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ioctl.c
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ioctl.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*/
#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/time.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/writeback.h>
#include <linux/compat.h>
#include <linux/security.h>
#include <linux/xattr.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/uuid.h>
#include <linux/btrfs.h>
#include <linux/uaccess.h>
#include <linux/iversion.h>
#include <linux/fileattr.h>
#include <linux/fsverity.h>
#include <linux/sched/xacct.h>
#include "ctree.h"
#include "disk-io.h"
#include "export.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "print-tree.h"
#include "volumes.h"
#include "locking.h"
#include "backref.h"
#include "rcu-string.h"
#include "send.h"
#include "dev-replace.h"
#include "props.h"
#include "sysfs.h"
#include "qgroup.h"
#include "tree-log.h"
#include "compression.h"
#include "space-info.h"
#include "delalloc-space.h"
#include "block-group.h"
#include "subpage.h"
#ifdef CONFIG_64BIT
/* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
* structures are incorrect, as the timespec structure from userspace
* is 4 bytes too small. We define these alternatives here to teach
* the kernel about the 32-bit struct packing.
*/
struct btrfs_ioctl_timespec_32 {
__u64 sec;
__u32 nsec;
} __attribute__ ((__packed__));
struct btrfs_ioctl_received_subvol_args_32 {
char uuid[BTRFS_UUID_SIZE]; /* in */
__u64 stransid; /* in */
__u64 rtransid; /* out */
struct btrfs_ioctl_timespec_32 stime; /* in */
struct btrfs_ioctl_timespec_32 rtime; /* out */
__u64 flags; /* in */
__u64 reserved[16]; /* in */
} __attribute__ ((__packed__));
#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
struct btrfs_ioctl_received_subvol_args_32)
#endif
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
struct btrfs_ioctl_send_args_32 {
__s64 send_fd; /* in */
__u64 clone_sources_count; /* in */
compat_uptr_t clone_sources; /* in */
__u64 parent_root; /* in */
__u64 flags; /* in */
__u32 version; /* in */
__u8 reserved[28]; /* in */
} __attribute__ ((__packed__));
#define BTRFS_IOC_SEND_32 _IOW(BTRFS_IOCTL_MAGIC, 38, \
struct btrfs_ioctl_send_args_32)
struct btrfs_ioctl_encoded_io_args_32 {
compat_uptr_t iov;
compat_ulong_t iovcnt;
__s64 offset;
__u64 flags;
__u64 len;
__u64 unencoded_len;
__u64 unencoded_offset;
__u32 compression;
__u32 encryption;
__u8 reserved[64];
};
#define BTRFS_IOC_ENCODED_READ_32 _IOR(BTRFS_IOCTL_MAGIC, 64, \
struct btrfs_ioctl_encoded_io_args_32)
#define BTRFS_IOC_ENCODED_WRITE_32 _IOW(BTRFS_IOCTL_MAGIC, 64, \
struct btrfs_ioctl_encoded_io_args_32)
#endif
/* Mask out flags that are inappropriate for the given type of inode. */
static unsigned int btrfs_mask_fsflags_for_type(struct inode *inode,
unsigned int flags)
{
if (S_ISDIR(inode->i_mode))
return flags;
else if (S_ISREG(inode->i_mode))
return flags & ~FS_DIRSYNC_FL;
else
return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
}
/*
* Export internal inode flags to the format expected by the FS_IOC_GETFLAGS
* ioctl.
