nilfs2: avoid double error caused by nilfs_transaction_end

Pekka Enberg pointed out that double error handlings found after
nilfs_transaction_end() can be avoided by separating abort operation:

 OK, I don't understand this. The only way nilfs_transaction_end() can
 fail is if we have NILFS_TI_SYNC set and we fail to construct the
 segment. But why do we want to construct a segment if we don't commit?

 I guess what I'm asking is why don't we have a separate
 nilfs_transaction_abort() function that can't fail for the erroneous
 case to avoid this double error value tracking thing?

This does the separation and renames nilfs_transaction_end() to
nilfs_transaction_commit() for clarification.

Since, some calls of these functions were used just for exclusion control
against the segment constructor, they are replaced with semaphore
operations.

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 135 insertions, 75 deletions

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 289d1798decb..4bf1e2c5bac6 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -77,7 +77,6 @@ int nilfs_get_block(struct inode *inode, sector_t blkoff,
                         goto out;
                 err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
                                         (unsigned long)bh_result);
-                nilfs_transaction_end(inode->i_sb, !err);
                 if (unlikely(err != 0)) {
                         if (err == -EEXIST) {
                                 /*
@@ -100,8 +99,10 @@ int nilfs_get_block(struct inode *inode, sector_t blkoff,
                                             inode->i_ino);
                                 err = -EIO;
                         }
+                        nilfs_transaction_abort(inode->i_sb);
                         goto out;
                 }
+                nilfs_transaction_commit(inode->i_sb); /* never fails */
                 /* Error handling should be detailed */
                 set_buffer_new(bh_result);
                 map_bh(bh_result, inode->i_sb, 0); /* dbn must be changed
@@ -203,7 +204,7 @@ static int nilfs_write_begin(struct file *file, struct address_space *mapping,
         err = block_write_begin(file, mapping, pos, len, flags, pagep,
                                 fsdata, nilfs_get_block);
         if (unlikely(err))
-                nilfs_transaction_end(inode->i_sb, 0);
+                nilfs_transaction_abort(inode->i_sb);
         return err;
 }
 
@@ -221,7 +222,7 @@ static int nilfs_write_end(struct file *file, struct address_space *mapping,
         copied = generic_write_end(file, mapping, pos, len, copied, page,
                                    fsdata);
         nilfs_set_file_dirty(NILFS_SB(inode->i_sb), inode, nr_dirty);
-        err = nilfs_transaction_end(inode->i_sb, 1);
+        err = nilfs_transaction_commit(inode->i_sb);
         return err ? : copied;
 }
 
@@ -641,7 +642,7 @@ void nilfs_truncate(struct inode *inode)
                 nilfs_set_transaction_flag(NILFS_TI_SYNC);
 
         nilfs_set_file_dirty(NILFS_SB(sb), inode, 0);
-        nilfs_transaction_end(sb, 1);
+        nilfs_transaction_commit(sb);
         /* May construct a logical segment and may fail in sync mode.
            But truncate has no return value. */
 }
@@ -669,7 +670,7 @@ void nilfs_delete_inode(struct inode *inode)
         /* nilfs_free_inode() marks inode buffer dirty */
         if (IS_SYNC(inode))
                 nilfs_set_transaction_flag(NILFS_TI_SYNC);
-        nilfs_transaction_end(sb, 1);
+        nilfs_transaction_commit(sb);
         /* May construct a logical segment and may fail in sync mode.
            But delete_inode has no return value. */
 }
@@ -679,7 +680,7 @@ int nilfs_setattr(struct dentry *dentry, struct iattr *iattr)
         struct nilfs_transaction_info ti;
         struct inode *inode = dentry->d_inode;
         struct super_block *sb = inode->i_sb;
-        int err, err2;
+        int err;
 
