Differential D25736 Diff 74926 head/sys/kern/subr_blist.c

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head/sys/kern/subr_blist.c

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*		*
* This module implements a general bitmap allocator/deallocator. The		* This module implements a general bitmap allocator/deallocator. The
* allocator eats around 2 bits per 'block'. The module does not		* allocator eats around 2 bits per 'block'. The module does not
* try to interpret the meaning of a 'block' other than to return		* try to interpret the meaning of a 'block' other than to return
* SWAPBLK_NONE on an allocation failure.		* SWAPBLK_NONE on an allocation failure.
*		*
* A radix tree controls access to pieces of the bitmap, and includes		* A radix tree controls access to pieces of the bitmap, and includes
* auxiliary information at each interior node about the availabilty of		* auxiliary information at each interior node about the availabilty of
* contiguous free blocks in the subtree rooted at that node. Two radix		* contiguous free blocks in the subtree rooted at that node. A radix
* constants are involved: one for the size of the bitmaps contained in the		* constant defines the size of the bitmaps contained in a leaf node
* leaf nodes (BLIST_BMAP_RADIX), and one for the number of descendents of		* and the number of descendents of each of the meta (interior) nodes.
* each of the meta (interior) nodes (BLIST_META_RADIX). Each subtree is		* Each subtree is associated with a range of blocks. The root of any
* associated with a range of blocks. The root of any subtree stores a		* subtree stores a hint field that defines an upper bound on the size
* hint field that defines an upper bound on the size of the largest		* of the largest allocation that can begin in the associated block
* allocation that can begin in the associated block range. A hint is an		* range. A hint is an upper bound on a potential allocation, but not
* upper bound on a potential allocation, but not necessarily a tight upper		* necessarily a tight upper bound.
* bound.
*		*
* The bitmap field in each node directs the search for available blocks.		* The bitmap field in each node directs the search for available blocks.
* For a leaf node, a bit is set if the corresponding block is free. For a		* For a leaf node, a bit is set if the corresponding block is free. For a
* meta node, a bit is set if the corresponding subtree contains a free		* meta node, a bit is set if the corresponding subtree contains a free
* block somewhere within it. The search at a meta node considers only		* block somewhere within it. The search at a meta node considers only
* children of that node that represent a range that includes a free block.		* children of that node that represent a range that includes a free block.
*		*
* The hinting greatly increases code efficiency for allocations while		* The hinting greatly increases code efficiency for allocations while
* the general radix structure optimizes both allocations and frees. The		* the general radix structure optimizes both allocations and frees. The
* radix tree should be able to operate well no matter how much		* radix tree should be able to operate well no matter how much
* fragmentation there is and no matter how large a bitmap is used.		* fragmentation there is and no matter how large a bitmap is used.
*		*
* The blist code wires all necessary memory at creation time. Neither		* The blist code wires all necessary memory at creation time. Neither
* allocations nor frees require interaction with the memory subsystem.		* allocations nor frees require interaction with the memory subsystem.
* The non-blocking nature of allocations and frees is required by swap		* The non-blocking nature of allocations and frees is required by swap
* code (vm/swap_pager.c).		* code (vm/swap_pager.c).
*		*
* LAYOUT: The radix tree is laid out recursively using a linear array.		* LAYOUT: The radix tree is laid out recursively using a linear array.
* Each meta node is immediately followed (laid out sequentially in		* Each meta node is immediately followed (laid out sequentially in
* memory) by BLIST_META_RADIX lower level nodes. This is a recursive		* memory) by BLIST_RADIX lower-level nodes. This is a recursive
* structure but one that can be easily scanned through a very simple		* structure but one that can be easily scanned through a very simple
* 'skip' calculation. The memory allocation is only large enough to		* 'skip' calculation. The memory allocation is only large enough to
* cover the number of blocks requested at creation time. Nodes that		* cover the number of blocks requested at creation time. Nodes that
* represent blocks beyond that limit, nodes that would never be read		* represent blocks beyond that limit, nodes that would never be read
* or written, are not allocated, so that the last of the		* or written, are not allocated, so that the last of the
* BLIST_META_RADIX lower level nodes of a some nodes may not be		* BLIST_RADIX lower-level nodes of a some nodes may not be allocated.
* allocated.
*		*
* NOTE: the allocator cannot currently allocate more than		* NOTE: the allocator cannot currently allocate more than
* BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too		* BLIST_RADIX blocks per call. It will panic with 'allocation too
* large' if you try. This is an area that could use improvement. The		* large' if you try. This is an area that could use improvement. The
* radix is large enough that this restriction does not effect the swap		* radix is large enough that this restriction does not effect the swap
* system, though. Currently only the allocation code is affected by		* system, though. Currently only the allocation code is affected by
* this algorithmic unfeature. The freeing code can handle arbitrary		* this algorithmic unfeature. The freeing code can handle arbitrary
* ranges.		* ranges.
*		*
* This code can be compiled stand-alone for debugging.		* This code can be compiled stand-alone for debugging.
*/		*/
▲ Show 20 Lines • Show All 61 Lines • ▼ Show 20 Lines
static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix,		static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix,
int tab);		int tab);
#endif		#endif

