diff mbox

[v2,4/8] Btrfs: maintain subvolume items in the UUID tree

Message ID c68d2db7aa4ed6455645cf788e305b1a9ebb88bc.1368523154.git.sbehrens@giantdisaster.de (mailing list archive)
State Superseded, archived
Headers show

Commit Message

Stefan Behrens May 14, 2013, 9:36 a.m. UTC 
When a new subvolume or snapshot is created, a new UUID item is added
to the UUID tree. Such items are removed when the subvolume is deleted.
The ioctl to set the received subvolume UUID is also touched and will
now also add this received UUID into the UUID tree together with the
ID of the subvolume. The latter is also done when read-only snapshots
are created which inherit all the send/receive information from the
parent subvolume.

User mode programs use the BTRFS_IOC_TREE_SEARCH ioctl to search and
read in the UUID tree.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
---
 fs/btrfs/ctree.h       |  1 +
 fs/btrfs/ioctl.c       | 74 +++++++++++++++++++++++++++++++++++++++++++-------
 fs/btrfs/transaction.c | 19 ++++++++++++-
 3 files changed, 83 insertions(+), 11 deletions(-)

Comments

Liu Bo May 14, 2013, 10:44 a.m. UTC | #1 
On Tue, May 14, 2013 at 11:36:56AM +0200, Stefan Behrens wrote:
> When a new subvolume or snapshot is created, a new UUID item is added
> to the UUID tree. Such items are removed when the subvolume is deleted.
> The ioctl to set the received subvolume UUID is also touched and will
> now also add this received UUID into the UUID tree together with the
> ID of the subvolume. The latter is also done when read-only snapshots
> are created which inherit all the send/receive information from the
> parent subvolume.
> 
> User mode programs use the BTRFS_IOC_TREE_SEARCH ioctl to search and
> read in the UUID tree.
> 
> Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
> ---
>  fs/btrfs/ctree.h       |  1 +
>  fs/btrfs/ioctl.c       | 74 +++++++++++++++++++++++++++++++++++++++++++-------
>  fs/btrfs/transaction.c | 19 ++++++++++++-
>  3 files changed, 83 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 6f9d760..73d797c 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -3634,6 +3634,7 @@ extern const struct dentry_operations btrfs_dentry_operations;
>  long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
>  void btrfs_update_iflags(struct inode *inode);
>  void btrfs_inherit_iflags(struct inode *inode, struct inode *dir);
> +int btrfs_is_empty_uuid(u8 *uuid);
>  int btrfs_defrag_file(struct inode *inode, struct file *file,
>  		      struct btrfs_ioctl_defrag_range_args *range,
>  		      u64 newer_than, unsigned long max_pages);
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index b2537c7..47bef5a 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -363,6 +363,13 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
>  	return 0;
>  }
>  
> +int btrfs_is_empty_uuid(u8 *uuid)
> +{
> +	static char empty_uuid[BTRFS_UUID_SIZE] = {0};
> +
> +	return !memcmp(uuid, empty_uuid, BTRFS_UUID_SIZE);
> +}
> +
>  static noinline int create_subvol(struct inode *dir,
>  				  struct dentry *dentry,
>  				  char *name, int namelen,
> @@ -396,7 +403,7 @@ static noinline int create_subvol(struct inode *dir,
>  	 * of create_snapshot().
>  	 */
>  	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
> -					       7, &qgroup_reserved);
> +					       8, &qgroup_reserved);
>  	if (ret)
>  		return ret;
>  
> @@ -518,9 +525,13 @@ static noinline int create_subvol(struct inode *dir,
>  	ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
>  				 objectid, root->root_key.objectid,
>  				 btrfs_ino(dir), index, name, namelen);
> -
>  	BUG_ON(ret);
>  

This uuid_root will not use trans->block_rsv but empty_rsv since it does not set
ref_cow, so you don't need to add one more to block_rsv, and same for
the below cases.

