inode-item.c

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/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include "ctree.h"
#include "disk-io.h"
#include "hash.h"
#include "transaction.h"
#include "print-tree.h"

static int find_name_in_backref(struct btrfs_path *path, const char *name,
             int name_len, struct btrfs_inode_ref **ref_ret)
{
    struct extent_buffer *leaf;
    struct btrfs_inode_ref *ref;
    unsigned long ptr;
    unsigned long name_ptr;
    u32 item_size;
    u32 cur_offset = 0;
    int len;

    leaf = path->nodes[0];
    item_size = btrfs_item_size_nr(leaf, path->slots[0]);
    ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
    while (cur_offset < item_size) {
        ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
        len = btrfs_inode_ref_name_len(leaf, ref);
        name_ptr = (unsigned long)(ref + 1);
        cur_offset += len + sizeof(*ref);
        if (len != name_len)
            continue;
        if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
            *ref_ret = ref;
            return 1;
        }
    }
    return 0;
}

int btrfs_find_name_in_ext_backref(struct btrfs_path *path, u64 ref_objectid,
                   const char *name, int name_len,
                   struct btrfs_inode_extref **extref_ret)
{
    struct extent_buffer *leaf;
    struct btrfs_inode_extref *extref;
    unsigned long ptr;
    unsigned long name_ptr;
    u32 item_size;
    u32 cur_offset = 0;
    int ref_name_len;

    leaf = path->nodes[0];
    item_size = btrfs_item_size_nr(leaf, path->slots[0]);
    ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);

    /*
     * Search all extended backrefs in this item. We're only
     * looking through any collisions so most of the time this is
     * just going to compare against one buffer. If all is well,
     * we'll return success and the inode ref object.
     */
    while (cur_offset < item_size) {
        extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
        name_ptr = (unsigned long)(&extref->name);
        ref_name_len = btrfs_inode_extref_name_len(leaf, extref);

        if (ref_name_len == name_len &&
            btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
            (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)) {
            if (extref_ret)
                *extref_ret = extref;
            return 1;
        }

        cur_offset += ref_name_len + sizeof(*extref);
    }
    return 0;
}

static struct btrfs_inode_ref *
btrfs_lookup_inode_ref(struct btrfs_trans_handle *trans,
               struct btrfs_root *root,
               struct btrfs_path *path,
               const char *name, int name_len,
               u64 inode_objectid, u64 ref_objectid, int ins_len,
               int cow)
{
    int ret;
    struct btrfs_key key;
    struct btrfs_inode_ref *ref;

    key.objectid = inode_objectid;
    key.type = BTRFS_INODE_REF_KEY;
    key.offset = ref_objectid;

    ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
    if (ret < 0)
        return ERR_PTR(ret);
    if (ret > 0)
        return NULL;
    if (!find_name_in_backref(path, name, name_len, &ref))
        return NULL;
    return ref;
}

/* Returns NULL if no extref found */
struct btrfs_inode_extref *
btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
              struct btrfs_root *root,
              struct btrfs_path *path,
              const char *name, int name_len,
              u64 inode_objectid, u64 ref_objectid, int ins_len,
              int cow)
{
    int ret;
    struct btrfs_key key;
    struct btrfs_inode_extref *extref;

    key.objectid = inode_objectid;
    key.type = BTRFS_INODE_EXTREF_KEY;
    key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

    ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
    if (ret < 0)
        return ERR_PTR(ret);
    if (ret > 0)
        return NULL;
    if (!btrfs_find_name_in_ext_backref(path, ref_objectid, name, name_len, &extref))
        return NULL;
    return extref;
}

int btrfs_get_inode_ref_index(struct btrfs_trans_handle *trans,
                  struct btrfs_root *root,
                  struct btrfs_path *path,
                  const char *name, int name_len,
                  u64 inode_objectid, u64 ref_objectid, int mod,
                  u64 *ret_index)
{
    struct btrfs_inode_ref *ref;
    struct btrfs_inode_extref *extref;
    int ins_len = mod < 0 ? -1 : 0;
    int cow = mod != 0;

    ref = btrfs_lookup_inode_ref(trans, root, path, name, name_len,
                     inode_objectid, ref_objectid, ins_len,
                     cow);
    if (IS_ERR(ref))
        return PTR_ERR(ref);

    if (ref != NULL) {
        *ret_index = btrfs_inode_ref_index(path->nodes[0], ref);
        return 0;
    }