*/
static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode)
{
unsigned int iflags = 0;
u32 flags = binode->flags;
u32 ro_flags = binode->ro_flags;
if (flags & BTRFS_INODE_SYNC)
iflags |= FS_SYNC_FL;
if (flags & BTRFS_INODE_IMMUTABLE)
iflags |= FS_IMMUTABLE_FL;
if (flags & BTRFS_INODE_APPEND)
iflags |= FS_APPEND_FL;
if (flags & BTRFS_INODE_NODUMP)
iflags |= FS_NODUMP_FL;
if (flags & BTRFS_INODE_NOATIME)
iflags |= FS_NOATIME_FL;
if (flags & BTRFS_INODE_DIRSYNC)
iflags |= FS_DIRSYNC_FL;
if (flags & BTRFS_INODE_NODATACOW)
iflags |= FS_NOCOW_FL;
if (ro_flags & BTRFS_INODE_RO_VERITY)
iflags |= FS_VERITY_FL;
if (flags & BTRFS_INODE_NOCOMPRESS)
iflags |= FS_NOCOMP_FL;
else if (flags & BTRFS_INODE_COMPRESS)
iflags |= FS_COMPR_FL;
return iflags;
}
/*
* Update inode->i_flags based on the btrfs internal flags.
*/
void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
{
struct btrfs_inode *binode = BTRFS_I(inode);
unsigned int new_fl = 0;
if (binode->flags & BTRFS_INODE_SYNC)
new_fl |= S_SYNC;
if (binode->flags & BTRFS_INODE_IMMUTABLE)
new_fl |= S_IMMUTABLE;
if (binode->flags & BTRFS_INODE_APPEND)
new_fl |= S_APPEND;
if (binode->flags & BTRFS_INODE_NOATIME)
new_fl |= S_NOATIME;
if (binode->flags & BTRFS_INODE_DIRSYNC)
new_fl |= S_DIRSYNC;
if (binode->ro_flags & BTRFS_INODE_RO_VERITY)
new_fl |= S_VERITY;
set_mask_bits(&inode->i_flags,
S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC |
S_VERITY, new_fl);
}
/*
* Check if @flags are a supported and valid set of FS_*_FL flags and that
* the old and new flags are not conflicting
*/
static int check_fsflags(unsigned int old_flags, unsigned int flags)
{
if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
FS_NOATIME_FL | FS_NODUMP_FL | \
FS_SYNC_FL | FS_DIRSYNC_FL | \
FS_NOCOMP_FL | FS_COMPR_FL |
FS_NOCOW_FL))
return -EOPNOTSUPP;
/* COMPR and NOCOMP on new/old are valid */
if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
return -EINVAL;
if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
return -EINVAL;
/* NOCOW and compression options are mutually exclusive */
if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
return -EINVAL;
if ((flags & FS_NOCOW_FL) && (old_flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
return -EINVAL;
return 0;
}
static int check_fsflags_compatible(struct btrfs_fs_info *fs_info,
unsigned int flags)
{
if (btrfs_is_zoned(fs_info) && (flags & FS_NOCOW_FL))
return -EPERM;
return 0;
}
/*
* Set flags/xflags from the internal inode flags. The remaining items of
* fsxattr are zeroed.
*/
int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
struct btrfs_inode *binode = BTRFS_I(d_inode(dentry));
fileattr_fill_flags(fa, btrfs_inode_flags_to_fsflags(binode));
return 0;
}
int btrfs_fileattr_set(struct user_namespace *mnt_userns,
struct dentry *dentry, struct fileattr *fa)
{
struct inode *inode = d_inode(dentry);
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct btrfs_inode *binode = BTRFS_I(inode);
struct btrfs_root *root = binode->root;
struct btrfs_trans_handle *trans;
unsigned int fsflags, old_fsflags;
int ret;
const char *comp = NULL;
u32 binode_flags;
if (btrfs_root_readonly(root))
return -EROFS;
if (fileattr_has_fsx(fa))
return -EOPNOTSUPP;
fsflags = btrfs_mask_fsflags_for_type(inode, fa->flags);
old_fsflags = btrfs_inode_flags_to_fsflags(binode);
ret = check_fsflags(old_fsflags, fsflags);
if (ret)
return ret;
ret = check_fsflags_compatible(fs_info, fsflags);
