/*
* gcinode.c - dummy inodes to buffer blocks for garbage collection
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Written by Seiji Kihara <kihara@osrg.net>, Amagai Yoshiji <amagai@osrg.net>,
* and Ryusuke Konishi <ryusuke@osrg.net>.
* Revised by Ryusuke Konishi <ryusuke@osrg.net>.
*
*/
/*
* This file adds the cache of on-disk blocks to be moved in garbage
* collection. The disk blocks are held with dummy inodes (called
* gcinodes), and this file provides lookup function of the dummy
* inodes and their buffer read function.
*
* Since NILFS2 keeps up multiple checkpoints/snapshots accross GC, it
* has to treat blocks that belong to a same file but have different
* checkpoint numbers. To avoid interference among generations, dummy
* inodes are managed separatly from actual inodes, and their lookup
* function (nilfs_gc_iget) is designed to be specified with a
* checkpoint number argument as well as an inode number.
*
* Buffers and pages held by the dummy inodes will be released each
* time after they are copied to a new log. Dirty blocks made on the
* current generation and the blocks to be moved by GC never overlap
* because the dirty blocks make a new generation; they rather must be
* written individually.
*/
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/hash.h>
#include <linux/swap.h>
#include "nilfs.h"
#include "page.h"
#include "mdt.h"
#include "dat.h"
#include "ifile.h"
static const struct address_space_operations def_gcinode_aops = {
.sync_page = block_sync_page,
};
/*
* nilfs_gccache_submit_read_data() - add data buffer and submit read request
* @inode - gc inode
* @blkoff - dummy offset treated as the key for the page cache
* @pbn - physical block number of the block
* @vbn - virtual block number of the block, 0 for non-virtual block
* @out_bh - indirect pointer to a buffer_head struct to receive the results
*
* Description: nilfs_gccache_submit_read_data() registers the data buffer
* specified by @pbn to the GC pagecache with the key @blkoff.
* This function sets @vbn (@pbn if @vbn is zero) in b_blocknr of the buffer.
*
* Return Value: On success, 0 is returned. On Error, one of the following
* negative error code is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*
* %-ENOENT - The block specified with @pbn does not exist.
*/
int nilfs_gccache_submit_read_data(struct inode *inode, sector_t blkoff,
sector_t pbn, __u64 vbn,
struct buffer_head **out_bh)
{
struct buffer_head *bh;
int err;
bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
if (unlikely(!bh))
return -ENOMEM;
if (buffer_uptodate(bh))
goto out;
if (pbn == 0) {
struct inode *dat_inode = NILFS_I_NILFS(inode)->ns_dat;
/* use original dat, not gc dat. */
err = nilfs_dat_translate(dat_inode, vbn, &pbn);
if (unlikely(err)) { /* -EIO, -ENOMEM, -ENOENT */
brelse(bh);
goto failed;
}
}
lock_buffer(bh);
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
goto out;
}
if (!buffer_mapped(bh)) {
bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
set_buffer_mapped(bh);
}
bh->b_blocknr = pbn;
bh->b_end_io = end_buffer_read_sync;
get_bh(bh);
submit_bh(READ, bh);
if (vbn)
bh->b_blocknr = vbn;
out:
err = 0;
*out_bh = bh;
failed:
unlock_page(bh->b_page);
page_cache_release(bh->b_page);
return err;
}
/*
* nilfs_gccache_submit_read_node() - add node buffer and submit read request
* @inode - gc inode
* @pbn - physical block number for the block
* @vbn - virtual block number for the block
* @out_bh - indirect pointer to a buffer_head struct to receive the results
*
* Description: nilfs_gccache_submit_read_node() registers the node buffer
* specified by @vbn to the GC pagecache. @pbn can be supplied by the
* caller to avoid translation of the disk block address.
*
* Return Value: On success, 0 is returned. On Error, one of the following
* negative error code is returned.
*
* %-EIO - I/O error.
*
* %-ENOMEM - Insufficient amount of memory available.
