fs/xfs/xfs_bio_io.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2019 Christoph Hellwig.
   4  */
   5 #include "xfs.h"
   6
   7 static inline unsigned int bio_max_vecs(unsigned int count)
   8 {
   9         return bio_max_segs(howmany(count, PAGE_SIZE));
  10 }
  11
  12 int
  13 xfs_rw_bdev(
  14         struct block_device     *bdev,
  15         sector_t                sector,
  16         unsigned int            count,
  17         char                    *data,
  18         enum req_op             op)
  19
  20 {
  21         unsigned int            is_vmalloc = is_vmalloc_addr(data);
  22         unsigned int            left = count;
  23         int                     error;
  24         struct bio              *bio;
  25
  26         if (is_vmalloc && op == REQ_OP_WRITE)
  27                 flush_kernel_vmap_range(data, count);
  28
  29         bio = bio_alloc(bdev, bio_max_vecs(left), op | REQ_META | REQ_SYNC,
  30                         GFP_KERNEL);
  31         bio->bi_iter.bi_sector = sector;
  32
  33         do {
  34                 struct page     *page = kmem_to_page(data);
  35                 unsigned int    off = offset_in_page(data);
  36                 unsigned int    len = min_t(unsigned, left, PAGE_SIZE - off);
  37
  38                 while (bio_add_page(bio, page, len, off) != len) {
  39                         struct bio      *prev = bio;
  40
  41                         bio = bio_alloc(prev->bi_bdev, bio_max_vecs(left),
  42                                         prev->bi_opf, GFP_KERNEL);
  43                         bio->bi_iter.bi_sector = bio_end_sector(prev);
  44                         bio_chain(prev, bio);
  45
  46                         submit_bio(prev);
  47                 }
  48
  49                 data += len;
  50                 left -= len;
  51         } while (left > 0);
  52
  53         error = submit_bio_wait(bio);
  54         bio_put(bio);
  55
  56         if (is_vmalloc && op == REQ_OP_READ)
  57                 invalidate_kernel_vmap_range(data, count);
  58         return error;
  59 }