         err = inode_change_ok(inode, iattr);
         if (err)
@@ -691,8 +692,12 @@ int nilfs_setattr(struct dentry *dentry, struct iattr *iattr)
         err = inode_setattr(inode, iattr);
         if (!err && (iattr->ia_valid & ATTR_MODE))
                 err = nilfs_acl_chmod(inode);
-        err2 = nilfs_transaction_end(sb, 1);
-        return err ? : err2;
+        if (likely(!err))
+                err = nilfs_transaction_commit(sb);
+        else
+                nilfs_transaction_abort(sb);
+
+        return err;
 }
 
 int nilfs_load_inode_block(struct nilfs_sb_info *sbi, struct inode *inode,
@@ -817,5 +822,5 @@ void nilfs_dirty_inode(struct inode *inode)
         nilfs_transaction_begin(inode->i_sb, &ti, 0);
         if (likely(inode->i_ino != NILFS_SKETCH_INO))
                 nilfs_mark_inode_dirty(inode);
-        nilfs_transaction_end(inode->i_sb, 1); /* never fails */
+        nilfs_transaction_commit(inode->i_sb); /* never fails */
 }
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 02e91e167ca2..5ce06a01c7ec 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -105,7 +105,11 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
         nilfs_transaction_begin(inode->i_sb, &ti, 0);
         ret = nilfs_cpfile_change_cpmode(
                 cpfile, cpmode.cm_cno, cpmode.cm_mode);
-        nilfs_transaction_end(inode->i_sb, !ret);
+        if (unlikely(ret < 0)) {
+                nilfs_transaction_abort(inode->i_sb);
+                return ret;
+        }
+        nilfs_transaction_commit(inode->i_sb); /* never fails */
         return ret;
 }
 
@@ -125,7 +129,11 @@ nilfs_ioctl_delete_checkpoint(struct inode *inode, struct file *filp,
 
         nilfs_transaction_begin(inode->i_sb, &ti, 0);
         ret = nilfs_cpfile_delete_checkpoint(cpfile, cno);
-        nilfs_transaction_end(inode->i_sb, !ret);
+        if (unlikely(ret < 0)) {
+                nilfs_transaction_abort(inode->i_sb);
+                return ret;
+        }
+        nilfs_transaction_commit(inode->i_sb); /* never fails */
         return ret;
 }
 
@@ -142,16 +150,17 @@ static int nilfs_ioctl_get_cpinfo(struct inode *inode, struct file *filp,
 {
         struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_argv argv;
-        struct nilfs_transaction_info ti;
         int ret;
 
         if (copy_from_user(&argv, argp, sizeof(argv)))
                 return -EFAULT;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
+        down_read(&nilfs->ns_segctor_sem);
         ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
                                     nilfs_ioctl_do_get_cpinfo);
-        nilfs_transaction_end(inode->i_sb, 0);
+        up_read(&nilfs->ns_segctor_sem);
+        if (ret < 0)
+                return ret;
 
         if (copy_to_user(argp, &argv, sizeof(argv)))
                 ret = -EFAULT;
@@ -161,14 +170,13 @@ static int nilfs_ioctl_get_cpinfo(struct inode *inode, struct file *filp,
 static int nilfs_ioctl_get_cpstat(struct inode *inode, struct file *filp,
                                   unsigned int cmd, void __user *argp)
 {
-        struct inode *cpfile = NILFS_SB(inode->i_sb)->s_nilfs->ns_cpfile;
+        struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_cpstat cpstat;
-        struct nilfs_transaction_info ti;
         int ret;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
-        ret = nilfs_cpfile_get_stat(cpfile, &cpstat);
-        nilfs_transaction_end(inode->i_sb, 0);
+        down_read(&nilfs->ns_segctor_sem);
+        ret = nilfs_cpfile_get_stat(nilfs->ns_cpfile, &cpstat);
+        up_read(&nilfs->ns_segctor_sem);
         if (ret < 0)
                 return ret;
 
