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Removing ZERO_PAGE abd_alloc_zero_scatter

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For MIPS architectures on Linux the ZERO_PAGE macro references
empty_zero_page, which is exported as a GPL symbol. The call to
ZERO_PAGE in abd_alloc_zero_scatter has been removed and a single
zero'd page is now allocated for each of the pages in abd_zero_scatter
in the kernel ABD code path.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
Closes #10428
This commit is contained in:
Brian Atkinson 2020-06-10 18:54:11 -06:00 committed by GitHub
parent 059f7c20e3
commit e08b993396
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 23 additions and 13 deletions
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1
include/sys/abd.h
View File

@ -42,7 +42,6 @@ typedef int abd_iter_func_t(void *buf, size_t len, void *priv);
typedef int abd_iter_func2_t(void *bufa, void *bufb, size_t len, void *priv);
extern int zfs_abd_scatter_enabled;
extern abd_t *abd_zero_scatter;
/*
* Allocations and deallocations

2
include/sys/abd_impl.h
View File

@ -92,6 +92,8 @@ struct abd_iter {
struct scatterlist *iter_sg; /* current sg */
};
extern abd_t *abd_zero_scatter;
abd_t *abd_gang_get_offset(abd_t *, size_t *);
/*

33
module/os/linux/zfs/abd_os.c
View File

@ -167,6 +167,13 @@ int zfs_abd_scatter_min_size = 512 * 3;
*/
abd_t *abd_zero_scatter = NULL;
struct page;
/*
* abd_zero_page we will be an allocated zero'd PAGESIZE buffer, which is
* assigned to set each of the pages of abd_zero_scatter.
*/
static struct page *abd_zero_page = NULL;
static kmem_cache_t *abd_cache = NULL;
static kstat_t *abd_ksp;
@ -439,8 +446,7 @@ abd_free_chunks(abd_t *abd)
/*
* Allocate scatter ABD of size SPA_MAXBLOCKSIZE, where each page in
* the scatterlist will be set to ZERO_PAGE(0). ZERO_PAGE(0) returns
* a global shared page that is always zero'd out.
* the scatterlist will be set to the zero'd out buffer abd_zero_page.
*/
static void
abd_alloc_zero_scatter(void)
@ -448,9 +454,16 @@ abd_alloc_zero_scatter(void)
struct scatterlist *sg = NULL;
struct sg_table table;
gfp_t gfp = __GFP_NOWARN | GFP_NOIO;
gfp_t gfp_zero_page = gfp | __GFP_ZERO;
int nr_pages = abd_chunkcnt_for_bytes(SPA_MAXBLOCKSIZE);
int i = 0;
while ((abd_zero_page = __page_cache_alloc(gfp_zero_page)) == NULL) {
ABDSTAT_BUMP(abdstat_scatter_page_alloc_retry);
schedule_timeout_interruptible(1);
}
abd_mark_zfs_page(abd_zero_page);
while (sg_alloc_table(&table, nr_pages, gfp)) {
ABDSTAT_BUMP(abdstat_scatter_sg_table_retry);
schedule_timeout_interruptible(1);
@ -468,7 +481,7 @@ abd_alloc_zero_scatter(void)
zfs_refcount_create(&abd_zero_scatter->abd_children);
abd_for_each_sg(abd_zero_scatter, sg, nr_pages, i) {
sg_set_page(sg, ZERO_PAGE(0), PAGESIZE, 0);
sg_set_page(sg, abd_zero_page, PAGESIZE, 0);
}
ABDSTAT_BUMP(abdstat_scatter_cnt);
@ -478,14 +491,6 @@ abd_alloc_zero_scatter(void)
#else /* _KERNEL */
struct page;
/*
* In user space abd_zero_page we will be an allocated zero'd PAGESIZE
* buffer, which is assigned to set each of the pages of abd_zero_scatter.
*/
static struct page *abd_zero_page = NULL;
#ifndef PAGE_SHIFT
#define PAGE_SHIFT (highbit64(PAGESIZE)-1)
#endif
@ -680,7 +685,11 @@ abd_free_zero_scatter(void)
abd_free_sg_table(abd_zero_scatter);
abd_free_struct(abd_zero_scatter);
abd_zero_scatter = NULL;
#if !defined(_KERNEL)
ASSERT3P(abd_zero_page, !=, NULL);
#if defined(_KERNEL)
abd_unmark_zfs_page(abd_zero_page);
__free_page(abd_zero_page);
#else
umem_free(abd_zero_page, PAGESIZE);
#endif /* _KERNEL */
}