Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2: (23 commits)
  nilfs2: disallow remount of snapshot from/to a regular mount
  nilfs2: use huge_encode_dev/huge_decode_dev
  nilfs2: update comment on deactivate_super at nilfs_get_sb
  nilfs2: replace MS_VERBOSE with MS_SILENT
  nilfs2: add missing initialization of s_mode
  nilfs2: fix misuse of open_bdev_exclusive/close_bdev_exclusive
  nilfs2: enlarge s_volume_name member in nilfs_super_block
  nilfs2: use checkpoint number instead of timestamp to select super block
  nilfs2: add missing endian conversion on super block magic number
  nilfs2: make nilfs_sc_*_ops static
  nilfs2: add kernel doc comments to persistent object allocator functions
  nilfs2: change sc_timer from a pointer to an embedded one in struct nilfs_sc_info
  nilfs2: remove nilfs_segctor_init() in segment.c
  nilfs2: insert checkpoint number in segment summary header
  nilfs2: add a print message after loading nilfs2
  nilfs2: cleanup multi kmem_cache_{create,destroy} code
  nilfs2: move out checksum routines to segment buffer code
  nilfs2: move pointer to super root block into logs
  nilfs2: change default of 'errors' mount option to 'remount-ro' mode
  nilfs2: Combine nilfs_btree_release_path() and nilfs_btree_free_path()
  ...

Documentation/filesystems/nilfs2.txt

@@ -50,8 +50,8 @@ NILFS2 supports the following mount options:
 (*) == default
 
 nobarrier		Disables barriers.
-errors=continue(*)	Keep going on a filesystem error.
-errors=remount-ro	Remount the filesystem read-only on an error.
+errors=continue		Keep going on a filesystem error.
+errors=remount-ro(*)	Remount the filesystem read-only on an error.
 errors=panic		Panic and halt the machine if an error occurs.
 cp=n			Specify the checkpoint-number of the snapshot to be
 			mounted.  Checkpoints and snapshots are listed by lscp

fs/nilfs2/alloc.h

@@ -29,6 +29,13 @@
 #include <linux/buffer_head.h>
 #include <linux/fs.h>
 
+/**
+ * nilfs_palloc_entries_per_group - get the number of entries per group
+ * @inode: inode of metadata file using this allocator
+ *
+ * The number of entries per group is defined by the number of bits
+ * that a bitmap block can maintain.
+ */
 static inline unsigned long
 nilfs_palloc_entries_per_group(const struct inode *inode)
 {

fs/nilfs2/btree.c

@@ -31,63 +31,16 @@
 #include "alloc.h"
 #include "dat.h"
 
-/**
- * struct nilfs_btree_path - A path on which B-tree operations are executed
- * @bp_bh: buffer head of node block
- * @bp_sib_bh: buffer head of sibling node block
- * @bp_index: index of child node
- * @bp_oldreq: ptr end request for old ptr
- * @bp_newreq: ptr alloc request for new ptr
- * @bp_op: rebalance operation
- */
-struct nilfs_btree_path {
-	struct buffer_head *bp_bh;
-	struct buffer_head *bp_sib_bh;
-	int bp_index;
-	union nilfs_bmap_ptr_req bp_oldreq;
-	union nilfs_bmap_ptr_req bp_newreq;
-	struct nilfs_btnode_chkey_ctxt bp_ctxt;
-	void (*bp_op)(struct nilfs_btree *, struct nilfs_btree_path *,
-		      int, __u64 *, __u64 *);
-};
-
-/*
- * B-tree path operations
- */
-
-static struct kmem_cache *nilfs_btree_path_cache;
-
-int __init nilfs_btree_path_cache_init(void)
-{
-	nilfs_btree_path_cache =
-		kmem_cache_create("nilfs2_btree_path_cache",
-				  sizeof(struct nilfs_btree_path) *
-				  NILFS_BTREE_LEVEL_MAX, 0, 0, NULL);
-	return (nilfs_btree_path_cache != NULL) ? 0 : -ENOMEM;
-}
-
-void nilfs_btree_path_cache_destroy(void)
-{
-	kmem_cache_destroy(nilfs_btree_path_cache);
-}
-
-static inline struct nilfs_btree_path *nilfs_btree_alloc_path(void)
-{
-	return kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
-}
-
-static inline void nilfs_btree_free_path(struct nilfs_btree_path *path)
+static struct nilfs_btree_path *nilfs_btree_alloc_path(void)
 {
-	kmem_cache_free(nilfs_btree_path_cache, path);
-}
+	struct nilfs_btree_path *path;
+	int level = NILFS_BTREE_LEVEL_DATA;
 