    btrfs_release_path(path);

    extref = btrfs_lookup_inode_extref(trans, root, path, name,
                       name_len, inode_objectid,
                       ref_objectid, ins_len, cow);
    if (IS_ERR(extref))
        return PTR_ERR(extref);

    if (extref) {
        *ret_index = btrfs_inode_extref_index(path->nodes[0], extref);
        return 0;
    }

    return -ENOENT;
}

int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
               struct btrfs_root *root,
               const char *name, int name_len,
               u64 inode_objectid, u64 ref_objectid, u64 *index)
{
    struct btrfs_path *path;
    struct btrfs_key key;
    struct btrfs_inode_extref *extref;
    struct extent_buffer *leaf;
    int ret;
    int del_len = name_len + sizeof(*extref);
    unsigned long ptr;
    unsigned long item_start;
    u32 item_size;

    key.objectid = inode_objectid;
    btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
    key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;

    path->leave_spinning = 1;

    ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
    if (ret > 0)
        ret = -ENOENT;
    if (ret < 0)
        goto out;

    /*
     * Sanity check - did we find the right item for this name?
     * This should always succeed so error here will make the FS
     * readonly.
     */
    if (!btrfs_find_name_in_ext_backref(path, ref_objectid,
                        name, name_len, &extref)) {
        btrfs_std_error(root->fs_info, -ENOENT);
        ret = -EROFS;
        goto out;
    }

    leaf = path->nodes[0];
    item_size = btrfs_item_size_nr(leaf, path->slots[0]);
    if (index)
        *index = btrfs_inode_extref_index(leaf, extref);

    if (del_len == item_size) {
        /*
         * Common case only one ref in the item, remove the
         * whole item.
         */
        ret = btrfs_del_item(trans, root, path);
        goto out;
    }

    ptr = (unsigned long)extref;
    item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);

    memmove_extent_buffer(leaf, ptr, ptr + del_len,
                  item_size - (ptr + del_len - item_start));

    btrfs_truncate_item(trans, root, path, item_size - del_len, 1);

out:
    btrfs_free_path(path);

    return ret;
}

int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
            struct btrfs_root *root,
            const char *name, int name_len,
            u64 inode_objectid, u64 ref_objectid, u64 *index)
{
    struct btrfs_path *path;
    struct btrfs_key key;
    struct btrfs_inode_ref *ref;
    struct extent_buffer *leaf;
    unsigned long ptr;
    unsigned long item_start;
    u32 item_size;
    u32 sub_item_len;
    int ret;
    int search_ext_refs = 0;
    int del_len = name_len + sizeof(*ref);

    key.objectid = inode_objectid;
    key.offset = ref_objectid;
    btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;

    path->leave_spinning = 1;

    ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
    if (ret > 0) {
        ret = -ENOENT;
        search_ext_refs = 1;
        goto out;
    } else if (ret < 0) {
        goto out;
    }
    if (!find_name_in_backref(path, name, name_len, &ref)) {
        ret = -ENOENT;
        search_ext_refs = 1;
        goto out;
    }
    leaf = path->nodes[0];
    item_size = btrfs_item_size_nr(leaf, path->slots[0]);

    if (index)
        *index = btrfs_inode_ref_index(leaf, ref);

    if (del_len == item_size) {
        ret = btrfs_del_item(trans, root, path);
        goto out;
    }
    ptr = (unsigned long)ref;
    sub_item_len = name_len + sizeof(*ref);
    item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
    memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
                  item_size - (ptr + sub_item_len - item_start));
    btrfs_truncate_item(trans, root, path, item_size - sub_item_len, 1);
out:
    btrfs_free_path(path);

    if (search_ext_refs) {
        /*
         * No refs were found, or we could not find the
         * name in our ref array. Find and remove the extended
         * inode ref then.
         */
        return btrfs_del_inode_extref(trans, root, name, name_len,
                          inode_objectid, ref_objectid, index);
    }

    return ret;
}

/*
 * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 *
 * The caller must have checked against BTRFS_LINK_MAX already.
 */
static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
                     struct btrfs_root *root,
                     const char *name, int name_len,
                     u64 inode_objectid, u64 ref_objectid, u64 index)
{
    struct btrfs_inode_extref *extref;
    int ret;
    int ins_len = name_len + sizeof(*extref);
    unsigned long ptr;
    struct btrfs_path *path;
    struct btrfs_key key;
    struct extent_buffer *leaf;
    struct btrfs_item *item;

