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c80da1fb85
Describe missing function parameters to prevent kernel-doc warnings: lib/scatterlist.c:288: warning: Function parameter or member 'first_chunk' not described in '__sg_alloc_table' lib/scatterlist.c:800: warning: Function parameter or member 'flags' not described in 'sg_miter_start' Link: https://lkml.kernel.org/r/20230912060848.4673-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1369 lines
35 KiB
C
1369 lines
35 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
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*
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* Scatterlist handling helpers.
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*/
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/scatterlist.h>
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#include <linux/highmem.h>
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#include <linux/kmemleak.h>
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#include <linux/bvec.h>
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#include <linux/uio.h>
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/**
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* sg_next - return the next scatterlist entry in a list
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* @sg: The current sg entry
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*
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* Description:
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* Usually the next entry will be @sg@ + 1, but if this sg element is part
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* of a chained scatterlist, it could jump to the start of a new
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* scatterlist array.
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*
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**/
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struct scatterlist *sg_next(struct scatterlist *sg)
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{
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if (sg_is_last(sg))
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return NULL;
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sg++;
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if (unlikely(sg_is_chain(sg)))
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sg = sg_chain_ptr(sg);
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return sg;
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}
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EXPORT_SYMBOL(sg_next);
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/**
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* sg_nents - return total count of entries in scatterlist
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* @sg: The scatterlist
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*
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* Description:
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* Allows to know how many entries are in sg, taking into account
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* chaining as well
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*
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**/
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int sg_nents(struct scatterlist *sg)
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{
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int nents;
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for (nents = 0; sg; sg = sg_next(sg))
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nents++;
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return nents;
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}
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EXPORT_SYMBOL(sg_nents);
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/**
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* sg_nents_for_len - return total count of entries in scatterlist
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* needed to satisfy the supplied length
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* @sg: The scatterlist
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* @len: The total required length
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*
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* Description:
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* Determines the number of entries in sg that are required to meet
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* the supplied length, taking into account chaining as well
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*
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* Returns:
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* the number of sg entries needed, negative error on failure
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*
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**/
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int sg_nents_for_len(struct scatterlist *sg, u64 len)
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{
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int nents;
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u64 total;
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if (!len)
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return 0;
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for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
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nents++;
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total += sg->length;
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if (total >= len)
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return nents;
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}
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return -EINVAL;
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}
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EXPORT_SYMBOL(sg_nents_for_len);
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/**
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* sg_last - return the last scatterlist entry in a list
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* @sgl: First entry in the scatterlist
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* @nents: Number of entries in the scatterlist
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*
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* Description:
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* Should only be used casually, it (currently) scans the entire list
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* to get the last entry.
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*
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* Note that the @sgl@ pointer passed in need not be the first one,
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* the important bit is that @nents@ denotes the number of entries that
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* exist from @sgl@.
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*
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**/
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struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
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{
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struct scatterlist *sg, *ret = NULL;
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unsigned int i;
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for_each_sg(sgl, sg, nents, i)
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ret = sg;
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BUG_ON(!sg_is_last(ret));
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return ret;
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}
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EXPORT_SYMBOL(sg_last);
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/**
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* sg_init_table - Initialize SG table
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* @sgl: The SG table
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* @nents: Number of entries in table
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*
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* Notes:
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* If this is part of a chained sg table, sg_mark_end() should be
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* used only on the last table part.
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*
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**/
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void sg_init_table(struct scatterlist *sgl, unsigned int nents)
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{
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memset(sgl, 0, sizeof(*sgl) * nents);
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sg_init_marker(sgl, nents);
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}
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EXPORT_SYMBOL(sg_init_table);
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/**
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* sg_init_one - Initialize a single entry sg list
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* @sg: SG entry
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* @buf: Virtual address for IO
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* @buflen: IO length
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*
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**/
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void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
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{
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sg_init_table(sg, 1);
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sg_set_buf(sg, buf, buflen);
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}
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EXPORT_SYMBOL(sg_init_one);
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/*
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* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
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* helpers.
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*/
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static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
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{
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if (nents == SG_MAX_SINGLE_ALLOC) {
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/*
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* Kmemleak doesn't track page allocations as they are not
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* commonly used (in a raw form) for kernel data structures.
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* As we chain together a list of pages and then a normal
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* kmalloc (tracked by kmemleak), in order to for that last
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* allocation not to become decoupled (and thus a
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* false-positive) we need to inform kmemleak of all the
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* intermediate allocations.
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*/
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void *ptr = (void *) __get_free_page(gfp_mask);
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kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
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return ptr;
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} else
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return kmalloc_array(nents, sizeof(struct scatterlist),
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gfp_mask);
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}
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static void sg_kfree(struct scatterlist *sg, unsigned int nents)
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{
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if (nents == SG_MAX_SINGLE_ALLOC) {
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kmemleak_free(sg);
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free_page((unsigned long) sg);
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} else
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kfree(sg);
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}
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/**
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* __sg_free_table - Free a previously mapped sg table
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* @table: The sg table header to use
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* @max_ents: The maximum number of entries per single scatterlist
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* @nents_first_chunk: Number of entries int the (preallocated) first
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* scatterlist chunk, 0 means no such preallocated first chunk
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* @free_fn: Free function
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* @num_ents: Number of entries in the table
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*
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* Description:
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* Free an sg table previously allocated and setup with
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* __sg_alloc_table(). The @max_ents value must be identical to
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* that previously used with __sg_alloc_table().
