https://github.com/torvalds/linux
Revision 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC, committed by Chris Mason on 10 December 2010, 21:29:10 UTC
This problem is found in meego testing: http://bugs.meego.com/show_bug.cgi?id=6672 A file in btrfs is mmaped and the mmaped buffer is passed to pwrite to write to the same page of the same file. In btrfs_file_aio_write(), the pages is locked by prepare_pages(). So when btrfs_copy_from_user() is called, page fault happens and the same page needs to be locked again in filemap_fault(). The fix is to move iov_iter_fault_in_readable() before prepage_pages() to make page fault happen before pages are locked. And also disable page fault in critical region in btrfs_copy_from_user(). Reviewed-by: Yan, Zheng<zheng.z.yan@intel.com> Signed-off-by: Zhong, Xin <xin.zhong@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent f106e82
Tip revision: 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Tip revision: 914ee29
vxfs_fshead.h
/*
* Copyright (c) 2000-2001 Christoph Hellwig.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL").
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#ifndef _VXFS_FSHEAD_H_
#define _VXFS_FSHEAD_H_
/*
* Veritas filesystem driver - fileset header structures.
*
* This file contains the physical structure of the VxFS
* fileset header.
*/
/*
* Fileset header
*/
struct vxfs_fsh {
u_int32_t fsh_version; /* fileset header version */
u_int32_t fsh_fsindex; /* fileset index */
u_int32_t fsh_time; /* modification time - sec */
u_int32_t fsh_utime; /* modification time - usec */
u_int32_t fsh_extop; /* extop flags */
vx_ino_t fsh_ninodes; /* allocated inodes */
u_int32_t fsh_nau; /* number of IAUs */
u_int32_t fsh_old_ilesize; /* old size of ilist */
u_int32_t fsh_dflags; /* flags */
u_int32_t fsh_quota; /* quota limit */
vx_ino_t fsh_maxinode; /* maximum inode number */
vx_ino_t fsh_iauino; /* IAU inode */
vx_ino_t fsh_ilistino[2]; /* ilist inodes */
vx_ino_t fsh_lctino; /* link count table inode */
/*
* Slightly more fields follow, but they
* a) are not of any interest for us, and
* b) differ a lot in different vxfs versions/ports
*/
};
#endif /* _VXFS_FSHEAD_H_ */
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