if (ret)
return ret;
binode_flags = binode->flags;
if (fsflags & FS_SYNC_FL)
binode_flags |= BTRFS_INODE_SYNC;
else
binode_flags &= ~BTRFS_INODE_SYNC;
if (fsflags & FS_IMMUTABLE_FL)
binode_flags |= BTRFS_INODE_IMMUTABLE;
else
binode_flags &= ~BTRFS_INODE_IMMUTABLE;
if (fsflags & FS_APPEND_FL)
binode_flags |= BTRFS_INODE_APPEND;
else
binode_flags &= ~BTRFS_INODE_APPEND;
if (fsflags & FS_NODUMP_FL)
binode_flags |= BTRFS_INODE_NODUMP;
else
binode_flags &= ~BTRFS_INODE_NODUMP;
if (fsflags & FS_NOATIME_FL)
binode_flags |= BTRFS_INODE_NOATIME;
else
binode_flags &= ~BTRFS_INODE_NOATIME;
/* If coming from FS_IOC_FSSETXATTR then skip unconverted flags */
if (!fa->flags_valid) {
/* 1 item for the inode */
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans))
return PTR_ERR(trans);
goto update_flags;
}
if (fsflags & FS_DIRSYNC_FL)
binode_flags |= BTRFS_INODE_DIRSYNC;
else
binode_flags &= ~BTRFS_INODE_DIRSYNC;
if (fsflags & FS_NOCOW_FL) {
if (S_ISREG(inode->i_mode)) {
/*
* It's safe to turn csums off here, no extents exist.
* Otherwise we want the flag to reflect the real COW
* status of the file and will not set it.
*/
if (inode->i_size == 0)
binode_flags |= BTRFS_INODE_NODATACOW |
BTRFS_INODE_NODATASUM;
} else {
binode_flags |= BTRFS_INODE_NODATACOW;
}
} else {
/*
* Revert back under same assumptions as above
*/
if (S_ISREG(inode->i_mode)) {
if (inode->i_size == 0)
binode_flags &= ~(BTRFS_INODE_NODATACOW |
BTRFS_INODE_NODATASUM);
} else {
binode_flags &= ~BTRFS_INODE_NODATACOW;
}
}
/*
* The COMPRESS flag can only be changed by users, while the NOCOMPRESS
* flag may be changed automatically if compression code won't make
* things smaller.
*/
if (fsflags & FS_NOCOMP_FL) {
binode_flags &= ~BTRFS_INODE_COMPRESS;
binode_flags |= BTRFS_INODE_NOCOMPRESS;
} else if (fsflags & FS_COMPR_FL) {
if (IS_SWAPFILE(inode))
return -ETXTBSY;
binode_flags |= BTRFS_INODE_COMPRESS;
binode_flags &= ~BTRFS_INODE_NOCOMPRESS;
comp = btrfs_compress_type2str(fs_info->compress_type);
if (!comp || comp[0] == 0)
comp = btrfs_compress_type2str(BTRFS_COMPRESS_ZLIB);
} else {
binode_flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
}
/*
* 1 for inode item
* 2 for properties
*/
trans = btrfs_start_transaction(root, 3);
if (IS_ERR(trans))
return PTR_ERR(trans);
if (comp) {
ret = btrfs_set_prop(trans, inode, "btrfs.compression", comp,
strlen(comp), 0);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out_end_trans;
}
} else {
ret = btrfs_set_prop(trans, inode, "btrfs.compression", NULL,
0, 0);
if (ret && ret != -ENODATA) {
btrfs_abort_transaction(trans, ret);
goto out_end_trans;
}
}
update_flags:
binode->flags = binode_flags;
btrfs_sync_inode_flags_to_i_flags(inode);
inode_inc_iversion(inode);
inode->i_ctime = current_time(inode);
ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
out_end_trans:
btrfs_end_transaction(trans);
return ret;
}
/*
* Start exclusive operation @type, return true on success
*/
bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,
enum btrfs_exclusive_operation type)
{
bool ret = false;
spin_lock(&fs_info->super_lock);
if (fs_info->exclusive_operation == BTRFS_EXCLOP_NONE) {
fs_info->exclusive_operation = type;
ret = true;
}
spin_unlock(&fs_info->super_lock);
return ret;
}
/*
* Conditionally allow to enter the exclusive operation in case it's compatible
* with the running one. This must be paired with btrfs_exclop_start_unlock and
* btrfs_exclop_finish.
