/*
 * Copyright (c) 2013, 2014
 * Phillip Lougher <phillip@squashfs.org.uk>
 *
 * This work is licensed under the terms of the GNU GPL, version 2. See
 * the COPYING file in the top-level directory.
 */

#include <linux/buffer_head.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/lz4.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"
#include "page_actor.h"

#define LZ4_LEGACY	1

struct lz4_comp_opts {
	__le32 version;
	__le32 flags;
};

struct squashfs_lz4 {
	void *input;
	void *output;
};


static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
	void *buff, int len)
{
	struct lz4_comp_opts *comp_opts = buff;

	/* LZ4 compressed filesystems always have compression options */
	if (comp_opts == NULL || len < sizeof(*comp_opts))
		return ERR_PTR(-EIO);

	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
		/* LZ4 format currently used by the kernel is the 'legacy'
		 * format */
		ERROR("Unknown LZ4 version\n");
		return ERR_PTR(-EINVAL);
	}

	return NULL;
}


static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
{
	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
	struct squashfs_lz4 *stream;

	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
	if (stream == NULL)
		goto failed;
	stream->input = vmalloc(block_size);
	if (stream->input == NULL)
		goto failed2;
	stream->output = vmalloc(block_size);
	if (stream->output == NULL)
		goto failed3;

	return stream;

failed3:
	vfree(stream->input);
failed2:
	kfree(stream);
failed:
	ERROR("Failed to initialise LZ4 decompressor\n");
	return ERR_PTR(-ENOMEM);
}


static void lz4_free(void *strm)
{
	struct squashfs_lz4 *stream = strm;

	if (stream) {
		vfree(stream->input);
		vfree(stream->output);
	}
	kfree(stream);
}


static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
	struct buffer_head **bh, int b, int offset, int length,
	struct squashfs_page_actor *output)
{
	struct squashfs_lz4 *stream = strm;
	void *buff = stream->input, *data;
	int avail, i, bytes = length, res;
	size_t dest_len = output->length;

	for (i = 0; i < b; i++) {
		avail = min(bytes, msblk->devblksize - offset);
		memcpy(buff, bh[i]->b_data + offset, avail);
		buff += avail;
		bytes -= avail;
		offset = 0;
		put_bh(bh[i]);
	}

	res = lz4_decompress_unknownoutputsize(stream->input, length,
					stream->output, &dest_len);
	if (res)
		return -EIO;

	bytes = dest_len;
	data = squashfs_first_page(output);
	buff = stream->output;
	while (data) {
		if (bytes <= PAGE_SIZE) {
			memcpy(data, buff, bytes);
			break;
		}
		memcpy(data, buff, PAGE_SIZE);
		buff += PAGE_SIZE;
		bytes -= PAGE_SIZE;
		data = squashfs_next_page(output);
	}
	squashfs_finish_page(output);

	return dest_len;
}

const struct squashfs_decompressor squashfs_lz4_comp_ops = {
	.init = lz4_init,
	.comp_opts = lz4_comp_opts,
	.free = lz4_free,
	.decompress = lz4_uncompress,
	.id = LZ4_COMPRESSION,
	.name = "lz4",
	.supported = 1
};
d=966d2b04e070bc040319aaebfec09e0144dc3341'>nfsd.h</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/nfsd/nfsd.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/fs/nfsd/nfsd.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/fs/nfsd/nfsd.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>fs/nfsd/nfsd.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/fs/nfsd/nfsd.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/fs/nfsd/nfsd.h?id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'fs/nfsd/nfsd.h')</div><table summary='diffstat' class='diffstat'>