ext4: Fix mb_find_next_bit not to return larger than max (e7dfb246) · Commits · 戴 / test

Some architectures implement ext4_find_next_bit and ext4_find_next_zero_bit in such a way that they return greater than max for some input values. Make sure mb_find_next_bit and mb_find_next_zero_bit return the right values. On 2.6.25 we have include/asm-x86/bitops_32.h static inline unsigned find_first_bit(const unsigned long *addr, unsigned size) { unsigned x = 0; while (x < size) { unsigned long val = *addr++; if (val) return __ffs(val) + x; x += (sizeof(*addr)<<3); } return x; } This can return value greater than size. Reported and fixed here for lustre https://bugzilla.lustre.org/show_bug.cgi?id=15932 https://bugzilla.lustre.org/attachment.cgi?id=17205 Signed-off-by:

Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by:

Mingming Cao <cmm@us.ibm.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/mballoc.c

+12 −8

Original line number	Diff line number	Diff line
		@@ -381,22 +381,28 @@ static inline void mb_clear_bit_atomic(spinlock_t lock, int bit, void addr)

		static inline int mb_find_next_zero_bit(void *addr, int max, int start)
		{
		int fix = 0;
		int fix = 0, ret, tmpmax;
		addr = mb_correct_addr_and_bit(&fix, addr);
		max += fix;
		tmpmax = max + fix;
		start += fix;

		return ext4_find_next_zero_bit(addr, max, start) - fix;
		ret = ext4_find_next_zero_bit(addr, tmpmax, start) - fix;
		if (ret > max)
		return max;
		return ret;
		}

		static inline int mb_find_next_bit(void *addr, int max, int start)
		{
		int fix = 0;
		int fix = 0, ret, tmpmax;
		addr = mb_correct_addr_and_bit(&fix, addr);
		max += fix;
		tmpmax = max + fix;
		start += fix;

		return ext4_find_next_bit(addr, max, start) - fix;
		ret = ext4_find_next_bit(addr, tmpmax, start) - fix;
		if (ret > max)
		return max;
		return ret;
		}

		static void mb_find_buddy(struct ext4_buddy e4b, int order, int *max)
		@@ -3473,8 +3479,6 @@ ext4_mb_release_inode_pa(struct ext4_buddy e4b, struct buffer_head bitmap_bh,
		if (bit >= end)
		break;
		next = mb_find_next_bit(bitmap_bh->b_data, end, bit);
		if (next > end)
		next = end;
		start = group * EXT4_BLOCKS_PER_GROUP(sb) + bit +
		le32_to_cpu(sbi->s_es->s_first_data_block);
		mb_debug(" free preallocated %u/%u in group %u\n",

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