thanks,
liubo

> +	ret = btrfs_insert_uuid_subvol_item(trans, root->fs_info->uuid_root,
> +					    root_item.uuid, objectid);
> +	if (ret)
> +		btrfs_abort_transaction(trans, root, ret);
> +
>  fail:
>  	trans->block_rsv = NULL;
>  	trans->bytes_reserved = 0;
> @@ -567,9 +578,10 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
>  	 * 1 - root item
>  	 * 2 - root ref/backref
>  	 * 1 - root of snapshot
> +	 * 1 - UUID item
>  	 */
>  	ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
> -					&pending_snapshot->block_rsv, 7,
> +					&pending_snapshot->block_rsv, 8,
>  					&pending_snapshot->qgroup_reserved);
>  	if (ret)
>  		goto out;
> @@ -2207,6 +2219,27 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
>  			goto out_end_trans;
>  		}
>  	}
> +
> +	ret = btrfs_del_uuid_subvol_item(trans, root->fs_info->uuid_root,
> +					 dest->root_item.uuid,
> +					 dest->root_key.objectid);
> +	if (ret && ret != -ENOENT) {
> +		btrfs_abort_transaction(trans, root, ret);
> +		err = ret;
> +		goto out_end_trans;
> +	}
> +	if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
> +		ret = btrfs_del_uuid_received_subvol_item(trans,
> +				root->fs_info->uuid_root,
> +				dest->root_item.received_uuid,
> +				dest->root_key.objectid);
> +		if (ret && ret != -ENOENT) {
> +			btrfs_abort_transaction(trans, root, ret);
> +			err = ret;
> +			goto out_end_trans;
> +		}
> +	}
> +
>  out_end_trans:
>  	trans->block_rsv = NULL;
>  	trans->bytes_reserved = 0;
> @@ -2418,7 +2451,6 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
>  	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
>  	int ret = 0;
>  	char *s_uuid = NULL;
> -	char empty_uuid[BTRFS_UUID_SIZE] = {0};
>  
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
> @@ -2427,7 +2459,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
>  	if (IS_ERR(di_args))
>  		return PTR_ERR(di_args);
>  
> -	if (memcmp(empty_uuid, di_args->uuid, BTRFS_UUID_SIZE) != 0)
> +	if (!btrfs_is_empty_uuid(di_args->uuid))
>  		s_uuid = di_args->uuid;
>  
>  	mutex_lock(&fs_devices->device_list_mutex);
> @@ -3952,6 +3984,7 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
>  	struct btrfs_trans_handle *trans;
>  	struct timespec ct = CURRENT_TIME;
>  	int ret = 0;
> +	int received_uuid_changed;
>  
>  	ret = mnt_want_write_file(file);
>  	if (ret < 0)
> @@ -3981,7 +4014,11 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
>  		goto out;
>  	}
>  
> -	trans = btrfs_start_transaction(root, 1);
> +	/*
> +	 * 1 - root item
> +	 * 2 - uuid items (received uuid + subvol uuid)
> +	 */
> +	trans = btrfs_start_transaction(root, 3);
>  	if (IS_ERR(trans)) {
>  		ret = PTR_ERR(trans);
>  		trans = NULL;
> @@ -3992,6 +4029,14 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
>  	sa->rtime.sec = ct.tv_sec;
>  	sa->rtime.nsec = ct.tv_nsec;
>  
> +	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
> +				       BTRFS_UUID_SIZE);
> +	if (received_uuid_changed &&
> +	    !btrfs_is_empty_uuid(root_item->received_uuid))
> +		btrfs_del_uuid_received_subvol_item(trans,
> +						    root->fs_info->uuid_root,
> +						    root_item->received_uuid,
> +						    root->root_key.objectid);
>  	memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
>  	btrfs_set_root_stransid(root_item, sa->stransid);
>  	btrfs_set_root_rtransid(root_item, sa->rtransid);
> @@ -4004,12 +4049,21 @@ static long btrfs_ioctl_set_received_subvol(struct file *file,
>  				&root->root_key, &root->root_item);
>  	if (ret < 0) {
>  		btrfs_end_transaction(trans, root);
> -		trans = NULL;
>  		goto out;
> -	} else {
> -		ret = btrfs_commit_transaction(trans, root);
> -		if (ret < 0)
> +	}
> +	if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
> +		ret = btrfs_insert_uuid_received_subvol_item(
> +			trans, root->fs_info->uuid_root, sa->uuid,
> +			root->root_key.objectid);
> +		if (ret < 0 && ret != -EEXIST) {
> +			btrfs_abort_transaction(trans, root, ret);
>  			goto out;
> +		}
> +	}
> +	ret = btrfs_commit_transaction(trans, root);
> +	if (ret < 0) {
> +		btrfs_abort_transaction(trans, root, ret);
> +		goto out;
>  	}
>  
>  	ret = copy_to_user(arg, sa, sizeof(*sa));
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 0544587..a3d92b3 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -1263,8 +1263,25 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
>  					 dentry->d_name.len * 2);
>  	parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
>  	ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
> -	if (ret)
> +	if (ret) {
> +		btrfs_abort_transaction(trans, root, ret);
> +		goto fail;
> +	}
> +	ret = btrfs_insert_uuid_subvol_item(trans, fs_info->uuid_root,
> +					    new_uuid.b, objectid);
> +	if (ret) {
>  		btrfs_abort_transaction(trans, root, ret);
> +		goto fail;
> +	}
> +	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
> +		ret = btrfs_insert_uuid_received_subvol_item(
> +			trans, fs_info->uuid_root, new_root_item->received_uuid,
> +			objectid);
> +		if (ret && ret != -EEXIST) {
> +			btrfs_abort_transaction(trans, root, ret);
> +			goto fail;
> +		}
> +	}
>  fail:
>  	pending->error = ret;
>  dir_item_existed:
> -- 
> 1.8.2.2
> 
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diff mbox

