linux/fs/nilfs2/mdt.c
Vyacheslav Dubeyko 8c26c4e269 nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption
The NILFS2 driver remounts itself in RO mode in the case of discovering
metadata corruption (for example, discovering a broken bmap).  But
usually, this takes place when there have been file system operations
before remounting in RO mode.

Thereby, NILFS2 driver can be in RO mode with presence of dirty pages in
modified inodes' address spaces.  It results in flush kernel thread's
infinite trying to flush dirty pages in RO mode.  As a result, it is
possible to see such side effects as: (1) flush kernel thread occupies
50% - 99% of CPU time; (2) system can't be shutdowned without manual
power switch off.

SYMPTOMS:
(1) System log contains error message: "Remounting filesystem read-only".
(2) The flush kernel thread occupies 50% - 99% of CPU time.
(3) The system can't be shutdowned without manual power switch off.

REPRODUCTION PATH:
(1) Create volume group with name "unencrypted" by means of vgcreate utility.
(2) Run script (prepared by Anthony Doggett <Anthony2486@interfaces.org.uk>):

  ----------------[BEGIN SCRIPT]--------------------
  #!/bin/bash

  VG=unencrypted
  #apt-get install nilfs-tools darcs
  lvcreate --size 2G --name ntest $VG
  mkfs.nilfs2 -b 1024 -B 8192 /dev/mapper/$VG-ntest
  mkdir /var/tmp/n
  mkdir /var/tmp/n/ntest
  mount /dev/mapper/$VG-ntest /var/tmp/n/ntest
  mkdir /var/tmp/n/ntest/thedir
  cd /var/tmp/n/ntest/thedir
  sleep 2
  date
  darcs init
  sleep 2
  dmesg|tail -n 5
  date
  darcs whatsnew || true
  date
  sleep 2
  dmesg|tail -n 5
  ----------------[END SCRIPT]--------------------

(3) Try to shutdown the system.

REPRODUCIBILITY: 100%

FIX:

This patch implements checking mount state of NILFS2 driver in
nilfs_writepage(), nilfs_writepages() and nilfs_mdt_write_page()
methods.  If it is detected the RO mount state then all dirty pages are
simply discarded with warning messages is written in system log.

[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Anthony Doggett <Anthony2486@interfaces.org.uk>
Cc: ARAI Shun-ichi <hermes@ceres.dti.ne.jp>
Cc: Piotr Szymaniak <szarpaj@grubelek.pl>
Cc: Zahid Chowdhury <zahid.chowdhury@starsolutions.com>
Cc: Elmer Zhang <freeboy6716@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:04 -07:00

601 lines
15 KiB
C

/*
* 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);
}