    key.objectid = inode_objectid;
    key.type = BTRFS_INODE_EXTREF_KEY;
    key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;

    path->leave_spinning = 1;
    ret = btrfs_insert_empty_item(trans, root, path, &key,
                      ins_len);
    if (ret == -EEXIST) {
        if (btrfs_find_name_in_ext_backref(path, ref_objectid,
                           name, name_len, NULL))
            goto out;

        btrfs_extend_item(trans, root, path, ins_len);
        ret = 0;
    }
    if (ret < 0)
        goto out;

    leaf = path->nodes[0];
    item = btrfs_item_nr(leaf, path->slots[0]);
    ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
    ptr += btrfs_item_size(leaf, item) - ins_len;
    extref = (struct btrfs_inode_extref *)ptr;

    btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
    btrfs_set_inode_extref_index(path->nodes[0], extref, index);
    btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);

    ptr = (unsigned long)&extref->name;
    write_extent_buffer(path->nodes[0], name, ptr, name_len);
    btrfs_mark_buffer_dirty(path->nodes[0]);

out:
    btrfs_free_path(path);
    return ret;
}

/* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
               struct btrfs_root *root,
               const char *name, int name_len,
               u64 inode_objectid, u64 ref_objectid, u64 index)
{
    struct btrfs_path *path;
    struct btrfs_key key;
    struct btrfs_inode_ref *ref;
    unsigned long ptr;
    int ret;
    int ins_len = name_len + sizeof(*ref);

    key.objectid = inode_objectid;
    key.offset = ref_objectid;
    btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);

    path = btrfs_alloc_path();
    if (!path)
        return -ENOMEM;

    path->leave_spinning = 1;
    ret = btrfs_insert_empty_item(trans, root, path, &key,
                      ins_len);
    if (ret == -EEXIST) {
        u32 old_size;

        if (find_name_in_backref(path, name, name_len, &ref))
            goto out;

        old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
        btrfs_extend_item(trans, root, path, ins_len);
        ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                     struct btrfs_inode_ref);
        ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
        btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
        btrfs_set_inode_ref_index(path->nodes[0], ref, index);
        ptr = (unsigned long)(ref + 1);
        ret = 0;
    } else if (ret < 0) {
        if (ret == -EOVERFLOW)
            ret = -EMLINK;
        goto out;
    } else {
        ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
                     struct btrfs_inode_ref);
        btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
        btrfs_set_inode_ref_index(path->nodes[0], ref, index);
        ptr = (unsigned long)(ref + 1);
    }
    write_extent_buffer(path->nodes[0], name, ptr, name_len);
    btrfs_mark_buffer_dirty(path->nodes[0]);

out:
    btrfs_free_path(path);

    if (ret == -EMLINK) {
        struct btrfs_super_block *disk_super = root->fs_info->super_copy;
        /* We ran out of space in the ref array. Need to
         * add an extended ref. */
        if (btrfs_super_incompat_flags(disk_super)
            & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
            ret = btrfs_insert_inode_extref(trans, root, name,
                            name_len,
                            inode_objectid,
                            ref_objectid, index);
    }

    return ret;
}

int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
                 struct btrfs_root *root,
                 struct btrfs_path *path, u64 objectid)
{
    struct btrfs_key key;
    int ret;
    key.objectid = objectid;
    btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
    key.offset = 0;

    ret = btrfs_insert_empty_item(trans, root, path, &key,
                      sizeof(struct btrfs_inode_item));
    return ret;
}

int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
               *root, struct btrfs_path *path,
               struct btrfs_key *location, int mod)
{
    int ins_len = mod < 0 ? -1 : 0;
    int cow = mod != 0;
    int ret;
    int slot;
    struct extent_buffer *leaf;
    struct btrfs_key found_key;

    ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
    if (ret > 0 && btrfs_key_type(location) == BTRFS_ROOT_ITEM_KEY &&
        location->offset == (u64)-1 && path->slots[0] != 0) {
        slot = path->slots[0] - 1;
        leaf = path->nodes[0];
        btrfs_item_key_to_cpu(leaf, &found_key, slot);
        if (found_key.objectid == location->objectid &&
            btrfs_key_type(&found_key) == btrfs_key_type(location)) {
            path->slots[0]--;
            return 0;
        }
    }
    return ret;
}