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a11f7e63c5
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>
109 lines
3.8 KiB
C
109 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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