linux/fs/nilfs2/btnode.c
Ryusuke Konishi b1f1b8ce0a nilfs2: fix preempt count underflow in nilfs_btnode_prepare_change_key
This will fix the following preempt count underflow reported from
users with the title "[NILFS users] segctord problem" (Message-ID:
<949415.6494.qm@web58808.mail.re1.yahoo.com> and Message-ID:
<debc30fc0908270825v747c1734xa59126623cfd5b05@mail.gmail.com>):

 WARNING: at kernel/sched.c:4890 sub_preempt_count+0x95/0xa0()
 Hardware name: HP Compaq 6530b (KR980UT#ABC)
 Modules linked in: bridge stp llc bnep rfcomm l2cap xfs exportfs nilfs2 cowloop loop vboxnetadp vboxnetflt vboxdrv btusb bluetooth uvcvideo videodev v4l1_compat v4l2_compat_ioctl32 arc4 snd_hda_codec_analog ecb iwlagn iwlcore rfkill lib80211 mac80211 snd_hda_intel snd_hda_codec ehci_hcd uhci_hcd usbcore snd_hwdep snd_pcm tg3 cfg80211 psmouse snd_timer joydev libphy ohci1394 snd_page_alloc hp_accel lis3lv02d ieee1394 led_class i915 drm i2c_algo_bit video backlight output i2c_core dm_crypt dm_mod
 Pid: 4197, comm: segctord Not tainted 2.6.30-gentoo-r4-64 #7
 Call Trace:
  [<ffffffff8023fa05>] ? sub_preempt_count+0x95/0xa0
  [<ffffffff802470f8>] warn_slowpath_common+0x78/0xd0
  [<ffffffff8024715f>] warn_slowpath_null+0xf/0x20
  [<ffffffff8023fa05>] sub_preempt_count+0x95/0xa0
  [<ffffffffa04ce4db>] nilfs_btnode_prepare_change_key+0x11b/0x190 [nilfs2]
  [<ffffffffa04d01ad>] nilfs_btree_assign_p+0x19d/0x1e0 [nilfs2]
  [<ffffffffa04d10ad>] nilfs_btree_assign+0xbd/0x130 [nilfs2]
  [<ffffffffa04cead7>] nilfs_bmap_assign+0x47/0x70 [nilfs2]
  [<ffffffffa04d9bc6>] nilfs_segctor_do_construct+0x956/0x20f0 [nilfs2]
  [<ffffffff805ac8e2>] ? _spin_unlock_irqrestore+0x12/0x40
  [<ffffffff803c06e0>] ? __up_write+0xe0/0x150
  [<ffffffff80262959>] ? up_write+0x9/0x10
  [<ffffffffa04ce9f3>] ? nilfs_bmap_test_and_clear_dirty+0x43/0x60 [nilfs2]
  [<ffffffffa04cd627>] ? nilfs_mdt_fetch_dirty+0x27/0x60 [nilfs2]
  [<ffffffffa04db5fc>] nilfs_segctor_construct+0x8c/0xd0 [nilfs2]
  [<ffffffffa04dc3dc>] nilfs_segctor_thread+0x15c/0x3a0 [nilfs2]
  [<ffffffffa04dbe20>] ? nilfs_construction_timeout+0x0/0x10 [nilfs2]
  [<ffffffff80252633>] ? add_timer+0x13/0x20
  [<ffffffff802370da>] ? __wake_up_common+0x5a/0x90
  [<ffffffff8025e960>] ? autoremove_wake_function+0x0/0x40
  [<ffffffffa04dc280>] ? nilfs_segctor_thread+0x0/0x3a0 [nilfs2]
  [<ffffffffa04dc280>] ? nilfs_segctor_thread+0x0/0x3a0 [nilfs2]
  [<ffffffff8025e556>] kthread+0x56/0x90
  [<ffffffff8020cdea>] child_rip+0xa/0x20
  [<ffffffff8025e500>] ? kthread+0x0/0x90
  [<ffffffff8020cde0>] ? child_rip+0x0/0x20

This problem was caused due to a missing radix_tree_preload() call in
the retry path of nilfs_btnode_prepare_change_key() function.

