2aa15890f3
Michael Leun reported that running parallel opens on a fuse filesystem
can trigger a "kernel BUG at mm/truncate.c:475"
Gurudas Pai reported the same bug on NFS.
The reason is, unmap_mapping_range() is not prepared for more than
one concurrent invocation per inode. For example:
thread1: going through a big range, stops in the middle of a vma and
stores the restart address in vm_truncate_count.
thread2: comes in with a small (e.g. single page) unmap request on
the same vma, somewhere before restart_address, finds that the
vma was already unmapped up to the restart address and happily
returns without doing anything.
Another scenario would be two big unmap requests, both having to
restart the unmapping and each one setting vm_truncate_count to its
own value. This could go on forever without any of them being able to
finish.
Truncate and hole punching already serialize with i_mutex. Other
callers of unmap_mapping_range() do not, and it's difficult to get
i_mutex protection for all callers. In particular ->d_revalidate(),
which calls invalidate_inode_pages2_range() in fuse, may be called
with or without i_mutex.
This patch adds a new mutex to 'struct address_space' to prevent
running multiple concurrent unmap_mapping_range() on the same mapping.
[ We'll hopefully get rid of all this with the upcoming mm
preemptibility series by Peter Zijlstra, the "mm: Remove i_mmap_mutex
lockbreak" patch in particular. But that is for 2.6.39 ]
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reported-by: Michael Leun <lkml20101129@newton.leun.net>
Reported-by: Gurudas Pai <gurudas.pai@oracle.com>
Tested-by: Gurudas Pai <gurudas.pai@oracle.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
87 lines
2.9 KiB
C
87 lines
2.9 KiB
C
/*
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* page.h - buffer/page management specific to NILFS
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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 Ryusuke Konishi <ryusuke@osrg.net>,
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* Seiji Kihara <kihara@osrg.net>.
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*/
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#ifndef _NILFS_PAGE_H
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#define _NILFS_PAGE_H
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#include <linux/buffer_head.h>
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#include "nilfs.h"
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/*
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* Extended buffer state bits
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*/
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enum {
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BH_NILFS_Allocated = BH_PrivateStart,
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BH_NILFS_Node,
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BH_NILFS_Volatile,
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BH_NILFS_Checked,
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BH_NILFS_Redirected,
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};
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BUFFER_FNS(NILFS_Allocated, nilfs_allocated) /* nilfs private buffers */
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BUFFER_FNS(NILFS_Node, nilfs_node) /* nilfs node buffers */
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BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
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BUFFER_FNS(NILFS_Checked, nilfs_checked) /* buffer is verified */
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BUFFER_FNS(NILFS_Redirected, nilfs_redirected) /* redirected to a copy */
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void nilfs_mark_buffer_dirty(struct buffer_head *bh);
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int __nilfs_clear_page_dirty(struct page *);
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struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
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unsigned long, unsigned long);
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void nilfs_forget_buffer(struct buffer_head *);
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void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
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int nilfs_page_buffers_clean(struct page *);
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void nilfs_page_bug(struct page *);
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struct page *nilfs_alloc_private_page(struct block_device *, int,
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unsigned long);
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void nilfs_free_private_page(struct page *);
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int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
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void nilfs_copy_back_pages(struct address_space *, struct address_space *);
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void nilfs_clear_dirty_pages(struct address_space *);
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void nilfs_mapping_init(struct address_space *mapping,
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struct backing_dev_info *bdi,
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const struct address_space_operations *aops);
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unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
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unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
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sector_t start_blk,
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sector_t *blkoff);
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#define NILFS_PAGE_BUG(page, m, a...) \
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do { nilfs_page_bug(page); BUG(); } while (0)
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static inline struct buffer_head *
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nilfs_page_get_nth_block(struct page *page, unsigned int count)
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{
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struct buffer_head *bh = page_buffers(page);
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while (count-- > 0)
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bh = bh->b_this_page;
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get_bh(bh);
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return bh;
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}
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#endif /* _NILFS_PAGE_H */
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