@@ -189,16 +197,17 @@ static int nilfs_ioctl_get_suinfo(struct inode *inode, struct file *filp,
 {
         struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_argv argv;
-        struct nilfs_transaction_info ti;
         int ret;
 
         if (copy_from_user(&argv, argp, sizeof(argv)))
                 return -EFAULT;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
+        down_read(&nilfs->ns_segctor_sem);
         ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
                                     nilfs_ioctl_do_get_suinfo);
-        nilfs_transaction_end(inode->i_sb, 0);
+        up_read(&nilfs->ns_segctor_sem);
+        if (ret < 0)
+                return ret;
 
         if (copy_to_user(argp, &argv, sizeof(argv)))
                 ret = -EFAULT;
@@ -208,14 +217,13 @@ static int nilfs_ioctl_get_suinfo(struct inode *inode, struct file *filp,
 static int nilfs_ioctl_get_sustat(struct inode *inode, struct file *filp,
                                   unsigned int cmd, void __user *argp)
 {
-        struct inode *sufile = NILFS_SB(inode->i_sb)->s_nilfs->ns_sufile;
+        struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_sustat sustat;
-        struct nilfs_transaction_info ti;
         int ret;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
-        ret = nilfs_sufile_get_stat(sufile, &sustat);
-        nilfs_transaction_end(inode->i_sb, 0);
+        down_read(&nilfs->ns_segctor_sem);
+        ret = nilfs_sufile_get_stat(nilfs->ns_sufile, &sustat);
+        up_read(&nilfs->ns_segctor_sem);
         if (ret < 0)
                 return ret;
 
@@ -236,16 +244,17 @@ static int nilfs_ioctl_get_vinfo(struct inode *inode, struct file *filp,
 {
         struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_argv argv;
-        struct nilfs_transaction_info ti;
         int ret;
 
         if (copy_from_user(&argv, argp, sizeof(argv)))
                 return -EFAULT;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
+        down_read(&nilfs->ns_segctor_sem);
         ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
                                     nilfs_ioctl_do_get_vinfo);
-        nilfs_transaction_end(inode->i_sb, 0);
+        up_read(&nilfs->ns_segctor_sem);
+        if (ret < 0)
+                return ret;
 
         if (copy_to_user(argp, &argv, sizeof(argv)))
                 ret = -EFAULT;
@@ -280,16 +289,17 @@ static int nilfs_ioctl_get_bdescs(struct inode *inode, struct file *filp,
 {
         struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
         struct nilfs_argv argv;
-        struct nilfs_transaction_info ti;
         int ret;
 
         if (copy_from_user(&argv, argp, sizeof(argv)))
                 return -EFAULT;
 
-        nilfs_transaction_begin(inode->i_sb, &ti, 0);
+        down_read(&nilfs->ns_segctor_sem);
         ret = nilfs_ioctl_wrap_copy(nilfs, &argv, _IOC_DIR(cmd),
                                     nilfs_ioctl_do_get_bdescs);
-        nilfs_transaction_end(inode->i_sb, 0);
+        up_read(&nilfs->ns_segctor_sem);
+        if (ret < 0)
+                return ret;
 
         if (copy_to_user(argp, &argv, sizeof(argv)))
                 ret = -EFAULT;
diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c
index 6ab847578615..e0a632b86feb 100644
--- a/fs/nilfs2/mdt.c
+++ b/fs/nilfs2/mdt.c
@@ -123,7 +123,10 @@ static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
         brelse(bh);
 
  failed_unlock:
-        nilfs_transaction_end(sb, !err);
+        if (likely(!err))
+                err = nilfs_transaction_commit(sb);
+        else
+                nilfs_transaction_abort(sb);
         if (writer)
                 nilfs_put_writer(nilfs);
  out:
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index 95d1b29bff3c..df70dadb336f 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -109,7 +109,7 @@ static int nilfs_create(struct inode *dir, struct dentry *dentry, int mode,
 {
         struct inode *inode;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         err = nilfs_transaction_begin(dir->i_sb, &ti, 1);
         if (err)
@@ -123,8 +123,12 @@ static int nilfs_create(struct inode *dir, struct dentry *dentry, int mode,
                 mark_inode_dirty(inode);
                 err = nilfs_add_nondir(dentry, inode);
         }
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 }
 