-static void nilfs_btree_init_path(struct nilfs_btree_path *path)
-{
-	int level;
+	path = kmem_cache_alloc(nilfs_btree_path_cache, GFP_NOFS);
+	if (path == NULL)
+		goto out;
 
-	for (level = NILFS_BTREE_LEVEL_DATA;
-	     level < NILFS_BTREE_LEVEL_MAX;
-	     level++) {
+	for (; level < NILFS_BTREE_LEVEL_MAX; level++) {
 		path[level].bp_bh = NULL;
 		path[level].bp_sib_bh = NULL;
 		path[level].bp_index = 0;
@@ -95,15 +48,19 @@ static void nilfs_btree_init_path(struct nilfs_btree_path *path)
 		path[level].bp_newreq.bpr_ptr = NILFS_BMAP_INVALID_PTR;
 		path[level].bp_op = NULL;
 	}
+
+out:
+	return path;
 }
 
-static void nilfs_btree_release_path(struct nilfs_btree_path *path)
+static void nilfs_btree_free_path(struct nilfs_btree_path *path)
 {
-	int level;
+	int level = NILFS_BTREE_LEVEL_DATA;
 
-	for (level = NILFS_BTREE_LEVEL_DATA; level < NILFS_BTREE_LEVEL_MAX;
-	     level++)
+	for (; level < NILFS_BTREE_LEVEL_MAX; level++)
 		brelse(path[level].bp_bh);
+
+	kmem_cache_free(nilfs_btree_path_cache, path);
 }
 
 /*
@@ -566,14 +523,12 @@ static int nilfs_btree_lookup(const struct nilfs_bmap *bmap,
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
 
 	if (ptrp != NULL)
 		*ptrp = ptr;
 
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 
 	return ret;
@@ -594,7 +549,7 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
+
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level);
 	if (ret < 0)
 		goto out;
@@ -655,7 +610,6 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *bmap,
 	*ptrp = ptr;
 	ret = cnt;
  out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 	return ret;
 }
@@ -1123,7 +1077,6 @@ static int nilfs_btree_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
 				    NILFS_BTREE_LEVEL_NODE_MIN);
@@ -1140,7 +1093,6 @@ static int nilfs_btree_insert(struct nilfs_bmap *bmap, __u64 key, __u64 ptr)
 	nilfs_bmap_add_blocks(bmap, stats.bs_nblocks);
 
  out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 	return ret;
 }
@@ -1456,7 +1408,7 @@ static int nilfs_btree_delete(struct nilfs_bmap *bmap, __u64 key)
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
+
 	ret = nilfs_btree_do_lookup(btree, path, key, NULL,
 				    NILFS_BTREE_LEVEL_NODE_MIN);
 	if (ret < 0)
@@ -1473,7 +1425,6 @@ static int nilfs_btree_delete(struct nilfs_bmap *bmap, __u64 key)
 	nilfs_bmap_sub_blocks(bmap, stats.bs_nblocks);
 
 out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 	return ret;
 }
@@ -1488,11 +1439,9 @@ static int nilfs_btree_last_key(const struct nilfs_bmap *bmap, __u64 *keyp)
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup_last(btree, path, keyp, NULL);
 