Reported-by: Eric A <eric225125@yahoo.com>
Reported-by: Jerome Poulin <jeromepoulin@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Jerome Poulin <jeromepoulin@gmail.com>
Cc: stable@kernel.org
2009-08-31 12:03:06 +09:00

320 lines
8.3 KiB
C

/*
* btnode.c - NILFS B-tree node cache
*
* 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
*
* This file was originally written by Seiji Kihara <kihara@osrg.net>
* and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for
* stabilization and simplification.
*
*/
#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include "nilfs.h"
#include "mdt.h"
#include "dat.h"
#include "page.h"
#include "btnode.h"
void nilfs_btnode_cache_init_once(struct address_space *btnc)
{
INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);
spin_lock_init(&btnc->tree_lock);
INIT_LIST_HEAD(&btnc->private_list);
spin_lock_init(&btnc->private_lock);
spin_lock_init(&btnc->i_mmap_lock);
INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);
INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);
}
static struct address_space_operations def_btnode_aops = {
.sync_page = block_sync_page,
};
void nilfs_btnode_cache_init(struct address_space *btnc,
struct backing_dev_info *bdi)
{
btnc->host = NULL; /* can safely set to host inode ? */
btnc->flags = 0;
mapping_set_gfp_mask(btnc, GFP_NOFS);
btnc->assoc_mapping = NULL;
btnc->backing_dev_info = bdi;
btnc->a_ops = &def_btnode_aops;
}
void nilfs_btnode_cache_clear(struct address_space *btnc)
{
invalidate_mapping_pages(btnc, 0, -1);
truncate_inode_pages(btnc, 0);
}
int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
sector_t pblocknr, struct buffer_head **pbh,
int newblk)
{
struct buffer_head *bh;
struct inode *inode = NILFS_BTNC_I(btnc);
int err;
bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
if (unlikely(!bh))
return -ENOMEM;
err = -EEXIST; /* internal code */
if (newblk) {
if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
buffer_dirty(bh))) {
brelse(bh);
BUG();
}
bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
bh->b_blocknr = blocknr;
set_buffer_mapped(bh);
set_buffer_uptodate(bh);
goto found;
}
if (buffer_uptodate(bh) || buffer_dirty(bh))
goto found;
if (pblocknr == 0) {
pblocknr = blocknr;
if (inode->i_ino != NILFS_DAT_INO) {
struct inode *dat =
nilfs_dat_inode(NILFS_I_NILFS(inode));
/* blocknr is a virtual block number */
err = nilfs_dat_translate(dat, blocknr, &pblocknr);
if (unlikely(err)) {
brelse(bh);
goto out_locked;
}
}
}
lock_buffer(bh);
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
err = -EEXIST; /* internal code */
goto found;
}
set_buffer_mapped(bh);
bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;
bh->b_blocknr = pblocknr; /* set block address for read */
bh->b_end_io = end_buffer_read_sync;
get_bh(bh);
submit_bh(READ, bh);
bh->b_blocknr = blocknr; /* set back to the given block address */
err = 0;
found:
*pbh = bh;
out_locked:
unlock_page(bh->b_page);
page_cache_release(bh->b_page);
return err;
}
int nilfs_btnode_get(struct address_space *btnc, __u64 blocknr,
sector_t pblocknr, struct buffer_head **pbh, int newblk)
{
struct buffer_head *bh;
int err;
err = nilfs_btnode_submit_block(btnc, blocknr, pblocknr, pbh, newblk);
if (err == -EEXIST) /* internal code (cache hit) */
return 0;
if (unlikely(err))
return err;
bh = *pbh;
wait_on_buffer(bh);
if (!buffer_uptodate(bh)) {
brelse(bh);
return -EIO;
}
return 0;
}
/**
* 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)
{
struct address_space *mapping;
struct page *page = bh->b_page;
pgoff_t index = page_index(page);
int still_dirty;
page_cache_get(page);
lock_page(page);
