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Revision b53df2e7442c73a932fb74228147fb946e531585 authored by Shin'ichiro Kawasaki on 21 February 2020, 01:37:08 UTC, committed by Jens Axboe on 12 March 2020, 13:54:39 UTC 
block: Fix partition support for host aware zoned block devices
 
Commit b72053072c0b ("block: allow partitions on host aware zone
devices") introduced the helper function disk_has_partitions() to check
if a given disk has valid partitions. However, since this function result
directly depends on the disk partition table length rather than the
actual existence of valid partitions in the table, it returns true even
after all partitions are removed from the disk. For host aware zoned
block devices, this results in zone management support to be kept
disabled even after removing all partitions.

Fix this by changing disk_has_partitions() to walk through the partition
table entries and return true if and only if a valid non-zero size
partition is found.

Fixes: b72053072c0b ("block: allow partitions on host aware zone devices")
Cc: stable@vger.kernel.org # 5.5
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Raw File
ptdump.c 
// SPDX-License-Identifier: GPL-2.0

#include <linux/pagewalk.h>
#include <linux/ptdump.h>
#include <linux/kasan.h>

#ifdef CONFIG_KASAN
/*
 * This is an optimization for KASAN=y case. Since all kasan page tables
 * eventually point to the kasan_early_shadow_page we could call note_page()
 * right away without walking through lower level page tables. This saves
 * us dozens of seconds (minutes for 5-level config) while checking for
 * W+X mapping or reading kernel_page_tables debugfs file.
 */
static inline int note_kasan_page_table(struct mm_walk *walk,
					unsigned long addr)
{
	struct ptdump_state *st = walk->private;

	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));

	walk->action = ACTION_CONTINUE;

	return 0;
}
#endif

static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pgd_t val = READ_ONCE(*pgd);

#if CONFIG_PGTABLE_LEVELS > 4 && defined(CONFIG_KASAN)
	if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
		return note_kasan_page_table(walk, addr);
#endif

	if (pgd_leaf(val))
		st->note_page(st, addr, 0, pgd_val(val));

	return 0;
}

static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	p4d_t val = READ_ONCE(*p4d);

#if CONFIG_PGTABLE_LEVELS > 3 && defined(CONFIG_KASAN)
	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
		return note_kasan_page_table(walk, addr);
#endif

	if (p4d_leaf(val))
		st->note_page(st, addr, 1, p4d_val(val));

	return 0;
}

static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pud_t val = READ_ONCE(*pud);

#if CONFIG_PGTABLE_LEVELS > 2 && defined(CONFIG_KASAN)
	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
		return note_kasan_page_table(walk, addr);
#endif

	if (pud_leaf(val))
		st->note_page(st, addr, 2, pud_val(val));

	return 0;
}

static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pmd_t val = READ_ONCE(*pmd);

#if defined(CONFIG_KASAN)
	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
		return note_kasan_page_table(walk, addr);
#endif

	if (pmd_leaf(val))
		st->note_page(st, addr, 3, pmd_val(val));

	return 0;
}

static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;

	st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte)));

	return 0;
}

static int ptdump_hole(unsigned long addr, unsigned long next,
		       int depth, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;

	st->note_page(st, addr, depth, 0);

	return 0;
}

static const struct mm_walk_ops ptdump_ops = {
	.pgd_entry	= ptdump_pgd_entry,
	.p4d_entry	= ptdump_p4d_entry,
	.pud_entry	= ptdump_pud_entry,
	.pmd_entry	= ptdump_pmd_entry,
	.pte_entry	= ptdump_pte_entry,
	.pte_hole	= ptdump_hole,
};

void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
{
	const struct ptdump_range *range = st->range;

	down_read(&mm->mmap_sem);
	while (range->start != range->end) {
		walk_page_range_novma(mm, range->start, range->end,
				      &ptdump_ops, pgd, st);
		range++;
	}
	up_read(&mm->mmap_sem);

	/* Flush out the last page */
	st->note_page(st, 0, -1, 0);
}
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