#ifdef _KERNEL		#ifdef _KERNEL
static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");		static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
#endif		#endif

_Static_assert(BLIST_BMAP_RADIX % BLIST_META_RADIX == 0,		#define BLIST_MASK (BLIST_RADIX - 1)
"radix divisibility error");
#define BLIST_BMAP_MASK (BLIST_BMAP_RADIX - 1)
#define BLIST_META_MASK (BLIST_META_RADIX - 1)

/*		/*
* For a subtree that can represent the state of up to 'radix' blocks, the		* For a subtree that can represent the state of up to 'radix' blocks, the
* number of leaf nodes of the subtree is L=radix/BLIST_BMAP_RADIX. If 'm'		* number of leaf nodes of the subtree is L=radix/BLIST_RADIX. If 'm'
* is short for BLIST_META_RADIX, then for a tree of height h with L=m**h		* is short for BLIST_RADIX, then for a tree of height h with L=m**h
* leaf nodes, the total number of tree nodes is 1 + m + m2 + ... + mh,		* leaf nodes, the total number of tree nodes is 1 + m + m2 + ... + mh,
* or, equivalently, (m**(h+1)-1)/(m-1). This quantity is called 'skip'		* or, equivalently, (m**(h+1)-1)/(m-1). This quantity is called 'skip'
* in the 'meta' functions that process subtrees. Since integer division		* in the 'meta' functions that process subtrees. Since integer division
* discards remainders, we can express this computation as		* discards remainders, we can express this computation as
* skip = (m * m**h) / (m - 1)		* skip = (m * m**h) / (m - 1)
* skip = (m * (radix / BLIST_BMAP_RADIX)) / (m - 1)		* skip = (m * (radix / m)) / (m - 1)
* and since m divides BLIST_BMAP_RADIX, we can simplify further to		* skip = radix / (m - 1)
* skip = (radix / (BLIST_BMAP_RADIX / m)) / (m - 1)
* skip = radix / ((BLIST_BMAP_RADIX / m) * (m - 1))
* so that simple integer division by a constant can safely be used for the		* so that simple integer division by a constant can safely be used for the
* calculation.		* calculation.
*/		*/
static inline daddr_t		static inline daddr_t
radix_to_skip(daddr_t radix)		radix_to_skip(daddr_t radix)
{		{

return (radix /		return (radix / BLIST_MASK);
((BLIST_BMAP_RADIX / BLIST_META_RADIX) * BLIST_META_MASK));
}		}

/*		/*
* Provide a mask with count bits set, starting as position n.		* Provide a mask with count bits set, starting as position n.
*/		*/
static inline u_daddr_t		static inline u_daddr_t
bitrange(int n, int count)		bitrange(int n, int count)
{		{

return (((u_daddr_t)-1 << n) &		return (((u_daddr_t)-1 << n) &
((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - (n + count))));		((u_daddr_t)-1 >> (BLIST_RADIX - (n + count))));
}		}

/*		/*
* Find the first bit set in a u_daddr_t.		* Find the first bit set in a u_daddr_t.
*/		*/
static inline int		static inline int
generic_bitpos(u_daddr_t mask)		generic_bitpos(u_daddr_t mask)
{		{
int hi, lo, mid;		int hi, lo, mid;

lo = 0;		lo = 0;
hi = BLIST_BMAP_RADIX;		hi = BLIST_RADIX;
while (lo + 1 < hi) {		while (lo + 1 < hi) {
mid = (lo + hi) >> 1;		mid = (lo + hi) >> 1;
if (mask & bitrange(0, mid))		if (mask & bitrange(0, mid))
hi = mid;		hi = mid;
else		else
lo = mid;		lo = mid;
}		}
return (lo);		return (lo);
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/*		/*
* blist_create() - create a blist capable of handling up to the specified		* blist_create() - create a blist capable of handling up to the specified
* number of blocks		* number of blocks
*		*
* blocks - must be greater than 0		* blocks - must be greater than 0
* flags - malloc flags		* flags - malloc flags
*		*
* The smallest blist consists of a single leaf node capable of		* The smallest blist consists of a single leaf node capable of
* managing BLIST_BMAP_RADIX blocks.		* managing BLIST_RADIX blocks.
*/		*/
blist_t		blist_t
blist_create(daddr_t blocks, int flags)		blist_create(daddr_t blocks, int flags)
{		{
blist_t bl;		blist_t bl;
u_daddr_t nodes, radix;		u_daddr_t nodes, radix;

KASSERT(blocks > 0, ("invalid block count"));		KASSERT(blocks > 0, ("invalid block count"));

