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btrfs: add btrfs_mount_root() and new file_system_type

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Add btrfs_mount_root() and new file_system_type for preparation of cleanup
of btrfs_mount(). Code path is not changed yet.

btrfs_mount_root() is almost the same as current btrfs_mount(), but doesn't
have subvolume related part.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Misono, Tomohiro 2017-12-14 17:24:30 +09:00 committed by David Sterba
parent aab6e9edf0
commit 72fa39f5c7
1 changed files with 123 additions and 0 deletions
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123
fs/btrfs/super.c
View File

@ -65,7 +65,15 @@
#include <trace/events/btrfs.h>
static const struct super_operations btrfs_super_ops;
/*
* Types for mounting the default subvolume and a subvolume explicitly
* requested by subvol=/path. That way the callchain is straightforward and we
* don't have to play tricks with the mount options and recursive calls to
* btrfs_mount.
*/
static struct file_system_type btrfs_fs_type;
static struct file_system_type btrfs_root_fs_type;
static int btrfs_remount(struct super_block *sb, int *flags, char *data);
@ -1549,6 +1557,112 @@ static int setup_security_options(struct btrfs_fs_info *fs_info,
return ret;
}
static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
int flags, const char *device_name, void *data)
{
struct block_device *bdev = NULL;
struct super_block *s;
struct btrfs_fs_devices *fs_devices = NULL;
struct btrfs_fs_info *fs_info = NULL;
struct security_mnt_opts new_sec_opts;
fmode_t mode = FMODE_READ;
char *subvol_name = NULL;
u64 subvol_objectid = 0;
int error = 0;
if (!(flags & SB_RDONLY))
mode |= FMODE_WRITE;
error = btrfs_parse_early_options(data, mode, fs_type,
&subvol_name, &subvol_objectid,
&fs_devices);
if (error) {
kfree(subvol_name);
return ERR_PTR(error);
}
security_init_mnt_opts(&new_sec_opts);
if (data) {
error = parse_security_options(data, &new_sec_opts);
if (error)
return ERR_PTR(error);
}
error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
if (error)
goto error_sec_opts;
/*
* Setup a dummy root and fs_info for test/set super. This is because
* we don't actually fill this stuff out until open_ctree, but we need
* it for searching for existing supers, so this lets us do that and
* then open_ctree will properly initialize everything later.
*/
fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
if (!fs_info) {
error = -ENOMEM;
goto error_sec_opts;
}
fs_info->fs_devices = fs_devices;
fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
security_init_mnt_opts(&fs_info->security_opts);
if (!fs_info->super_copy || !fs_info->super_for_commit) {
error = -ENOMEM;
goto error_fs_info;
}
error = btrfs_open_devices(fs_devices, mode, fs_type);
if (error)
goto error_fs_info;
if (!(flags & SB_RDONLY) && fs_devices->rw_devices == 0) {
error = -EACCES;
goto error_close_devices;
}
bdev = fs_devices->latest_bdev;
s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | SB_NOSEC,
fs_info);
if (IS_ERR(s)) {
error = PTR_ERR(s);
goto error_close_devices;
}
if (s->s_root) {
btrfs_close_devices(fs_devices);
free_fs_info(fs_info);
if ((flags ^ s->s_flags) & SB_RDONLY)
error = -EBUSY;
} else {
snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
btrfs_sb(s)->bdev_holder = fs_type;
error = btrfs_fill_super(s, fs_devices, data);
}
if (error) {
deactivate_locked_super(s);
goto error_sec_opts;
}
fs_info = btrfs_sb(s);
error = setup_security_options(fs_info, s, &new_sec_opts);
if (error) {
deactivate_locked_super(s);
goto error_sec_opts;
}
return dget(s->s_root);
error_close_devices:
btrfs_close_devices(fs_devices);
error_fs_info:
free_fs_info(fs_info);
error_sec_opts:
security_free_mnt_opts(&new_sec_opts);
return ERR_PTR(error);
}
/*
* Find a superblock for the given device / mount point.
*
@ -2170,6 +2284,15 @@ static struct file_system_type btrfs_fs_type = {
.kill_sb = btrfs_kill_super,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
};
static struct file_system_type btrfs_root_fs_type = {
.owner = THIS_MODULE,
.name = "btrfs",
.mount = btrfs_mount_root,
.kill_sb = btrfs_kill_super,
.fs_flags = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
};
MODULE_ALIAS_FS("btrfs");
static int btrfs_control_open(struct inode *inode, struct file *file)