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*
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**/
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void __sg_free_table(struct sg_table *table, unsigned int max_ents,
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unsigned int nents_first_chunk, sg_free_fn *free_fn,
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unsigned int num_ents)
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{
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struct scatterlist *sgl, *next;
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unsigned curr_max_ents = nents_first_chunk ?: max_ents;
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if (unlikely(!table->sgl))
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return;
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sgl = table->sgl;
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while (num_ents) {
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unsigned int alloc_size = num_ents;
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unsigned int sg_size;
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/*
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* If we have more than max_ents segments left,
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* then assign 'next' to the sg table after the current one.
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* sg_size is then one less than alloc size, since the last
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* element is the chain pointer.
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*/
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if (alloc_size > curr_max_ents) {
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next = sg_chain_ptr(&sgl[curr_max_ents - 1]);
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alloc_size = curr_max_ents;
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sg_size = alloc_size - 1;
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} else {
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sg_size = alloc_size;
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next = NULL;
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}
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num_ents -= sg_size;
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if (nents_first_chunk)
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nents_first_chunk = 0;
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else
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free_fn(sgl, alloc_size);
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sgl = next;
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curr_max_ents = max_ents;
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}
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table->sgl = NULL;
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}
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EXPORT_SYMBOL(__sg_free_table);
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/**
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* sg_free_append_table - Free a previously allocated append sg table.
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* @table: The mapped sg append table header
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*
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**/
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void sg_free_append_table(struct sg_append_table *table)
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{
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__sg_free_table(&table->sgt, SG_MAX_SINGLE_ALLOC, 0, sg_kfree,
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table->total_nents);
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}
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EXPORT_SYMBOL(sg_free_append_table);
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/**
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* sg_free_table - Free a previously allocated sg table
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* @table: The mapped sg table header
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*
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**/
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void sg_free_table(struct sg_table *table)
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{
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__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree,
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table->orig_nents);
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}
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EXPORT_SYMBOL(sg_free_table);
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/**
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* __sg_alloc_table - Allocate and initialize an sg table with given allocator
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @max_ents: The maximum number of entries the allocator returns per call
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* @first_chunk: first SGL if preallocated (may be %NULL)
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* @nents_first_chunk: Number of entries in the (preallocated) first
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* scatterlist chunk, 0 means no such preallocated chunk provided by user
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* @gfp_mask: GFP allocation mask
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* @alloc_fn: Allocator to use
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*
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* Description:
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* This function returns a @table @nents long. The allocator is
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* defined to return scatterlist chunks of maximum size @max_ents.
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* Thus if @nents is bigger than @max_ents, the scatterlists will be
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* chained in units of @max_ents.
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*
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* Notes:
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* If this function returns non-0 (eg failure), the caller must call
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* __sg_free_table() to cleanup any leftover allocations.
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*
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**/
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int __sg_alloc_table(struct sg_table *table, unsigned int nents,
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unsigned int max_ents, struct scatterlist *first_chunk,
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unsigned int nents_first_chunk, gfp_t gfp_mask,
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sg_alloc_fn *alloc_fn)
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{
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struct scatterlist *sg, *prv;
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unsigned int left;
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unsigned curr_max_ents = nents_first_chunk ?: max_ents;
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unsigned prv_max_ents;
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memset(table, 0, sizeof(*table));
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if (nents == 0)
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return -EINVAL;
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#ifdef CONFIG_ARCH_NO_SG_CHAIN
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if (WARN_ON_ONCE(nents > max_ents))
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return -EINVAL;
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#endif
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left = nents;
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prv = NULL;
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do {
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unsigned int sg_size, alloc_size = left;
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if (alloc_size > curr_max_ents) {
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alloc_size = curr_max_ents;
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sg_size = alloc_size - 1;
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} else
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sg_size = alloc_size;
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left -= sg_size;
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if (first_chunk) {
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sg = first_chunk;
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first_chunk = NULL;
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} else {
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sg = alloc_fn(alloc_size, gfp_mask);
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}
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if (unlikely(!sg)) {
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/*
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* Adjust entry count to reflect that the last
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* entry of the previous table won't be used for
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* linkage. Without this, sg_kfree() may get
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* confused.
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*/
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if (prv)
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table->nents = ++table->orig_nents;
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return -ENOMEM;
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}
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sg_init_table(sg, alloc_size);
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table->nents = table->orig_nents += sg_size;
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/*
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* If this is the first mapping, assign the sg table header.
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* If this is not the first mapping, chain previous part.
