![Jeff Mahoney](/assets/img/avatar_default.png)
btrfs currently handles most errors with BUG_ON. This patch is a work-in- progress but aims to handle most errors other than internal logic errors and ENOMEM more gracefully. This iteration prevents most crashes but can run into lockups with the page lock on occasion when the timing "works out." Signed-off-by: Jeff Mahoney <jeffm@suse.com>
318 lines
7.8 KiB
C
318 lines
7.8 KiB
C
#include <linux/fs.h>
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#include <linux/types.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "btrfs_inode.h"
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#include "print-tree.h"
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#include "export.h"
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#include "compat.h"
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#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
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parent_objectid) / 4)
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#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
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parent_root_objectid) / 4)
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#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
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static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
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int connectable)
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{
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struct btrfs_fid *fid = (struct btrfs_fid *)fh;
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struct inode *inode = dentry->d_inode;
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int len = *max_len;
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int type;
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if (connectable && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
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*max_len = BTRFS_FID_SIZE_CONNECTABLE;
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return 255;
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} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
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*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
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return 255;
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}
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len = BTRFS_FID_SIZE_NON_CONNECTABLE;
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type = FILEID_BTRFS_WITHOUT_PARENT;
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fid->objectid = btrfs_ino(inode);
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fid->root_objectid = BTRFS_I(inode)->root->objectid;
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fid->gen = inode->i_generation;
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if (connectable && !S_ISDIR(inode->i_mode)) {
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struct inode *parent;
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u64 parent_root_id;
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spin_lock(&dentry->d_lock);
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parent = dentry->d_parent->d_inode;
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fid->parent_objectid = BTRFS_I(parent)->location.objectid;
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fid->parent_gen = parent->i_generation;
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parent_root_id = BTRFS_I(parent)->root->objectid;
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spin_unlock(&dentry->d_lock);
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if (parent_root_id != fid->root_objectid) {
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fid->parent_root_objectid = parent_root_id;
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len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
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type = FILEID_BTRFS_WITH_PARENT_ROOT;
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} else {
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len = BTRFS_FID_SIZE_CONNECTABLE;
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type = FILEID_BTRFS_WITH_PARENT;
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}
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}
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*max_len = len;
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return type;
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}
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static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
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u64 root_objectid, u32 generation,
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int check_generation)
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{
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struct btrfs_fs_info *fs_info = btrfs_sb(sb);
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struct btrfs_root *root;
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struct inode *inode;
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struct btrfs_key key;
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int index;
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int err = 0;
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if (objectid < BTRFS_FIRST_FREE_OBJECTID)
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return ERR_PTR(-ESTALE);
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key.objectid = root_objectid;
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btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
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key.offset = (u64)-1;
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index = srcu_read_lock(&fs_info->subvol_srcu);
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root = btrfs_read_fs_root_no_name(fs_info, &key);
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if (IS_ERR(root)) {
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err = PTR_ERR(root);
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goto fail;
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}
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if (btrfs_root_refs(&root->root_item) == 0) {
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err = -ENOENT;
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goto fail;
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}
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key.objectid = objectid;
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btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
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key.offset = 0;
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inode = btrfs_iget(sb, &key, root, NULL);
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if (IS_ERR(inode)) {
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err = PTR_ERR(inode);
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goto fail;
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}
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srcu_read_unlock(&fs_info->subvol_srcu, index);
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if (check_generation && generation != inode->i_generation) {
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iput(inode);
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return ERR_PTR(-ESTALE);
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}
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return d_obtain_alias(inode);
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fail:
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srcu_read_unlock(&fs_info->subvol_srcu, index);
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return ERR_PTR(err);
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}
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static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
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int fh_len, int fh_type)
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{
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struct btrfs_fid *fid = (struct btrfs_fid *) fh;
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u64 objectid, root_objectid;
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u32 generation;
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if (fh_type == FILEID_BTRFS_WITH_PARENT) {
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if (fh_len != BTRFS_FID_SIZE_CONNECTABLE)
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return NULL;
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root_objectid = fid->root_objectid;
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} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
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if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
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return NULL;
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root_objectid = fid->parent_root_objectid;
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} else
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return NULL;
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objectid = fid->parent_objectid;
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generation = fid->parent_gen;
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return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
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}
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static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
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int fh_len, int fh_type)
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{
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struct btrfs_fid *fid = (struct btrfs_fid *) fh;
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u64 objectid, root_objectid;
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u32 generation;
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if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
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fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
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(fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
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fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
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(fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
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fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
