Btrfs: Add mount into directory support (4b82d6e4) · Commits · 戴 / test

fs/btrfs/super.c

+120 −3

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		* Boston, MA 021110-1307, USA.
		*/

		#include <linux/blkdev.h>
		#include <linux/module.h>
		#include <linux/buffer_head.h>
		#include <linux/fs.h>
		@@ -26,6 +27,7 @@
		#include <linux/string.h>
		#include <linux/smp_lock.h>
		#include <linux/backing-dev.h>
		#include <linux/mount.h>
		#include <linux/mpage.h>
		#include <linux/swap.h>
		#include <linux/writeback.h>
		@@ -145,11 +147,126 @@ static void btrfs_write_super(struct super_block *sb)
		sb->s_dirt = 0;
		}

		/*
		* This is almost a copy of get_sb_bdev in fs/super.c.
		* We need the local copy to allow direct mounting of
		* subvolumes, but this could be easily integrated back
		* into the generic version. --hch
		*/

		/* start copy & paste */
		static int set_bdev_super(struct super_block s, void data)
		{
		s->s_bdev = data;
		s->s_dev = s->s_bdev->bd_dev;
		return 0;
		}

		static int test_bdev_super(struct super_block s, void data)
		{
		return (void *)s->s_bdev == data;
		}

		int btrfs_get_sb_bdev(struct file_system_type *fs_type,
		int flags, const char dev_name, void data,
		int (fill_super)(struct super_block , void *, int),
		struct vfsmount mnt, const char subvol)
		{
		struct block_device *bdev = NULL;
		struct super_block *s;
		struct dentry *root;
		int error = 0;

		bdev = open_bdev_excl(dev_name, flags, fs_type);
		if (IS_ERR(bdev))
		return PTR_ERR(bdev);

		/*
		* once the super is inserted into the list by sget, s_umount
		* will protect the lockfs code from trying to start a snapshot
		* while we are mounting
		*/
		down(&bdev->bd_mount_sem);
		s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
		up(&bdev->bd_mount_sem);
		if (IS_ERR(s))
		goto error_s;

		if (s->s_root) {
		if ((flags ^ s->s_flags) & MS_RDONLY) {
		up_write(&s->s_umount);
		deactivate_super(s);
		error = -EBUSY;
		goto error_bdev;
		}

		close_bdev_excl(bdev);
		} else {
		char b[BDEVNAME_SIZE];

		s->s_flags = flags;
		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
		sb_set_blocksize(s, block_size(bdev));
		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
		if (error) {
		up_write(&s->s_umount);
		deactivate_super(s);
		goto error;
		}

		s->s_flags \|= MS_ACTIVE;
		}

		if (subvol) {
		root = lookup_one_len(subvol, s->s_root, strlen(subvol));
		if (IS_ERR(root)) {
		up_write(&s->s_umount);
		deactivate_super(s);
		error = PTR_ERR(root);
		goto error;
		}
		if (!root->d_inode) {
		dput(root);
		up_write(&s->s_umount);
		deactivate_super(s);
		error = -ENXIO;
		goto error;
		}
		} else {
		root = dget(s->s_root);
		}

		mnt->mnt_sb = s;
		mnt->mnt_root = root;
		return 0;

		error_s:
		error = PTR_ERR(s);
		error_bdev:
		close_bdev_excl(bdev);
		error:
		return error;
		}
		/* end copy & paste */

		static int btrfs_get_sb(struct file_system_type *fs_type,
		int flags, const char dev_name, void data, struct vfsmount *mnt)
		int flags, const char identifier, void data, struct vfsmount *mnt)
		{
		return get_sb_bdev(fs_type, flags, dev_name, data,
		btrfs_fill_super, mnt);
		int ret;
		char *_identifier = kstrdup(identifier, GFP_KERNEL);
		char *subvol_name;
		const char *dev_name;

		subvol_name = _identifier;
		dev_name = strsep(&subvol_name, ":");
		if (!dev_name)
		return -ENOMEM;

		ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
		btrfs_fill_super, mnt,
		subvol_name ? subvol_name : "default");
		kfree(_identifier);
		return ret;
		}

		static int btrfs_statfs(struct dentry dentry, struct kstatfs buf)

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