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*/
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if (prv)
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sg_chain(prv, prv_max_ents, sg);
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else
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table->sgl = sg;
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/*
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* If no more entries after this one, mark the end
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*/
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if (!left)
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sg_mark_end(&sg[sg_size - 1]);
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prv = sg;
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prv_max_ents = curr_max_ents;
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curr_max_ents = max_ents;
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} while (left);
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return 0;
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}
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EXPORT_SYMBOL(__sg_alloc_table);
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/**
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* sg_alloc_table - Allocate and initialize an sg table
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @gfp_mask: GFP allocation mask
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*
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* Description:
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* Allocate and initialize an sg table. If @nents@ is larger than
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* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
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*
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**/
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int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
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{
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int ret;
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ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
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NULL, 0, gfp_mask, sg_kmalloc);
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if (unlikely(ret))
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sg_free_table(table);
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return ret;
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}
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EXPORT_SYMBOL(sg_alloc_table);
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static struct scatterlist *get_next_sg(struct sg_append_table *table,
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struct scatterlist *cur,
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unsigned long needed_sges,
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gfp_t gfp_mask)
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{
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struct scatterlist *new_sg, *next_sg;
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unsigned int alloc_size;
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if (cur) {
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next_sg = sg_next(cur);
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/* Check if last entry should be keeped for chainning */
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if (!sg_is_last(next_sg) || needed_sges == 1)
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return next_sg;
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}
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alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC);
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new_sg = sg_kmalloc(alloc_size, gfp_mask);
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if (!new_sg)
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return ERR_PTR(-ENOMEM);
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sg_init_table(new_sg, alloc_size);
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if (cur) {
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table->total_nents += alloc_size - 1;
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__sg_chain(next_sg, new_sg);
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} else {
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table->sgt.sgl = new_sg;
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table->total_nents = alloc_size;
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}
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return new_sg;
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}
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static bool pages_are_mergeable(struct page *a, struct page *b)
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{
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if (page_to_pfn(a) != page_to_pfn(b) + 1)
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return false;
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if (!zone_device_pages_have_same_pgmap(a, b))
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return false;
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return true;
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}
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/**
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* sg_alloc_append_table_from_pages - Allocate and initialize an append sg
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* table from an array of pages
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* @sgt_append: The sg append table to use
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* @pages: Pointer to an array of page pointers
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* @n_pages: Number of pages in the pages array
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* @offset: Offset from start of the first page to the start of a buffer
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* @size: Number of valid bytes in the buffer (after offset)
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* @max_segment: Maximum size of a scatterlist element in bytes
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* @left_pages: Left pages caller have to set after this call
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* @gfp_mask: GFP allocation mask
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*
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* Description:
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* In the first call it allocate and initialize an sg table from a list of
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* pages, else reuse the scatterlist from sgt_append. Contiguous ranges of
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* the pages are squashed into a single scatterlist entry up to the maximum
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* size specified in @max_segment. A user may provide an offset at a start
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* and a size of valid data in a buffer specified by the page array. The
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* returned sg table is released by sg_free_append_table
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*
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* Returns:
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* 0 on success, negative error on failure
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*
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* Notes:
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* If this function returns non-0 (eg failure), the caller must call
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* sg_free_append_table() to cleanup any leftover allocations.
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*
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* In the fist call, sgt_append must by initialized.
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*/
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int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append,
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struct page **pages, unsigned int n_pages, unsigned int offset,
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unsigned long size, unsigned int max_segment,
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unsigned int left_pages, gfp_t gfp_mask)
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{
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unsigned int chunks, cur_page, seg_len, i, prv_len = 0;
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unsigned int added_nents = 0;
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struct scatterlist *s = sgt_append->prv;
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struct page *last_pg;
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/*
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* The algorithm below requires max_segment to be aligned to PAGE_SIZE
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* otherwise it can overshoot.
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*/
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max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE);
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if (WARN_ON(max_segment < PAGE_SIZE))
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return -EINVAL;
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if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && sgt_append->prv)
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return -EOPNOTSUPP;
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if (sgt_append->prv) {
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unsigned long next_pfn = (page_to_phys(sg_page(sgt_append->prv)) +
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sgt_append->prv->offset + sgt_append->prv->length) / PAGE_SIZE;
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if (WARN_ON(offset))
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return -EINVAL;
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/* Merge contiguous pages into the last SG */
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prv_len = sgt_append->prv->length;
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if (page_to_pfn(pages[0]) == next_pfn) {
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last_pg = pfn_to_page(next_pfn - 1);
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while (n_pages && pages_are_mergeable(pages[0], last_pg)) {
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if (sgt_append->prv->length + PAGE_SIZE > max_segment)
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break;
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sgt_append->prv->length += PAGE_SIZE;
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last_pg = pages[0];
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pages++;
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n_pages--;
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}
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if (!n_pages)
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goto out;
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}
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}
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/* compute number of contiguous chunks */
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chunks = 1;
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seg_len = 0;
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for (i = 1; i < n_pages; i++) {
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seg_len += PAGE_SIZE;
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if (seg_len >= max_segment ||
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!pages_are_mergeable(pages[i], pages[i - 1])) {
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chunks++;
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seg_len = 0;
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}
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}
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/* merging chunks and putting them into the scatterlist */
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|
cur_page = 0;
|
|
for (i = 0; i < chunks; i++) {
|
|
unsigned int j, chunk_size;
|
|
|
|
/* look for the end of the current chunk */
|
|
seg_len = 0;
|
|
for (j = cur_page + 1; j < n_pages; j++) {
|
|
seg_len += PAGE_SIZE;
|
|
if (seg_len >= max_segment ||
|
|
!pages_are_mergeable(pages[j], pages[j - 1]))
|
|
break;
|
|
}
|
|
|
|
/* Pass how many chunks might be left */
|
|
s = get_next_sg(sgt_append, s, chunks - i + left_pages,
|
|
gfp_mask);
|
|
if (IS_ERR(s)) {
|
|
/*
|
|
* Adjust entry length to be as before function was
|
|
* called.
