sbi);
         return err;