Revision 03cdadb04077b9311bbc67d98cc5401aff76482d authored by Dan Williams on 26 February 2016, 23:19:43 UTC, committed by Linus Torvalds on 27 February 2016, 18:28:52 UTC
The recent *sync enabling discovered that we are inserting into the block_device pagecache counter to the expectations of the dirty data tracking for dax mappings. This can lead to data corruption. We want to support DAX for block devices eventually, but it requires wider changes to properly manage the pagecache. dump_stack+0x85/0xc2 dax_writeback_mapping_range+0x60/0xe0 blkdev_writepages+0x3f/0x50 do_writepages+0x21/0x30 __filemap_fdatawrite_range+0xc6/0x100 filemap_write_and_wait+0x4a/0xa0 set_blocksize+0x70/0xd0 sb_set_blocksize+0x1d/0x50 ext4_fill_super+0x75b/0x3360 mount_bdev+0x180/0x1b0 ext4_mount+0x15/0x20 mount_fs+0x38/0x170 Mark the support broken so its disabled by default, but otherwise still available for testing. Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Suggested-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@fb.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cordic.c
/*
* Copyright (c) 2011 Broadcom Corporation
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <linux/module.h>
#include <linux/cordic.h>
#define CORDIC_ANGLE_GEN 39797
#define CORDIC_PRECISION_SHIFT 16
#define CORDIC_NUM_ITER (CORDIC_PRECISION_SHIFT + 2)
#define FIXED(X) ((s32)((X) << CORDIC_PRECISION_SHIFT))
#define FLOAT(X) (((X) >= 0) \
? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \
: -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1))
static const s32 arctan_table[] = {
2949120,
1740967,
919879,
466945,
234379,
117304,
58666,
29335,
14668,
7334,
3667,
1833,
917,
458,
229,
115,
57,
29
};
/*
* cordic_calc_iq() - calculates the i/q coordinate for given angle
*
* theta: angle in degrees for which i/q coordinate is to be calculated
* coord: function output parameter holding the i/q coordinate
*/
struct cordic_iq cordic_calc_iq(s32 theta)
{
struct cordic_iq coord;
s32 angle, valtmp;
unsigned iter;
int signx = 1;
int signtheta;
coord.i = CORDIC_ANGLE_GEN;
coord.q = 0;
angle = 0;
theta = FIXED(theta);
signtheta = (theta < 0) ? -1 : 1;
theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) -
FIXED(180) * signtheta;
if (FLOAT(theta) > 90) {
theta -= FIXED(180);
signx = -1;
} else if (FLOAT(theta) < -90) {
theta += FIXED(180);
signx = -1;
}
for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
if (theta > angle) {
valtmp = coord.i - (coord.q >> iter);
coord.q += (coord.i >> iter);
angle += arctan_table[iter];
} else {
valtmp = coord.i + (coord.q >> iter);
coord.q -= (coord.i >> iter);
angle -= arctan_table[iter];
}
coord.i = valtmp;
}
coord.i *= signx;
coord.q *= signx;
return coord;
}
EXPORT_SYMBOL(cordic_calc_iq);
MODULE_DESCRIPTION("CORDIC algorithm");
MODULE_AUTHOR("Broadcom Corporation");
MODULE_LICENSE("Dual BSD/GPL");
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