fs/erofs/zdata.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2018 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  */
   6 #ifndef __EROFS_FS_ZDATA_H
   7 #define __EROFS_FS_ZDATA_H
   8
   9 #include "internal.h"
  10 #include "zpvec.h"
  11
  12 #define Z_EROFS_PCLUSTER_MAX_PAGES      (Z_EROFS_PCLUSTER_MAX_SIZE / PAGE_SIZE)
  13 #define Z_EROFS_NR_INLINE_PAGEVECS      3
  14
  15 /*
  16  * Structure fields follow one of the following exclusion rules.
  17  *
  18  * I: Modifiable by initialization/destruction paths and read-only
  19  *    for everyone else;
  20  *
  21  * L: Field should be protected by pageset lock;
  22  *
  23  * A: Field should be accessed / updated in atomic for parallelized code.
  24  */
  25 struct z_erofs_collection {
  26         struct mutex lock;
  27
  28         /* I: page offset of start position of decompression */
  29         unsigned short pageofs;
  30
  31         /* L: maximum relative page index in pagevec[] */
  32         unsigned short nr_pages;
  33
  34         /* L: total number of pages in pagevec[] */
  35         unsigned int vcnt;
  36
  37         union {
  38                 /* L: inline a certain number of pagevecs for bootstrap */
  39                 erofs_vtptr_t pagevec[Z_EROFS_NR_INLINE_PAGEVECS];
  40
  41                 /* I: can be used to free the pcluster by RCU. */
  42                 struct rcu_head rcu;
  43         };
  44 };
  45
  46 #define Z_EROFS_PCLUSTER_FULL_LENGTH    0x00000001
  47 #define Z_EROFS_PCLUSTER_LENGTH_BIT     1
  48
  49 /*
  50  * let's leave a type here in case of introducing
  51  * another tagged pointer later.
  52  */
  53 typedef void *z_erofs_next_pcluster_t;
  54
  55 struct z_erofs_pcluster {
  56         struct erofs_workgroup obj;
  57         struct z_erofs_collection primary_collection;
  58
  59         /* A: point to next chained pcluster or TAILs */
  60         z_erofs_next_pcluster_t next;
  61
  62         /* A: lower limit of decompressed length and if full length or not */
  63         unsigned int length;
  64
  65         /* I: physical cluster size in pages */
  66         unsigned short pclusterpages;
  67
  68         /* I: compression algorithm format */
  69         unsigned char algorithmformat;
  70
  71         /* A: compressed pages (can be cached or inplaced pages) */
  72         struct page *compressed_pages[];
  73 };
  74
  75 #define z_erofs_primarycollection(pcluster) (&(pcluster)->primary_collection)
  76
  77 /* let's avoid the valid 32-bit kernel addresses */
  78
  79 /* the chained workgroup has't submitted io (still open) */
  80 #define Z_EROFS_PCLUSTER_TAIL           ((void *)0x5F0ECAFE)
  81 /* the chained workgroup has already submitted io */
  82 #define Z_EROFS_PCLUSTER_TAIL_CLOSED    ((void *)0x5F0EDEAD)
  83
  84 #define Z_EROFS_PCLUSTER_NIL            (NULL)
  85
  86 struct z_erofs_decompressqueue {
  87         struct super_block *sb;
  88         atomic_t pending_bios;
  89         z_erofs_next_pcluster_t head;
  90
  91         union {
  92                 wait_queue_head_t wait;
  93                 struct work_struct work;
  94         } u;
  95 };
  96
  97 #define MNGD_MAPPING(sbi)       ((sbi)->managed_cache->i_mapping)
  98 static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
  99                                          struct page *page)
 100 {
 101         return page->mapping == MNGD_MAPPING(sbi);
 102 }
 103
 104 #define Z_EROFS_ONLINEPAGE_COUNT_BITS   2
 105 #define Z_EROFS_ONLINEPAGE_COUNT_MASK   ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
 106 #define Z_EROFS_ONLINEPAGE_INDEX_SHIFT  (Z_EROFS_ONLINEPAGE_COUNT_BITS)
 107
 108 /*
 109  * waiters (aka. ongoing_packs): # to unlock the page
 110  * sub-index: 0 - for partial page, >= 1 full page sub-index
 111  */
 112 typedef atomic_t z_erofs_onlinepage_t;
 113
 114 /* type punning */
 115 union z_erofs_onlinepage_converter {
 116         z_erofs_onlinepage_t *o;
 117         unsigned long *v;
 118 };
 119
 120 static inline unsigned int z_erofs_onlinepage_index(struct page *page)
 121 {
 122         union z_erofs_onlinepage_converter u;
 123
 124         DBG_BUGON(!PagePrivate(page));
 125         u.v = &page_private(page);
 126
 127         return atomic_read(u.o) >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
 128 }
 129
 130 static inline void z_erofs_onlinepage_init(struct page *page)
 131 {
 132         union {
 133                 z_erofs_onlinepage_t o;
 134                 unsigned long v;
 135         /* keep from being unlocked in advance */
 136         } u = { .o = ATOMIC_INIT(1) };
 137
 138         set_page_private(page, u.v);
 139         smp_wmb();
 140         SetPagePrivate(page);
 141 }
 142
 143 static inline void z_erofs_onlinepage_fixup(struct page *page,
 144         uintptr_t index, bool down)
 145 {
 146         union z_erofs_onlinepage_converter u = { .v = &page_private(page) };
 147         int orig, orig_index, val;
 148
 149 repeat:
 150         orig = atomic_read(u.o);
 151         orig_index = orig >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
 152         if (orig_index) {
 153                 if (!index)
 154                         return;
 155
 156                 DBG_BUGON(orig_index != index);
 157         }
 158
 159         val = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
 160                 ((orig & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
 161         if (atomic_cmpxchg(u.o, orig, val) != orig)
 162                 goto repeat;
 163 }
 164
 165 static inline void z_erofs_onlinepage_endio(struct page *page)
 166 {
 167         union z_erofs_onlinepage_converter u;
 168         unsigned int v;
 169
 170         DBG_BUGON(!PagePrivate(page));
 171         u.v = &page_private(page);
 172
 173         v = atomic_dec_return(u.o);
 174         if (!(v & Z_EROFS_ONLINEPAGE_COUNT_MASK)) {
 175                 set_page_private(page, 0);
 176                 ClearPagePrivate(page);
 177                 if (!PageError(page))
 178                         SetPageUptodate(page);
 179                 unlock_page(page);
 180         }
 181         erofs_dbg("%s, page %p value %x", __func__, page, atomic_read(u.o));
 182 }
 183
 184 #define Z_EROFS_VMAP_ONSTACK_PAGES      \
 185         min_t(unsigned int, THREAD_SIZE / 8 / sizeof(struct page *), 96U)
 186 #define Z_EROFS_VMAP_GLOBAL_PAGES       2048
 187
 188 #endif
 189