/*		/*
* Calculate the radix and node count used for scanning.		* Calculate the radix and node count used for scanning.
*/		*/
nodes = 1;		nodes = 1;
radix = BLIST_BMAP_RADIX;		for (radix = 1; radix <= blocks / BLIST_RADIX; radix *= BLIST_RADIX)
while (radix <= blocks) {		nodes += 1 + (blocks - 1) / radix / BLIST_RADIX;
nodes += 1 + (blocks - 1) / radix;
radix *= BLIST_META_RADIX;
}

bl = malloc(offsetof(struct blist, bl_root[nodes]), M_SWAP, flags \|		bl = malloc(offsetof(struct blist, bl_root[nodes]), M_SWAP, flags \|
M_ZERO);		M_ZERO);
if (bl == NULL)		if (bl == NULL)
return (NULL);		return (NULL);

bl->bl_blocks = blocks;		bl->bl_blocks = blocks;
bl->bl_radix = radix;		bl->bl_radix = radix;
▲ Show 20 Lines • Show All 276 Lines • ▼ Show 20 Lines	blist_stats(blist_t bl, struct sbuf *s)
struct gap_stats gstats;		struct gap_stats gstats;
struct gap_stats *stats = &gstats;		struct gap_stats *stats = &gstats;
daddr_t i, nodes, radix;		daddr_t i, nodes, radix;
u_daddr_t diff, mask;		u_daddr_t diff, mask;
int digit;		int digit;

init_gap_stats(stats);		init_gap_stats(stats);
nodes = 0;		nodes = 0;
i = bl->bl_radix;		radix = bl->bl_radix;
while (i < bl->bl_radix + bl->bl_blocks) {		for (i = 0; i < bl->bl_blocks; ) {
/*		/*
* Find max size subtree starting at i.
*/
radix = BLIST_BMAP_RADIX;
while (((i / radix) & BLIST_META_MASK) == 0)
radix *= BLIST_META_RADIX;

/*
* Check for skippable subtrees starting at i.		* Check for skippable subtrees starting at i.
*/		*/
while (radix > BLIST_BMAP_RADIX) {		while (radix != 1) {
if (bl->bl_root[nodes].bm_bitmap == 0) {		if (bl->bl_root[nodes].bm_bitmap == 0) {
if (gap_stats_counting(stats))		if (gap_stats_counting(stats))
update_gap_stats(stats, i);		update_gap_stats(stats, i);
break;		break;
}		}

/*		/*
* Skip subtree root.		* Skip subtree root.
*/		*/
nodes++;		nodes++;
radix /= BLIST_META_RADIX;		radix /= BLIST_RADIX;
}		}
if (radix == BLIST_BMAP_RADIX) {		if (radix == 1) {
/*		/*
* Scan leaf.		* Scan leaf.
*/		*/
mask = bl->bl_root[nodes].bm_bitmap;		mask = bl->bl_root[nodes].bm_bitmap;
diff = mask ^ (mask << 1);		diff = mask ^ (mask << 1);
if (gap_stats_counting(stats))		if (gap_stats_counting(stats))
diff ^= 1;		diff ^= 1;
while (diff != 0) {		while (diff != 0) {
digit = bitpos(diff);		digit = bitpos(diff);
update_gap_stats(stats, i + digit);		update_gap_stats(stats, i + digit);
diff ^= bitrange(digit, 1);		diff ^= bitrange(digit, 1);
}		}
}		}
nodes += radix_to_skip(radix);		nodes += radix_to_skip(radix * BLIST_RADIX);
i += radix;		i += radix * BLIST_RADIX;

		/*
		* Find max size subtree starting at i.
		*/
		for (radix = 1;
		((i / BLIST_RADIX / radix) & BLIST_MASK) == 0;
		radix *= BLIST_RADIX)
		;
}		}
update_gap_stats(stats, i);		update_gap_stats(stats, i);
dump_gap_stats(stats, s);		dump_gap_stats(stats, s);
}		}

/************************************************************************		/************************************************************************
* ALLOCATION SUPPORT FUNCTIONS *		* ALLOCATION SUPPORT FUNCTIONS *
************************************************************************		************************************************************************
Show All 17 Lines
*/		*/
static int		static int
blst_next_leaf_alloc(blmeta_t *scan, daddr_t start, int count, int maxcount)		blst_next_leaf_alloc(blmeta_t *scan, daddr_t start, int count, int maxcount)
{		{
u_daddr_t radix;		u_daddr_t radix;
daddr_t blk;		daddr_t blk;
int avail, digit;		int avail, digit;

