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Commit 3f82ff55 authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Al Viro
Browse files

nilfs2: get rid of sget use for checking if current mount is present 



This stops using sget() for checking if an r/w-mount or an r/o-mount
exists on the device.  This elimination uses a back pointer to the
current mount added to nilfs object.

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 33c8e57c

fs/nilfs2/super.c

+32 −60
Original line number Diff line number Diff line
@@ -67,8 +67,6 @@ MODULE_LICENSE("GPL"); 


static void nilfs_write_super(struct super_block *sb);

static int nilfs_remount(struct super_block *sb, int *flags, char *data);

static int test_exclusive_mount(struct file_system_type *fs_type,

				struct block_device *bdev, int flags);



/**

 * nilfs_error() - report failure condition on a filesystem
@@ -329,6 +327,10 @@ static void nilfs_put_super(struct super_block *sb) 
		nilfs_commit_super(sbi, 1);

		up_write(&nilfs->ns_sem);

	}

	down_write(&nilfs->ns_sem);

	if (nilfs->ns_current == sbi)

		nilfs->ns_current = NULL;

	up_write(&nilfs->ns_sem);



	nilfs_detach_checkpoint(sbi);

	put_nilfs(sbi->s_nilfs);
@@ -880,6 +882,11 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, 
		goto failed_root;

	}



	down_write(&nilfs->ns_sem);

	if (!nilfs_test_opt(sbi, SNAPSHOT))

		nilfs->ns_current = sbi;

	up_write(&nilfs->ns_sem);



	return 0;



 failed_root:
@@ -958,14 +965,16 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) 
		 * by fsck since we originally mounted the partition.)

		 */

		down(&sb->s_bdev->bd_mount_sem);

		/* Check existing RW-mount */

		if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {

		down_read(&nilfs->ns_sem);

		if (nilfs->ns_current && nilfs->ns_current != sbi) {

			printk(KERN_WARNING "NILFS (device %s): couldn't "

			       "remount because a RW-mount exists.\n",

			       "remount because an RW-mount exists.\n",

			       sb->s_id);

			up_read(&nilfs->ns_sem);

			err = -EBUSY;

			goto rw_remount_failed;

		}

		up_read(&nilfs->ns_sem);

		if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {

			printk(KERN_WARNING "NILFS (device %s): couldn't "

			       "remount because the current RO-mount is not "
@@ -984,6 +993,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data) 


		down_write(&nilfs->ns_sem);

		nilfs_setup_super(sbi);

		nilfs->ns_current = sbi;

		up_write(&nilfs->ns_sem);



		up(&sb->s_bdev->bd_mount_sem);
@@ -1118,11 +1128,24 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	}



	down(&sd.bdev->bd_mount_sem);

	if (!sd.cno &&

	    (err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {

		err = (err < 0) ? : -EBUSY;



	if (!sd.cno) {

		/*

		 * Check if an exclusive mount exists or not.

		 * Snapshot mounts coexist with a current mount

		 * (i.e. rw-mount or ro-mount), whereas rw-mount and

		 * ro-mount are mutually exclusive.

		 */

		down_read(&nilfs->ns_sem);

		if (nilfs->ns_current &&

		    ((nilfs->ns_current->s_super->s_flags ^ flags)

		     & MS_RDONLY)) {

			up_read(&nilfs->ns_sem);

			err = -EBUSY;

			goto failed_unlock;

		}

		up_read(&nilfs->ns_sem);

	}



	/*

	 * Search specified snapshot or R/W mode super_block
@@ -1182,57 +1205,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, 
	return err;

}



static int nilfs_test_bdev_super3(struct super_block *s, void *data)

{

	struct nilfs_super_data *sd = data;

	int ret;



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

		return 0;

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

		ret = (s->s_flags & MS_RDONLY) && s->s_root &&

			nilfs_test_opt(NILFS_SB(s), SNAPSHOT);

		up_read(&s->s_umount);

		if (ret)

			return 0; /* ignore snapshot mounts */

	}

	return !((sd->flags ^ s->s_flags) & MS_RDONLY);

}



static int __false_bdev_super(struct super_block *s, void *data)

{

#if 0 /* XXX: workaround for lock debug. This is not good idea */

	up_write(&s->s_umount);

#endif

	return -EFAULT;

}



/**

 * test_exclusive_mount - check whether an exclusive RW/RO mount exists or not.

 * fs_type: filesystem type

 * bdev: block device

 * flag: 0 (check rw-mount) or MS_RDONLY (check ro-mount)

 * res: pointer to an integer to store result

 *

 * This function must be called within a section protected by bd_mount_mutex.

 */

static int test_exclusive_mount(struct file_system_type *fs_type,

				struct block_device *bdev, int flags)

{

	struct super_block *s;

	struct nilfs_super_data sd = { .flags = flags, .bdev = bdev };



	s = sget(fs_type, nilfs_test_bdev_super3, __false_bdev_super, &sd);

	if (IS_ERR(s)) {

		if (PTR_ERR(s) != -EFAULT)

			return PTR_ERR(s);

		return 0;  /* Not found */

	}

	up_write(&s->s_umount);

	deactivate_super(s);

	return 1;  /* Found */

}



struct file_system_type nilfs_fs_type = {

	.owner    = THIS_MODULE,

	.name     = "nilfs2",

fs/nilfs2/the_nilfs.h

+3 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ enum { 
 * @ns_sem: semaphore for shared states

 * @ns_writer_mutex: mutex protecting ns_writer attach/detach

 * @ns_writer_refcount: number of referrers on ns_writer

 * @ns_current: back pointer to current mount

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

 * @ns_sbp: pointers to super block data

 * @ns_sbwtime: previous write time of super blocks
@@ -98,6 +99,8 @@ struct the_nilfs { 
	struct mutex		ns_writer_mutex;

	atomic_t		ns_writer_refcount;



	struct nilfs_sb_info   *ns_current;



	/*

	 * used for

	 * - loading the latest checkpoint exclusively.