linux/fs/nilfs2/btnode.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * NILFS B-tree node cache
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Originally written by Seiji Kihara.
 * Fully revised by Ryusuke Konishi for stabilization and simplification.
 *
 */

#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/gfp.h>
#include "nilfs.h"
#include "mdt.h"
#include "dat.h"
#include "page.h"
#include "btnode.h"


/**
 * nilfs_init_btnc_inode - initialize B-tree node cache inode
 * @btnc_inode: inode to be initialized
 *
 * nilfs_init_btnc_inode() sets up an inode for B-tree node cache.
 */
void nilfs_init_btnc_inode(struct inode *btnc_inode)
{ … }

void nilfs_btnode_cache_clear(struct address_space *btnc)
{ … }

struct buffer_head *
nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
{ … }

int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
			      sector_t pblocknr, blk_opf_t opf,
			      struct buffer_head **pbh, sector_t *submit_ptr)
{ … }

/**
 * nilfs_btnode_delete - delete B-tree node buffer
 * @bh: buffer to be deleted
 *
 * nilfs_btnode_delete() invalidates the specified buffer and delete the page
 * including the buffer if the page gets unbusy.
 */
void nilfs_btnode_delete(struct buffer_head *bh)
{ … }

/**
 * nilfs_btnode_prepare_change_key - prepare to change the search key of a
 *                                   b-tree node block
 * @btnc: page cache in which the b-tree node block is buffered
 * @ctxt: structure for exchanging context information for key change
 *
 * nilfs_btnode_prepare_change_key() prepares to move the contents of the
 * b-tree node block of the old key given in the "oldkey" member of @ctxt to
 * the position of the new key given in the "newkey" member of @ctxt in the
 * page cache @btnc.  Here, the key of the block is an index in units of
 * blocks, and if the page and block sizes match, it matches the page index
 * in the page cache.
 *
 * If the page size and block size match, this function attempts to move the
 * entire folio, and in preparation for this, inserts the original folio into
 * the new index of the cache.  If this insertion fails or if the page size
 * and block size are different, it falls back to a copy preparation using
 * nilfs_btnode_create_block(), inserts a new block at the position
 * corresponding to "newkey", and stores the buffer head pointer in the
 * "newbh" member of @ctxt.
 *
 * Note that the current implementation does not support folio sizes larger
 * than the page size.
 *
 * Return: 0 on success, or the following negative error code on failure.
 * * %-EIO	- I/O error (metadata corruption).
 * * %-ENOMEM	- Insufficient memory available.
 */
int nilfs_btnode_prepare_change_key(struct address_space *btnc,
				    struct nilfs_btnode_chkey_ctxt *ctxt)
{ … }

/**
 * nilfs_btnode_commit_change_key - commit the change of the search key of
 *                                  a b-tree node block
 * @btnc: page cache in which the b-tree node block is buffered
 * @ctxt: structure for exchanging context information for key change
 *
 * nilfs_btnode_commit_change_key() executes the key change based on the
 * context @ctxt prepared by nilfs_btnode_prepare_change_key().  If no valid
 * block buffer is prepared in "newbh" of @ctxt (i.e., a full folio move),
 * this function removes the folio from the old index and completes the move.
 * Otherwise, it copies the block data and inherited flag states of "oldbh"
 * to "newbh" and clears the "oldbh" from the cache.  In either case, the
 * relocated buffer is marked as dirty.
 *
 * As with nilfs_btnode_prepare_change_key(), the current implementation does
 * not support folio sizes larger than the page size.
 */
void nilfs_btnode_commit_change_key(struct address_space *btnc,
				    struct nilfs_btnode_chkey_ctxt *ctxt)
{ … }

/**
 * nilfs_btnode_abort_change_key - abort the change of the search key of a
 *                                 b-tree node block
 * @btnc: page cache in which the b-tree node block is buffered
 * @ctxt: structure for exchanging context information for key change
 *
 * nilfs_btnode_abort_change_key() cancels the key change associated with the
 * context @ctxt prepared via nilfs_btnode_prepare_change_key() and performs
 * any necessary cleanup.  If no valid block buffer is prepared in "newbh" of
 * @ctxt, this function removes the folio from the destination index and aborts
 * the move.  Otherwise, it clears "newbh" from the cache.
 *
 * As with nilfs_btnode_prepare_change_key(), the current implementation does
 * not support folio sizes larger than the page size.
 */
void nilfs_btnode_abort_change_key(struct address_space *btnc,
				   struct nilfs_btnode_chkey_ctxt *ctxt)
{ … }