start += BLIST_BMAP_RADIX;		start += BLIST_RADIX;
for (blk = start; blk - start < maxcount; blk += BLIST_BMAP_RADIX) {		for (blk = start; blk - start < maxcount; blk += BLIST_RADIX) {
/* Skip meta-nodes, as long as they promise more free blocks. */		/* Skip meta-nodes, as long as they promise more free blocks. */
radix = BLIST_BMAP_RADIX;		radix = BLIST_RADIX;
while (((++scan)->bm_bitmap & 1) == 1 &&		while (((++scan)->bm_bitmap & 1) == 1 &&
((blk / radix) & BLIST_META_MASK) == 0)		((blk / radix) & BLIST_MASK) == 0)
radix *= BLIST_META_RADIX;		radix *= BLIST_RADIX;
if (~scan->bm_bitmap != 0) {		if (~scan->bm_bitmap != 0) {
/*		/*
* Either there is no next leaf with any free blocks,		* Either there is no next leaf with any free blocks,
* or we've reached the next leaf and found that some		* or we've reached the next leaf and found that some
* of its blocks are not free. In the first case,		* of its blocks are not free. In the first case,
* bitpos() returns zero here.		* bitpos() returns zero here.
*/		*/
avail = blk - start + bitpos(~scan->bm_bitmap);		avail = blk - start + bitpos(~scan->bm_bitmap);
if (avail < count \|\| avail == 0) {		if (avail < count \|\| avail == 0) {
/*		/*
* There isn't a next leaf with enough free		* There isn't a next leaf with enough free
* blocks at its beginning to bother		* blocks at its beginning to bother
* allocating.		* allocating.
*/		*/
return (avail);		return (avail);
}		}
maxcount = imin(avail, maxcount);		maxcount = imin(avail, maxcount);
if (maxcount % BLIST_BMAP_RADIX == 0) {		if (maxcount % BLIST_RADIX == 0) {
/*		/*
* There was no next leaf. Back scan up to		* There was no next leaf. Back scan up to
* last leaf.		* last leaf.
*/		*/
		do {
		radix /= BLIST_RADIX;
--scan;		--scan;
while (radix != BLIST_BMAP_RADIX) {		} while (radix != 1);
radix /= BLIST_META_RADIX;		blk -= BLIST_RADIX;
--scan;
}		}
blk -= BLIST_BMAP_RADIX;
}		}
}		}
}

/*		/*
* 'scan' is the last leaf that provides blocks. Clear from 1 to		* 'scan' is the last leaf that provides blocks. Clear from 1 to
* BLIST_BMAP_RADIX bits to represent the allocation of those last		* BLIST_RADIX bits to represent the allocation of those last blocks.
* blocks.
*/		*/
if (maxcount % BLIST_BMAP_RADIX != 0)		if (maxcount % BLIST_RADIX != 0)
scan->bm_bitmap &= ~bitrange(0, maxcount % BLIST_BMAP_RADIX);		scan->bm_bitmap &= ~bitrange(0, maxcount % BLIST_RADIX);
else		else
scan->bm_bitmap = 0;		scan->bm_bitmap = 0;

for (;;) {		for (;;) {
/* Back up over meta-nodes, clearing bits if necessary. */		/* Back up over meta-nodes, clearing bits if necessary. */
blk -= BLIST_BMAP_RADIX;		blk -= BLIST_RADIX;
radix = BLIST_BMAP_RADIX;		for (radix = BLIST_RADIX;
while ((digit = ((blk / radix) & BLIST_META_MASK)) == 0) {		(digit = ((blk / radix) & BLIST_MASK)) == 0;
		radix *= BLIST_RADIX) {
if ((scan--)->bm_bitmap == 0)		if ((scan--)->bm_bitmap == 0)
scan->bm_bitmap ^= 1;		scan->bm_bitmap ^= 1;
radix *= BLIST_META_RADIX;
}		}
if ((scan--)->bm_bitmap == 0)		if ((scan--)->bm_bitmap == 0)
scan[-digit * radix_to_skip(radix)].bm_bitmap ^=		scan[-digit * radix_to_skip(radix)].bm_bitmap ^=
(u_daddr_t)1 << digit;		(u_daddr_t)1 << digit;

if (blk == start)		if (blk == start)
break;		break;
/* Clear all the bits of this leaf. */		/* Clear all the bits of this leaf. */
Show All 38 Lines	if (~mask == 0) {
* Update bighint. There is no allocation bigger than		* Update bighint. There is no allocation bigger than
* count1 >> num_shifts starting in this leaf.		* count1 >> num_shifts starting in this leaf.
*/		*/
scan->bm_bighint = bighint;		scan->bm_bighint = bighint;
return (SWAPBLK_NONE);		return (SWAPBLK_NONE);
}		}

/* Discard any candidates that appear before blk. */		/* Discard any candidates that appear before blk. */
if ((blk & BLIST_BMAP_MASK) != 0) {		if ((blk & BLIST_MASK) != 0) {
if ((~mask & bitrange(0, blk & BLIST_BMAP_MASK)) != 0) {		if ((~mask & bitrange(0, blk & BLIST_MASK)) != 0) {
/* Grow bighint in case all discarded bits are set. */		/* Grow bighint in case all discarded bits are set. */
bighint += blk & BLIST_BMAP_MASK;		bighint += blk & BLIST_MASK;
mask \|= bitrange(0, blk & BLIST_BMAP_MASK);		mask \|= bitrange(0, blk & BLIST_MASK);
if (~mask == 0) {		if (~mask == 0) {
scan->bm_bighint = bighint;		scan->bm_bighint = bighint;
return (SWAPBLK_NONE);		return (SWAPBLK_NONE);
}		}
}		}
blk -= blk & BLIST_BMAP_MASK;		blk -= blk & BLIST_MASK;
}		}

/*		/*
* The least significant set bit in mask marks the start of the first		* The least significant set bit in mask marks the start of the first
* available range of sufficient size. Find its position.		* available range of sufficient size. Find its position.
*/		*/
lo = bitpos(~mask);		lo = bitpos(~mask);