*
* Compatibility:
* - the same type is already running
* - when trying to add a device and balance has been paused
* - not BTRFS_EXCLOP_NONE - this is intentionally incompatible and the caller
* must check the condition first that would allow none -> @type
*/
bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,
enum btrfs_exclusive_operation type)
{
spin_lock(&fs_info->super_lock);
if (fs_info->exclusive_operation == type ||
(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED &&
type == BTRFS_EXCLOP_DEV_ADD))
return true;
spin_unlock(&fs_info->super_lock);
return false;
}
void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info)
{
spin_unlock(&fs_info->super_lock);
}
void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)
{
spin_lock(&fs_info->super_lock);
WRITE_ONCE(fs_info->exclusive_operation, BTRFS_EXCLOP_NONE);
spin_unlock(&fs_info->super_lock);
sysfs_notify(&fs_info->fs_devices->fsid_kobj, NULL, "exclusive_operation");
}
void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
enum btrfs_exclusive_operation op)
{
switch (op) {
case BTRFS_EXCLOP_BALANCE_PAUSED:
spin_lock(&fs_info->super_lock);
ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE ||
fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD);
fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE_PAUSED;
spin_unlock(&fs_info->super_lock);
break;
case BTRFS_EXCLOP_BALANCE:
spin_lock(&fs_info->super_lock);
ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED);
fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE;
spin_unlock(&fs_info->super_lock);
break;
default:
btrfs_warn(fs_info,
"invalid exclop balance operation %d requested", op);
}
}
static int btrfs_ioctl_getversion(struct inode *inode, int __user *arg)
{
return put_user(inode->i_generation, arg);
}
static noinline int btrfs_ioctl_fitrim(struct btrfs_fs_info *fs_info,
void __user *arg)
{
struct btrfs_device *device;
struct fstrim_range range;
u64 minlen = ULLONG_MAX;
u64 num_devices = 0;
int ret;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/*
* btrfs_trim_block_group() depends on space cache, which is not
* available in zoned filesystem. So, disallow fitrim on a zoned
* filesystem for now.
*/
if (btrfs_is_zoned(fs_info))
return -EOPNOTSUPP;
/*
* If the fs is mounted with nologreplay, which requires it to be
* mounted in RO mode as well, we can not allow discard on free space
* inside block groups, because log trees refer to extents that are not
* pinned in a block group's free space cache (pinning the extents is
* precisely the first phase of replaying a log tree).
*/
if (btrfs_test_opt(fs_info, NOLOGREPLAY))
return -EROFS;
rcu_read_lock();
list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
dev_list) {
if (!device->bdev || !bdev_max_discard_sectors(device->bdev))
continue;
num_devices++;
minlen = min_t(u64, bdev_discard_granularity(device->bdev),
minlen);
}
rcu_read_unlock();
if (!num_devices)
return -EOPNOTSUPP;
if (copy_from_user(&range, arg, sizeof(range)))
return -EFAULT;
/*
* NOTE: Don't truncate the range using super->total_bytes. Bytenr of
* block group is in the logical address space, which can be any
* sectorsize aligned bytenr in the range [0, U64_MAX].
*/
if (range.len < fs_info->sb->s_blocksize)
return -EINVAL;
range.minlen = max(range.minlen, minlen);
ret = btrfs_trim_fs(fs_info, &range);
if (ret < 0)
return ret;
if (copy_to_user(arg, &range, sizeof(range)))
return -EFAULT;
return 0;
}
int __pure btrfs_is_empty_uuid(u8 *uuid)
{
int i;
for (i = 0; i < BTRFS_UUID_SIZE; i++) {
if (uuid[i])
return 0;
}
return 1;
}
/*
* Calculate the number of transaction items to reserve for creating a subvolume
* or snapshot, not including the inode, directory entries, or parent directory.
