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Revision 227823d2074da0c138d2abc0074b2dd281bbf923 authored by Dai Ngo on 23 January 2020, 01:45:39 UTC, committed by Anna Schumaker on 04 February 2020, 15:50:44 UTC 
nfs: optimise readdir cache page invalidation
 
When the directory is large and it's being modified by one client
while another client is doing the 'ls -l' on the same directory then
the cache page invalidation from nfs_force_use_readdirplus causes
the reading client to keep restarting READDIRPLUS from cookie 0
which causes the 'ls -l' to take a very long time to complete,
possibly never completing.

Currently when nfs_force_use_readdirplus is called to switch from
READDIR to READDIRPLUS, it invalidates all the cached pages of the
directory. This cache page invalidation causes the next nfs_readdir
to re-read the directory content from cookie 0.

This patch is to optimise the cache invalidation in
nfs_force_use_readdirplus by only truncating the cached pages from
last page index accessed to the end the file. It also marks the
inode to delay invalidating all the cached page of the directory
until the next initial nfs_readdir of the next 'ls' instance.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Reviewed-by: Trond Myklebust <trond.myklebust@hammerspace.com>
[Anna - Fix conflicts with Trond's readdir patches]
[Anna - Remove redundant call to nfs_zap_mapping()]
[Anna - Replace d_inode(file_dentry(desc->file)) with file_inode(desc->file)]
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
1 parent 93a6ab7
Raw File
memtest.c 
// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/memblock.h>

static u64 patterns[] __initdata = {
	/* The first entry has to be 0 to leave memtest with zeroed memory */
	0,
	0xffffffffffffffffULL,
	0x5555555555555555ULL,
	0xaaaaaaaaaaaaaaaaULL,
	0x1111111111111111ULL,
	0x2222222222222222ULL,
	0x4444444444444444ULL,
	0x8888888888888888ULL,
	0x3333333333333333ULL,
	0x6666666666666666ULL,
	0x9999999999999999ULL,
	0xccccccccccccccccULL,
	0x7777777777777777ULL,
	0xbbbbbbbbbbbbbbbbULL,
	0xddddddddddddddddULL,
	0xeeeeeeeeeeeeeeeeULL,
	0x7a6c7258554e494cULL, /* yeah ;-) */
};

static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
{
	pr_info("  %016llx bad mem addr %pa - %pa reserved\n",
		cpu_to_be64(pattern), &start_bad, &end_bad);
	memblock_reserve(start_bad, end_bad - start_bad);
}

static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
{
	u64 *p, *start, *end;
	phys_addr_t start_bad, last_bad;
	phys_addr_t start_phys_aligned;
	const size_t incr = sizeof(pattern);

	start_phys_aligned = ALIGN(start_phys, incr);
	start = __va(start_phys_aligned);
	end = start + (size - (start_phys_aligned - start_phys)) / incr;
	start_bad = 0;
	last_bad = 0;

	for (p = start; p < end; p++)
		*p = pattern;

	for (p = start; p < end; p++, start_phys_aligned += incr) {
		if (*p == pattern)
			continue;
		if (start_phys_aligned == last_bad + incr) {
			last_bad += incr;
			continue;
		}
		if (start_bad)
			reserve_bad_mem(pattern, start_bad, last_bad + incr);
		start_bad = last_bad = start_phys_aligned;
	}
	if (start_bad)
		reserve_bad_mem(pattern, start_bad, last_bad + incr);
}

static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
{
	u64 i;
	phys_addr_t this_start, this_end;

	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
				&this_end, NULL) {
		this_start = clamp(this_start, start, end);
		this_end = clamp(this_end, start, end);
		if (this_start < this_end) {
			pr_info("  %pa - %pa pattern %016llx\n",
				&this_start, &this_end, cpu_to_be64(pattern));
			memtest(pattern, this_start, this_end - this_start);
		}
	}
}

/* default is disabled */
static unsigned int memtest_pattern __initdata;

static int __init parse_memtest(char *arg)
{
	int ret = 0;

	if (arg)
		ret = kstrtouint(arg, 0, &memtest_pattern);
	else
		memtest_pattern = ARRAY_SIZE(patterns);

	return ret;
}

early_param("memtest", parse_memtest);

void __init early_memtest(phys_addr_t start, phys_addr_t end)
{
	unsigned int i;
	unsigned int idx = 0;

	if (!memtest_pattern)
		return;

	pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
	for (i = memtest_pattern-1; i < UINT_MAX; --i) {
		idx = i % ARRAY_SIZE(patterns);
		do_one_pass(patterns[idx], start, end);
	}
}
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