wait_on_page_writeback(page);
nilfs_forget_buffer(bh);
still_dirty = PageDirty(page);
mapping = page->mapping;
unlock_page(page);
page_cache_release(page);
if (!still_dirty && mapping)
invalidate_inode_pages2_range(mapping, index, index);
}
/**
* nilfs_btnode_prepare_change_key
* prepare to move contents of the block for old key to one of new key.
* the old buffer will not be removed, but might be reused for new buffer.
* it might return -ENOMEM because of memory allocation errors,
* and might return -EIO because of disk read errors.
*/
int nilfs_btnode_prepare_change_key(struct address_space *btnc,
struct nilfs_btnode_chkey_ctxt *ctxt)
{
struct buffer_head *obh, *nbh;
struct inode *inode = NILFS_BTNC_I(btnc);
__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
int err;
if (oldkey == newkey)
return 0;
obh = ctxt->bh;
ctxt->newbh = NULL;
if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
lock_page(obh->b_page);
/*
* We cannot call radix_tree_preload for the kernels older
* than 2.6.23, because it is not exported for modules.
*/
retry:
err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
if (err)
goto failed_unlock;
/* BUG_ON(oldkey != obh->b_page->index); */
if (unlikely(oldkey != obh->b_page->index))
NILFS_PAGE_BUG(obh->b_page,
"invalid oldkey %lld (newkey=%lld)",
(unsigned long long)oldkey,
(unsigned long long)newkey);
spin_lock_irq(&btnc->tree_lock);
err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
spin_unlock_irq(&btnc->tree_lock);
/*
* Note: page->index will not change to newkey until
* nilfs_btnode_commit_change_key() will be called.
* To protect the page in intermediate state, the page lock
* is held.
*/
radix_tree_preload_end();
if (!err)
return 0;
else if (err != -EEXIST)
goto failed_unlock;
err = invalidate_inode_pages2_range(btnc, newkey, newkey);
if (!err)
goto retry;
/* fallback to copy mode */
unlock_page(obh->b_page);
}
err = nilfs_btnode_get(btnc, newkey, 0, &nbh, 1);
if (likely(!err)) {
BUG_ON(nbh == obh);
ctxt->newbh = nbh;
}
return err;
failed_unlock:
unlock_page(obh->b_page);
return err;
}
/**
* nilfs_btnode_commit_change_key
* commit the change_key operation prepared by prepare_change_key().
*/
void nilfs_btnode_commit_change_key(struct address_space *btnc,
struct nilfs_btnode_chkey_ctxt *ctxt)
{
struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
struct page *opage;
if (oldkey == newkey)
return;
if (nbh == NULL) { /* blocksize == pagesize */
opage = obh->b_page;
if (unlikely(oldkey != opage->index))
NILFS_PAGE_BUG(opage,
"invalid oldkey %lld (newkey=%lld)",
(unsigned long long)oldkey,
(unsigned long long)newkey);
if (!test_set_buffer_dirty(obh) && TestSetPageDirty(opage))
BUG();
spin_lock_irq(&btnc->tree_lock);
radix_tree_delete(&btnc->page_tree, oldkey);
radix_tree_tag_set(&btnc->page_tree, newkey,
PAGECACHE_TAG_DIRTY);
spin_unlock_irq(&btnc->tree_lock);
opage->index = obh->b_blocknr = newkey;
unlock_page(opage);
} else {
nilfs_copy_buffer(nbh, obh);
nilfs_btnode_mark_dirty(nbh);
nbh->b_blocknr = newkey;
ctxt->bh = nbh;
nilfs_btnode_delete(obh); /* will decrement bh->b_count */
}
}
/**
* nilfs_btnode_abort_change_key
* abort the change_key operation prepared by prepare_change_key().
*/
void nilfs_btnode_abort_change_key(struct address_space *btnc,
struct nilfs_btnode_chkey_ctxt *ctxt)
{
struct buffer_head *nbh = ctxt->newbh;
__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
if (oldkey == newkey)
return;
if (nbh == NULL) { /* blocksize == pagesize */
spin_lock_irq(&btnc->tree_lock);
radix_tree_delete(&btnc->page_tree, newkey);
spin_unlock_irq(&btnc->tree_lock);
unlock_page(ctxt->bh->b_page);
} else
brelse(nbh);
}