Commit 6dd47406 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Al Viro
Browse files

nilfs2: simplify remaining sget() use 



This simplifies the test function passed on the remaining sget()
callsite in nilfs.

Instead of checking mount type (i.e. ro-mount/rw-mount/snapshot mount)
in the test function passed to sget(), this patch first looks up the
nilfs_sb_info struct which the given mount type matches, and then
acquires the super block instance holding the nilfs_sb_info.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3f82ff55

fs/nilfs2/sb.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ struct nilfs_sb_info { 
	struct super_block *s_super;	/* reverse pointer to super_block */

	struct the_nilfs *s_nilfs;

	struct list_head s_list;	/* list head for nilfs->ns_supers */

	atomic_t s_count;		/* reference count */



	/* Segment constructor */

	struct list_head s_dirty_files;	/* dirty files list */

fs/nilfs2/super.c

+17 −25
Original line number Diff line number Diff line
@@ -336,7 +336,7 @@ static void nilfs_put_super(struct super_block *sb) 
	put_nilfs(sbi->s_nilfs);

	sbi->s_super = NULL;

	sb->s_fs_info = NULL;

	kfree(sbi);

	nilfs_put_sbinfo(sbi);



	unlock_kernel();

}
@@ -785,6 +785,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 
	get_nilfs(nilfs);

	sbi->s_nilfs = nilfs;

	sbi->s_super = sb;

	atomic_set(&sbi->s_count, 1);



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

	if (err)
@@ -902,7 +903,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 
 failed_sbi:

	put_nilfs(nilfs);

	sb->s_fs_info = NULL;

	kfree(sbi);

	nilfs_put_sbinfo(sbi);

	return err;

}
@@ -1014,6 +1015,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) 


struct nilfs_super_data {

	struct block_device *bdev;

	struct nilfs_sb_info *sbi;

	__u64 cno;

	int flags;

};
@@ -1071,27 +1073,8 @@ static int nilfs_set_bdev_super(struct super_block *s, void *data) 
static int nilfs_test_bdev_super(struct super_block *s, void *data)

{

	struct nilfs_super_data *sd = data;

	int ret;



	if (s->s_bdev != sd->bdev)

		return 0;



	if (!((s->s_flags | sd->flags) & MS_RDONLY))

		return 1; /* Reuse an old R/W-mode super_block */



	if (s->s_flags & sd->flags & MS_RDONLY) {

		if (down_read_trylock(&s->s_umount)) {

			ret = s->s_root &&

				(sd->cno == NILFS_SB(s)->s_snapshot_cno);

			up_read(&s->s_umount);

			/*

			 * This path is locked with sb_lock by sget().

			 * So, drop_super() causes deadlock.

			 */

			return ret;

		}

	}

	return 0;

	return sd->sbi && s->s_fs_info == (void *)sd->sbi;

}



static int
@@ -1112,7 +1095,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	 * much more information than normal filesystems to identify mount

	 * instance.  For snapshot mounts, not only a mount type (ro-mount

	 * or rw-mount) but also a checkpoint number is required.

	 * The results are passed in sget() using nilfs_super_data.

	 */

	sd.cno = 0;

	sd.flags = flags;
@@ -1148,13 +1130,23 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	}



	/*

	 * Search specified snapshot or R/W mode super_block

	 * Find existing nilfs_sb_info struct

	 */

	sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);



	if (!sd.cno)

		/* trying to get the latest checkpoint.  */

		sd.cno = nilfs_last_cno(nilfs);



	/*

	 * Get super block instance holding the nilfs_sb_info struct.

	 * A new instance is allocated if no existing mount is present or

	 * existing instance has been unmounted.

	 */

	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, &sd);

	if (sd.sbi)

		nilfs_put_sbinfo(sd.sbi);



	if (IS_ERR(s)) {

		err = PTR_ERR(s);

		goto failed_unlock;

fs/nilfs2/the_nilfs.c

+50 −0
Original line number Diff line number Diff line
@@ -664,6 +664,56 @@ int nilfs_near_disk_full(struct the_nilfs *nilfs) 
	return ret;

}



/**

 * nilfs_find_sbinfo - find existing nilfs_sb_info structure

 * @nilfs: nilfs object

 * @rw_mount: mount type (non-zero value for read/write mount)

 * @cno: checkpoint number (zero for read-only mount)

 *

 * nilfs_find_sbinfo() returns the nilfs_sb_info structure which

 * @rw_mount and @cno (in case of snapshots) matched.  If no instance

 * was found, NULL is returned.  Although the super block instance can

 * be unmounted after this function returns, the nilfs_sb_info struct

 * is kept on memory until nilfs_put_sbinfo() is called.

 */

struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,

					int rw_mount, __u64 cno)

{

	struct nilfs_sb_info *sbi;



	down_read(&nilfs->ns_sem);

	/*

	 * The SNAPSHOT flag and sb->s_flags are supposed to be

	 * protected with nilfs->ns_sem.

	 */

	sbi = nilfs->ns_current;

	if (rw_mount) {

		if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))

			goto found; /* read/write mount */

		else

			goto out;

	} else if (cno == 0) {

		if (sbi && (sbi->s_super->s_flags & MS_RDONLY))

			goto found; /* read-only mount */

		else

			goto out;

	}



	list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {

		if (nilfs_test_opt(sbi, SNAPSHOT) &&

		    sbi->s_snapshot_cno == cno)

			goto found; /* snapshot mount */

	}

 out:

	up_read(&nilfs->ns_sem);

	return NULL;



 found:

	atomic_inc(&sbi->s_count);

	up_read(&nilfs->ns_sem);

	return sbi;

}



int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,

				int snapshot_mount)

{

fs/nilfs2/the_nilfs.h

+7 −0
Original line number Diff line number Diff line
@@ -201,6 +201,7 @@ void put_nilfs(struct the_nilfs *); 
int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);

int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);

int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);

struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);

int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);

int nilfs_near_disk_full(struct the_nilfs *);

void nilfs_fall_back_super_block(struct the_nilfs *);
@@ -243,6 +244,12 @@ nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 
	mutex_unlock(&nilfs->ns_writer_mutex);

}



static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)

{

	if (!atomic_dec_and_test(&sbi->s_count))

		kfree(sbi);

}



static inline void

nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,

			sector_t *seg_start, sector_t *seg_end)

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