|
|
*/
|
|
if (sgt_append->prv)
|
|
sgt_append->prv->length = prv_len;
|
|
return PTR_ERR(s);
|
|
}
|
|
chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
|
|
sg_set_page(s, pages[cur_page],
|
|
min_t(unsigned long, size, chunk_size), offset);
|
|
added_nents++;
|
|
size -= chunk_size;
|
|
offset = 0;
|
|
cur_page = j;
|
|
}
|
|
sgt_append->sgt.nents += added_nents;
|
|
sgt_append->sgt.orig_nents = sgt_append->sgt.nents;
|
|
sgt_append->prv = s;
|
|
out:
|
|
if (!left_pages)
|
|
sg_mark_end(s);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(sg_alloc_append_table_from_pages);
|
|
|
|
/**
|
|
* sg_alloc_table_from_pages_segment - Allocate and initialize an sg table from
|
|
* an array of pages and given maximum
|
|
* segment.
|
|
* @sgt: The sg table header to use
|
|
* @pages: Pointer to an array of page pointers
|
|
* @n_pages: Number of pages in the pages array
|
|
* @offset: Offset from start of the first page to the start of a buffer
|
|
* @size: Number of valid bytes in the buffer (after offset)
|
|
* @max_segment: Maximum size of a scatterlist element in bytes
|
|
* @gfp_mask: GFP allocation mask
|
|
*
|
|
* Description:
|
|
* Allocate and initialize an sg table from a list of pages. Contiguous
|
|
* ranges of the pages are squashed into a single scatterlist node up to the
|
|
* maximum size specified in @max_segment. A user may provide an offset at a
|
|
* start and a size of valid data in a buffer specified by the page array.
|
|
*
|
|
* The returned sg table is released by sg_free_table.
|
|
*
|
|
* Returns:
|
|
* 0 on success, negative error on failure
|
|
*/
|
|
int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
|
|
unsigned int n_pages, unsigned int offset,
|
|
unsigned long size, unsigned int max_segment,
|
|
gfp_t gfp_mask)
|
|
{
|
|
struct sg_append_table append = {};
|
|
int err;
|
|
|
|
err = sg_alloc_append_table_from_pages(&append, pages, n_pages, offset,
|
|
size, max_segment, 0, gfp_mask);
|
|
if (err) {
|
|
sg_free_append_table(&append);
|
|
return err;
|
|
}
|
|
memcpy(sgt, &append.sgt, sizeof(*sgt));
|
|
WARN_ON(append.total_nents != sgt->orig_nents);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(sg_alloc_table_from_pages_segment);
|
|
|
|
#ifdef CONFIG_SGL_ALLOC
|
|
|
|
/**
|
|
* sgl_alloc_order - allocate a scatterlist and its pages
|
|
* @length: Length in bytes of the scatterlist. Must be at least one
|
|
* @order: Second argument for alloc_pages()
|
|
* @chainable: Whether or not to allocate an extra element in the scatterlist
|
|
* for scatterlist chaining purposes
|
|
* @gfp: Memory allocation flags
|
|
* @nent_p: [out] Number of entries in the scatterlist that have pages
|
|
*
|
|
* Returns: A pointer to an initialized scatterlist or %NULL upon failure.
|
|
*/
|
|
struct scatterlist *sgl_alloc_order(unsigned long long length,
|
|
unsigned int order, bool chainable,
|
|
gfp_t gfp, unsigned int *nent_p)
|
|
{
|
|
struct scatterlist *sgl, *sg;
|
|
struct page *page;
|
|
unsigned int nent, nalloc;
|
|
u32 elem_len;
|
|
|
|
nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
|
|
/* Check for integer overflow */
|
|
if (length > (nent << (PAGE_SHIFT + order)))
|
|
return NULL;
|
|
nalloc = nent;
|
|
if (chainable) {
|
|
/* Check for integer overflow */
|
|
if (nalloc + 1 < nalloc)
|
|
return NULL;
|
|
nalloc++;
|
|
}
|
|
sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
|
|
gfp & ~GFP_DMA);
|
|
if (!sgl)
|
|
return NULL;
|
|
|
|
sg_init_table(sgl, nalloc);
|
|
sg = sgl;
|
|
while (length) {
|
|
elem_len = min_t(u64, length, PAGE_SIZE << order);
|
|
page = alloc_pages(gfp, order);
|
|
if (!page) {
|
|
sgl_free_order(sgl, order);
|
|
return NULL;
|
|
}
|
|
|
|
sg_set_page(sg, page, elem_len, 0);
|
|
length -= elem_len;
|
|
sg = sg_next(sg);
|
|
}
|
|
WARN_ONCE(length, "length = %lld\n", length);
|
|
if (nent_p)
|
|
*nent_p = nent;
|
|
return sgl;
|
|
}
|
|
EXPORT_SYMBOL(sgl_alloc_order);
|
|
|
|
/**
|
|
* sgl_alloc - allocate a scatterlist and its pages
|
|
* @length: Length in bytes of the scatterlist
|
|
* @gfp: Memory allocation flags
|
|
* @nent_p: [out] Number of entries in the scatterlist
|
|
*
|
|
* Returns: A pointer to an initialized scatterlist or %NULL upon failure.
|
|
*/
|
|
struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
|
|
unsigned int *nent_p)
|
|
{
|
|
return sgl_alloc_order(length, 0, false, gfp, nent_p);
|
|
}
|
|
EXPORT_SYMBOL(sgl_alloc);
|
|
|
|
/**
|
|
* sgl_free_n_order - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
* @nents: Maximum number of elements to free
|
|
* @order: Second argument for __free_pages()
|
|
*
|
|
* Notes:
|
|
* - If several scatterlists have been chained and each chain element is
|
|
* freed separately then it's essential to set nents correctly to avoid that a
|
|
* page would get freed twice.