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return NULL;
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objectid = fid->objectid;
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root_objectid = fid->root_objectid;
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generation = fid->gen;
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return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
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}
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static struct dentry *btrfs_get_parent(struct dentry *child)
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{
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struct inode *dir = child->d_inode;
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struct btrfs_root *root = BTRFS_I(dir)->root;
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struct btrfs_path *path;
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struct extent_buffer *leaf;
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struct btrfs_root_ref *ref;
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struct btrfs_key key;
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struct btrfs_key found_key;
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int ret;
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path = btrfs_alloc_path();
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if (!path)
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return ERR_PTR(-ENOMEM);
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if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
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key.objectid = root->root_key.objectid;
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key.type = BTRFS_ROOT_BACKREF_KEY;
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key.offset = (u64)-1;
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root = root->fs_info->tree_root;
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} else {
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key.objectid = btrfs_ino(dir);
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key.type = BTRFS_INODE_REF_KEY;
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key.offset = (u64)-1;
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}
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0)
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goto fail;
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BUG_ON(ret == 0); /* Key with offset of -1 found */
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if (path->slots[0] == 0) {
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ret = -ENOENT;
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goto fail;
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}
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path->slots[0]--;
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leaf = path->nodes[0];
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btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
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if (found_key.objectid != key.objectid || found_key.type != key.type) {
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ret = -ENOENT;
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goto fail;
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}
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if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
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ref = btrfs_item_ptr(leaf, path->slots[0],
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struct btrfs_root_ref);
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key.objectid = btrfs_root_ref_dirid(leaf, ref);
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} else {
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key.objectid = found_key.offset;
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}
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btrfs_free_path(path);
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if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
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return btrfs_get_dentry(root->fs_info->sb, key.objectid,
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found_key.offset, 0, 0);
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}
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key.type = BTRFS_INODE_ITEM_KEY;
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key.offset = 0;
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return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
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fail:
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btrfs_free_path(path);
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return ERR_PTR(ret);
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}
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static int btrfs_get_name(struct dentry *parent, char *name,
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struct dentry *child)
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{
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struct inode *inode = child->d_inode;
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struct inode *dir = parent->d_inode;
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struct btrfs_path *path;
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struct btrfs_root *root = BTRFS_I(dir)->root;
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struct btrfs_inode_ref *iref;
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struct btrfs_root_ref *rref;
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struct extent_buffer *leaf;
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unsigned long name_ptr;
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struct btrfs_key key;
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int name_len;
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int ret;
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u64 ino;
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if (!dir || !inode)
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return -EINVAL;
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if (!S_ISDIR(dir->i_mode))
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return -EINVAL;
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ino = btrfs_ino(inode);
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path = btrfs_alloc_path();
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if (!path)
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return -ENOMEM;
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path->leave_spinning = 1;
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if (ino == BTRFS_FIRST_FREE_OBJECTID) {
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key.objectid = BTRFS_I(inode)->root->root_key.objectid;
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key.type = BTRFS_ROOT_BACKREF_KEY;
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key.offset = (u64)-1;
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root = root->fs_info->tree_root;
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} else {
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key.objectid = ino;
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key.offset = btrfs_ino(dir);
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key.type = BTRFS_INODE_REF_KEY;
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}
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ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
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if (ret < 0) {
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btrfs_free_path(path);
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return ret;
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} else if (ret > 0) {
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if (ino == BTRFS_FIRST_FREE_OBJECTID) {
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path->slots[0]--;
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} else {
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btrfs_free_path(path);
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return -ENOENT;
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}
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}
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leaf = path->nodes[0];
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if (ino == BTRFS_FIRST_FREE_OBJECTID) {
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rref = btrfs_item_ptr(leaf, path->slots[0],
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struct btrfs_root_ref);
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name_ptr = (unsigned long)(rref + 1);
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name_len = btrfs_root_ref_name_len(leaf, rref);
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} else {
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iref = btrfs_item_ptr(leaf, path->slots[0],
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struct btrfs_inode_ref);
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name_ptr = (unsigned long)(iref + 1);
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name_len = btrfs_inode_ref_name_len(leaf, iref);
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}
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read_extent_buffer(leaf, name, name_ptr, name_len);
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btrfs_free_path(path);
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/*
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* have to add the null termination to make sure that reconnect_path
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* gets the right len for strlen
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*/
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name[name_len] = '\0';
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return 0;
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}
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const struct export_operations btrfs_export_ops = {
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.encode_fh = btrfs_encode_fh,
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.fh_to_dentry = btrfs_fh_to_dentry,
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.fh_to_parent = btrfs_fh_to_parent,
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.get_parent = btrfs_get_parent,
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.get_name = btrfs_get_name,
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};
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