// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2007 Jens Axboe <[email protected]> * * Scatterlist handling helpers. */ #include <linux/export.h> #include <linux/slab.h> #include <linux/scatterlist.h> #include <linux/highmem.h> #include <linux/kmemleak.h> #include <linux/bvec.h> #include <linux/uio.h> /** * sg_next - return the next scatterlist entry in a list * @sg: The current sg entry * * Description: * Usually the next entry will be @sg@ + 1, but if this sg element is part * of a chained scatterlist, it could jump to the start of a new * scatterlist array. * **/ struct scatterlist *sg_next(struct scatterlist *sg) { … } EXPORT_SYMBOL(…); /** * sg_nents - return total count of entries in scatterlist * @sg: The scatterlist * * Description: * Allows to know how many entries are in sg, taking into account * chaining as well * **/ int sg_nents(struct scatterlist *sg) { … } EXPORT_SYMBOL(…); /** * sg_nents_for_len - return total count of entries in scatterlist * needed to satisfy the supplied length * @sg: The scatterlist * @len: The total required length * * Description: * Determines the number of entries in sg that are required to meet * the supplied length, taking into account chaining as well * * Returns: * the number of sg entries needed, negative error on failure * **/ int sg_nents_for_len(struct scatterlist *sg, u64 len) { … } EXPORT_SYMBOL(…); /** * sg_last - return the last scatterlist entry in a list * @sgl: First entry in the scatterlist * @nents: Number of entries in the scatterlist * * Description: * Should only be used casually, it (currently) scans the entire list * to get the last entry. * * Note that the @sgl@ pointer passed in need not be the first one, * the important bit is that @nents@ denotes the number of entries that * exist from @sgl@. * **/ struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) { … } EXPORT_SYMBOL(…); /** * sg_init_table - Initialize SG table * @sgl: The SG table * @nents: Number of entries in table * * Notes: * If this is part of a chained sg table, sg_mark_end() should be * used only on the last table part. * **/ void sg_init_table(struct scatterlist *sgl, unsigned int nents) { … } EXPORT_SYMBOL(…); /** * sg_init_one - Initialize a single entry sg list * @sg: SG entry * @buf: Virtual address for IO * @buflen: IO length * **/ void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) { … } EXPORT_SYMBOL(…); /* * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree * helpers. */ static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) { … } static void sg_kfree(struct scatterlist *sg, unsigned int nents) { … } /** * __sg_free_table - Free a previously mapped sg table * @table: The sg table header to use * @max_ents: The maximum number of entries per single scatterlist * @nents_first_chunk: Number of entries int the (preallocated) first * scatterlist chunk, 0 means no such preallocated first chunk * @free_fn: Free function * @num_ents: Number of entries in the table * * Description: * Free an sg table previously allocated and setup with * __sg_alloc_table(). The @max_ents value must be identical to * that previously used with __sg_alloc_table(). * **/ void __sg_free_table(struct sg_table *table, unsigned int max_ents, unsigned int nents_first_chunk, sg_free_fn *free_fn, unsigned int num_ents) { … } EXPORT_SYMBOL(…); /** * sg_free_append_table - Free a previously allocated append sg table. * @table: The mapped sg append table header * **/ void sg_free_append_table(struct sg_append_table *table) { … } EXPORT_SYMBOL(…); /** * sg_free_table - Free a previously allocated sg table * @table: The mapped sg table header * **/ void sg_free_table(struct sg_table *table) { … } EXPORT_SYMBOL(…); /** * __sg_alloc_table - Allocate and initialize an sg table with given allocator * @table: The sg table header to use * @nents: Number of entries in sg list * @max_ents: The maximum number of entries the allocator returns per call * @first_chunk: first SGL if preallocated (may be %NULL) * @nents_first_chunk: Number of entries in the (preallocated) first * scatterlist chunk, 0 means no such preallocated chunk provided by user * @gfp_mask: GFP allocation mask * @alloc_fn: Allocator to use * * Description: * This function returns a @table @nents long. The allocator is * defined to return scatterlist chunks of maximum size @max_ents. * Thus if @nents is bigger than @max_ents, the scatterlists will be * chained in units of @max_ents. * * Notes: * If this function returns non-0 (eg failure), the caller must call * __sg_free_table() to cleanup any leftover allocations. * **/ int __sg_alloc_table(struct sg_table *table, unsigned int nents, unsigned int max_ents, struct scatterlist *first_chunk, unsigned int nents_first_chunk, gfp_t gfp_mask, sg_alloc_fn *alloc_fn) { … } EXPORT_SYMBOL(…); /** * sg_alloc_table - Allocate and initialize an sg table * @table: The sg table header to use * @nents: Number of entries in sg list * @gfp_mask: GFP allocation mask * * Description: * Allocate and initialize an sg table. If @nents@ is larger than * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. * **/ int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) { … } EXPORT_SYMBOL(…); static struct scatterlist *get_next_sg(struct sg_append_table *table, struct scatterlist *cur, unsigned long needed_sges, gfp_t gfp_mask) { … } static bool pages_are_mergeable(struct page *a, struct page *b) { … } /** * sg_alloc_append_table_from_pages - Allocate and initialize an append sg * table from an array of pages * @sgt_append: The sg append table 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 * @left_pages: Left pages caller have to set after this call * @gfp_mask: GFP allocation mask * * Description: * In the first call it allocate and initialize an sg table from a list of * pages, else reuse the scatterlist from sgt_append. Contiguous ranges of * the pages are squashed into a single scatterlist entry 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_append_table * * Returns: * 0 on success, negative error on failure * * Notes: * If this function returns non-0 (eg failure), the caller must call * sg_free_append_table() to cleanup any leftover allocations. * * In the fist call, sgt_append must by initialized. */ int sg_alloc_append_table_from_pages(struct sg_append_table *sgt_append, struct page **pages, unsigned int n_pages, unsigned int offset, unsigned long size, unsigned int max_segment, unsigned int left_pages, gfp_t gfp_mask) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); #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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * sgl_free - free a scatterlist and its pages * @sgl: Scatterlist with one or more elements */ void sgl_free(struct scatterlist *sgl) { … } EXPORT_SYMBOL(…); #endif /* CONFIG_SGL_ALLOC */ void __sg_page_iter_start(struct sg_page_iter *piter, struct scatterlist *sglist, unsigned int nents, unsigned long pgoffset) { … } EXPORT_SYMBOL(…); static int sg_page_count(struct scatterlist *sg) { … } bool __sg_page_iter_next(struct sg_page_iter *piter) { … } EXPORT_SYMBOL(…); static int sg_dma_page_count(struct scatterlist *sg) { … } bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) { … } /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /** * 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) { … } EXPORT_SYMBOL(…); /* * 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) { … } /* * 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) { … } /* * 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) { … } /* * 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) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…);
Codebase Browser
linux