*/
static unsigned int create_subvol_num_items(struct btrfs_qgroup_inherit *inherit)
{
/*
* 1 to add root block
* 1 to add root item
* 1 to add root ref
* 1 to add root backref
* 1 to add UUID item
* 1 to add qgroup info
* 1 to add qgroup limit
*
* Ideally the last two would only be accounted if qgroups are enabled,
* but that can change between now and the time we would insert them.
*/
unsigned int num_items = 7;
if (inherit) {
/* 2 to add qgroup relations for each inherited qgroup */
num_items += 2 * inherit->num_qgroups;
}
return num_items;
}
static noinline int create_subvol(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *dentry,
struct btrfs_qgroup_inherit *inherit)
{
struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
struct btrfs_trans_handle *trans;
struct btrfs_key key;
struct btrfs_root_item *root_item;
struct btrfs_inode_item *inode_item;
struct extent_buffer *leaf;
struct btrfs_root *root = BTRFS_I(dir)->root;
struct btrfs_root *new_root;
struct btrfs_block_rsv block_rsv;
struct timespec64 cur_time = current_time(dir);
struct btrfs_new_inode_args new_inode_args = {
.dir = dir,
.dentry = dentry,
.subvol = true,
};
unsigned int trans_num_items;
int ret;
dev_t anon_dev;
u64 objectid;
root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
if (!root_item)
return -ENOMEM;
ret = btrfs_get_free_objectid(fs_info->tree_root, &objectid);
if (ret)
goto out_root_item;
/*
* Don't create subvolume whose level is not zero. Or qgroup will be
* screwed up since it assumes subvolume qgroup's level to be 0.
*/
if (btrfs_qgroup_level(objectid)) {
ret = -ENOSPC;
goto out_root_item;
}
ret = get_anon_bdev(&anon_dev);
if (ret < 0)
goto out_root_item;
new_inode_args.inode = btrfs_new_subvol_inode(mnt_userns, dir);
if (!new_inode_args.inode) {
ret = -ENOMEM;
goto out_anon_dev;
}
ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
if (ret)
goto out_inode;
trans_num_items += create_subvol_num_items(inherit);
btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
trans_num_items, false);
if (ret)
goto out_new_inode_args;
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
btrfs_subvolume_release_metadata(root, &block_rsv);
goto out_new_inode_args;
}
trans->block_rsv = &block_rsv;
trans->bytes_reserved = block_rsv.size;
ret = btrfs_qgroup_inherit(trans, 0, objectid, inherit);
if (ret)
goto out;
leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0,
BTRFS_NESTING_NORMAL);
if (IS_ERR(leaf)) {
ret = PTR_ERR(leaf);
goto out;
}
btrfs_mark_buffer_dirty(leaf);
inode_item = &root_item->inode;
btrfs_set_stack_inode_generation(inode_item, 1);
btrfs_set_stack_inode_size(inode_item, 3);
btrfs_set_stack_inode_nlink(inode_item, 1);
btrfs_set_stack_inode_nbytes(inode_item,
fs_info->nodesize);
btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);
btrfs_set_root_flags(root_item, 0);
btrfs_set_root_limit(root_item, 0);
btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT);
btrfs_set_root_bytenr(root_item, leaf->start);
btrfs_set_root_generation(root_item, trans->transid);
btrfs_set_root_level(root_item, 0);
btrfs_set_root_refs(root_item, 1);
btrfs_set_root_used(root_item, leaf->len);
btrfs_set_root_last_snapshot(root_item, 0);
btrfs_set_root_generation_v2(root_item,
btrfs_root_generation(root_item));
generate_random_guid(root_item->uuid);
btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
root_item->ctime = root_item->otime;
btrfs_set_root_ctransid(root_item, trans->transid);
btrfs_set_root_otransid(root_item, trans->transid);
btrfs_tree_unlock(leaf);
btrfs_set_root_dirid(root_item, BTRFS_FIRST_FREE_OBJECTID);
key.objectid = objectid;
key.offset = 0;
key.type = BTRFS_ROOT_ITEM_KEY;
ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
root_item);
if (ret) {
/*
* Since we don't abort the transaction in this case, free the
* tree block so that we don't leak space and leave the
* filesystem in an inconsistent state (an extent item in the
* extent tree with a backreference for a root that does not
* exists).