Patch

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 6f9d760..73d797c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3634,6 +3634,7 @@  extern const struct dentry_operations btrfs_dentry_operations;
 long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 void btrfs_update_iflags(struct inode *inode);
 void btrfs_inherit_iflags(struct inode *inode, struct inode *dir);
+int btrfs_is_empty_uuid(u8 *uuid);
 int btrfs_defrag_file(struct inode *inode, struct file *file,
 		      struct btrfs_ioctl_defrag_range_args *range,
 		      u64 newer_than, unsigned long max_pages);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b2537c7..47bef5a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -363,6 +363,13 @@  static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
 	return 0;
 }
 
+int btrfs_is_empty_uuid(u8 *uuid)
+{
+	static char empty_uuid[BTRFS_UUID_SIZE] = {0};
+
+	return !memcmp(uuid, empty_uuid, BTRFS_UUID_SIZE);
+}
+
 static noinline int create_subvol(struct inode *dir,
 				  struct dentry *dentry,
 				  char *name, int namelen,
@@ -396,7 +403,7 @@  static noinline int create_subvol(struct inode *dir,
 	 * of create_snapshot().
 	 */
 	ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
-					       7, &qgroup_reserved);
+					       8, &qgroup_reserved);
 	if (ret)
 		return ret;
 
@@ -518,9 +525,13 @@  static noinline int create_subvol(struct inode *dir,
 	ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
 				 objectid, root->root_key.objectid,
 				 btrfs_ino(dir), index, name, namelen);
-
 	BUG_ON(ret);
 
+	ret = btrfs_insert_uuid_subvol_item(trans, root->fs_info->uuid_root,
+					    root_item.uuid, objectid);
+	if (ret)
+		btrfs_abort_transaction(trans, root, ret);
+
 fail:
 	trans->block_rsv = NULL;
 	trans->bytes_reserved = 0;
@@ -567,9 +578,10 @@  static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 	 * 1 - root item
 	 * 2 - root ref/backref
 	 * 1 - root of snapshot
+	 * 1 - UUID item
 	 */
 	ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
-					&pending_snapshot->block_rsv, 7,
+					&pending_snapshot->block_rsv, 8,
 					&pending_snapshot->qgroup_reserved);
 	if (ret)
 		goto out;
@@ -2207,6 +2219,27 @@  static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 			goto out_end_trans;
 		}
 	}
+
+	ret = btrfs_del_uuid_subvol_item(trans, root->fs_info->uuid_root,
+					 dest->root_item.uuid,
+					 dest->root_key.objectid);
+	if (ret && ret != -ENOENT) {
+		btrfs_abort_transaction(trans, root, ret);
+		err = ret;
+		goto out_end_trans;
+	}
+	if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+		ret = btrfs_del_uuid_received_subvol_item(trans,
+				root->fs_info->uuid_root,
+				dest->root_item.received_uuid,
+				dest->root_key.objectid);
+		if (ret && ret != -ENOENT) {
+			btrfs_abort_transaction(trans, root, ret);
+			err = ret;
+			goto out_end_trans;
+		}
+	}
+
 out_end_trans:
 	trans->block_rsv = NULL;
 	trans->bytes_reserved = 0;
@@ -2418,7 +2451,6 @@  static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
 	struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
 	int ret = 0;
 	char *s_uuid = NULL;
-	char empty_uuid[BTRFS_UUID_SIZE] = {0};
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
@@ -2427,7 +2459,7 @@  static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
 	if (IS_ERR(di_args))
 		return PTR_ERR(di_args);
 
