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FreeBSD: use zero_region instead of allocating a dedicated page #13406

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merged 1 commit into from
May 4, 2022
Merged

FreeBSD: use zero_region instead of allocating a dedicated page #13406

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10 changes: 3 additions & 7 deletions module/os/freebsd/zfs/abd_os.c
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,6 @@ static kstat_t *abd_ksp;
* memory by only using a single zero buffer for the scatter chunks.
*/
abd_t *abd_zero_scatter = NULL;
static char *abd_zero_buf = NULL;

static uint_t
abd_chunkcnt_for_bytes(size_t size)
Expand Down Expand Up @@ -241,26 +240,24 @@ abd_free_struct_impl(abd_t *abd)

/*
* Allocate scatter ABD of size SPA_MAXBLOCKSIZE, where
* each chunk in the scatterlist will be set to abd_zero_buf.
* each chunk in the scatterlist will be set to the same area.
*/
_Static_assert(ZERO_REGION_SIZE >= PAGE_SIZE, "zero_region too small");
static void
abd_alloc_zero_scatter(void)
{
uint_t i, n;

n = abd_chunkcnt_for_bytes(SPA_MAXBLOCKSIZE);
abd_zero_buf = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE);
memset(abd_zero_buf, 0, PAGE_SIZE);
abd_zero_scatter = abd_alloc_struct(SPA_MAXBLOCKSIZE);

abd_zero_scatter->abd_flags |= ABD_FLAG_OWNER | ABD_FLAG_ZEROS;
abd_zero_scatter->abd_size = SPA_MAXBLOCKSIZE;

ABD_SCATTER(abd_zero_scatter).abd_offset = 0;

for (i = 0; i < n; i++) {
ABD_SCATTER(abd_zero_scatter).abd_chunks[i] =
abd_zero_buf;
__DECONST(void *, zero_region);
}

ABDSTAT_BUMP(abdstat_scatter_cnt);
Expand All @@ -275,7 +272,6 @@ abd_free_zero_scatter(void)

abd_free_struct(abd_zero_scatter);
abd_zero_scatter = NULL;
kmem_cache_free(abd_chunk_cache, abd_zero_buf);
}

static int
Expand Down