nilfs2: eliminate removal list of segments

This will clean up the removal list of segments and the related
functions from segment.c and ioctl.c, which have hurt code
readability.

This elimination is applied by using nilfs_sufile_updatev() previously
introduced in the patch ("nilfs2: add sufile function that can modify
multiple segment usages").
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/ioctl.c

@@ -435,24 +435,6 @@ static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs,
 	return nmembs;
 }
 
-static int nilfs_ioctl_free_segments(struct the_nilfs *nilfs,
-				     struct nilfs_argv *argv, void *buf)
-{
-	size_t nmembs = argv->v_nmembs;
-	struct nilfs_sb_info *sbi = nilfs->ns_writer;
-	int ret;
-
-	if (unlikely(!sbi)) {
-		/* never happens because called for a writable mount */
-		WARN_ON(1);
-		return -EROFS;
-	}
-	ret = nilfs_segctor_add_segments_to_be_freed(
-		NILFS_SC(sbi), buf, nmembs);
-
-	return (ret < 0) ? ret : nmembs;
-}
-
 int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
 				       struct nilfs_argv *argv, void **kbufs)
 {
@@ -491,14 +473,6 @@ int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *nilfs,
 		msg = "cannot mark copying blocks dirty";
 		goto failed;
 	}
-	ret = nilfs_ioctl_free_segments(nilfs, &argv[4], kbufs[4]);
-	if (ret < 0) {
-		/*
-		 * can safely abort because this operation is atomic.
-		 */
-		msg = "cannot set segments to be freed";
-		goto failed;
-	}
 	return 0;
 
  failed:

fs/nilfs2/segbuf.c

@@ -26,7 +26,6 @@
 #include <linux/crc32.h>
 #include "page.h"
 #include "segbuf.h"
-#include "seglist.h"
 
 
 static struct kmem_cache *nilfs_segbuf_cachep;

fs/nilfs2/seglist.h

@@ -32,11 +32,6 @@
 struct nilfs_segment_entry {
 	__u64			segnum;
 
-#define NILFS_SLH_FREED		0x0001	/* The segment was freed provisonally.
-					   It must be cancelled if
-					   construction aborted */
-
-	unsigned		flags;
 	struct list_head	list;
 	struct buffer_head     *bh_su;
 	struct nilfs_segment_usage *raw_su;
@@ -52,7 +47,6 @@ nilfs_alloc_segment_entry(__u64 segnum)
 
 	if (likely(ent)) {
 		ent->segnum = segnum;
-		ent->flags = 0;
 		ent->bh_su = NULL;
 		ent->raw_su = NULL;
 		INIT_LIST_HEAD(&ent->list);

fs/nilfs2/segment.c

@@ -39,7 +39,6 @@
 #include "sufile.h"
 #include "cpfile.h"
 #include "ifile.h"
-#include "seglist.h"
 #include "segbuf.h"
 
 
@@ -79,7 +78,8 @@ enum {
 /* State flags of collection */
 #define NILFS_CF_NODE		0x0001	/* Collecting node blocks */
 #define NILFS_CF_IFILE_STARTED	0x0002	/* IFILE stage has started */
-#define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED)
+#define NILFS_CF_SUFREED	0x0004	/* segment usages has been freed */
+#define NILFS_CF_HISTORY_MASK	(NILFS_CF_IFILE_STARTED | NILFS_CF_SUFREED)
 
 /* Operations depending on the construction mode and file type */
 struct nilfs_sc_operations {
@@ -810,7 +810,7 @@ static int nilfs_segctor_clean(struct nilfs_sc_info *sci)
 {
 	return list_empty(&sci->sc_dirty_files) &&
 		!test_bit(NILFS_SC_DIRTY, &sci->sc_flags) &&
-		list_empty(&sci->sc_cleaning_segments) &&
+		sci->sc_nfreesegs == 0 &&
 		(!nilfs_doing_gc() || list_empty(&sci->sc_gc_inodes));
 }
 
@@ -1005,44 +1005,6 @@ static void nilfs_drop_collected_inodes(struct list_head *head)
 	}
 }
 
-static void nilfs_segctor_cancel_free_segments(struct nilfs_sc_info *sci,
-					       struct inode *sufile)
-
-{
-	struct list_head *head = &sci->sc_cleaning_segments;
-	struct nilfs_segment_entry *ent;
-	int err;
-
-	list_for_each_entry(ent, head, list) {
-		if (!(ent->flags & NILFS_SLH_FREED))
-			break;
-		err = nilfs_sufile_cancel_free(sufile, ent->segnum);
-		WARN_ON(err); /* do not happen */
-		ent->flags &= ~NILFS_SLH_FREED;
-	}
-}
-
-static int nilfs_segctor_prepare_free_segments(struct nilfs_sc_info *sci,
-					       struct inode *sufile)
-{
-	struct list_head *head = &sci->sc_cleaning_segments;
-	struct nilfs_segment_entry *ent;
-	int err;
-
-	list_for_each_entry(ent, head, list) {
-		err = nilfs_sufile_free(sufile, ent->segnum);
-		if (unlikely(err))
-			return err;
-		ent->flags |= NILFS_SLH_FREED;
-	}
-	return 0;
-}
-
-static void nilfs_segctor_commit_free_segments(struct nilfs_sc_info *sci)
-{
-	nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
-}
-
 static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
 				       struct inode *inode,
 				       struct list_head *listp,
@@ -1161,6 +1123,7 @@ static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
 	struct the_nilfs *nilfs = sbi->s_nilfs;
 	struct list_head *head;
 	struct nilfs_inode_info *ii;
+	size_t ndone;
 	int err = 0;
 
 	switch (sci->sc_stage.scnt) {
@@ -1250,10 +1213,16 @@ static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
 			break;
 		sci->sc_stage.scnt++;  /* Fall through */
 	case NILFS_ST_SUFILE:
-		err = nilfs_segctor_prepare_free_segments(sci,
-							  nilfs->ns_sufile);
-		if (unlikely(err))
+		err = nilfs_sufile_freev(nilfs->ns_sufile, sci->sc_freesegs,
+					 sci->sc_nfreesegs, &ndone);
+		if (unlikely(err)) {
+			nilfs_sufile_cancel_freev(nilfs->ns_sufile,
+						  sci->sc_freesegs, ndone,
+						  NULL);
 			break;
+		}
+		sci->sc_stage.flags |= NILFS_CF_SUFREED;
+
 		err = nilfs_segctor_scan_file(sci, nilfs->ns_sufile,
 					      &nilfs_sc_file_ops);
 		if (unlikely(err))
@@ -1486,7 +1455,15 @@ static void nilfs_segctor_end_construction(struct nilfs_sc_info *sci,
 {
 	if (unlikely(err)) {
 		nilfs_segctor_free_incomplete_segments(sci, nilfs);
-		nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
+		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
+			int ret;
+
+			ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
+							sci->sc_freesegs,
+							sci->sc_nfreesegs,
+							NULL);
+			WARN_ON(ret); /* do not happen */
+		}
 	}
 	nilfs_segctor_clear_segment_buffers(sci);
 }
@@ -1585,7 +1562,13 @@ static int nilfs_segctor_collect(struct nilfs_sc_info *sci,
 		if (mode != SC_LSEG_SR || sci->sc_stage.scnt < NILFS_ST_CPFILE)
 			break;
 
-		nilfs_segctor_cancel_free_segments(sci, nilfs->ns_sufile);
+		if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
+			err = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
+							sci->sc_freesegs,
+							sci->sc_nfreesegs,
+							NULL);
+			WARN_ON(err); /* do not happen */
+		}
 		nilfs_segctor_clear_segment_buffers(sci);
 
 		err = nilfs_segctor_extend_segments(sci, nilfs, nadd);
@@ -2224,10 +2207,8 @@ static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
 		nilfs_segctor_complete_write(sci);
 
 		/* Commit segments */
-		if (has_sr) {
-			nilfs_segctor_commit_free_segments(sci);
+		if (has_sr)
 			nilfs_segctor_clear_metadata_dirty(sci);
-		}
 
 		nilfs_segctor_end_construction(sci, nilfs, 0);
 
@@ -2301,48 +2282,6 @@ void nilfs_flush_segment(struct super_block *sb, ino_t ino)
 					/* assign bit 0 to data files */
 }
 
-int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *sci,
-					   __u64 *segnum, size_t nsegs)
-{
-	struct nilfs_segment_entry *ent;
-	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
-	struct inode *sufile = nilfs->ns_sufile;
-	LIST_HEAD(list);
-	__u64 *pnum;
-	size_t i;
-	int err;
-
-	for (pnum = segnum, i = 0; i < nsegs; pnum++, i++) {
-		ent = nilfs_alloc_segment_entry(*pnum);
-		if (unlikely(!ent)) {
-			err = -ENOMEM;
-			goto failed;
-		}
-		list_add_tail(&ent->list, &list);
-
-		err = nilfs_open_segment_entry(ent, sufile);
-		if (unlikely(err))
-			goto failed;
-
-		if (unlikely(!nilfs_segment_usage_dirty(ent->raw_su)))
-			printk(KERN_WARNING "NILFS: unused segment is "
-			       "requested to be cleaned (segnum=%llu)\n",
-			       (unsigned long long)ent->segnum);
-		nilfs_close_segment_entry(ent, sufile);
-	}
-	list_splice(&list, sci->sc_cleaning_segments.prev);
-	return 0;
-
- failed:
-	nilfs_dispose_segment_list(&list);
-	return err;
-}
-
-void nilfs_segctor_clear_segments_to_be_freed(struct nilfs_sc_info *sci)
-{
-	nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
-}
-
 struct nilfs_segctor_wait_request {
 	wait_queue_t	wq;
 	__u32		seq;
@@ -2607,10 +2546,13 @@ int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
 	err = nilfs_init_gcdat_inode(nilfs);
 	if (unlikely(err))
 		goto out_unlock;
+
 	err = nilfs_ioctl_prepare_clean_segments(nilfs, argv, kbufs);
 	if (unlikely(err))
 		goto out_unlock;
 
+	sci->sc_freesegs = kbufs[4];
+	sci->sc_nfreesegs = argv[4].v_nmembs;
 	list_splice_init(&nilfs->ns_gc_inodes, sci->sc_gc_inodes.prev);
 
 	for (;;) {
@@ -2629,6 +2571,8 @@ int nilfs_clean_segments(struct super_block *sb, struct nilfs_argv *argv,
 	}
 
  out_unlock:
+	sci->sc_freesegs = NULL;
+	sci->sc_nfreesegs = 0;
 	nilfs_clear_gcdat_inode(nilfs);
 	nilfs_transaction_unlock(sbi);
 	return err;
@@ -2835,7 +2779,6 @@ static struct nilfs_sc_info *nilfs_segctor_new(struct nilfs_sb_info *sbi)
 	INIT_LIST_HEAD(&sci->sc_dirty_files);
 	INIT_LIST_HEAD(&sci->sc_segbufs);
 	INIT_LIST_HEAD(&sci->sc_gc_inodes);
-	INIT_LIST_HEAD(&sci->sc_cleaning_segments);
 	INIT_LIST_HEAD(&sci->sc_copied_buffers);
 
 	sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
@@ -2901,9 +2844,6 @@ static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
 		nilfs_dispose_list(sbi, &sci->sc_dirty_files, 1);
 	}
 
-	if (!list_empty(&sci->sc_cleaning_segments))
-		nilfs_dispose_segment_list(&sci->sc_cleaning_segments);
-
 	WARN_ON(!list_empty(&sci->sc_segbufs));
 
 	down_write(&sbi->s_nilfs->ns_segctor_sem);

fs/nilfs2/segment.h

@@ -90,8 +90,9 @@ struct nilfs_segsum_pointer {
  * @sc_nblk_inc: Block count of current generation
  * @sc_dirty_files: List of files to be written
  * @sc_gc_inodes: List of GC inodes having blocks to be written
- * @sc_cleaning_segments: List of segments to be freed through construction
  * @sc_copied_buffers: List of copied buffers (buffer heads) to freeze data
+ * @sc_freesegs: array of segment numbers to be freed
+ * @sc_nfreesegs: number of segments on @sc_freesegs
  * @sc_dsync_inode: inode whose data pages are written for a sync operation
  * @sc_dsync_start: start byte offset of data pages
  * @sc_dsync_end: end byte offset of data pages (inclusive)
@@ -131,9 +132,11 @@ struct nilfs_sc_info {
 
 	struct list_head	sc_dirty_files;
 	struct list_head	sc_gc_inodes;
-	struct list_head	sc_cleaning_segments;
 	struct list_head	sc_copied_buffers;
 
+	__u64		       *sc_freesegs;
+	size_t			sc_nfreesegs;
+
 	struct nilfs_inode_info *sc_dsync_inode;
 	loff_t			sc_dsync_start;
 	loff_t			sc_dsync_end;
@@ -225,10 +228,6 @@ extern void nilfs_flush_segment(struct super_block *, ino_t);
 extern int nilfs_clean_segments(struct super_block *, struct nilfs_argv *,
 				void **);
 
-extern int nilfs_segctor_add_segments_to_be_freed(struct nilfs_sc_info *,
-						  __u64 *, size_t);
-extern void nilfs_segctor_clear_segments_to_be_freed(struct nilfs_sc_info *);
-
 extern int nilfs_attach_segment_constructor(struct nilfs_sb_info *);
 extern void nilfs_detach_segment_constructor(struct nilfs_sb_info *);
 

fs/nilfs2/sufile.h

@@ -54,35 +54,15 @@ int nilfs_sufile_update(struct inode *, __u64, int,
 			void (*dofunc)(struct inode *, __u64,
 				       struct buffer_head *,
 				       struct buffer_head *));
-void nilfs_sufile_do_cancel_free(struct inode *, __u64, struct buffer_head *,
-				 struct buffer_head *);
 void nilfs_sufile_do_scrap(struct inode *, __u64, struct buffer_head *,
 			   struct buffer_head *);
 void nilfs_sufile_do_free(struct inode *, __u64, struct buffer_head *,
 			  struct buffer_head *);
+void nilfs_sufile_do_cancel_free(struct inode *, __u64, struct buffer_head *,
+				 struct buffer_head *);
 void nilfs_sufile_do_set_error(struct inode *, __u64, struct buffer_head *,
 			       struct buffer_head *);
 
-/**
- * nilfs_sufile_cancel_free -
- * @sufile: inode of segment usage file
- * @segnum: segment number
- *
- * Description:
- *
- * Return Value: On success, 0 is returned. On error, one of the following
- * negative error codes is returned.
- *
- * %-EIO - I/O error.
- *
- * %-ENOMEM - Insufficient amount of memory available.
- */
-static inline int nilfs_sufile_cancel_free(struct inode *sufile, __u64 segnum)
-{
-	return nilfs_sufile_update(sufile, segnum, 0,
-				   nilfs_sufile_do_cancel_free);
-}
-
 /**
  * nilfs_sufile_scrap - make a segment garbage
  * @sufile: inode of segment usage file
@@ -103,6 +83,38 @@ static inline int nilfs_sufile_free(struct inode *sufile, __u64 segnum)
 	return nilfs_sufile_update(sufile, segnum, 0, nilfs_sufile_do_free);
 }
 
+/**
+ * nilfs_sufile_freev - free segments
+ * @sufile: inode of segment usage file
+ * @segnumv: array of segment numbers
+ * @nsegs: size of @segnumv array
+ * @ndone: place to store the number of freed segments
+ */
+static inline int nilfs_sufile_freev(struct inode *sufile, __u64 *segnumv,
+				     size_t nsegs, size_t *ndone)
+{
+	return nilfs_sufile_updatev(sufile, segnumv, nsegs, 0, ndone,
+				    nilfs_sufile_do_free);
+}
+
+/**
+ * nilfs_sufile_cancel_freev - reallocate freeing segments
+ * @sufile: inode of segment usage file
+ * @segnumv: array of segment numbers
+ * @nsegs: size of @segnumv array
+ * @ndone: place to store the number of cancelled segments
+ *
+ * Return Value: On success, 0 is returned. On error, a negative error codes
+ * is returned.
+ */
+static inline int nilfs_sufile_cancel_freev(struct inode *sufile,
+					    __u64 *segnumv, size_t nsegs,
+					    size_t *ndone)
+{
+	return nilfs_sufile_updatev(sufile, segnumv, nsegs, 0, ndone,
+				    nilfs_sufile_do_cancel_free);
+}
+
 /**
  * nilfs_sufile_set_error - mark a segment as erroneous
  * @sufile: inode of segment usage file