2009-04-07 02:01:40 +00:00
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/*
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2009-04-07 02:01:45 +00:00
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* gcinode.c - dummy inodes to buffer blocks for garbage collection
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2009-04-07 02:01:40 +00:00
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*
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* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
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* and Ryusuke Konishi <ryusuke@osrg.net>.
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* Revised by Ryusuke Konishi <ryusuke@osrg.net>.
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*
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*/
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2009-04-07 02:01:45 +00:00
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/*
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* This file adds the cache of on-disk blocks to be moved in garbage
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* collection. The disk blocks are held with dummy inodes (called
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* gcinodes), and this file provides lookup function of the dummy
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* inodes and their buffer read function.
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*
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* Since NILFS2 keeps up multiple checkpoints/snapshots accross GC, it
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* has to treat blocks that belong to a same file but have different
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* checkpoint numbers. To avoid interference among generations, dummy
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* inodes are managed separatly from actual inodes, and their lookup
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* function (nilfs_gc_iget) is designed to be specified with a
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* checkpoint number argument as well as an inode number.
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*
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* Buffers and pages held by the dummy inodes will be released each
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* time after they are copied to a new log. Dirty blocks made on the
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* current generation and the blocks to be moved by GC never overlap
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* because the dirty blocks make a new generation; they rather must be
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* written individually.
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*/
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2009-04-07 02:01:40 +00:00
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#include <linux/buffer_head.h>
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#include <linux/mpage.h>
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#include <linux/hash.h>
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#include <linux/swap.h>
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#include "nilfs.h"
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#include "page.h"
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#include "mdt.h"
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#include "dat.h"
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#include "ifile.h"
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static struct address_space_operations def_gcinode_aops = {};
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/* XXX need def_gcinode_iops/fops? */
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/*
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* nilfs_gccache_submit_read_data() - add data buffer and submit read request
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* @inode - gc inode
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* @blkoff - dummy offset treated as the key for the page cache
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* @pbn - physical block number of the block
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* @vbn - virtual block number of the block, 0 for non-virtual block
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* @out_bh - indirect pointer to a buffer_head struct to receive the results
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*
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* Description: nilfs_gccache_submit_read_data() registers the data buffer
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* specified by @pbn to the GC pagecache with the key @blkoff.
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* This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
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*
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* Return Value: On success, 0 is returned. On Error, one of the following
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* negative error code is returned.
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*
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* %-EIO - I/O error.
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*
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* %-ENOMEM - Insufficient amount of memory available.
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*
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* %-ENOENT - The block specified with @pbn does not exist.
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*/
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int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
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sector_t pbn, __u64 vbn,
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struct buffer_head **out_bh)
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{
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struct buffer_head *bh;
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int err;
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bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
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if (unlikely(!bh))
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return -ENOMEM;
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if (buffer_uptodate(bh))
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goto out;
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if (pbn == 0) {
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struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
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/* use original dat, not gc dat. */
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err = nilfs_dat_translate(dat_inode, vbn, &pbn);
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if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
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brelse(bh);
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goto failed;
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}
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}
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lock_buffer(bh);
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if (buffer_uptodate(bh)) {
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unlock_buffer(bh);
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goto out;
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}
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if (!buffer_mapped(bh)) {
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bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
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set_buffer_mapped(bh);
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}
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bh->b_blocknr = pbn;
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bh->b_end_io = end_buffer_read_sync;
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get_bh(bh);
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submit_bh(READ, bh);
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if (vbn)
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bh->b_blocknr = vbn;
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out:
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err = 0;
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*out_bh = bh;
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failed:
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unlock_page(bh->b_page);
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page_cache_release(bh->b_page);
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return err;
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}
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/*
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* nilfs_gccache_submit_read_node() - add node buffer and submit read request
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* @inode - gc inode
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* @pbn - physical block number for the block
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* @vbn - virtual block number for the block
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* @out_bh - indirect pointer to a buffer_head struct to receive the results
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*
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* Description: nilfs_gccache_submit_read_node() registers the node buffer
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* specified by @vbn to the GC pagecache. @pbn can be supplied by the
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* caller to avoid translation of the disk block address.
