int nilfs_btnode_prepare_change_key(struct address_space *btnc, struct nilfs_btnode_chkey_ctxt *ctxt) { struct buffer_head *obh, *nbh; struct inode *inode = NILFS_BTNC_I(btnc); __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey; int err; if (oldkey == newkey) return 0; obh = ctxt->bh; ctxt->newbh = NULL; if (inode->i_blkbits == PAGE_CACHE_SHIFT) { lock_page(obh->b_page); retry: err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM); if (err) goto failed_unlock; if (unlikely(oldkey != obh->b_page->index)) NILFS_PAGE_BUG(obh->b_page, "invalid oldkey %lld (newkey=%lld)", (unsigned long long)oldkey, (unsigned long long)newkey); spin_lock_irq(&btnc->tree_lock); err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page); spin_unlock_irq(&btnc->tree_lock); radix_tree_preload_end(); if (!err) return 0; else if (err != -EEXIST) goto failed_unlock; err = invalidate_inode_pages2_range(btnc, newkey, newkey); if (!err) goto retry; unlock_page(obh->b_page); } nbh = nilfs_btnode_create_block(btnc, newkey); if (!nbh) return -ENOMEM; BUG_ON(nbh == obh); ctxt->newbh = nbh; return 0; failed_unlock: unlock_page(obh->b_page); return err; }
/** * nilfs_btnode_prepare_change_key * prepare to move contents of the block for old key to one of new key. * the old buffer will not be removed, but might be reused for new buffer. * it might return -ENOMEM because of memory allocation errors, * and might return -EIO because of disk read errors. */ int nilfs_btnode_prepare_change_key(struct address_space *btnc, struct nilfs_btnode_chkey_ctxt *ctxt) { struct buffer_head *obh, *nbh; struct inode *inode = NILFS_BTNC_I(btnc); __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey; int err; if (oldkey == newkey) return 0; obh = ctxt->bh; ctxt->newbh = NULL; if (inode->i_blkbits == PAGE_CACHE_SHIFT) { lock_page(obh->b_page); /* * We cannot call radix_tree_preload for the kernels older * than 2.6.23, because it is not exported for modules. */ retry: err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM); if (err) goto failed_unlock; /* BUG_ON(oldkey != obh->b_page->index); */ if (unlikely(oldkey != obh->b_page->index)) NILFS_PAGE_BUG(obh->b_page, "invalid oldkey %lld (newkey=%lld)", (unsigned long long)oldkey, (unsigned long long)newkey); spin_lock_irq(&btnc->tree_lock); err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page); spin_unlock_irq(&btnc->tree_lock); /* * Note: page->index will not change to newkey until * nilfs_btnode_commit_change_key() will be called. * To protect the page in intermediate state, the page lock * is held. */ radix_tree_preload_end(); if (!err) return 0; else if (err != -EEXIST) goto failed_unlock; err = invalidate_inode_pages2_range(btnc, newkey, newkey); if (!err) goto retry; /* fallback to copy mode */ unlock_page(obh->b_page); } nbh = nilfs_btnode_create_block(btnc, newkey); if (!nbh) return -ENOMEM; BUG_ON(nbh == obh); ctxt->newbh = nbh; return 0; failed_unlock: unlock_page(obh->b_page); return err; }