|
|
* - All pages in a chained scatterlist can be freed at once by setting @nents
|
|
* to a high number.
|
|
*/
|
|
void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
|
|
{
|
|
struct scatterlist *sg;
|
|
struct page *page;
|
|
int i;
|
|
|
|
for_each_sg(sgl, sg, nents, i) {
|
|
if (!sg)
|
|
break;
|
|
page = sg_page(sg);
|
|
if (page)
|
|
__free_pages(page, order);
|
|
}
|
|
kfree(sgl);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free_n_order);
|
|
|
|
/**
|
|
* sgl_free_order - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
* @order: Second argument for __free_pages()
|
|
*/
|
|
void sgl_free_order(struct scatterlist *sgl, int order)
|
|
{
|
|
sgl_free_n_order(sgl, INT_MAX, order);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free_order);
|
|
|
|
/**
|
|
* sgl_free - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
*/
|
|
void sgl_free(struct scatterlist *sgl)
|
|
{
|
|
sgl_free_order(sgl, 0);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free);
|
|
|
|
#endif /* CONFIG_SGL_ALLOC */
|
|
|
|
void __sg_page_iter_start(struct sg_page_iter *piter,
|
|
struct scatterlist *sglist, unsigned int nents,
|
|
unsigned long pgoffset)
|
|
{
|
|
piter->__pg_advance = 0;
|
|
piter->__nents = nents;
|
|
|
|
piter->sg = sglist;
|
|
piter->sg_pgoffset = pgoffset;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_start);
|
|
|
|
static int sg_page_count(struct scatterlist *sg)
|
|
{
|
|
return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
|
|
}
|
|
|
|
bool __sg_page_iter_next(struct sg_page_iter *piter)
|
|
{
|
|
if (!piter->__nents || !piter->sg)
|
|
return false;
|
|
|
|
piter->sg_pgoffset += piter->__pg_advance;
|
|
piter->__pg_advance = 1;
|
|
|
|
while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
|
|
piter->sg_pgoffset -= sg_page_count(piter->sg);
|
|
piter->sg = sg_next(piter->sg);
|
|
if (!--piter->__nents || !piter->sg)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_next);
|
|
|
|
static int sg_dma_page_count(struct scatterlist *sg)
|
|
{
|
|
return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT;
|
|
}
|
|
|
|
bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter)
|
|
{
|
|
struct sg_page_iter *piter = &dma_iter->base;
|
|
|
|
if (!piter->__nents || !piter->sg)
|
|
return false;
|
|
|
|
piter->sg_pgoffset += piter->__pg_advance;
|
|
piter->__pg_advance = 1;
|
|
|
|
while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) {
|
|
piter->sg_pgoffset -= sg_dma_page_count(piter->sg);
|
|
piter->sg = sg_next(piter->sg);
|
|
if (!--piter->__nents || !piter->sg)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_dma_next);
|
|
|
|
/**
|
|
* sg_miter_start - start mapping iteration over a sg list
|
|
* @miter: sg mapping iter to be started
|
|
* @sgl: sg list to iterate over
|
|
* @nents: number of sg entries
|
|
* @flags: sg iterator flags
|
|
*
|
|
* Description:
|
|
* Starts mapping iterator @miter.
|
|
*
|
|
* Context:
|
|
* Don't care.
|
|
*/
|
|
void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
|
|
unsigned int nents, unsigned int flags)
|
|
{
|
|
memset(miter, 0, sizeof(struct sg_mapping_iter));
|
|
|
|
__sg_page_iter_start(&miter->piter, sgl, nents, 0);
|
|
WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
|
|
miter->__flags = flags;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_start);
|
|
|
|
static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
|
|
{
|
|
if (!miter->__remaining) {
|
|
struct scatterlist *sg;
|
|
|
|
if (!__sg_page_iter_next(&miter->piter))
|
|
return false;
|
|
|
|
sg = miter->piter.sg;
|
|
|
|
miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset;
|
|
miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT;
|
|
miter->__offset &= PAGE_SIZE - 1;
|
|
miter->__remaining = sg->offset + sg->length -
|
|
(miter->piter.sg_pgoffset << PAGE_SHIFT) -
|
|
miter->__offset;
|
|
miter->__remaining = min_t(unsigned long, miter->__remaining,
|
|
PAGE_SIZE - miter->__offset);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* sg_miter_skip - reposition mapping iterator
|
|
* @miter: sg mapping iter to be skipped
|
|
* @offset: number of bytes to plus the current location
|
|
*
|
|
* Description:
|
|
* Sets the offset of @miter to its current location plus @offset bytes.
|
|
* If mapping iterator @miter has been proceeded by sg_miter_next(), this
|
|
* stops @miter.
|
|
*
|
|
* Context:
|
|
* Don't care.
|
|
*
|
|
* Returns:
|
|
* true if @miter contains the valid mapping. false if end of sg
|
|
* list is reached.
