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btrfs: Factor out the main deletion process from btrfs_ioctl_snap_des…
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…troy()

Factor out the second half of btrfs_ioctl_snap_destroy() as
btrfs_delete_subvolume(), which performs some subvolume specific checks
before deletion:

1. send is not in progress
2. the subvolume is not the default subvolume
3. the subvolume does not contain other subvolumes

and actual deletion process. btrfs_delete_subvolume() requires
inode_lock for both @dir and inode of @dentRy. The remaining part of
btrfs_ioctl_snap_destroy() is mainly permission checks.

Note that call of d_delete() is not included in btrfs_delete_subvolume()
as this function will also be used by btrfs_rmdir() to delete an empty
subvolume and in that case d_delete() is called in VFS layer.

As a result, btrfs_unlink_subvol() and may_destroy_subvol()
become static functions. No functional changes.

Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor comment updates ]
Signed-off-by: David Sterba <dsterba@suse.com>
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@t-msn @kdave
t-msn authored and kdave committed May 28, 2018
1 parent ec42f16 commit f60a236
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Showing 3 changed files with 144 additions and 136 deletions.
6 changes: 1 addition & 5 deletions fs/btrfs/ctree.h
View file
Expand Up @@ -3193,11 +3193,7 @@ int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
int btrfs_add_link(struct btrfs_trans_handle *trans,
struct btrfs_inode *parent_inode, struct btrfs_inode *inode,
const char *name, int name_len, int add_backref, u64 index);
int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct inode *dir, u64 objectid,
const char *name, int name_len);
noinline int may_destroy_subvol(struct btrfs_root *root);
int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry);
int btrfs_truncate_block(struct inode *inode, loff_t from, loff_t len,
int front);
int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
Expand Down
143 changes: 141 additions & 2 deletions fs/btrfs/inode.c
View file
Expand Up @@ -4245,7 +4245,7 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
return ret;
}

int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct inode *dir, u64 objectid,
const char *name, int name_len)
Expand Down Expand Up @@ -4330,7 +4330,7 @@ int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
* Helper to check if the subvolume references other subvolumes or if it's
* default.
*/
noinline int may_destroy_subvol(struct btrfs_root *root)
static noinline int may_destroy_subvol(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_path *path;
Expand Down Expand Up @@ -4381,6 +4381,145 @@ noinline int may_destroy_subvol(struct btrfs_root *root)
return ret;
}

int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
{
struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
struct btrfs_root *root = BTRFS_I(dir)->root;
struct inode *inode = d_inode(dentry);
struct btrfs_root *dest = BTRFS_I(inode)->root;
struct btrfs_trans_handle *trans;
struct btrfs_block_rsv block_rsv;
u64 root_flags;
u64 qgroup_reserved;
int ret;
int err;

/*
* Don't allow to delete a subvolume with send in progress. This is
* inside the inode lock so the error handling that has to drop the bit
* again is not run concurrently.
*/
spin_lock(&dest->root_item_lock);
root_flags = btrfs_root_flags(&dest->root_item);
if (dest->send_in_progress == 0) {
btrfs_set_root_flags(&dest->root_item,
root_flags | BTRFS_ROOT_SUBVOL_DEAD);
spin_unlock(&dest->root_item_lock);
} else {
spin_unlock(&dest->root_item_lock);
btrfs_warn(fs_info,
"attempt to delete subvolume %llu during send",
dest->root_key.objectid);
return -EPERM;
}

down_write(&fs_info->subvol_sem);

err = may_destroy_subvol(dest);
if (err)
goto out_up_write;

btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
/*
* One for dir inode,
* two for dir entries,
* two for root ref/backref.
*/
err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
5, &qgroup_reserved, true);
if (err)
goto out_up_write;

trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_release;
}
trans->block_rsv = &block_rsv;
trans->bytes_reserved = block_rsv.size;

btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));

ret = btrfs_unlink_subvol(trans, root, dir,
dest->root_key.objectid,
dentry->d_name.name,
dentry->d_name.len);
if (ret) {
err = ret;
btrfs_abort_transaction(trans, ret);
goto out_end_trans;
}

btrfs_record_root_in_trans(trans, dest);

memset(&dest->root_item.drop_progress, 0,
sizeof(dest->root_item.drop_progress));
dest->root_item.drop_level = 0;
btrfs_set_root_refs(&dest->root_item, 0);

if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
ret = btrfs_insert_orphan_item(trans,
fs_info->tree_root,
dest->root_key.objectid);
if (ret) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
}

ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid,
BTRFS_UUID_KEY_SUBVOL,
dest->root_key.objectid);
if (ret && ret != -ENOENT) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
ret = btrfs_uuid_tree_rem(trans, fs_info,
dest->root_item.received_uuid,
BTRFS_UUID_KEY_RECEIVED_SUBVOL,
dest->root_key.objectid);
if (ret && ret != -ENOENT) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
}

out_end_trans:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
ret = btrfs_end_transaction(trans);
if (ret && !err)
err = ret;
inode->i_flags |= S_DEAD;
out_release:
btrfs_subvolume_release_metadata(fs_info, &block_rsv);
out_up_write:
up_write(&fs_info->subvol_sem);
if (err) {
spin_lock(&dest->root_item_lock);
root_flags = btrfs_root_flags(&dest->root_item);
btrfs_set_root_flags(&dest->root_item,
root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
spin_unlock(&dest->root_item_lock);
} else {
d_invalidate(dentry);
btrfs_invalidate_inodes(dest);
ASSERT(dest->send_in_progress == 0);

/* the last ref */
if (dest->ino_cache_inode) {
iput(dest->ino_cache_inode);
dest->ino_cache_inode = NULL;
}
}

return err;
}

static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
Expand Down
131 changes: 2 additions & 129 deletions fs/btrfs/ioctl.c
View file
Expand Up @@ -2255,12 +2255,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
struct btrfs_root *root = BTRFS_I(dir)->root;
struct btrfs_root *dest = NULL;
struct btrfs_ioctl_vol_args *vol_args;
struct btrfs_trans_handle *trans;
struct btrfs_block_rsv block_rsv;
u64 root_flags;
u64 qgroup_reserved;
int namelen;
int ret;
int err = 0;

if (!S_ISDIR(dir->i_mode))
Expand Down Expand Up @@ -2344,133 +2339,11 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
}

inode_lock(inode);

/*
* Don't allow to delete a subvolume with send in progress. This is
* inside the i_mutex so the error handling that has to drop the bit
* again is not run concurrently.
*/
spin_lock(&dest->root_item_lock);
root_flags = btrfs_root_flags(&dest->root_item);
if (dest->send_in_progress == 0) {
btrfs_set_root_flags(&dest->root_item,
root_flags | BTRFS_ROOT_SUBVOL_DEAD);
spin_unlock(&dest->root_item_lock);
} else {
spin_unlock(&dest->root_item_lock);
btrfs_warn(fs_info,
"Attempt to delete subvolume %llu during send",
dest->root_key.objectid);
err = -EPERM;
goto out_unlock_inode;
}

down_write(&fs_info->subvol_sem);

err = may_destroy_subvol(dest);
if (err)
goto out_up_write;

btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
/*
* One for dir inode, two for dir entries, two for root
* ref/backref.
*/
err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
5, &qgroup_reserved, true);
if (err)
goto out_up_write;

trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_release;
}
trans->block_rsv = &block_rsv;
trans->bytes_reserved = block_rsv.size;

btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));

ret = btrfs_unlink_subvol(trans, root, dir,
dest->root_key.objectid,
dentry->d_name.name,
dentry->d_name.len);
if (ret) {
err = ret;
btrfs_abort_transaction(trans, ret);
goto out_end_trans;
}

btrfs_record_root_in_trans(trans, dest);

memset(&dest->root_item.drop_progress, 0,
sizeof(dest->root_item.drop_progress));
dest->root_item.drop_level = 0;
btrfs_set_root_refs(&dest->root_item, 0);

if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
ret = btrfs_insert_orphan_item(trans,
fs_info->tree_root,
dest->root_key.objectid);
if (ret) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
}

ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid,
BTRFS_UUID_KEY_SUBVOL,
dest->root_key.objectid);
if (ret && ret != -ENOENT) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
ret = btrfs_uuid_tree_rem(trans, fs_info,
dest->root_item.received_uuid,
BTRFS_UUID_KEY_RECEIVED_SUBVOL,
dest->root_key.objectid);
if (ret && ret != -ENOENT) {
btrfs_abort_transaction(trans, ret);
err = ret;
goto out_end_trans;
}
}

out_end_trans:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
ret = btrfs_end_transaction(trans);
if (ret && !err)
err = ret;
inode->i_flags |= S_DEAD;
out_release:
btrfs_subvolume_release_metadata(fs_info, &block_rsv);
out_up_write:
up_write(&fs_info->subvol_sem);
if (err) {
spin_lock(&dest->root_item_lock);
root_flags = btrfs_root_flags(&dest->root_item);
btrfs_set_root_flags(&dest->root_item,
root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
spin_unlock(&dest->root_item_lock);
}
out_unlock_inode:
err = btrfs_delete_subvolume(dir, dentry);
inode_unlock(inode);
if (!err) {
d_invalidate(dentry);
btrfs_invalidate_inodes(dest);
if (!err)
d_delete(dentry);
ASSERT(dest->send_in_progress == 0);

/* the last ref */
if (dest->ino_cache_inode) {
iput(dest->ino_cache_inode);
dest->ino_cache_inode = NULL;
}
}
out_dput:
dput(dentry);
out_unlock_dir:
Expand Down

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