drivers/md/raid1-10.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Maximum size of each resync request */
   3 #define RESYNC_BLOCK_SIZE (64*1024)
   4 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
   5
   6 /*
   7  * Number of guaranteed raid bios in case of extreme VM load:
   8  */
   9 #define NR_RAID_BIOS 256
  10
  11 /* when we get a read error on a read-only array, we redirect to another
  12  * device without failing the first device, or trying to over-write to
  13  * correct the read error.  To keep track of bad blocks on a per-bio
  14  * level, we store IO_BLOCKED in the appropriate 'bios' pointer
  15  */
  16 #define IO_BLOCKED ((struct bio *)1)
  17 /* When we successfully write to a known bad-block, we need to remove the
  18  * bad-block marking which must be done from process context.  So we record
  19  * the success by setting devs[n].bio to IO_MADE_GOOD
  20  */
  21 #define IO_MADE_GOOD ((struct bio *)2)
  22
  23 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
  24
  25 /* When there are this many requests queue to be written by
  26  * the raid thread, we become 'congested' to provide back-pressure
  27  * for writeback.
  28  */
  29 static int max_queued_requests = 1024;
  30
  31 /* for managing resync I/O pages */
  32 struct resync_pages {
  33         void            *raid_bio;
  34         struct page     *pages[RESYNC_PAGES];
  35 };
  36
  37 static void rbio_pool_free(void *rbio, void *data)
  38 {
  39         kfree(rbio);
  40 }
  41
  42 static inline int resync_alloc_pages(struct resync_pages *rp,
  43                                      gfp_t gfp_flags)
  44 {
  45         int i;
  46
  47         for (i = 0; i < RESYNC_PAGES; i++) {
  48                 rp->pages[i] = alloc_page(gfp_flags);
  49                 if (!rp->pages[i])
  50                         goto out_free;
  51         }
  52
  53         return 0;
  54
  55 out_free:
  56         while (--i >= 0)
  57                 put_page(rp->pages[i]);
  58         return -ENOMEM;
  59 }
  60
  61 static inline void resync_free_pages(struct resync_pages *rp)
  62 {
  63         int i;
  64
  65         for (i = 0; i < RESYNC_PAGES; i++)
  66                 put_page(rp->pages[i]);
  67 }
  68
  69 static inline void resync_get_all_pages(struct resync_pages *rp)
  70 {
  71         int i;
  72
  73         for (i = 0; i < RESYNC_PAGES; i++)
  74                 get_page(rp->pages[i]);
  75 }
  76
  77 static inline struct page *resync_fetch_page(struct resync_pages *rp,
  78                                              unsigned idx)
  79 {
  80         if (WARN_ON_ONCE(idx >= RESYNC_PAGES))
  81                 return NULL;
  82         return rp->pages[idx];
  83 }
  84
  85 /*
  86  * 'strct resync_pages' stores actual pages used for doing the resync
  87  *  IO, and it is per-bio, so make .bi_private points to it.
  88  */
  89 static inline struct resync_pages *get_resync_pages(struct bio *bio)
  90 {
  91         return bio->bi_private;
  92 }
  93
  94 /* generally called after bio_reset() for reseting bvec */
  95 static void md_bio_reset_resync_pages(struct bio *bio, struct resync_pages *rp,
  96                                int size)
  97 {
  98         int idx = 0;
  99
 100         /* initialize bvec table again */
 101         do {
 102                 struct page *page = resync_fetch_page(rp, idx);
 103                 int len = min_t(int, size, PAGE_SIZE);
 104
 105                 /*
 106                  * won't fail because the vec table is big
 107                  * enough to hold all these pages
 108                  */
 109                 bio_add_page(bio, page, len, 0);
 110                 size -= len;
 111         } while (idx++ < RESYNC_PAGES && size > 0);
 112 }