|
|
*/
|
|
bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
|
|
{
|
|
sg_miter_stop(miter);
|
|
|
|
while (offset) {
|
|
off_t consumed;
|
|
|
|
if (!sg_miter_get_next_page(miter))
|
|
return false;
|
|
|
|
consumed = min_t(off_t, offset, miter->__remaining);
|
|
miter->__offset += consumed;
|
|
miter->__remaining -= consumed;
|
|
offset -= consumed;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_skip);
|
|
|
|
/**
|
|
* sg_miter_next - proceed mapping iterator to the next mapping
|
|
* @miter: sg mapping iter to proceed
|
|
*
|
|
* Description:
|
|
* Proceeds @miter to the next mapping. @miter should have been started
|
|
* using sg_miter_start(). On successful return, @miter->page,
|
|
* @miter->addr and @miter->length point to the current mapping.
|
|
*
|
|
* Context:
|
|
* May sleep if !SG_MITER_ATOMIC.
|
|
*
|
|
* Returns:
|
|
* true if @miter contains the next mapping. false if end of sg
|
|
* list is reached.
|
|
*/
|
|
bool sg_miter_next(struct sg_mapping_iter *miter)
|
|
{
|
|
sg_miter_stop(miter);
|
|
|
|
/*
|
|
* Get to the next page if necessary.
|
|
* __remaining, __offset is adjusted by sg_miter_stop
|
|
*/
|
|
if (!sg_miter_get_next_page(miter))
|
|
return false;
|
|
|
|
miter->page = sg_page_iter_page(&miter->piter);
|
|
miter->consumed = miter->length = miter->__remaining;
|
|
|
|
if (miter->__flags & SG_MITER_ATOMIC)
|
|
miter->addr = kmap_atomic(miter->page) + miter->__offset;
|
|
else
|
|
miter->addr = kmap(miter->page) + miter->__offset;
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_next);
|
|
|
|
/**
|
|
* sg_miter_stop - stop mapping iteration
|
|
* @miter: sg mapping iter to be stopped
|
|
*
|
|
* Description:
|
|
* Stops mapping iterator @miter. @miter should have been started
|
|
* using sg_miter_start(). A stopped iteration can be resumed by
|
|
* calling sg_miter_next() on it. This is useful when resources (kmap)
|
|
* need to be released during iteration.
|
|
*
|
|
* Context:
|
|
* Don't care otherwise.
|
|
*/
|
|
void sg_miter_stop(struct sg_mapping_iter *miter)
|
|
{
|
|
WARN_ON(miter->consumed > miter->length);
|
|
|
|
/* drop resources from the last iteration */
|
|
if (miter->addr) {
|
|
miter->__offset += miter->consumed;
|
|
miter->__remaining -= miter->consumed;
|
|
|
|
if (miter->__flags & SG_MITER_TO_SG)
|
|
flush_dcache_page(miter->page);
|
|
|
|
if (miter->__flags & SG_MITER_ATOMIC) {
|
|
WARN_ON_ONCE(!pagefault_disabled());
|
|
kunmap_atomic(miter->addr);
|
|
} else
|
|
kunmap(miter->page);
|
|
|
|
miter->page = NULL;
|
|
miter->addr = NULL;
|
|
miter->length = 0;
|
|
miter->consumed = 0;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_stop);
|
|
|
|
/**
|
|
* sg_copy_buffer - Copy data between a linear buffer and an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
* @to_buffer: transfer direction (true == from an sg list to a
|
|
* buffer, false == from a buffer to an sg list)
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
|
|
size_t buflen, off_t skip, bool to_buffer)
|
|
{
|
|
unsigned int offset = 0;
|
|
struct sg_mapping_iter miter;
|
|
unsigned int sg_flags = SG_MITER_ATOMIC;
|
|
|
|
if (to_buffer)
|
|
sg_flags |= SG_MITER_FROM_SG;
|
|
else
|
|
sg_flags |= SG_MITER_TO_SG;
|
|
|
|
sg_miter_start(&miter, sgl, nents, sg_flags);
|
|
|
|
if (!sg_miter_skip(&miter, skip))
|
|
return 0;
|
|
|
|
while ((offset < buflen) && sg_miter_next(&miter)) {
|
|
unsigned int len;
|
|
|
|
len = min(miter.length, buflen - offset);
|
|
|
|
if (to_buffer)
|
|
memcpy(buf + offset, miter.addr, len);
|
|
else
|
|
memcpy(miter.addr, buf + offset, len);
|
|
|
|
offset += len;
|
|
}
|
|
|
|
sg_miter_stop(&miter);
|
|
|
|
return offset;
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_buffer);
|
|
|
|
/**
|
|
* sg_copy_from_buffer - Copy from a linear buffer to an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_from_buffer);
|
|
|
|
/**
|
|
* sg_copy_to_buffer - Copy from an SG list to a linear buffer
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy to
|
|
* @buflen: The number of bytes to copy
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_to_buffer);
|
|
|
|
/**
|
|
* sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen, off_t skip)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
|
|
}
|
|
EXPORT_SYMBOL(sg_pcopy_from_buffer);
|
|
|
|
/**
|
|
* sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy to
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen, off_t skip)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
|
|
}
|
|
EXPORT_SYMBOL(sg_pcopy_to_buffer);
|
|
|
|
/**
|
|
* sg_zero_buffer - Zero-out a part of a SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buflen: The number of bytes to zero out
|
|
* @skip: Number of bytes to skip before zeroing
|
|
*
|
|
* Returns the number of bytes zeroed.
