Btrfs: Add mount into directory support

Modified form of original patch from Christoph Hellwig to make btrfs
mount into the default subvolume by default.

mount /dev/somedevice:subvolumename to get other subvolumes or
mount /dev/somedevice:. to get the root

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Yan 2007-08-29 09:11:44 -04:00 committed by David Woodhouse
parent 1b4ab1bb4b
commit 4b82d6e4a5

View File

@ -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;
}
static int btrfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
/*
* 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)
{
return get_sb_bdev(fs_type, flags, dev_name, data,
btrfs_fill_super, mnt);
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 *identifier, void *data, struct vfsmount *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)