*/
int nilfs_gccache_submit_read_node(struct inode *inode, sector_t pbn,
__u64 vbn, struct buffer_head **out_bh)
{
int ret = nilfs_btnode_submit_block(&NILFS_I(inode)->i_btnode_cache,
vbn ? : pbn, pbn, out_bh);
if (ret == -EEXIST) /* internal code (cache hit) */
ret = 0;
return ret;
}
int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *bh)
{
wait_on_buffer(bh);
if (!buffer_uptodate(bh))
return -EIO;
if (buffer_dirty(bh))
return -EEXIST;
if (buffer_nilfs_node(bh))
nilfs_btnode_mark_dirty(bh);
else
nilfs_mdt_mark_buffer_dirty(bh);
return 0;
}
/*
* nilfs_init_gccache() - allocate and initialize gc_inode hash table
* @nilfs - the_nilfs
*
* Return Value: On success, 0.
* On error, a negative error code is returned.
*/
int nilfs_init_gccache(struct the_nilfs *nilfs)
{
int loop;
BUG_ON(nilfs->ns_gc_inodes_h);
INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
nilfs->ns_gc_inodes_h =
kmalloc(sizeof(struct hlist_head) * NILFS_GCINODE_HASH_SIZE,
GFP_NOFS);
if (nilfs->ns_gc_inodes_h == NULL)
return -ENOMEM;
for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++)
INIT_HLIST_HEAD(&nilfs->ns_gc_inodes_h[loop]);
return 0;
}
/*
* nilfs_destroy_gccache() - free gc_inode hash table
* @nilfs - the nilfs
*/
void nilfs_destroy_gccache(struct the_nilfs *nilfs)
{
if (nilfs->ns_gc_inodes_h) {
nilfs_remove_all_gcinode(nilfs);
kfree(nilfs->ns_gc_inodes_h);
nilfs->ns_gc_inodes_h = NULL;
}
}
static struct inode *alloc_gcinode(struct the_nilfs *nilfs, ino_t ino,
__u64 cno)
{
struct inode *inode;
struct nilfs_inode_info *ii;
inode = nilfs_mdt_new_common(nilfs, NULL, ino, GFP_NOFS, 0);
if (!inode)
return NULL;
inode->i_op = NULL;
inode->i_fop = NULL;
inode->i_mapping->a_ops = &def_gcinode_aops;
ii = NILFS_I(inode);
ii->i_cno = cno;
ii->i_flags = 0;
ii->i_state = 1 << NILFS_I_GCINODE;
ii->i_bh = NULL;
nilfs_bmap_init_gc(ii->i_bmap);
return inode;
}
static unsigned long ihash(ino_t ino, __u64 cno)
{
return hash_long((unsigned long)((ino << 2) + cno),
NILFS_GCINODE_HASH_BITS);
}
/*
* nilfs_gc_iget() - find or create gc inode with specified (ino,cno)
*/
struct inode *nilfs_gc_iget(struct the_nilfs *nilfs, ino_t ino, __u64 cno)
{
struct hlist_head *head = nilfs->ns_gc_inodes_h + ihash(ino, cno);
struct hlist_node *node;
struct inode *inode;
hlist_for_each_entry(inode, node, head, i_hash) {
if (inode->i_ino == ino && NILFS_I(inode)->i_cno == cno)
return inode;
}
inode = alloc_gcinode(nilfs, ino, cno);
if (likely(inode)) {
hlist_add_head(&inode->i_hash, head);
list_add(&NILFS_I(inode)->i_dirty, &nilfs->ns_gc_inodes);
}
return inode;
}
/*
* nilfs_clear_gcinode() - clear and free a gc inode
*/
void nilfs_clear_gcinode(struct inode *inode)
{
nilfs_mdt_destroy(inode);
}
/*
* nilfs_remove_all_gcinode() - remove all inodes from the_nilfs
*/
void nilfs_remove_all_gcinode(struct the_nilfs *nilfs)
{
struct hlist_head *head = nilfs->ns_gc_inodes_h;
struct hlist_node *node, *n;
struct inode *inode;
int loop;
for (loop = 0; loop < NILFS_GCINODE_HASH_SIZE; loop++, head++) {
hlist_for_each_entry_safe(inode, node, n, head, i_hash) {
hlist_del_init(&inode->i_hash);
list_del_init(&NILFS_I(inode)->i_dirty);
nilfs_clear_gcinode(inode); /* might sleep */
}
}
}