|
|
**/
|
|
size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
size_t buflen, off_t skip)
|
|
{
|
|
unsigned int offset = 0;
|
|
struct sg_mapping_iter miter;
|
|
unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
|
|
|
|
sg_miter_start(&miter, sgl, nents, sg_flags);
|
|
|
|
if (!sg_miter_skip(&miter, skip))
|
|
return false;
|
|
|
|
while (offset < buflen && sg_miter_next(&miter)) {
|
|
unsigned int len;
|
|
|
|
len = min(miter.length, buflen - offset);
|
|
memset(miter.addr, 0, len);
|
|
|
|
offset += len;
|
|
}
|
|
|
|
sg_miter_stop(&miter);
|
|
return offset;
|
|
}
|
|
EXPORT_SYMBOL(sg_zero_buffer);
|
|
|
|
/*
|
|
* Extract and pin a list of up to sg_max pages from UBUF- or IOVEC-class
|
|
* iterators, and add them to the scatterlist.
|
|
*/
|
|
static ssize_t extract_user_to_sg(struct iov_iter *iter,
|
|
ssize_t maxsize,
|
|
struct sg_table *sgtable,
|
|
unsigned int sg_max,
|
|
iov_iter_extraction_t extraction_flags)
|
|
{
|
|
struct scatterlist *sg = sgtable->sgl + sgtable->nents;
|
|
struct page **pages;
|
|
unsigned int npages;
|
|
ssize_t ret = 0, res;
|
|
size_t len, off;
|
|
|
|
/* We decant the page list into the tail of the scatterlist */
|
|
pages = (void *)sgtable->sgl +
|
|
array_size(sg_max, sizeof(struct scatterlist));
|
|
pages -= sg_max;
|
|
|
|
do {
|
|
res = iov_iter_extract_pages(iter, &pages, maxsize, sg_max,
|
|
extraction_flags, &off);
|
|
if (res < 0)
|
|
goto failed;
|
|
|
|
len = res;
|
|
maxsize -= len;
|
|
ret += len;
|
|
npages = DIV_ROUND_UP(off + len, PAGE_SIZE);
|
|
sg_max -= npages;
|
|
|
|
for (; npages > 0; npages--) {
|
|
struct page *page = *pages;
|
|
size_t seg = min_t(size_t, PAGE_SIZE - off, len);
|
|
|
|
*pages++ = NULL;
|
|
sg_set_page(sg, page, seg, off);
|
|
sgtable->nents++;
|
|
sg++;
|
|
len -= seg;
|
|
off = 0;
|
|
}
|
|
} while (maxsize > 0 && sg_max > 0);
|
|
|
|
return ret;
|
|
|
|
failed:
|
|
while (sgtable->nents > sgtable->orig_nents)
|
|
unpin_user_page(sg_page(&sgtable->sgl[--sgtable->nents]));
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Extract up to sg_max pages from a BVEC-type iterator and add them to the
|
|
* scatterlist. The pages are not pinned.
|
|
*/
|
|
static ssize_t extract_bvec_to_sg(struct iov_iter *iter,
|
|
ssize_t maxsize,
|
|
struct sg_table *sgtable,
|
|
unsigned int sg_max,
|
|
iov_iter_extraction_t extraction_flags)
|
|
{
|
|
const struct bio_vec *bv = iter->bvec;
|
|
struct scatterlist *sg = sgtable->sgl + sgtable->nents;
|
|
unsigned long start = iter->iov_offset;
|
|
unsigned int i;
|
|
ssize_t ret = 0;
|
|
|
|
for (i = 0; i < iter->nr_segs; i++) {
|
|
size_t off, len;
|
|
|
|
len = bv[i].bv_len;
|
|
if (start >= len) {
|
|
start -= len;
|
|
continue;
|
|
}
|
|
|
|
len = min_t(size_t, maxsize, len - start);
|
|
off = bv[i].bv_offset + start;
|
|
|
|
sg_set_page(sg, bv[i].bv_page, len, off);
|
|
sgtable->nents++;
|
|
sg++;
|
|
sg_max--;
|
|
|
|
ret += len;
|
|
maxsize -= len;
|
|
if (maxsize <= 0 || sg_max == 0)
|
|
break;
|
|
start = 0;
|
|
}
|
|
|
|
if (ret > 0)
|
|
iov_iter_advance(iter, ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Extract up to sg_max pages from a KVEC-type iterator and add them to the
|
|
* scatterlist. This can deal with vmalloc'd buffers as well as kmalloc'd or
|
|
* static buffers. The pages are not pinned.
