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authorJosef Bacik <josef@toxicpanda.com>2020-02-04 13:18:55 -0500
committerDavid Sterba <dsterba@suse.com>2020-03-23 17:01:27 +0100
commit6f4ad559ea1cb5c5e78217405e4141c6a5981f86 (patch)
tree05ae88f85db260595adbaf4bd782636fbef3940d /tools/perf/scripts/python/bin/stackcollapse-record
parentbtrfs: add a comment describing block reserves (diff)
btrfs: add a comment describing delalloc space reservation
delalloc space reservation is tricky because it encompasses both data and metadata. Make it clear what each side does, the general flow of how space is moved throughout the lifetime of a write, and what goes into the calculations. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'tools/perf/scripts/python/bin/stackcollapse-record')
0 files changed, 0 insertions, 0 deletions
Copyright © 1996 – 2026 Jason A. Donenfeld. All Rights Reverse Engineered.
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// SPDX-License-Identifier: GPL-2.0-only
#include <linux/init.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.h>

#define SG_MEMPOOL_NR		ARRAY_SIZE(sg_pools)
#define SG_MEMPOOL_SIZE		2

struct sg_pool {
	size_t		size;
	char		*name;
	struct kmem_cache	*slab;
	mempool_t	*pool;
};

#define SP(x) { .size = x, "sgpool-" __stringify(x) }
#if (SG_CHUNK_SIZE < 32)
#error SG_CHUNK_SIZE is too small (must be 32 or greater)
#endif
static struct sg_pool sg_pools[] = {
	SP(8),
	SP(16),
#if (SG_CHUNK_SIZE > 32)
	SP(32),
#if (SG_CHUNK_SIZE > 64)
	SP(64),
#if (SG_CHUNK_SIZE > 128)
	SP(128),
#if (SG_CHUNK_SIZE > 256)
#error SG_CHUNK_SIZE is too large (256 MAX)
#endif
#endif
#endif
#endif
	SP(SG_CHUNK_SIZE)
};
#undef SP

static inline unsigned int sg_pool_index(unsigned short nents)
{
	unsigned int index;

	BUG_ON(nents > SG_CHUNK_SIZE);

	if (nents <= 8)
		index = 0;
	else
		index = get_count_order(nents) - 3;

	return index;
}

static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
{
	struct sg_pool *sgp;

	sgp = sg_pools + sg_pool_index(nents);
	mempool_free(sgl, sgp->pool);
}

static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
{
	struct sg_pool *sgp;

	sgp = sg_pools + sg_pool_index(nents);
	return mempool_alloc(sgp->pool, gfp_mask);
}

/**
 * sg_free_table_chained - Free a previously mapped sg table
 * @table:	The sg table header to use
 * @nents_first_chunk: size of the first_chunk SGL passed to
 *		sg_alloc_table_chained
 *
 *  Description:
 *    Free an sg table previously allocated and setup with
 *    sg_alloc_table_chained().
 *
 *    @nents_first_chunk has to be same with that same parameter passed
 *    to sg_alloc_table_chained().
 *
 **/
void sg_free_table_chained(struct sg_table *table,
		unsigned nents_first_chunk)
{
	if (table->orig_nents <= nents_first_chunk)
		return;

	if (nents_first_chunk == 1)
		nents_first_chunk = 0;

	__sg_free_table(table, SG_CHUNK_SIZE, nents_first_chunk, sg_pool_free,
			table->orig_nents);
}
EXPORT_SYMBOL_GPL(sg_free_table_chained);

/**
 * sg_alloc_table_chained - Allocate and chain SGLs in an sg table
 * @table:	The sg table header to use
 * @nents:	Number of entries in sg list
 * @first_chunk: first SGL
 * @nents_first_chunk: number of the SGL of @first_chunk
 *
 *  Description:
 *    Allocate and chain SGLs in an sg table. If @nents@ is larger than
 *    @nents_first_chunk a chained sg table will be setup. @first_chunk is
 *    ignored if nents_first_chunk <= 1 because user expects the SGL points
 *    non-chain SGL.
 *
 **/
int sg_alloc_table_chained(struct sg_table *table, int nents,
		struct scatterlist *first_chunk, unsigned nents_first_chunk)
{
	int ret;

	BUG_ON(!nents);

	if (first_chunk && nents_first_chunk) {
		if (nents <= nents_first_chunk) {
			table->nents = table->orig_nents = nents;
			sg_init_table(table->sgl, nents);
			return 0;
		}
	}

	/* User supposes that the 1st SGL includes real entry */
	if (nents_first_chunk <= 1) {
		first_chunk = NULL;
		nents_first_chunk = 0;
	}

	ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
			       first_chunk, nents_first_chunk,
			       GFP_ATOMIC, sg_pool_alloc);
	if (unlikely(ret))
		sg_free_table_chained(table, nents_first_chunk);
	return ret;
}
EXPORT_SYMBOL_GPL(sg_alloc_table_chained);

static __init int sg_pool_init(void)
{
	int i;

	for (i = 0; i < SG_MEMPOOL_NR; i++) {
		struct sg_pool *sgp = sg_pools + i;
		int size = sgp->size * sizeof(struct scatterlist);

		sgp->slab = kmem_cache_create(sgp->name, size, 0,
				SLAB_HWCACHE_ALIGN, NULL);
		if (!sgp->slab) {
			printk(KERN_ERR "SG_POOL: can't init sg slab %s\n",
					sgp->name);
			goto cleanup_sdb;
		}

		sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
						     sgp->slab);
		if (!sgp->pool) {
			printk(KERN_ERR "SG_POOL: can't init sg mempool %s\n",
					sgp->name);
			goto cleanup_sdb;
		}
	}

	return 0;

cleanup_sdb:
	for (i = 0; i < SG_MEMPOOL_NR; i++) {
		struct sg_pool *sgp = sg_pools + i;

		mempool_destroy(sgp->pool);
		kmem_cache_destroy(sgp->slab);
	}

	return -ENOMEM;
}

subsys_initcall(sg_pool_init);