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![Mark Fasheh](/assets/img/avatar_default.png)
Fix a corruption that can happen when we have (two or more) outstanding
aio's to an overlapping unaligned region. Ext4
(e9e3bcecf4
) and xfs recently had to fix
similar issues.
In our case what happens is that we can have an outstanding aio on a region
and if a write comes in with some bytes overlapping the original aio we may
decide to read that region into a page before continuing (typically because
of buffered-io fallback). Since we have no ordering guarantees with the
aio, we can read stale or bad data into the page and then write it back out.
If the i/o is page and block aligned, then we avoid this issue as there
won't be any need to read data from disk.
I took the same approach as Eric in the ext4 patch and introduced some
serialization of unaligned async direct i/o. I don't expect this to have an
effect on the most common cases of AIO. Unaligned aio will be slower
though, but that's far more acceptable than data corruption.
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <jlbec@evilplan.org>
108 lines
3.8 KiB
C
108 lines
3.8 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* Copyright (C) 2002, 2004, 2005 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (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 GNU
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* 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
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef OCFS2_AOPS_H
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#define OCFS2_AOPS_H
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handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
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struct page *page,
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unsigned from,
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unsigned to);
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int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
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struct inode *inode, unsigned int from,
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unsigned int to, int new);
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void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages);
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int walk_page_buffers( handle_t *handle,
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struct buffer_head *head,
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unsigned from,
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unsigned to,
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int *partial,
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int (*fn)( handle_t *handle,
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struct buffer_head *bh));
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int ocfs2_write_end_nolock(struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied,
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struct page *page, void *fsdata);
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int ocfs2_write_begin_nolock(struct file *filp,
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struct address_space *mapping,
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loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, void **fsdata,
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struct buffer_head *di_bh, struct page *mmap_page);
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int ocfs2_read_inline_data(struct inode *inode, struct page *page,
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struct buffer_head *di_bh);
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int ocfs2_size_fits_inline_data(struct buffer_head *di_bh, u64 new_size);
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int ocfs2_get_block(struct inode *inode, sector_t iblock,
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struct buffer_head *bh_result, int create);
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/* all ocfs2_dio_end_io()'s fault */
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#define ocfs2_iocb_is_rw_locked(iocb) \
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test_bit(0, (unsigned long *)&iocb->private)
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static inline void ocfs2_iocb_set_rw_locked(struct kiocb *iocb, int level)
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{
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set_bit(0, (unsigned long *)&iocb->private);
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if (level)
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set_bit(1, (unsigned long *)&iocb->private);
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else
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clear_bit(1, (unsigned long *)&iocb->private);
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}
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/*
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* Using a named enum representing lock types in terms of #N bit stored in
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* iocb->private, which is going to be used for communication between
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* ocfs2_dio_end_io() and ocfs2_file_aio_write/read().
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*/
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enum ocfs2_iocb_lock_bits {
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OCFS2_IOCB_RW_LOCK = 0,
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OCFS2_IOCB_RW_LOCK_LEVEL,
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OCFS2_IOCB_SEM,
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OCFS2_IOCB_UNALIGNED_IO,
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OCFS2_IOCB_NUM_LOCKS
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};
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#define ocfs2_iocb_clear_rw_locked(iocb) \
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clear_bit(OCFS2_IOCB_RW_LOCK, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_rw_locked_level(iocb) \
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test_bit(OCFS2_IOCB_RW_LOCK_LEVEL, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_set_sem_locked(iocb) \
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set_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_clear_sem_locked(iocb) \
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clear_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_is_sem_locked(iocb) \
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test_bit(OCFS2_IOCB_SEM, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_set_unaligned_aio(iocb) \
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set_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_clear_unaligned_aio(iocb) \
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clear_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
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#define ocfs2_iocb_is_unaligned_aio(iocb) \
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test_bit(OCFS2_IOCB_UNALIGNED_IO, (unsigned long *)&iocb->private)
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#define OCFS2_IOEND_WQ_HASH_SZ 37
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#define ocfs2_ioend_wq(v) (&ocfs2__ioend_wq[((unsigned long)(v)) %\
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OCFS2_IOEND_WQ_HASH_SZ])
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extern wait_queue_head_t ocfs2__ioend_wq[OCFS2_IOEND_WQ_HASH_SZ];
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#endif /* OCFS2_FILE_H */
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