|
|
*/
|
|
static ssize_t extract_kvec_to_sg(struct iov_iter *iter,
|
|
ssize_t maxsize,
|
|
struct sg_table *sgtable,
|
|
unsigned int sg_max,
|
|
iov_iter_extraction_t extraction_flags)
|
|
{
|
|
const struct kvec *kv = iter->kvec;
|
|
struct scatterlist *sg = sgtable->sgl + sgtable->nents;
|
|
unsigned long start = iter->iov_offset;
|
|
unsigned int i;
|
|
ssize_t ret = 0;
|
|
|
|
for (i = 0; i < iter->nr_segs; i++) {
|
|
struct page *page;
|
|
unsigned long kaddr;
|
|
size_t off, len, seg;
|
|
|
|
len = kv[i].iov_len;
|
|
if (start >= len) {
|
|
start -= len;
|
|
continue;
|
|
}
|
|
|
|
kaddr = (unsigned long)kv[i].iov_base + start;
|
|
off = kaddr & ~PAGE_MASK;
|
|
len = min_t(size_t, maxsize, len - start);
|
|
kaddr &= PAGE_MASK;
|
|
|
|
maxsize -= len;
|
|
ret += len;
|
|
do {
|
|
seg = min_t(size_t, len, PAGE_SIZE - off);
|
|
if (is_vmalloc_or_module_addr((void *)kaddr))
|
|
page = vmalloc_to_page((void *)kaddr);
|
|
else
|
|
page = virt_to_page((void *)kaddr);
|
|
|
|
sg_set_page(sg, page, len, off);
|
|
sgtable->nents++;
|
|
sg++;
|
|
sg_max--;
|
|
|
|
len -= seg;
|
|
kaddr += PAGE_SIZE;
|
|
off = 0;
|
|
} while (len > 0 && sg_max > 0);
|
|
|
|
if (maxsize <= 0 || sg_max == 0)
|
|
break;
|
|
start = 0;
|
|
}
|
|
|
|
if (ret > 0)
|
|
iov_iter_advance(iter, ret);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Extract up to sg_max folios from an XARRAY-type iterator and add them to
|
|
* the scatterlist. The pages are not pinned.
|
|
*/
|
|
static ssize_t extract_xarray_to_sg(struct iov_iter *iter,
|
|
ssize_t maxsize,
|
|
struct sg_table *sgtable,
|
|
unsigned int sg_max,
|
|
iov_iter_extraction_t extraction_flags)
|
|
{
|
|
struct scatterlist *sg = sgtable->sgl + sgtable->nents;
|
|
struct xarray *xa = iter->xarray;
|
|
struct folio *folio;
|
|
loff_t start = iter->xarray_start + iter->iov_offset;
|
|
pgoff_t index = start / PAGE_SIZE;
|
|
ssize_t ret = 0;
|
|
size_t offset, len;
|
|
XA_STATE(xas, xa, index);
|
|
|
|
rcu_read_lock();
|
|
|
|
xas_for_each(&xas, folio, ULONG_MAX) {
|
|
if (xas_retry(&xas, folio))
|
|
continue;
|
|
if (WARN_ON(xa_is_value(folio)))
|
|
break;
|
|
if (WARN_ON(folio_test_hugetlb(folio)))
|
|
break;
|
|
|
|
offset = offset_in_folio(folio, start);
|
|
len = min_t(size_t, maxsize, folio_size(folio) - offset);
|
|
|
|
sg_set_page(sg, folio_page(folio, 0), len, offset);
|
|
sgtable->nents++;
|
|
sg++;
|
|
sg_max--;
|
|
|
|
maxsize -= len;
|
|
ret += len;
|
|
if (maxsize <= 0 || sg_max == 0)
|
|
break;
|
|
}
|
|
|
|
rcu_read_unlock();
|
|
if (ret > 0)
|
|
iov_iter_advance(iter, ret);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* extract_iter_to_sg - Extract pages from an iterator and add to an sglist
|
|
* @iter: The iterator to extract from
|
|
* @maxsize: The amount of iterator to copy
|
|
* @sgtable: The scatterlist table to fill in
|
|
* @sg_max: Maximum number of elements in @sgtable that may be filled
|
|
* @extraction_flags: Flags to qualify the request
|
|
*
|
|
* Extract the page fragments from the given amount of the source iterator and
|
|
* add them to a scatterlist that refers to all of those bits, to a maximum
|
|
* addition of @sg_max elements.
|
|
*
|
|
* The pages referred to by UBUF- and IOVEC-type iterators are extracted and
|
|
* pinned; BVEC-, KVEC- and XARRAY-type are extracted but aren't pinned; PIPE-
|
|
* and DISCARD-type are not supported.
|
|
*
|
|
* No end mark is placed on the scatterlist; that's left to the caller.
|
|
*
|
|
* @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA
|
|
* be allowed on the pages extracted.
|
|
*
|
|
* If successful, @sgtable->nents is updated to include the number of elements
|
|
* added and the number of bytes added is returned. @sgtable->orig_nents is
|
|
* left unaltered.
|
|
*
|
|
* The iov_iter_extract_mode() function should be used to query how cleanup
|
|
* should be performed.
|
|
*/
|
|
ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t maxsize,
|
|
struct sg_table *sgtable, unsigned int sg_max,
|
|
iov_iter_extraction_t extraction_flags)
|
|
{
|
|
if (maxsize == 0)
|
|
return 0;
|
|
|
|
switch (iov_iter_type(iter)) {
|
|
case ITER_UBUF:
|
|
case ITER_IOVEC:
|
|
return extract_user_to_sg(iter, maxsize, sgtable, sg_max,
|
|
extraction_flags);
|
|
case ITER_BVEC:
|
|
return extract_bvec_to_sg(iter, maxsize, sgtable, sg_max,
|
|
extraction_flags);
|
|
case ITER_KVEC:
|
|
return extract_kvec_to_sg(iter, maxsize, sgtable, sg_max,
|
|
extraction_flags);
|
|
case ITER_XARRAY:
|
|
return extract_xarray_to_sg(iter, maxsize, sgtable, sg_max,
|
|
extraction_flags);
|
|
default:
|
|
pr_err("%s(%u) unsupported\n", __func__, iov_iter_type(iter));
|
|
WARN_ON_ONCE(1);
|
|
return -EIO;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(extract_iter_to_sg);
|