original development tree for Linux kernel GTP module; now long in mainline.
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/*
* mdt.c - meta data file for NILFS
*
* 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 Ryusuke Konishi <ryusuke@osrg.net>
*/
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/mm.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include "nilfs.h"
#include "btnode.h"
#include "segment.h"
#include "page.h"
#include "mdt.h"
#define NILFS_MDT_MAX_RA_BLOCKS (16 - 1)
static int
nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
struct buffer_head *bh,
void (*init_block)(struct inode *,
struct buffer_head *, void *))
{
struct nilfs_inode_info *ii = NILFS_I(inode);
void *kaddr;
int ret;
/* Caller exclude read accesses using page lock */
/* set_buffer_new(bh); */
bh->b_blocknr = 0;
ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
if (unlikely(ret))
return ret;
set_buffer_mapped(bh);
kaddr = kmap_atomic(bh->b_page);
memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
if (init_block)
init_block(inode, bh, kaddr);
flush_dcache_page(bh->b_page);
kunmap_atomic(kaddr);
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
nilfs_mdt_mark_dirty(inode);
return 0;
}
static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
struct buffer_head **out_bh,
void (*init_block)(struct inode *,
struct buffer_head *,
void *))
{
struct super_block *sb = inode->i_sb;
struct nilfs_transaction_info ti;
struct buffer_head *bh;
int err;
nilfs_transaction_begin(sb, &ti, 0);
err = -ENOMEM;
bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
if (unlikely(!bh))
goto failed_unlock;
err = -EEXIST;
if (buffer_uptodate(bh))
goto failed_bh;
wait_on_buffer(bh);
if (buffer_uptodate(bh))
goto failed_bh;
bh->b_bdev = sb->s_bdev;
err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
if (likely(!err)) {
get_bh(bh);
*out_bh = bh;
}
failed_bh:
unlock_page(bh->b_page);
page_cache_release(bh->b_page);
brelse(bh);
failed_unlock:
if (likely(!err))
err = nilfs_transaction_commit(sb);
else
nilfs_transaction_abort(sb);
return err;
}
static int
nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
int mode, struct buffer_head **out_bh)
{
struct buffer_head *bh;
__u64 blknum = 0;
int ret = -ENOMEM;
bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
if (unlikely(!bh))
goto failed;
ret = -EEXIST; /* internal code */
if (buffer_uptodate(bh))
goto out;
if (mode == READA) {
if (!trylock_buffer(bh)) {
ret = -EBUSY;
goto failed_bh;
}
} else /* mode == READ */
lock_buffer(bh);
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
goto out;
}
ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
if (unlikely(ret)) {
unlock_buffer(bh);
goto failed_bh;
}
map_bh(bh, inode->i_sb, (sector_t)blknum);
bh->b_end_io = end_buffer_read_sync;
get_bh(bh);
submit_bh(mode, bh);
ret = 0;
out:
get_bh(bh);
*out_bh = bh;
failed_bh:
unlock_page(bh->b_page);
page_cache_release(bh->b_page);
brelse(bh);
failed:
return ret;
}
static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
int readahead, struct buffer_head **out_bh)
{
struct buffer_head *first_bh, *bh;
unsigned long blkoff;
int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
int err;
err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
if (err == -EEXIST) /* internal code */
goto out;
if (unlikely(err))
goto failed;
if (readahead) {
blkoff = block + 1;
for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
if (likely(!err || err == -EEXIST))
brelse(bh);
else if (err != -EBUSY)
break;
/* abort readahead if bmap lookup failed */
if (!buffer_locked(first_bh))
goto out_no_wait;
}
}
wait_on_buffer(first_bh);
out_no_wait:
err = -EIO;
if (!buffer_uptodate(first_bh))
goto failed_bh;
out:
*out_bh = first_bh;
return 0;
failed_bh:
brelse(first_bh);
failed:
return err;
}
/**
* nilfs_mdt_get_block - read or create a buffer on meta data file.
* @inode: inode of the meta data file
* @blkoff: block offset
* @create: create flag
* @init_block: initializer used for newly allocated block
* @out_bh: output of a pointer to the buffer_head
*
* nilfs_mdt_get_block() looks up the specified buffer and tries to create
* a new buffer if @create is not zero. On success, the returned buffer is
* assured to be either existing or formatted using a buffer lock on success.
* @out_bh is substituted only when zero is returned.