/*		/*
* Find how much space is available starting at that position.		* Find how much space is available starting at that position.
*/		*/
if ((mask & (mask + 1)) != 0) {		if ((mask & (mask + 1)) != 0) {
/* Count the 1 bits starting at position lo. */		/* Count the 1 bits starting at position lo. */
hi = bitpos(mask & (mask + 1)) + count1;		hi = bitpos(mask & (mask + 1)) + count1;
if (maxcount < hi - lo)		if (maxcount < hi - lo)
hi = lo + maxcount;		hi = lo + maxcount;
*count = hi - lo;		*count = hi - lo;
mask = ~bitrange(lo, *count);		mask = ~bitrange(lo, *count);
} else if (maxcount <= BLIST_BMAP_RADIX - lo) {		} else if (maxcount <= BLIST_RADIX - lo) {
/* All the blocks we can use are available here. */		/* All the blocks we can use are available here. */
hi = lo + maxcount;		hi = lo + maxcount;
*count = maxcount;		*count = maxcount;
mask = ~bitrange(lo, *count);		mask = ~bitrange(lo, *count);
if (hi == BLIST_BMAP_RADIX)		if (hi == BLIST_RADIX)
scan->bm_bighint = bighint;		scan->bm_bighint = bighint;
} else {		} else {
/* Check next leaf for some of the blocks we want or need. */		/* Check next leaf for some of the blocks we want or need. */
count1 = *count - (BLIST_BMAP_RADIX - lo);		count1 = *count - (BLIST_RADIX - lo);
maxcount -= BLIST_BMAP_RADIX - lo;		maxcount -= BLIST_RADIX - lo;
hi = blst_next_leaf_alloc(scan, blk, count1, maxcount);		hi = blst_next_leaf_alloc(scan, blk, count1, maxcount);
if (hi < count1)		if (hi < count1)
/*		/*
* The next leaf cannot supply enough blocks to reach		* The next leaf cannot supply enough blocks to reach
* the minimum required allocation. The hint cannot be		* the minimum required allocation. The hint cannot be
* updated, because the same allocation request could		* updated, because the same allocation request could
* be satisfied later, by this leaf, if the state of		* be satisfied later, by this leaf, if the state of
* the next leaf changes, and without any changes to		* the next leaf changes, and without any changes to
* this leaf.		* this leaf.
*/		*/
return (SWAPBLK_NONE);		return (SWAPBLK_NONE);
*count = BLIST_BMAP_RADIX - lo + hi;		*count = BLIST_RADIX - lo + hi;
scan->bm_bighint = bighint;		scan->bm_bighint = bighint;
}		}

/* Clear the allocated bits from this leaf. */		/* Clear the allocated bits from this leaf. */
scan->bm_bitmap &= mask;		scan->bm_bitmap &= mask;
return (blk + lo);		return (blk + lo);
}		}

Show All 9 Lines
blst_meta_alloc(blmeta_t scan, daddr_t cursor, int count,		blst_meta_alloc(blmeta_t scan, daddr_t cursor, int count,
int maxcount, u_daddr_t radix)		int maxcount, u_daddr_t radix)
{		{
daddr_t blk, i, r, skip;		daddr_t blk, i, r, skip;
u_daddr_t mask;		u_daddr_t mask;
bool scan_from_start;		bool scan_from_start;
int digit;		int digit;

if (radix == BLIST_BMAP_RADIX)		if (radix == 1)
return (blst_leaf_alloc(scan, cursor, count, maxcount));		return (blst_leaf_alloc(scan, cursor, count, maxcount));
blk = cursor & -radix;		blk = cursor & -(radix * BLIST_RADIX);
scan_from_start = (cursor == blk);		scan_from_start = (cursor == blk);
radix /= BLIST_META_RADIX;
skip = radix_to_skip(radix);		skip = radix_to_skip(radix);
mask = scan->bm_bitmap;		mask = scan->bm_bitmap;

/* Discard any candidates that appear before cursor. */		/* Discard any candidates that appear before cursor. */
digit = (cursor / radix) & BLIST_META_MASK;		digit = (cursor / radix) & BLIST_MASK;
mask &= (u_daddr_t)-1 << digit;		mask &= (u_daddr_t)-1 << digit;
if (mask == 0)		if (mask == 0)
return (SWAPBLK_NONE);		return (SWAPBLK_NONE);

/*		/*
* If the first try is for a block that includes the cursor, pre-undo		* If the first try is for a block that includes the cursor, pre-undo
* the digit * radix offset in the first call; otherwise, ignore the		* the digit * radix offset in the first call; otherwise, ignore the
* cursor entirely.		* cursor entirely.
Show All 9 Lines	blst_meta_alloc(blmeta_t scan, daddr_t cursor, int count,
do {		do {
digit = bitpos(mask);		digit = bitpos(mask);
i = 1 + digit * skip;		i = 1 + digit * skip;
if (*count <= scan[i].bm_bighint) {		if (*count <= scan[i].bm_bighint) {
/*		/*
* The allocation might fit beginning in the i'th subtree.		* The allocation might fit beginning in the i'th subtree.
*/		*/
r = blst_meta_alloc(&scan[i], cursor + digit * radix,		r = blst_meta_alloc(&scan[i], cursor + digit * radix,
count, maxcount, radix);		count, maxcount, radix / BLIST_RADIX);
if (r != SWAPBLK_NONE) {		if (r != SWAPBLK_NONE) {
if (scan[i].bm_bitmap == 0)		if (scan[i].bm_bitmap == 0)
scan->bm_bitmap ^= bitrange(digit, 1);		scan->bm_bitmap ^= bitrange(digit, 1);
return (r);		return (r);
}		}
}		}
cursor = blk;		cursor = blk;
} while ((mask ^= bitrange(digit, 1)) != 0);		} while ((mask ^= bitrange(digit, 1)) != 0);