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 
 	return ret;
@@ -1923,7 +1872,6 @@ static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	if (buffer_nilfs_node(bh)) {
 		node = (struct nilfs_btree_node *)bh->b_data;
@@ -1947,7 +1895,6 @@ static int nilfs_btree_propagate(const struct nilfs_bmap *bmap,
 		nilfs_btree_propagate_p(btree, path, level, bh);
 
  out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 
 	return ret;
@@ -2108,7 +2055,6 @@ static int nilfs_btree_assign(struct nilfs_bmap *bmap,
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	if (buffer_nilfs_node(*bh)) {
 		node = (struct nilfs_btree_node *)(*bh)->b_data;
@@ -2130,7 +2076,6 @@ static int nilfs_btree_assign(struct nilfs_bmap *bmap,
 		nilfs_btree_assign_p(btree, path, level, bh, blocknr, binfo);
 
  out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 
 	return ret;
@@ -2175,7 +2120,6 @@ static int nilfs_btree_mark(struct nilfs_bmap *bmap, __u64 key, int level)
 	path = nilfs_btree_alloc_path();
 	if (path == NULL)
 		return -ENOMEM;
-	nilfs_btree_init_path(path);
 
 	ret = nilfs_btree_do_lookup(btree, path, key, &ptr, level + 1);
 	if (ret < 0) {
@@ -2195,7 +2139,6 @@ static int nilfs_btree_mark(struct nilfs_bmap *bmap, __u64 key, int level)
 		nilfs_bmap_set_dirty(&btree->bt_bmap);
 
  out:
-	nilfs_btree_release_path(path);
 	nilfs_btree_free_path(path);
 	return ret;
 }

fs/nilfs2/btree.h

@@ -30,9 +30,6 @@
 #include "btnode.h"
 #include "bmap.h"
 
-struct nilfs_btree;
-struct nilfs_btree_path;
-
 /**
  * struct nilfs_btree - B-tree structure
  * @bt_bmap: bmap base structure
@@ -41,6 +38,25 @@ struct nilfs_btree {
 	struct nilfs_bmap bt_bmap;
 };
 
+/**
+ * struct nilfs_btree_path - A path on which B-tree operations are executed
+ * @bp_bh: buffer head of node block
+ * @bp_sib_bh: buffer head of sibling node block
+ * @bp_index: index of child node
+ * @bp_oldreq: ptr end request for old ptr
+ * @bp_newreq: ptr alloc request for new ptr
+ * @bp_op: rebalance operation
+ */
+struct nilfs_btree_path {
+	struct buffer_head *bp_bh;
+	struct buffer_head *bp_sib_bh;
+	int bp_index;
+	union nilfs_bmap_ptr_req bp_oldreq;
+	union nilfs_bmap_ptr_req bp_newreq;
+	struct nilfs_btnode_chkey_ctxt bp_ctxt;
+	void (*bp_op)(struct nilfs_btree *, struct nilfs_btree_path *,
+		      int, __u64 *, __u64 *);
+};
 
 #define NILFS_BTREE_ROOT_SIZE		NILFS_BMAP_SIZE
 #define NILFS_BTREE_ROOT_NCHILDREN_MAX					\
@@ -57,6 +73,7 @@ struct nilfs_btree {
 #define NILFS_BTREE_KEY_MIN	((__u64)0)
 #define NILFS_BTREE_KEY_MAX	(~(__u64)0)
 
+extern struct kmem_cache *nilfs_btree_path_cache;
 
 int nilfs_btree_path_cache_init(void);
 void nilfs_btree_path_cache_destroy(void);

fs/nilfs2/inode.c

@@ -451,7 +451,7 @@ static int __nilfs_read_inode(struct super_block *sb, unsigned long ino,
 		inode->i_op = &nilfs_special_inode_operations;
 		init_special_inode(
 			inode, inode->i_mode,
-			new_decode_dev(le64_to_cpu(raw_inode->i_device_code)));
+			huge_decode_dev(le64_to_cpu(raw_inode->i_device_code)));
 	}
 	nilfs_ifile_unmap_inode(sbi->s_ifile, ino, bh);
 	brelse(bh);
@@ -511,7 +511,7 @@ void nilfs_write_inode_common(struct inode *inode,
 		nilfs_bmap_write(ii->i_bmap, raw_inode);
 	else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode))
 		raw_inode->i_device_code =
-			cpu_to_le64(new_encode_dev(inode->i_rdev));
+			cpu_to_le64(huge_encode_dev(inode->i_rdev));
 	/* When extending inode, nilfs->ns_inode_size should be checked
 	   for substitutions of appended fields */
 }

fs/nilfs2/recovery.c

@@ -105,6 +105,8 @@ static void store_segsum_info(struct nilfs_segsum_info *ssi,
 
 	ssi->nsumblk = DIV_ROUND_UP(ssi->sumbytes, blocksize);
 	ssi->nfileblk = ssi->nblocks - ssi->nsumblk - !!NILFS_SEG_HAS_SR(ssi);
+
+	/* need to verify ->ss_bytes field if read ->ss_cno */
 }
 
 /**

fs/nilfs2/segbuf.c

@@ -40,35 +40,10 @@ struct nilfs_write_info {
 	sector_t		blocknr;
 };
 
-
 static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 			      struct the_nilfs *nilfs);
 static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);
 
-
-static struct kmem_cache *nilfs_segbuf_cachep;
-
-static void nilfs_segbuf_init_once(void *obj)
-{
-	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
-}
-
-int __init nilfs_init_segbuf_cache(void)
-{
-	nilfs_segbuf_cachep =
-		kmem_cache_create("nilfs2_segbuf_cache",
-				  sizeof(struct nilfs_segment_buffer),
-				  0, SLAB_RECLAIM_ACCOUNT,
-				  nilfs_segbuf_init_once);
-
-	return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
-}
-
-void nilfs_destroy_segbuf_cache(void)
-{
-	kmem_cache_destroy(nilfs_segbuf_cachep);
-}
-
 struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
 {
 	struct nilfs_segment_buffer *segbuf;
@@ -81,6 +56,7 @@ struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
 	INIT_LIST_HEAD(&segbuf->sb_list);
 	INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
 	INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
+	segbuf->sb_super_root = NULL;
 
 	init_completion(&segbuf->sb_bio_event);
 	atomic_set(&segbuf->sb_err, 0);
@@ -158,7 +134,7 @@ int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
 }
 
 int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
-		       time_t ctime)
+		       time_t ctime, __u64 cno)
 {
 	int err;
 
@@ -171,6 +147,7 @@ int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
 	segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
 	segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
 	segbuf->sb_sum.ctime = ctime;
+	segbuf->sb_sum.cno = cno;
 	return 0;
 }
 
@@ -196,13 +173,14 @@ void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
 	raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
 	raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
 	raw_sum->ss_pad      = 0;
+	raw_sum->ss_cno      = cpu_to_le64(segbuf->sb_sum.cno);
 }
 
 /*
  * CRC calculation routines
  */
-void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
-				     u32 seed)
+static void
+nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf, u32 seed)
 {
 	struct buffer_head *bh;
 	struct nilfs_segment_summary *raw_sum;
@@ -229,7 +207,7 @@ void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
 	raw_sum->ss_sumsum = cpu_to_le32(crc);
 }
 
-void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
+static void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
 					  u32 seed)
 {
 	struct buffer_head *bh;
@@ -256,6 +234,20 @@ void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
 	raw_sum->ss_datasum = cpu_to_le32(crc);
 }
 
+static void
+nilfs_segbuf_fill_in_super_root_crc(struct nilfs_segment_buffer *segbuf,
+				    u32 seed)
+{
+	struct nilfs_super_root *raw_sr;
+	u32 crc;
+
+	raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
+	crc = crc32_le(seed,
+		       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
+		       NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
+	raw_sr->sr_sum = cpu_to_le32(crc);
+}
+
 static void nilfs_release_buffers(struct list_head *list)
 {
 	struct buffer_head *bh, *n;
@@ -282,6 +274,7 @@ static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
 {
 	nilfs_release_buffers(&segbuf->sb_segsum_buffers);
 	nilfs_release_buffers(&segbuf->sb_payload_buffers);
+	segbuf->sb_super_root = NULL;
 }
 