*
* Return Value: On success, it returns 0. On error, the following negative
* error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - the specified block does not exist (hole block)
*
* %-EROFS - Read only filesystem (for create mode)
*/
int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
void (*init_block)(struct inode *,
struct buffer_head *, void *),
struct buffer_head **out_bh)
{
int ret;
/* Should be rewritten with merging nilfs_mdt_read_block() */
retry:
ret = nilfs_mdt_read_block(inode, blkoff, !create, out_bh);
if (!create || ret != -ENOENT)
return ret;
ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
if (unlikely(ret == -EEXIST)) {
/* create = 0; */ /* limit read-create loop retries */
goto retry;
}
return ret;
}
/**
* nilfs_mdt_delete_block - make a hole on the meta data file.
* @inode: inode of the meta data file
* @block: block offset
*
* Return Value: On success, zero is returned.
* On error, one of the following negative error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*/
int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
{
struct nilfs_inode_info *ii = NILFS_I(inode);
int err;
err = nilfs_bmap_delete(ii->i_bmap, block);
if (!err || err == -ENOENT) {
nilfs_mdt_mark_dirty(inode);
nilfs_mdt_forget_block(inode, block);
}
return err;
}
/**
* nilfs_mdt_forget_block - discard dirty state and try to remove the page
* @inode: inode of the meta data file
* @block: block offset
*
* nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
* tries to release the page including the buffer from a page cache.
*
* Return Value: On success, 0 is returned. On error, one of the following
* negative error code is returned.
*
* %-EBUSY - page has an active buffer.
*
* %-ENOENT - page cache has no page addressed by the offset.
*/
int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
{
pgoff_t index = (pgoff_t)block >>
(PAGE_CACHE_SHIFT - inode->i_blkbits);
struct page *page;
unsigned long first_block;
int ret = 0;
int still_dirty;
page = find_lock_page(inode->i_mapping, index);
if (!page)
return -ENOENT;
wait_on_page_writeback(page);
first_block = (unsigned long)index <<
(PAGE_CACHE_SHIFT - inode->i_blkbits);
if (page_has_buffers(page)) {
struct buffer_head *bh;
bh = nilfs_page_get_nth_block(page, block - first_block);
nilfs_forget_buffer(bh);
}
still_dirty = PageDirty(page);
unlock_page(page);
page_cache_release(page);
if (still_dirty ||
invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
ret = -EBUSY;
return ret;
}
/**
* nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
* @inode: inode of the meta data file
* @block: block offset
*
* Return Value: On success, it returns 0. On error, the following negative
* error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - the specified block does not exist (hole block)
*/
int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
{
struct buffer_head *bh;
int err;
err = nilfs_mdt_read_block(inode, block, 0, &bh);
if (unlikely(err))
return err;
mark_buffer_dirty(bh);
nilfs_mdt_mark_dirty(inode);
brelse(bh);
return 0;
}
int nilfs_mdt_fetch_dirty(struct inode *inode)
{
struct nilfs_inode_info *ii = NILFS_I(inode);
if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
set_bit(NILFS_I_DIRTY, &ii->i_state);
return 1;
}
return test_bit(NILFS_I_DIRTY, &ii->i_state);
}
static int
nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
struct super_block *sb;
int err = 0;
if (inode && (inode->i_sb->s_flags & MS_RDONLY)) {
/*
* It means that filesystem was remounted in read-only
* mode because of error or metadata corruption. But we
* have dirty pages that try to be flushed in background.
* So, here we simply discard this dirty page.