/*		/*
* We couldn't allocate count in this subtree. If the whole tree was		* We couldn't allocate count in this subtree. If the whole tree was
* scanned, and the last tree node is allocated, update bighint.		* scanned, and the last tree node is allocated, update bighint.
*/		*/
if (scan_from_start && !(digit == BLIST_META_RADIX - 1 &&		if (scan_from_start && !(digit == BLIST_RADIX - 1 &&
scan[i].bm_bighint == BLIST_MAX_ALLOC))		scan[i].bm_bighint == BLIST_MAX_ALLOC))
scan->bm_bighint = *count - 1;		scan->bm_bighint = *count - 1;

return (SWAPBLK_NONE);		return (SWAPBLK_NONE);
}		}

/*		/*
* BLST_LEAF_FREE() - free allocated block from leaf bitmap		* BLST_LEAF_FREE() - free allocated block from leaf bitmap
*		*
*/		*/
static void		static void
blst_leaf_free(blmeta_t *scan, daddr_t blk, int count)		blst_leaf_free(blmeta_t *scan, daddr_t blk, int count)
{		{
u_daddr_t mask;		u_daddr_t mask;

/*		/*
* free some data in this bitmap		* free some data in this bitmap
* mask=0000111111111110000		* mask=0000111111111110000
* \_________/\__/		* \_________/\__/
* count n		* count n
*/		*/
mask = bitrange(blk & BLIST_BMAP_MASK, count);		mask = bitrange(blk & BLIST_MASK, count);
KASSERT((scan->bm_bitmap & mask) == 0,		KASSERT((scan->bm_bitmap & mask) == 0,
("freeing free block: %jx, size %d, mask %jx",		("freeing free block: %jx, size %d, mask %jx",
(uintmax_t)blk, count, (uintmax_t)scan->bm_bitmap & mask));		(uintmax_t)blk, count, (uintmax_t)scan->bm_bitmap & mask));
scan->bm_bitmap \|= mask;		scan->bm_bitmap \|= mask;
}		}

/*		/*
* BLST_META_FREE() - free allocated blocks from radix tree meta info		* BLST_META_FREE() - free allocated blocks from radix tree meta info
Show All 14 Lines	blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, u_daddr_t radix)
/*		/*
* We could probably do a better job here. We are required to make		* We could probably do a better job here. We are required to make
* bighint at least as large as the biggest allocable block of data.		* bighint at least as large as the biggest allocable block of data.
* If we just shoehorn it, a little extra overhead will be incurred		* If we just shoehorn it, a little extra overhead will be incurred
* on the next allocation (but only that one typically).		* on the next allocation (but only that one typically).
*/		*/
scan->bm_bighint = BLIST_MAX_ALLOC;		scan->bm_bighint = BLIST_MAX_ALLOC;

if (radix == BLIST_BMAP_RADIX)		if (radix == 1)
return (blst_leaf_free(scan, freeBlk, count));		return (blst_leaf_free(scan, freeBlk, count));

endBlk = ummin(freeBlk + count, (freeBlk + radix) & -radix);		endBlk = freeBlk + count;
radix /= BLIST_META_RADIX;		blk = (freeBlk + radix * BLIST_RADIX) & -(radix * BLIST_RADIX);
		/*
		* blk is first block past the end of the range of this meta node,
		* or 0 in case of overflow.
		*/
		if (blk != 0)
		endBlk = ummin(endBlk, blk);
skip = radix_to_skip(radix);		skip = radix_to_skip(radix);
blk = freeBlk & -radix;		blk = freeBlk & -radix;
digit = (blk / radix) & BLIST_META_MASK;		digit = (blk / radix) & BLIST_MASK;
endDigit = 1 + (((endBlk - 1) / radix) & BLIST_META_MASK);		endDigit = 1 + (((endBlk - 1) / radix) & BLIST_MASK);
scan->bm_bitmap \|= bitrange(digit, endDigit - digit);		scan->bm_bitmap \|= bitrange(digit, endDigit - digit);
for (i = 1 + digit * skip; blk < endBlk; i += skip) {		for (i = 1 + digit * skip; blk < endBlk; i += skip) {
blk += radix;		blk += radix;
count = ummin(blk, endBlk) - freeBlk;		count = ummin(blk, endBlk) - freeBlk;
blst_meta_free(&scan[i], freeBlk, count, radix);		blst_meta_free(&scan[i], freeBlk, count, radix / BLIST_RADIX);
freeBlk = blk;		freeBlk = blk;
}		}
}		}

