We should gurantee that parent and clone root can not be destroyed during send, for this we have two ideas.
1.by holding @subvol_sem, this might be a nightmare, because it will block all subvolumes deletion for a long time. 2.Miao pointed out we can reuse @send_in_progress, that mean we will skip snapshot deletion if root sending is in progress. Here we adopt the second approach since it won't block other subvolumes deletion for a long time. Signed-off-by: Wang Shilong <[email protected]> Reviewed-by: Miao Xie <[email protected]> --- fs/btrfs/ctree.h | 13 ++++++++++--- fs/btrfs/send.c | 17 +++++++++++++++++ 2 files changed, 27 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 71e1fc7..ea19eff 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -3505,12 +3505,19 @@ static inline int btrfs_fs_closing(struct btrfs_fs_info *fs_info) } /* - * If we remount the fs to be R/O or umount the fs, the cleaner needn't do - * anything except sleeping. This function is used to check the status of - * the fs. + * If we remount the fs to be R/O, umount the fs or we are sending a + * subvolume, the cleaner needn't do anything except sleeping. This + * function is used to check the status of the fs. */ static inline int btrfs_need_cleaner_sleep(struct btrfs_root *root) { + spin_lock(&root->root_item_lock); + if (root->send_in_progress) { + spin_unlock(&root->root_item_lock); + return 1; + } + spin_unlock(&root->root_item_lock); + return (root->fs_info->sb->s_flags & MS_RDONLY || btrfs_fs_closing(root->fs_info)); } diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 076b066..f9cdeb7 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -4752,6 +4752,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) u32 i; u64 *clone_sources_tmp = NULL; int clone_sources_to_rollback = 0; + int index; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -4892,20 +4893,28 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) key.objectid = clone_sources_tmp[i]; key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; + + index = srcu_read_lock(&fs_info->subvol_srcu); + clone_root = btrfs_read_fs_root_no_name(fs_info, &key); if (IS_ERR(clone_root)) { + srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(clone_root); goto out; } clone_sources_to_rollback = i + 1; + spin_lock(&clone_root->root_item_lock); clone_root->send_in_progress++; if (!btrfs_root_readonly(clone_root)) { spin_unlock(&clone_root->root_item_lock); + srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EPERM; goto out; } spin_unlock(&clone_root->root_item_lock); + srcu_read_unlock(&fs_info->subvol_srcu, index); + sctx->clone_roots[i].root = clone_root; } clone_sources_to_rollback--; @@ -4917,19 +4926,27 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) key.objectid = arg->parent_root; key.type = BTRFS_ROOT_ITEM_KEY; key.offset = (u64)-1; + + index = srcu_read_lock(&fs_info->subvol_srcu); + sctx->parent_root = btrfs_read_fs_root_no_name(fs_info, &key); if (IS_ERR(sctx->parent_root)) { + srcu_read_unlock(&fs_info->subvol_srcu, index); ret = PTR_ERR(sctx->parent_root); goto out; } + spin_lock(&sctx->parent_root->root_item_lock); sctx->parent_root->send_in_progress++; if (!btrfs_root_readonly(sctx->parent_root)) { spin_unlock(&sctx->parent_root->root_item_lock); + srcu_read_unlock(&fs_info->subvol_srcu, index); ret = -EPERM; goto out; } spin_unlock(&sctx->parent_root->root_item_lock); + + srcu_read_unlock(&fs_info->subvol_srcu, index); } /* -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