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*
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* Return Value: On success, 0 is returned. On Error, one of the following
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* negative error code is returned.
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*
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* %-EIO - I/O error.
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*
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* %-ENOMEM - Insufficient amount of memory available.
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*/
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int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
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__u64 vbn, struct buffer_head **out_bh)
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{
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int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
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vbn ? : pbn, pbn, out_bh, 0);
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if (ret == -EEXIST) /* internal code (cache hit) */
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ret = 0;
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return ret;
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}
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int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
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{
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wait_on_buffer(bh);
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if (!buffer_uptodate(bh))
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return -EIO;
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if (buffer_dirty(bh))
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return -EEXIST;
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if (buffer_nilfs_node(bh))
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nilfs_btnode_mark_dirty(bh);
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else
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nilfs_mdt_mark_buffer_dirty(bh);
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return 0;
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}
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/*
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* nilfs_init_gccache() - allocate and initialize gc_inode hash table
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* @nilfs - the_nilfs
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*
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* Return Value: On success, 0.
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* On error, a negative error code is returned.
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*/
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int nilfs_init_gccache(struct the_nilfs *nilfs)
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{
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int loop;
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BUG_ON(nilfs->ns_gc_inodes_h);
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INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
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nilfs->ns_gc_inodes_h =
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kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
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GFP_NOFS);
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if (nilfs->ns_gc_inodes_h == NULL)
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return -ENOMEM;
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for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
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INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
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return 0;
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}
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/*
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* nilfs_destroy_gccache() - free gc_inode hash table
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* @nilfs - the nilfs
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*/
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void nilfs_destroy_gccache(struct the_nilfs *nilfs)
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{
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if (nilfs->ns_gc_inodes_h) {
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nilfs_remove_all_gcinode(nilfs);
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kfree(nilfs->ns_gc_inodes_h);
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nilfs->ns_gc_inodes_h = NULL;
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}
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}
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static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
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__u64 cno)
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{
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struct inode *inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS);
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struct nilfs_inode_info *ii;
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if (!inode)
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return NULL;
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inode->i_op = NULL;
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inode->i_fop = NULL;
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inode->i_mapping->a_ops = &def_gcinode_aops;
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ii = NILFS_I(inode);
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ii->i_cno = cno;
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ii->i_flags = 0;
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ii->i_state = 1 << NILFS_I_GCINODE;
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ii->i_bh = NULL;
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nilfs_bmap_init_gc(ii->i_bmap);
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return inode;
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}
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static unsigned long ihash(ino_t ino, __u64 cno)
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{
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return hash_long((unsigned long)((ino << 2) + cno),
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NILFS_GCINODE_HASH_BITS);
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}
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/*
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* nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
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*/
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struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
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{
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struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
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struct hlist_node *node;
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struct inode *inode;
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hlist_for_each_entry(inode, node, head, i_hash) {
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if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
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return inode;
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}
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inode = alloc_gcinode(nilfs, ino, cno);
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if (likely(inode)) {
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hlist_add_head(&inode->i_hash, head);
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list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
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}
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return inode;
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}
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/*
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* nilfs_clear_gcinode() - clear and free a gc inode
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*/
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void nilfs_clear_gcinode(struct inode *inode)
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{
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nilfs_mdt_clear(inode);
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nilfs_mdt_destroy(inode);
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}
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/*
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* nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
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*/
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void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
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{
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struct hlist_head *head = nilfs->ns_gc_inodes_h;
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struct hlist_node *node, *n;
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struct inode *inode;
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int loop;
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for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
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hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
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hlist_del_init(&inode->i_hash);
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list_del_init(&NILFS_I(inode)->i_dirty);
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nilfs_clear_gcinode(inode); /* might sleep */
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}
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}
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}
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