/*		/*
* BLST_COPY() - copy one radix tree to another		* BLST_COPY() - copy one radix tree to another
*		*
* Locates free space in the source tree and frees it in the destination		* Locates free space in the source tree and frees it in the destination
* tree. The space may not already be free in the destination.		* tree. The space may not already be free in the destination.
*/		*/
static void		static void
blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest,		blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest,
daddr_t count)		daddr_t count)
{		{
daddr_t endBlk, i, skip;		daddr_t endBlk, i, skip;

/*		/*
* Leaf node		* Leaf node
*/		*/

if (radix == BLIST_BMAP_RADIX) {		if (radix == 1) {
u_daddr_t v = scan->bm_bitmap;		u_daddr_t v = scan->bm_bitmap;

if (v == (u_daddr_t)-1) {		if (v == (u_daddr_t)-1) {
blist_free(dest, blk, count);		blist_free(dest, blk, count);
} else if (v != 0) {		} else if (v != 0) {
int i;		int i;

for (i = 0; i < count; ++i) {		for (i = 0; i < count; ++i) {
Show All 11 Lines	blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest,
if (scan->bm_bitmap == 0) {		if (scan->bm_bitmap == 0) {
/*		/*
* Source all allocated, leave dest allocated		* Source all allocated, leave dest allocated
*/		*/
return;		return;
}		}

endBlk = blk + count;		endBlk = blk + count;
radix /= BLIST_META_RADIX;
skip = radix_to_skip(radix);		skip = radix_to_skip(radix);
for (i = 1; blk < endBlk; i += skip) {		for (i = 1; blk < endBlk; i += skip) {
blk += radix;		blk += radix;
count = radix;		count = radix;
if (blk >= endBlk)		if (blk >= endBlk)
count -= blk - endBlk;		count -= blk - endBlk;
blst_copy(&scan[i], blk - radix, radix, dest, count);		blst_copy(&scan[i], blk - radix,
		radix / BLIST_RADIX, dest, count);
}		}
}		}

/*		/*
* BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap		* BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
*		*
* This routine allocates all blocks in the specified range		* This routine allocates all blocks in the specified range
* regardless of any existing allocations in that range. Returns		* regardless of any existing allocations in that range. Returns
* the number of blocks allocated by the call.		* the number of blocks allocated by the call.
*/		*/
static daddr_t		static daddr_t
blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)		blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
{		{
daddr_t nblks;		daddr_t nblks;
u_daddr_t mask;		u_daddr_t mask;

mask = bitrange(blk & BLIST_BMAP_MASK, count);		mask = bitrange(blk & BLIST_MASK, count);

/* Count the number of blocks that we are allocating. */		/* Count the number of blocks that we are allocating. */
nblks = bitcount64(scan->bm_bitmap & mask);		nblks = bitcount64(scan->bm_bitmap & mask);

scan->bm_bitmap &= ~mask;		scan->bm_bitmap &= ~mask;
return (nblks);		return (nblks);
}		}

/*		/*
* BLIST_META_FILL() - allocate specific blocks at a meta node		* BLIST_META_FILL() - allocate specific blocks at a meta node
*		*
* This routine allocates the specified range of blocks,		* This routine allocates the specified range of blocks,
* regardless of any existing allocations in the range. The		* regardless of any existing allocations in the range. The
* range must be within the extent of this node. Returns the		* range must be within the extent of this node. Returns the
* number of blocks allocated by the call.		* number of blocks allocated by the call.
*/		*/
static daddr_t		static daddr_t
blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, u_daddr_t radix)		blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, u_daddr_t radix)
{		{
daddr_t blk, endBlk, i, nblks, skip;		daddr_t blk, endBlk, i, nblks, skip;
int digit;		int digit;

if (radix == BLIST_BMAP_RADIX)		if (radix == 1)
return (blst_leaf_fill(scan, allocBlk, count));		return (blst_leaf_fill(scan, allocBlk, count));

endBlk = ummin(allocBlk + count, (allocBlk + radix) & -radix);		endBlk = allocBlk + count;
radix /= BLIST_META_RADIX;		blk = (allocBlk + radix * BLIST_RADIX) & -(radix * BLIST_RADIX);
		/*
		* blk is first block past the end of the range of this meta node,
		* or 0 in case of overflow.
		*/
		if (blk != 0)
		endBlk = ummin(endBlk, blk);
skip = radix_to_skip(radix);		skip = radix_to_skip(radix);
blk = allocBlk & -radix;		blk = allocBlk & -radix;
nblks = 0;		nblks = 0;
while (blk < endBlk) {		while (blk < endBlk) {
digit = (blk / radix) & BLIST_META_MASK;		digit = (blk / radix) & BLIST_MASK;
i = 1 + digit * skip;		i = 1 + digit * skip;
blk += radix;		blk += radix;
count = ummin(blk, endBlk) - allocBlk;		count = ummin(blk, endBlk) - allocBlk;
nblks += blst_meta_fill(&scan[i], allocBlk, count, radix);		nblks += blst_meta_fill(&scan[i], allocBlk, count,
		radix / BLIST_RADIX);
if (scan[i].bm_bitmap == 0)		if (scan[i].bm_bitmap == 0)
scan->bm_bitmap &= ~((u_daddr_t)1 << digit);		scan->bm_bitmap &= ~((u_daddr_t)1 << digit);
allocBlk = blk;		allocBlk = blk;
}		}
return (nblks);		return (nblks);
}		}