 static int
@@ -132,7 +136,7 @@ nilfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
 {
         struct inode *inode;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         if (!new_valid_dev(rdev))
                 return -EINVAL;
@@ -147,8 +151,12 @@ nilfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t rdev)
                 mark_inode_dirty(inode);
                 err = nilfs_add_nondir(dentry, inode);
         }
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 }
 
 static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
@@ -158,7 +166,7 @@ static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
         struct super_block *sb = dir->i_sb;
         unsigned l = strlen(symname)+1;
         struct inode *inode;
-        int err, err2;
+        int err;
 
         if (l > sb->s_blocksize)
                 return -ENAMETOOLONG;
@@ -184,8 +192,12 @@ static int nilfs_symlink(struct inode *dir, struct dentry *dentry,
 
         err = nilfs_add_nondir(dentry, inode);
 out:
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 
 out_fail:
         inode_dec_link_count(inode);
@@ -198,7 +210,7 @@ static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
 {
         struct inode *inode = old_dentry->d_inode;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         if (inode->i_nlink >= NILFS_LINK_MAX)
                 return -EMLINK;
@@ -212,15 +224,19 @@ static int nilfs_link(struct dentry *old_dentry, struct inode *dir,
         atomic_inc(&inode->i_count);
 
         err = nilfs_add_nondir(dentry, inode);
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 }
 
 static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 {
         struct inode *inode;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         if (dir->i_nlink >= NILFS_LINK_MAX)
                 return -EMLINK;
@@ -252,8 +268,12 @@ static int nilfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 
         d_instantiate(dentry, inode);
 out:
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 
 out_fail:
         inode_dec_link_count(inode);
@@ -270,7 +290,7 @@ static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
         struct nilfs_dir_entry *de;
         struct page *page;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
         if (err)
@@ -300,15 +320,19 @@ static int nilfs_unlink(struct inode *dir, struct dentry *dentry)
         inode_dec_link_count(inode);
         err = 0;
 out:
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 }
 
 static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
         struct inode *inode = dentry->d_inode;
         struct nilfs_transaction_info ti;
-        int err, err2;
+        int err;
 
         err = nilfs_transaction_begin(dir->i_sb, &ti, 0);
         if (err)
@@ -323,8 +347,12 @@ static int nilfs_rmdir(struct inode *dir, struct dentry *dentry)
                         inode_dec_link_count(dir);
                 }
         }
-        err2 = nilfs_transaction_end(dir->i_sb, !err);
-        return err ? : err2;
+        if (!err)
+                err = nilfs_transaction_commit(dir->i_sb);
+        else
+                nilfs_transaction_abort(dir->i_sb);
+
+        return err;
 }
 
 static int nilfs_rename(struct inode *old_dir, struct dentry *old_dentry,
@@ -404,7 +432,7 @@ static int nilfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                 inode_dec_link_count(old_dir);
         }
 
-        err = nilfs_transaction_end(old_dir->i_sb, 1);
+        err = nilfs_transaction_commit(old_dir->i_sb);
         return err;
 
 out_dir:
@@ -416,7 +444,7 @@ out_old:
         kunmap(old_page);
         page_cache_release(old_page);
 out:
-        nilfs_transaction_end(old_dir->i_sb, 0);
+        nilfs_transaction_abort(old_dir->i_sb);
         return err;
 }
 
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 17458ad4a809..48c070676cc5 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -166,7 +166,8 @@ struct nilfs_transaction_info {
 
 int nilfs_transaction_begin(struct super_block *,
                             struct nilfs_transaction_info *, int);
-int nilfs_transaction_end(struct super_block *, int);
+int nilfs_transaction_commit(struct super_block *);
+void nilfs_transaction_abort(struct super_block *);
 
