diff options
Diffstat (limited to 'fs/btrfs/export.c')
| -rw-r--r-- | fs/btrfs/export.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c new file mode 100644 index 000000000..665ec85cb --- /dev/null +++ b/fs/btrfs/export.c @@ -0,0 +1,305 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/fs.h> +#include <linux/types.h> +#include "ctree.h" +#include "disk-io.h" +#include "btrfs_inode.h" +#include "print-tree.h" +#include "export.h" + +#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \ + parent_objectid) / 4) +#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \ + parent_root_objectid) / 4) +#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4) + +static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, + struct inode *parent) +{ + struct btrfs_fid *fid = (struct btrfs_fid *)fh; + int len = *max_len; + int type; + + if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) { + *max_len = BTRFS_FID_SIZE_CONNECTABLE; + return FILEID_INVALID; + } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { + *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; + return FILEID_INVALID; + } + + len = BTRFS_FID_SIZE_NON_CONNECTABLE; + type = FILEID_BTRFS_WITHOUT_PARENT; + + fid->objectid = btrfs_ino(BTRFS_I(inode)); + fid->root_objectid = BTRFS_I(inode)->root->objectid; + fid->gen = inode->i_generation; + + if (parent) { + u64 parent_root_id; + + fid->parent_objectid = BTRFS_I(parent)->location.objectid; + fid->parent_gen = parent->i_generation; + parent_root_id = BTRFS_I(parent)->root->objectid; + + if (parent_root_id != fid->root_objectid) { + fid->parent_root_objectid = parent_root_id; + len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; + type = FILEID_BTRFS_WITH_PARENT_ROOT; + } else { + len = BTRFS_FID_SIZE_CONNECTABLE; + type = FILEID_BTRFS_WITH_PARENT; + } + } + + *max_len = len; + return type; +} + +struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, + u64 root_objectid, u32 generation, + int check_generation) +{ + struct btrfs_fs_info *fs_info = btrfs_sb(sb); + struct btrfs_root *root; + struct inode *inode; + struct btrfs_key key; + int index; + int err = 0; + + if (objectid < BTRFS_FIRST_FREE_OBJECTID) + return ERR_PTR(-ESTALE); + + key.objectid = root_objectid; + key.type = BTRFS_ROOT_ITEM_KEY; + key.offset = (u64)-1; + + index = srcu_read_lock(&fs_info->subvol_srcu); + + root = btrfs_read_fs_root_no_name(fs_info, &key); + if (IS_ERR(root)) { + err = PTR_ERR(root); + goto fail; + } + + key.objectid = objectid; + key.type = BTRFS_INODE_ITEM_KEY; + key.offset = 0; + + inode = btrfs_iget(sb, &key, root, NULL); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto fail; + } + + srcu_read_unlock(&fs_info->subvol_srcu, index); + + if (check_generation && generation != inode->i_generation) { + iput(inode); + return ERR_PTR(-ESTALE); + } + + return d_obtain_alias(inode); +fail: + srcu_read_unlock(&fs_info->subvol_srcu, index); + return ERR_PTR(err); +} + +static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, + int fh_len, int fh_type) +{ + struct btrfs_fid *fid = (struct btrfs_fid *) fh; + u64 objectid, root_objectid; + u32 generation; + + if (fh_type == FILEID_BTRFS_WITH_PARENT) { + if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) + return NULL; + root_objectid = fid->root_objectid; + } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { + if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) + return NULL; + root_objectid = fid->parent_root_objectid; + } else + return NULL; + + objectid = fid->parent_objectid; + generation = fid->parent_gen; + + return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); +} + +static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, + int fh_len, int fh_type) +{ + struct btrfs_fid *fid = (struct btrfs_fid *) fh; + u64 objectid, root_objectid; + u32 generation; + + if ((fh_type != FILEID_BTRFS_WITH_PARENT || + fh_len < BTRFS_FID_SIZE_CONNECTABLE) && + (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || + fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && + (fh_type != FILEID_BTRFS_WITHOUT_PARENT || + fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) + return NULL; + + objectid = fid->objectid; + root_objectid = fid->root_objectid; + generation = fid->gen; + + return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); +} + +struct dentry *btrfs_get_parent(struct dentry *child) +{ + struct inode *dir = d_inode(child); + struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); + struct btrfs_root *root = BTRFS_I(dir)->root; + struct btrfs_path *path; + struct extent_buffer *leaf; + struct btrfs_root_ref *ref; + struct btrfs_key key; + struct btrfs_key found_key; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return ERR_PTR(-ENOMEM); + + if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { + key.objectid = root->root_key.objectid; + key.type = BTRFS_ROOT_BACKREF_KEY; + key.offset = (u64)-1; + root = fs_info->tree_root; + } else { + key.objectid = btrfs_ino(BTRFS_I(dir)); + key.type = BTRFS_INODE_REF_KEY; + key.offset = (u64)-1; + } + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) + goto fail; + + BUG_ON(ret == 0); /* Key with offset of -1 found */ + if (path->slots[0] == 0) { + ret = -ENOENT; + goto fail; + } + + path->slots[0]--; + leaf = path->nodes[0]; + + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); + if (found_key.objectid != key.objectid || found_key.type != key.type) { + ret = -ENOENT; + goto fail; + } + + if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { + ref = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_root_ref); + key.objectid = btrfs_root_ref_dirid(leaf, ref); + } else { + key.objectid = found_key.offset; + } + btrfs_free_path(path); + + if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { + return btrfs_get_dentry(fs_info->sb, key.objectid, + found_key.offset, 0, 0); + } + + key.type = BTRFS_INODE_ITEM_KEY; + key.offset = 0; + return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root, NULL)); +fail: + btrfs_free_path(path); + return ERR_PTR(ret); +} + +static int btrfs_get_name(struct dentry *parent, char *name, + struct dentry *child) +{ + struct inode *inode = d_inode(child); + struct inode *dir = d_inode(parent); + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); + struct btrfs_path *path; + struct btrfs_root *root = BTRFS_I(dir)->root; + struct btrfs_inode_ref *iref; + struct btrfs_root_ref *rref; + struct extent_buffer *leaf; + unsigned long name_ptr; + struct btrfs_key key; + int name_len; + int ret; + u64 ino; + + if (!S_ISDIR(dir->i_mode)) + return -EINVAL; + + ino = btrfs_ino(BTRFS_I(inode)); + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + path->leave_spinning = 1; + + if (ino == BTRFS_FIRST_FREE_OBJECTID) { + key.objectid = BTRFS_I(inode)->root->root_key.objectid; + key.type = BTRFS_ROOT_BACKREF_KEY; + key.offset = (u64)-1; + root = fs_info->tree_root; + } else { + key.objectid = ino; + key.offset = btrfs_ino(BTRFS_I(dir)); + key.type = BTRFS_INODE_REF_KEY; + } + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret < 0) { + btrfs_free_path(path); + return ret; + } else if (ret > 0) { + if (ino == BTRFS_FIRST_FREE_OBJECTID) { + path->slots[0]--; + } else { + btrfs_free_path(path); + return -ENOENT; + } + } + leaf = path->nodes[0]; + + if (ino == BTRFS_FIRST_FREE_OBJECTID) { + rref = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_root_ref); + name_ptr = (unsigned long)(rref + 1); + name_len = btrfs_root_ref_name_len(leaf, rref); + } else { + iref = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_inode_ref); + name_ptr = (unsigned long)(iref + 1); + name_len = btrfs_inode_ref_name_len(leaf, iref); + } + + read_extent_buffer(leaf, name, name_ptr, name_len); + btrfs_free_path(path); + + /* + * have to add the null termination to make sure that reconnect_path + * gets the right len for strlen + */ + name[name_len] = '\0'; + + return 0; +} + +const struct export_operations btrfs_export_ops = { + .encode_fh = btrfs_encode_fh, + .fh_to_dentry = btrfs_fh_to_dentry, + .fh_to_parent = btrfs_fh_to_parent, + .get_parent = btrfs_get_parent, + .get_name = btrfs_get_name, +}; |