#ifdef BLIST_DEBUG		#ifdef BLIST_DEBUG

static void		static void
blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int tab)		blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int tab)
{		{
daddr_t skip;		daddr_t skip;
u_daddr_t mask;		u_daddr_t mask;
int digit;		int digit;

if (radix == BLIST_BMAP_RADIX) {		if (radix == 1) {
printf(		printf(
"%.s(%08llx,%lld): bitmap %0*llx big=%lld\n",		"%.s(%08llx,%lld): bitmap %0*llx big=%lld\n",
tab, tab, "",		tab, tab, "",
(long long)blk, (long long)radix,		(long long)blk, (long long)BLIST_RADIX,
1 + (BLIST_BMAP_RADIX - 1) / 4,		(int)(1 + (BLIST_RADIX - 1) / 4),
(long long)scan->bm_bitmap,		(long long)scan->bm_bitmap,
(long long)scan->bm_bighint		(long long)scan->bm_bighint
);		);
return;		return;
}		}

printf(		printf(
"%.s(%08llx): subtree (%lld/%lld) bitmap %0*llx big=%lld {\n",		"%.s(%08llx): subtree (%lld/%lld) bitmap %0*llx big=%lld {\n",
tab, tab, "",		tab, tab, "",
(long long)blk, (long long)radix,		(long long)blk, (long long)radix * BLIST_RADIX,
(long long)radix,		(long long)radix * BLIST_RADIX,
1 + (BLIST_META_RADIX - 1) / 4,		(int)(1 + (BLIST_RADIX - 1) / 4),
(long long)scan->bm_bitmap,		(long long)scan->bm_bitmap,
(long long)scan->bm_bighint		(long long)scan->bm_bighint
);		);

radix /= BLIST_META_RADIX;
skip = radix_to_skip(radix);		skip = radix_to_skip(radix);
tab += 4;		tab += 4;

mask = scan->bm_bitmap;		mask = scan->bm_bitmap;
/* Examine the nonempty subtree associated with each bit set in mask */		/* Examine the nonempty subtree associated with each bit set in mask */
do {		do {
digit = bitpos(mask);		digit = bitpos(mask);
blst_radix_print(&scan[1 + digit * skip], blk + digit * radix,		blst_radix_print(&scan[1 + digit * skip], blk + digit * radix,
radix, tab);		radix / BLIST_RADIX, tab);
} while ((mask ^= bitrange(digit, 1)) != 0);		} while ((mask ^= bitrange(digit, 1)) != 0);
tab -= 4;		tab -= 4;

printf(		printf(
"%.s}\n",		"%.s}\n",
tab, tab, ""		tab, tab, ""
);		);
}		}

#endif		#endif

#ifdef BLIST_DEBUG		#ifdef BLIST_DEBUG

int		int
main(int ac, char **av)		main(int ac, char **av)
{		{
int size = BLIST_META_RADIX * BLIST_BMAP_RADIX;		daddr_t size = BLIST_RADIX * BLIST_RADIX;
int i;		int i;
blist_t bl;		blist_t bl;
struct sbuf *s;		struct sbuf *s;

for (i = 1; i < ac; ++i) {		for (i = 1; i < ac; ++i) {
const char *ptr = av[i];		const char *ptr = av[i];
if (*ptr != '-') {		if (*ptr != '-') {
size = strtol(ptr, NULL, 0);		size = strtoll(ptr, NULL, 0);
continue;		continue;
}		}
ptr += 2;		ptr += 2;
fprintf(stderr, "Bad option: %s\n", ptr - 2);		fprintf(stderr, "Bad option: %s\n", ptr - 2);
exit(1);		exit(1);
}		}
bl = blist_create(size, M_WAITOK);		bl = blist_create(size, M_WAITOK);
		if (bl == NULL) {
		fprintf(stderr, "blist_create failed\n");
		exit(1);
		}
blist_free(bl, 0, size);		blist_free(bl, 0, size);

for (;;) {		for (;;) {
char buf[1024];		char buf[1024];
long long da = 0;		long long da = 0;
int count = 0, maxcount = 0;		int count = 0, maxcount = 0;

printf("%lld/%lld/%lld> ", (long long)blist_avail(bl),		printf("%lld/%lld/%lld> ", (long long)blist_avail(bl),
(long long)size, (long long)bl->bl_radix);		(long long)size, (long long)bl->bl_radix * BLIST_RADIX);
fflush(stdout);		fflush(stdout);
if (fgets(buf, sizeof(buf), stdin) == NULL)		if (fgets(buf, sizeof(buf), stdin) == NULL)
break;		break;
switch(buf[0]) {		switch(buf[0]) {
case 'r':		case 'r':
if (sscanf(buf + 1, "%d", &count) == 1) {		if (sscanf(buf + 1, "%d", &count) == 1) {
blist_resize(&bl, count, 1, M_WAITOK);		blist_resize(&bl, count, 1, M_WAITOK);
} else {		} else {
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