 static inline void nilfs_set_transaction_flag(unsigned int flag)
 {
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index ad65a737aff4..6d66c5cb7b51 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -163,8 +163,8 @@ static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
                 else {
                         /*
                          * If journal_info field is occupied by other FS,
-                         * we save it and restore on nilfs_transaction_end().
-                         * But this should never happen.
+                         * it is saved and will be restored on
+                         * nilfs_transaction_commit().
                          */
                         printk(KERN_WARNING
                                "NILFS warning: journal info from a different "
@@ -195,7 +195,7 @@ static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
  *
  * nilfs_transaction_begin() acquires a reader/writer semaphore, called
  * the segment semaphore, to make a segment construction and write tasks
- * exclusive.  The function is used with nilfs_transaction_end() in pairs.
+ * exclusive.  The function is used with nilfs_transaction_commit() in pairs.
  * The region enclosed by these two functions can be nested.  To avoid a
  * deadlock, the semaphore is only acquired or released in the outermost call.
  *
@@ -212,8 +212,6 @@ static int nilfs_prepare_segment_lock(struct nilfs_transaction_info *ti)
  *
  * %-ENOMEM - Insufficient memory available.
  *
- * %-ERESTARTSYS - Interrupted
- *
  * %-ENOSPC - No space left on device
  */
 int nilfs_transaction_begin(struct super_block *sb,
@@ -248,16 +246,17 @@ int nilfs_transaction_begin(struct super_block *sb,
 }
 
 /**
- * nilfs_transaction_end - end indivisible file operations.
+ * nilfs_transaction_commit - commit indivisible file operations.
  * @sb: super block
- * @commit: commit flag (0 for no change)
  *
- * nilfs_transaction_end() releases the read semaphore which is
- * acquired by nilfs_transaction_begin(). Its releasing is only done
- * in outermost call of this function. If the nilfs_transaction_info
- * was allocated dynamically, it is given back to a slab cache.
+ * nilfs_transaction_commit() releases the read semaphore which is
+ * acquired by nilfs_transaction_begin(). This is only performed
+ * in outermost call of this function.  If a commit flag is set,
+ * nilfs_transaction_commit() sets a timer to start the segment
+ * constructor.  If a sync flag is set, it starts construction
+ * directly.
  */
-int nilfs_transaction_end(struct super_block *sb, int commit)
+int nilfs_transaction_commit(struct super_block *sb)
 {
         struct nilfs_transaction_info *ti = current->journal_info;
         struct nilfs_sb_info *sbi;
@@ -265,9 +264,7 @@ int nilfs_transaction_end(struct super_block *sb, int commit)
         int err = 0;
 
         BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
-
-        if (commit)
-                ti->ti_flags |= NILFS_TI_COMMIT;
+        ti->ti_flags |= NILFS_TI_COMMIT;
         if (ti->ti_count > 0) {
                 ti->ti_count--;
                 return 0;
@@ -291,6 +288,22 @@ int nilfs_transaction_end(struct super_block *sb, int commit)
         return err;
 }
 
+void nilfs_transaction_abort(struct super_block *sb)
+{
+        struct nilfs_transaction_info *ti = current->journal_info;
+
+        BUG_ON(ti == NULL || ti->ti_magic != NILFS_TI_MAGIC);
+        if (ti->ti_count > 0) {
+                ti->ti_count--;
+                return;
+        }
+        up_read(&NILFS_SB(sb)->s_nilfs->ns_segctor_sem);
+
+        current->journal_info = ti->ti_save;
+        if (ti->ti_flags & NILFS_TI_DYNAMIC_ALLOC)
+                kmem_cache_free(nilfs_transaction_cachep, ti);
+}
+
 void nilfs_relax_pressure_in_lock(struct super_block *sb)
 {
         struct nilfs_sb_info *sbi = NILFS_SB(sb);
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index dee8d83e0549..9cd3c113f052 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -112,8 +112,8 @@ struct the_nilfs {
         /*
          * Following fields are dedicated to a writable FS-instance.
          * Except for the period seeking checkpoint, code outside the segment
-         * constructor must lock a segment semaphore with transaction_begin()
-         * and transaction_end(), when accessing these fields.
+         * constructor must lock a segment semaphore while accessing these
+         * fields.
          * The writable FS-instance is sole during a lifetime of the_nilfs.
          */
         u64                     ns_seg_seq;