 /*
@@ -334,6 +327,23 @@ int nilfs_wait_on_logs(struct list_head *logs)
 	return ret;
 }
 
+/**
+ * nilfs_add_checksums_on_logs - add checksums on the logs
+ * @logs: list of segment buffers storing target logs
+ * @seed: checksum seed value
+ */
+void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed)
+{
+	struct nilfs_segment_buffer *segbuf;
+
+	list_for_each_entry(segbuf, logs, sb_list) {
+		if (segbuf->sb_super_root)
+			nilfs_segbuf_fill_in_super_root_crc(segbuf, seed);
+		nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
+		nilfs_segbuf_fill_in_data_crc(segbuf, seed);
+	}
+}
+
 /*
  * BIO operations
  */

fs/nilfs2/segbuf.h

@@ -37,6 +37,7 @@
  * @sumbytes: Byte count of segment summary
  * @nfileblk: Total number of file blocks
  * @seg_seq: Segment sequence number
+ * @cno: Checkpoint number
  * @ctime: Creation time
  * @next: Block number of the next full segment
  */
@@ -48,6 +49,7 @@ struct nilfs_segsum_info {
 	unsigned long		sumbytes;
 	unsigned long		nfileblk;
 	u64			seg_seq;
+	__u64			cno;
 	time_t			ctime;
 	sector_t		next;
 };
@@ -76,6 +78,7 @@ struct nilfs_segsum_info {
  * @sb_rest_blocks: Number of residual blocks in the current segment
  * @sb_segsum_buffers: List of buffers for segment summaries
  * @sb_payload_buffers: List of buffers for segment payload
+ * @sb_super_root: Pointer to buffer storing a super root block (if exists)
  * @sb_nbio: Number of flying bio requests
  * @sb_err: I/O error status
  * @sb_bio_event: Completion event of log writing
@@ -95,6 +98,7 @@ struct nilfs_segment_buffer {
 	/* Buffers */
 	struct list_head	sb_segsum_buffers;
 	struct list_head	sb_payload_buffers; /* including super root */
+	struct buffer_head     *sb_super_root;
 
 	/* io status */
 	int			sb_nbio;
@@ -121,6 +125,7 @@ struct nilfs_segment_buffer {
 		    b_assoc_buffers))
 #define NILFS_SEGBUF_BH_IS_LAST(bh, head)  ((bh)->b_assoc_buffers.next == head)
 
+extern struct kmem_cache *nilfs_segbuf_cachep;
 
 int __init nilfs_init_segbuf_cache(void);
 void nilfs_destroy_segbuf_cache(void);
@@ -132,13 +137,11 @@ void nilfs_segbuf_map_cont(struct nilfs_segment_buffer *segbuf,
 			   struct nilfs_segment_buffer *prev);
 void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *, __u64,
 				  struct the_nilfs *);
-int nilfs_segbuf_reset(struct nilfs_segment_buffer *, unsigned, time_t);
+int nilfs_segbuf_reset(struct nilfs_segment_buffer *, unsigned, time_t, __u64);
 int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *);
 int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *,
 				struct buffer_head **);
 void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *);
-void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *, u32);
-void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *, u32);
 
 static inline void
 nilfs_segbuf_add_segsum_buffer(struct nilfs_segment_buffer *segbuf,
@@ -171,6 +174,7 @@ void nilfs_truncate_logs(struct list_head *logs,
 			 struct nilfs_segment_buffer *last);
 int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs);
 int nilfs_wait_on_logs(struct list_head *logs);
+void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed);
 
 static inline void nilfs_destroy_logs(struct list_head *logs)
 {

fs/nilfs2/segment.h

@@ -100,7 +100,6 @@ struct nilfs_segsum_pointer {
  * @sc_write_logs: List of segment buffers to hold logs under writing
  * @sc_segbuf_nblocks: Number of available blocks in segment buffers.
  * @sc_curseg: Current segment buffer
- * @sc_super_root: Pointer to the super root buffer
  * @sc_stage: Collection stage
  * @sc_finfo_ptr: pointer to the current finfo struct in the segment summary
  * @sc_binfo_ptr: pointer to the current binfo struct in the segment summary
@@ -148,7 +147,6 @@ struct nilfs_sc_info {
 	struct list_head	sc_write_logs;
 	unsigned long		sc_segbuf_nblocks;
 	struct nilfs_segment_buffer *sc_curseg;
-	struct buffer_head     *sc_super_root;
 
 	struct nilfs_cstage	sc_stage;
 
@@ -179,7 +177,7 @@ struct nilfs_sc_info {
 	unsigned long		sc_lseg_stime;	/* in 1/HZ seconds */
 	unsigned long		sc_watermark;
 
-	struct timer_list      *sc_timer;
+	struct timer_list	sc_timer;
 	struct task_struct     *sc_task;
 };
 
@@ -219,6 +217,8 @@ enum {
  */
 #define NILFS_SC_DEFAULT_WATERMARK  3600
 
+/* super.c */
+extern struct kmem_cache *nilfs_transaction_cachep;
 
 /* segment.c */
 extern int nilfs_init_transaction_cache(void);

fs/nilfs2/the_nilfs.c

@@ -486,11 +486,15 @@ static int nilfs_load_super_block(struct the_nilfs *nilfs,
 		printk(KERN_WARNING
 		       "NILFS warning: unable to read secondary superblock\n");
 
+	/*
+	 * Compare two super blocks and set 1 in swp if the secondary
+	 * super block is valid and newer.  Otherwise, set 0 in swp.
+	 */
 	valid[0] = nilfs_valid_sb(sbp[0]);
 	valid[1] = nilfs_valid_sb(sbp[1]);
-	swp = valid[1] &&
-		(!valid[0] ||
-		 le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
+	swp = valid[1] && (!valid[0] ||
+			   le64_to_cpu(sbp[1]->s_last_cno) >
+			   le64_to_cpu(sbp[0]->s_last_cno));
 
 	if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
 		brelse(sbh[1]);

include/linux/nilfs2_fs.h

@@ -207,8 +207,7 @@ struct nilfs_super_block {
 	__le16	s_segment_usage_size;	/* Size of a segment usage */
 
 	__u8	s_uuid[16];		/* 128-bit uuid for volume */
-	char	s_volume_name[16]; 	/* volume name */
-	char	s_last_mounted[64]; 	/* directory where last mounted */
+	char	s_volume_name[80];	/* volume name */
 
 	__le32  s_c_interval;           /* Commit interval of segment */
 	__le32  s_c_block_max;          /* Threshold of data amount for
@@ -377,6 +376,7 @@ union nilfs_binfo {
  * @ss_nfinfo: number of finfo structures
  * @ss_sumbytes: total size of segment summary in bytes
  * @ss_pad: padding
+ * @ss_cno: checkpoint number
  */
 struct nilfs_segment_summary {
 	__le32 ss_datasum;
@@ -391,6 +391,7 @@ struct nilfs_segment_summary {
 	__le32 ss_nfinfo;
 	__le32 ss_sumbytes;
 	__le32 ss_pad;
+	__le64 ss_cno;
 	/* array of finfo structures */
 };
 
@@ -437,10 +438,10 @@ struct nilfs_palloc_group_desc {
 
 /**
  * struct nilfs_dat_entry - disk address translation entry
- * @dt_blocknr: block number
- * @dt_start: start checkpoint number
- * @dt_end: end checkpoint number
- * @dt_rsv: reserved for future use
+ * @de_blocknr: block number
+ * @de_start: start checkpoint number
+ * @de_end: end checkpoint number
+ * @de_rsv: reserved for future use
  */
 struct nilfs_dat_entry {
 	__le64 de_blocknr;