*/
nilfs_clear_dirty_page(page, false);
unlock_page(page);
return -EROFS;
}
redirty_page_for_writepage(wbc, page);
unlock_page(page);
if (!inode)
return 0;
sb = inode->i_sb;
if (wbc->sync_mode == WB_SYNC_ALL)
err = nilfs_construct_segment(sb);
else if (wbc->for_reclaim)
nilfs_flush_segment(sb, inode->i_ino);
return err;
}
static const struct address_space_operations def_mdt_aops = {
.writepage = nilfs_mdt_write_page,
};
static const struct inode_operations def_mdt_iops;
static const struct file_operations def_mdt_fops;
int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
{
struct nilfs_mdt_info *mi;
mi = kzalloc(max(sizeof(*mi), objsz), GFP_NOFS);
if (!mi)
return -ENOMEM;
init_rwsem(&mi->mi_sem);
inode->i_private = mi;
inode->i_mode = S_IFREG;
mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
inode->i_op = &def_mdt_iops;
inode->i_fop = &def_mdt_fops;
inode->i_mapping->a_ops = &def_mdt_aops;
return 0;
}
void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
unsigned header_size)
{
struct nilfs_mdt_info *mi = NILFS_MDT(inode);
mi->mi_entry_size = entry_size;
mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
}
/**
* nilfs_mdt_setup_shadow_map - setup shadow map and bind it to metadata file
* @inode: inode of the metadata file
* @shadow: shadow mapping
*/
int nilfs_mdt_setup_shadow_map(struct inode *inode,
struct nilfs_shadow_map *shadow)
{
struct nilfs_mdt_info *mi = NILFS_MDT(inode);
struct backing_dev_info *bdi = inode->i_sb->s_bdi;
INIT_LIST_HEAD(&shadow->frozen_buffers);
address_space_init_once(&shadow->frozen_data);
nilfs_mapping_init(&shadow->frozen_data, inode, bdi);
address_space_init_once(&shadow->frozen_btnodes);
nilfs_mapping_init(&shadow->frozen_btnodes, inode, bdi);
mi->mi_shadow = shadow;
return 0;
}
/**
* nilfs_mdt_save_to_shadow_map - copy bmap and dirty pages to shadow map
* @inode: inode of the metadata file
*/
int nilfs_mdt_save_to_shadow_map(struct inode *inode)
{
struct nilfs_mdt_info *mi = NILFS_MDT(inode);
struct nilfs_inode_info *ii = NILFS_I(inode);
struct nilfs_shadow_map *shadow = mi->mi_shadow;
int ret;
ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
if (ret)
goto out;
ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
&ii->i_btnode_cache);
if (ret)
goto out;
nilfs_bmap_save(ii->i_bmap, &shadow->bmap_store);
out:
return ret;
}
int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
{
struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
struct buffer_head *bh_frozen;
struct page *page;
int blkbits = inode->i_blkbits;
page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
if (!page)
return -ENOMEM;
if (!page_has_buffers(page))
create_empty_buffers(page, 1 << blkbits, 0);
bh_frozen = nilfs_page_get_nth_block(page, bh_offset(bh) >> blkbits);
if (!buffer_uptodate(bh_frozen))
nilfs_copy_buffer(bh_frozen, bh);
if (list_empty(&bh_frozen->b_assoc_buffers)) {
list_add_tail(&bh_frozen->b_assoc_buffers,
&shadow->frozen_buffers);
set_buffer_nilfs_redirected(bh);
} else {
brelse(bh_frozen); /* already frozen */
}
unlock_page(page);
page_cache_release(page);
return 0;
}
struct buffer_head *
nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
{
struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
struct buffer_head *bh_frozen = NULL;
struct page *page;
int n;
page = find_lock_page(&shadow->frozen_data, bh->b_page->index);
if (page) {
if (page_has_buffers(page)) {
n = bh_offset(bh) >> inode->i_blkbits;
bh_frozen = nilfs_page_get_nth_block(page, n);
}
unlock_page(page);
page_cache_release(page);
}
return bh_frozen;
}
static void nilfs_release_frozen_buffers(struct nilfs_shadow_map *shadow)
{
struct list_head *head = &shadow->frozen_buffers;
struct buffer_head *bh;
while (!list_empty(head)) {
bh = list_first_entry(head, struct buffer_head,
b_assoc_buffers);
list_del_init(&bh->b_assoc_buffers);
brelse(bh); /* drop ref-count to make it releasable */
}
}
/**
* nilfs_mdt_restore_from_shadow_map - restore dirty pages and bmap state
* @inode: inode of the metadata file
*/
void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
{
struct nilfs_mdt_info *mi = NILFS_MDT(inode);
struct nilfs_inode_info *ii = NILFS_I(inode);
struct nilfs_shadow_map *shadow = mi->mi_shadow;
down_write(&mi->mi_sem);
if (mi->mi_palloc_cache)
nilfs_palloc_clear_cache(inode);
nilfs_clear_dirty_pages(inode->i_mapping, true);
nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
nilfs_clear_dirty_pages(&ii->i_btnode_cache, true);
nilfs_copy_back_pages(&ii->i_btnode_cache, &shadow->frozen_btnodes);
nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
up_write(&mi->mi_sem);
}
/**
* nilfs_mdt_clear_shadow_map - truncate pages in shadow map caches
* @inode: inode of the metadata file
*/
void nilfs_mdt_clear_shadow_map(struct inode *inode)
{
struct nilfs_mdt_info *mi = NILFS_MDT(inode);
struct nilfs_shadow_map *shadow = mi->mi_shadow;
down_write(&mi->mi_sem);
nilfs_release_frozen_buffers(shadow);
truncate_inode_pages(&shadow->frozen_data, 0);
truncate_inode_pages(&shadow->frozen_btnodes, 0);
up_write(&mi->mi_sem);
}