-	if (memcmp(empty_uuid, di_args->uuid, BTRFS_UUID_SIZE) != 0)
+	if (!btrfs_is_empty_uuid(di_args->uuid))
 		s_uuid = di_args->uuid;
 
 	mutex_lock(&fs_devices->device_list_mutex);
@@ -3952,6 +3984,7 @@  static long btrfs_ioctl_set_received_subvol(struct file *file,
 	struct btrfs_trans_handle *trans;
 	struct timespec ct = CURRENT_TIME;
 	int ret = 0;
+	int received_uuid_changed;
 
 	ret = mnt_want_write_file(file);
 	if (ret < 0)
@@ -3981,7 +4014,11 @@  static long btrfs_ioctl_set_received_subvol(struct file *file,
 		goto out;
 	}
 
-	trans = btrfs_start_transaction(root, 1);
+	/*
+	 * 1 - root item
+	 * 2 - uuid items (received uuid + subvol uuid)
+	 */
+	trans = btrfs_start_transaction(root, 3);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
 		trans = NULL;
@@ -3992,6 +4029,14 @@  static long btrfs_ioctl_set_received_subvol(struct file *file,
 	sa->rtime.sec = ct.tv_sec;
 	sa->rtime.nsec = ct.tv_nsec;
 
+	received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
+				       BTRFS_UUID_SIZE);
+	if (received_uuid_changed &&
+	    !btrfs_is_empty_uuid(root_item->received_uuid))
+		btrfs_del_uuid_received_subvol_item(trans,
+						    root->fs_info->uuid_root,
+						    root_item->received_uuid,
+						    root->root_key.objectid);
 	memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
 	btrfs_set_root_stransid(root_item, sa->stransid);
 	btrfs_set_root_rtransid(root_item, sa->rtransid);
@@ -4004,12 +4049,21 @@  static long btrfs_ioctl_set_received_subvol(struct file *file,
 				&root->root_key, &root->root_item);
 	if (ret < 0) {
 		btrfs_end_transaction(trans, root);
-		trans = NULL;
 		goto out;
-	} else {
-		ret = btrfs_commit_transaction(trans, root);
-		if (ret < 0)
+	}
+	if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
+		ret = btrfs_insert_uuid_received_subvol_item(
+			trans, root->fs_info->uuid_root, sa->uuid,
+			root->root_key.objectid);
+		if (ret < 0 && ret != -EEXIST) {
+			btrfs_abort_transaction(trans, root, ret);
 			goto out;
+		}
+	}
+	ret = btrfs_commit_transaction(trans, root);
+	if (ret < 0) {
+		btrfs_abort_transaction(trans, root, ret);
+		goto out;
 	}
 
 	ret = copy_to_user(arg, sa, sizeof(*sa));
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 0544587..a3d92b3 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1263,8 +1263,25 @@  static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 					 dentry->d_name.len * 2);
 	parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
 	ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
-	if (ret)
+	if (ret) {
+		btrfs_abort_transaction(trans, root, ret);
+		goto fail;
+	}
+	ret = btrfs_insert_uuid_subvol_item(trans, fs_info->uuid_root,
+					    new_uuid.b, objectid);
+	if (ret) {
 		btrfs_abort_transaction(trans, root, ret);
+		goto fail;
+	}
+	if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
+		ret = btrfs_insert_uuid_received_subvol_item(
+			trans, fs_info->uuid_root, new_root_item->received_uuid,
+			objectid);
+		if (ret && ret != -EEXIST) {
+			btrfs_abort_transaction(trans, root, ret);
+			goto fail;
+		}
+	}
 fail:
 	pending->error = ret;
 dir_item_existed: