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Commit 348fe8da authored by Ryusuke Konishi's avatar Ryusuke Konishi
Browse files

nilfs2: simplify life cycle management of nilfs object 



This stops pre-allocating nilfs object in nilfs_get_sb routine, and
stops managing its life cycle by reference counting.

nilfs_find_or_create_nilfs() function, nilfs->ns_mount_mutex,
nilfs_objects list, and the reference counter will be removed through
the simplification.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
parent f11459ad

fs/nilfs2/ioctl.c

+2 −2
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp, 
	if (copy_from_user(&cpmode, argp, sizeof(cpmode)))

		goto out;



	mutex_lock(&nilfs->ns_mount_mutex);

	down_read(&inode->i_sb->s_umount);



	nilfs_transaction_begin(inode->i_sb, &ti, 0);

	ret = nilfs_cpfile_change_cpmode(
@@ -127,7 +127,7 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp, 
	else

		nilfs_transaction_commit(inode->i_sb); /* never fails */



	mutex_unlock(&nilfs->ns_mount_mutex);

	up_read(&inode->i_sb->s_umount);

out:

	mnt_drop_write(filp->f_path.mnt);

	return ret;

fs/nilfs2/super.c

+22 −45
Original line number Diff line number Diff line
@@ -356,7 +356,7 @@ static void nilfs_put_super(struct super_block *sb) 
		up_write(&nilfs->ns_sem);

	}



	put_nilfs(sbi->s_nilfs);

	destroy_nilfs(nilfs);

	sbi->s_super = NULL;

	sb->s_fs_info = NULL;

	kfree(sbi);
@@ -836,15 +836,14 @@ static int nilfs_try_to_shrink_tree(struct dentry *root_dentry) 
 * @sb: super_block

 * @data: mount options

 * @silent: silent mode flag

 * @nilfs: the_nilfs struct

 *

 * This function is called exclusively by nilfs->ns_mount_mutex.

 * So, the recovery process is protected from other simultaneous mounts.

 */

static int

nilfs_fill_super(struct super_block *sb, void *data, int silent,

		 struct the_nilfs *nilfs)

nilfs_fill_super(struct super_block *sb, void *data, int silent)

{

	struct the_nilfs *nilfs;

	struct nilfs_sb_info *sbi;

	struct nilfs_root *fsroot;

	__u64 cno;
@@ -855,14 +854,18 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 
		return -ENOMEM;



	sb->s_fs_info = sbi;

	sbi->s_super = sb;



	get_nilfs(nilfs);

	nilfs = alloc_nilfs(sb->s_bdev);

	if (!nilfs) {

		err = -ENOMEM;

		goto failed_sbi;

	}

	sbi->s_nilfs = nilfs;

	sbi->s_super = sb;



	err = init_nilfs(nilfs, sbi, (char *)data);

	if (err)

		goto failed_sbi;

		goto failed_nilfs;



	spin_lock_init(&sbi->s_inode_lock);

	INIT_LIST_HEAD(&sbi->s_dirty_files);
@@ -885,14 +888,14 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 


	err = load_nilfs(nilfs, sbi);

	if (err)

		goto failed_sbi;

		goto failed_nilfs;



	cno = nilfs_last_cno(nilfs);

	err = nilfs_attach_checkpoint(sbi, cno, true, &fsroot);

	if (err) {

		printk(KERN_ERR "NILFS: error loading last checkpoint "

		       "(checkpoint number=%llu).\n", (unsigned long long)cno);

		goto failed_sbi;

		goto failed_nilfs;

	}



	if (!(sb->s_flags & MS_RDONLY)) {
@@ -921,8 +924,10 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 
 failed_checkpoint:

	nilfs_put_root(fsroot);



 failed_nilfs:

	destroy_nilfs(nilfs);



 failed_sbi:

	put_nilfs(nilfs);

	sb->s_fs_info = NULL;

	kfree(sbi);

	return err;
@@ -1077,7 +1082,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	struct nilfs_super_data sd;

	struct super_block *s;

	fmode_t mode = FMODE_READ;

	struct the_nilfs *nilfs;

	struct dentry *root_dentry;

	int err, s_new = false;
@@ -1095,18 +1099,10 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
		goto failed;

	}



	nilfs = find_or_create_nilfs(sd.bdev);

	if (!nilfs) {

		err = -ENOMEM;

		goto failed;

	}



	mutex_lock(&nilfs->ns_mount_mutex);



	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, sd.bdev);

	if (IS_ERR(s)) {

		err = PTR_ERR(s);

		goto failed_unlock;

		goto failed;

	}



	if (!s->s_root) {
@@ -1120,10 +1116,9 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
		strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));

		sb_set_blocksize(s, block_size(sd.bdev));



		err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0,

				       nilfs);

		err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);

		if (err)

			goto cancel_new;

			goto failed_super;



		s->s_flags |= MS_ACTIVE;

	} else if (!sd.cno) {
@@ -1153,17 +1148,12 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 


	if (sd.cno) {

		err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);

		if (err) {

			if (s_new)

				goto cancel_new;

		if (err)

			goto failed_super;

		}

	} else {

		root_dentry = dget(s->s_root);

	}



	mutex_unlock(&nilfs->ns_mount_mutex);

	put_nilfs(nilfs);

	if (!s_new)

		close_bdev_exclusive(sd.bdev, mode);
@@ -1173,24 +1163,11 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 


 failed_super:

	deactivate_locked_super(s);

 failed_unlock:

	mutex_unlock(&nilfs->ns_mount_mutex);

	put_nilfs(nilfs);



 failed:

	if (!s_new)

		close_bdev_exclusive(sd.bdev, mode);

	return err;



 cancel_new:

	/* Abandoning the newly allocated superblock */

	mutex_unlock(&nilfs->ns_mount_mutex);

	put_nilfs(nilfs);

	deactivate_locked_super(s);

	/*

	 * This deactivate_locked_super() invokes close_bdev_exclusive().

	 * We must finish all post-cleaning before this call;

	 * put_nilfs() needs the block device.

	 */

	return err;

}



struct file_system_type nilfs_fs_type = {

fs/nilfs2/the_nilfs.c

+5 −70
Original line number Diff line number Diff line
@@ -35,9 +35,6 @@ 
#include "segbuf.h"





static LIST_HEAD(nilfs_objects);

static DEFINE_SPINLOCK(nilfs_lock);



static int nilfs_valid_sb(struct nilfs_super_block *sbp);



void nilfs_set_last_segment(struct the_nilfs *nilfs,
@@ -61,16 +58,13 @@ void nilfs_set_last_segment(struct the_nilfs *nilfs, 
}



/**

 * alloc_nilfs - allocate the_nilfs structure

 * alloc_nilfs - allocate a nilfs object

 * @bdev: block device to which the_nilfs is related

 *

 * alloc_nilfs() allocates memory for the_nilfs and

 * initializes its reference count and locks.

 *

 * Return Value: On success, pointer to the_nilfs is returned.

 * On error, NULL is returned.

 */

static struct the_nilfs *alloc_nilfs(struct block_device *bdev)

struct the_nilfs *alloc_nilfs(struct block_device *bdev)

{

	struct the_nilfs *nilfs;
@@ -79,12 +73,9 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev) 
		return NULL;



	nilfs->ns_bdev = bdev;

	atomic_set(&nilfs->ns_count, 1);

	atomic_set(&nilfs->ns_ndirtyblks, 0);

	init_rwsem(&nilfs->ns_sem);

	mutex_init(&nilfs->ns_mount_mutex);

	init_rwsem(&nilfs->ns_writer_sem);

	INIT_LIST_HEAD(&nilfs->ns_list);

	INIT_LIST_HEAD(&nilfs->ns_gc_inodes);

	spin_lock_init(&nilfs->ns_last_segment_lock);

	nilfs->ns_cptree = RB_ROOT;
@@ -95,67 +86,11 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev) 
}



/**

 * find_or_create_nilfs - find or create nilfs object

 * @bdev: block device to which the_nilfs is related

 *

 * find_nilfs() looks up an existent nilfs object created on the

 * device and gets the reference count of the object.  If no nilfs object

 * is found on the device, a new nilfs object is allocated.