*/
btrfs_tree_lock(leaf);
btrfs_clean_tree_block(leaf);
btrfs_tree_unlock(leaf);
btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
free_extent_buffer(leaf);
goto out;
}
free_extent_buffer(leaf);
leaf = NULL;
new_root = btrfs_get_new_fs_root(fs_info, objectid, anon_dev);
if (IS_ERR(new_root)) {
ret = PTR_ERR(new_root);
btrfs_abort_transaction(trans, ret);
goto out;
}
/* anon_dev is owned by new_root now. */
anon_dev = 0;
BTRFS_I(new_inode_args.inode)->root = new_root;
/* ... and new_root is owned by new_inode_args.inode now. */
ret = btrfs_record_root_in_trans(trans, new_root);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
ret = btrfs_uuid_tree_add(trans, root_item->uuid,
BTRFS_UUID_KEY_SUBVOL, objectid);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
ret = btrfs_create_new_inode(trans, &new_inode_args);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
d_instantiate_new(dentry, new_inode_args.inode);
new_inode_args.inode = NULL;
out:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
btrfs_subvolume_release_metadata(root, &block_rsv);
if (ret)
btrfs_end_transaction(trans);
else
ret = btrfs_commit_transaction(trans);
out_new_inode_args:
btrfs_new_inode_args_destroy(&new_inode_args);
out_inode:
iput(new_inode_args.inode);
out_anon_dev:
if (anon_dev)
free_anon_bdev(anon_dev);
out_root_item:
kfree(root_item);
return ret;
}
static int create_snapshot(struct btrfs_root *root, struct inode *dir,
struct dentry *dentry, bool readonly,
struct btrfs_qgroup_inherit *inherit)
{
struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
struct inode *inode;
struct btrfs_pending_snapshot *pending_snapshot;
unsigned int trans_num_items;
struct btrfs_trans_handle *trans;
int ret;
/* We do not support snapshotting right now. */
if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
btrfs_warn(fs_info,
"extent tree v2 doesn't support snapshotting yet");
return -EOPNOTSUPP;
}
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
return -EINVAL;
if (atomic_read(&root->nr_swapfiles)) {
btrfs_warn(fs_info,
"cannot snapshot subvolume with active swapfile");
return -ETXTBSY;
}
pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_KERNEL);
if (!pending_snapshot)
return -ENOMEM;
ret = get_anon_bdev(&pending_snapshot->anon_dev);
if (ret < 0)
goto free_pending;
pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
GFP_KERNEL);
pending_snapshot->path = btrfs_alloc_path();
if (!pending_snapshot->root_item || !pending_snapshot->path) {
ret = -ENOMEM;
goto free_pending;
}
btrfs_init_block_rsv(&pending_snapshot->block_rsv,
BTRFS_BLOCK_RSV_TEMP);
/*
* 1 to add dir item
* 1 to add dir index
* 1 to update parent inode item
*/
trans_num_items = create_subvol_num_items(inherit) + 3;
ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
&pending_snapshot->block_rsv,
trans_num_items, false);
if (ret)
goto free_pending;
pending_snapshot->dentry = dentry;
pending_snapshot->root = root;
pending_snapshot->readonly = readonly;
pending_snapshot->dir = dir;
pending_snapshot->inherit = inherit;
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto fail;
}
trans->pending_snapshot = pending_snapshot;
ret = btrfs_commit_transaction(trans);
if (ret)
goto fail;
ret = pending_snapshot->error;
if (ret)
goto fail;
ret = btrfs_orphan_cleanup(pending_snapshot->snap);
if (ret)
goto fail;
inode = btrfs_lookup_dentry(d_inode(dentry->d_parent), dentry);
if (IS_ERR(inode)) {
ret = PTR_ERR(inode);
goto fail;
}
d_instantiate(dentry, inode);
ret = 0;
pending_snapshot->anon_dev = 0;
fail:
/* Prevent double freeing of anon_dev */
if (ret && pending_snapshot->snap)
pending_snapshot->snap->anon_dev = 0;
btrfs_put_root(pending_snapshot->snap);
btrfs_subvolume_release_metadata(root, &pending_snapshot->block_rsv);
free_pending:
if (pending_snapshot->anon_dev)
free_anon_bdev(pending_snapshot->anon_dev);
kfree(pending_snapshot->root_item);
btrfs_free_path(pending_snapshot->path);
kfree(pending_snapshot);
return ret;
}
/* copy of may_delete in fs/namei.c()
* Check whether we can remove a link victim from directory dir, check
* whether the type of victim is right.