 *

 * Return Value: On success, pointer to the nilfs object is returned.

 * On error, NULL is returned.

 * destroy_nilfs - destroy nilfs object

 * @nilfs: nilfs object to be released

 */

struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)

void destroy_nilfs(struct the_nilfs *nilfs)

{

	struct the_nilfs *nilfs, *new = NULL;



 retry:

	spin_lock(&nilfs_lock);

	list_for_each_entry(nilfs, &nilfs_objects, ns_list) {

		if (nilfs->ns_bdev == bdev) {

			get_nilfs(nilfs);

			spin_unlock(&nilfs_lock);

			if (new)

				put_nilfs(new);

			return nilfs; /* existing object */

		}

	}

	if (new) {

		list_add_tail(&new->ns_list, &nilfs_objects);

		spin_unlock(&nilfs_lock);

		return new; /* new object */

	}

	spin_unlock(&nilfs_lock);



	new = alloc_nilfs(bdev);

	if (new)

		goto retry;

	return NULL; /* insufficient memory */

}



/**

 * put_nilfs - release a reference to the_nilfs

 * @nilfs: the_nilfs structure to be released

 *

 * put_nilfs() decrements a reference counter of the_nilfs.

 * If the reference count reaches zero, the_nilfs is freed.

 */

void put_nilfs(struct the_nilfs *nilfs)

{

	spin_lock(&nilfs_lock);

	if (!atomic_dec_and_test(&nilfs->ns_count)) {

		spin_unlock(&nilfs_lock);

		return;

	}

	list_del_init(&nilfs->ns_list);

	spin_unlock(&nilfs_lock);



	/*

	 * Increment of ns_count never occurs below because the caller

	 * of get_nilfs() holds at least one reference to the_nilfs.

	 * Thus its exclusion control is not required here.

	 */



	might_sleep();

	if (nilfs_loaded(nilfs)) {

		nilfs_mdt_destroy(nilfs->ns_sufile);

fs/nilfs2/the_nilfs.h

+2 −14
Original line number Diff line number Diff line
@@ -46,13 +46,10 @@ enum { 
/**

 * struct the_nilfs - struct to supervise multiple nilfs mount points

 * @ns_flags: flags

 * @ns_count: reference count

 * @ns_list: list head for nilfs_list

 * @ns_bdev: block device

 * @ns_bdi: backing dev info

 * @ns_writer: back pointer to writable nilfs_sb_info

 * @ns_sem: semaphore for shared states

 * @ns_mount_mutex: mutex protecting mount process of nilfs

 * @ns_writer_sem: semaphore protecting ns_writer attach/detach

 * @ns_sbh: buffer heads of on-disk super blocks

 * @ns_sbp: pointers to super block data
@@ -94,14 +91,11 @@ enum { 
 */

struct the_nilfs {

	unsigned long		ns_flags;

	atomic_t		ns_count;

	struct list_head	ns_list;



	struct block_device    *ns_bdev;

	struct backing_dev_info *ns_bdi;

	struct nilfs_sb_info   *ns_writer;

	struct rw_semaphore	ns_sem;

	struct mutex		ns_mount_mutex;

	struct rw_semaphore	ns_writer_sem;



	/*
@@ -239,8 +233,8 @@ static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs) 
}



void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);

struct the_nilfs *find_or_create_nilfs(struct block_device *);

void put_nilfs(struct the_nilfs *);

struct the_nilfs *alloc_nilfs(struct block_device *bdev);

void destroy_nilfs(struct the_nilfs *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);
@@ -256,12 +250,6 @@ void nilfs_fall_back_super_block(struct the_nilfs *); 
void nilfs_swap_super_block(struct the_nilfs *);





static inline void get_nilfs(struct the_nilfs *nilfs)

{

	/* Caller must have at least one reference of the_nilfs. */

	atomic_inc(&nilfs->ns_count);

}



static inline void nilfs_get_root(struct nilfs_root *root)

{

	atomic_inc(&root->count);