* 1. We can't do it if dir is read-only (done in permission())
* 2. We should have write and exec permissions on dir
* 3. We can't remove anything from append-only dir
* 4. We can't do anything with immutable dir (done in permission())
* 5. If the sticky bit on dir is set we should either
* a. be owner of dir, or
* b. be owner of victim, or
* c. have CAP_FOWNER capability
* 6. If the victim is append-only or immutable we can't do anything with
* links pointing to it.
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
* 9. We can't remove a root or mountpoint.
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
static int btrfs_may_delete(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *victim, int isdir)
{
int error;
if (d_really_is_negative(victim))
return -ENOENT;
BUG_ON(d_inode(victim->d_parent) != dir);
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
if (error)
return error;
if (IS_APPEND(dir))
return -EPERM;
if (check_sticky(mnt_userns, dir, d_inode(victim)) ||
IS_APPEND(d_inode(victim)) || IS_IMMUTABLE(d_inode(victim)) ||
IS_SWAPFILE(d_inode(victim)))
return -EPERM;
if (isdir) {
if (!d_is_dir(victim))
return -ENOTDIR;
if (IS_ROOT(victim))
return -EBUSY;
} else if (d_is_dir(victim))
return -EISDIR;
if (IS_DEADDIR(dir))
return -ENOENT;
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
return -EBUSY;
return 0;
}
/* copy of may_create in fs/namei.c() */
static inline int btrfs_may_create(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *child)
{
if (d_really_is_positive(child))
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
return -EOVERFLOW;
return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
}
/*
* Create a new subvolume below @parent. This is largely modeled after
* sys_mkdirat and vfs_mkdir, but we only do a single component lookup
* inside this filesystem so it's quite a bit simpler.
*/
static noinline int btrfs_mksubvol(const struct path *parent,
struct user_namespace *mnt_userns,
const char *name, int namelen,
struct btrfs_root *snap_src,
bool readonly,
struct btrfs_qgroup_inherit *inherit)
{
struct inode *dir = d_inode(parent->dentry);
struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
struct dentry *dentry;
int error;
error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
if (error == -EINTR)
return error;
dentry = lookup_one(mnt_userns, name, parent->dentry, namelen);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_unlock;
error = btrfs_may_create(mnt_userns, dir, dentry);
if (error)
goto out_dput;
/*
* even if this name doesn't exist, we may get hash collisions.
* check for them now when we can safely fail
*/
error = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
dir->i_ino, name,
namelen);
if (error)
goto out_dput;
down_read(&fs_info->subvol_sem);
if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
goto out_up_read;
if (snap_src)
error = create_snapshot(snap_src, dir, dentry, readonly, inherit);
else
error = create_subvol(mnt_userns, dir, dentry, inherit);
if (!error)
fsnotify_mkdir(dir, dentry);
out_up_read:
up_read(&fs_info->subvol_sem);
out_dput:
dput(dentry);
out_unlock:
btrfs_inode_unlock(dir, 0);
return error;
}
static noinline int btrfs_mksnapshot(const struct path *parent,
struct user_namespace *mnt_userns,
const char *name, int namelen,