fs/erofs/zdata.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2018 HUAWEI, Inc.
   4  *             http://www.huawei.com/
   5  * Created by Gao Xiang <gaoxiang25@huawei.com>
   6  */
   7 #ifndef __EROFS_FS_ZDATA_H
   8 #define __EROFS_FS_ZDATA_H
   9
  10 #include "internal.h"
  11 #include "zpvec.h"
  12
  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: compressed pages (including multi-usage pages) */
  63         struct page *compressed_pages[Z_EROFS_CLUSTER_MAX_PAGES];
  64
  65         /* A: lower limit of decompressed length and if full length or not */
  66         unsigned int length;
  67
  68         /* I: compression algorithm format */
  69         unsigned char algorithmformat;
  70         /* I: bit shift of physical cluster size */
  71         unsigned char clusterbits;
  72 };
  73
  74 #define z_erofs_primarycollection(pcluster) (&(pcluster)->primary_collection)
  75
  76 /* let's avoid the valid 32-bit kernel addresses */
  77
  78 /* the chained workgroup has't submitted io (still open) */
  79 #define Z_EROFS_PCLUSTER_TAIL           ((void *)0x5F0ECAFE)
  80 /* the chained workgroup has already submitted io */
  81 #define Z_EROFS_PCLUSTER_TAIL_CLOSED    ((void *)0x5F0EDEAD)
  82
  83 #define Z_EROFS_PCLUSTER_NIL            (NULL)
  84
  85 #define Z_EROFS_WORKGROUP_SIZE  sizeof(struct z_erofs_pcluster)
  86
  87 struct z_erofs_decompressqueue {
  88         struct super_block *sb;
  89         atomic_t pending_bios;
  90         z_erofs_next_pcluster_t head;
  91
  92         union {
  93                 wait_queue_head_t wait;
  94                 struct work_struct work;
  95         } u;
  96 };
  97
  98 #define MNGD_MAPPING(sbi)       ((sbi)->managed_cache->i_mapping)
  99 static inline bool erofs_page_is_managed(const struct erofs_sb_info *sbi,
 100                                          struct page *page)
 101 {
 102         return page->mapping == MNGD_MAPPING(sbi);
 103 }
 104
 105 #define Z_EROFS_ONLINEPAGE_COUNT_BITS   2
 106 #define Z_EROFS_ONLINEPAGE_COUNT_MASK   ((1 << Z_EROFS_ONLINEPAGE_COUNT_BITS) - 1)
 107 #define Z_EROFS_ONLINEPAGE_INDEX_SHIFT  (Z_EROFS_ONLINEPAGE_COUNT_BITS)
 108
 109 /*
 110  * waiters (aka. ongoing_packs): # to unlock the page
 111  * sub-index: 0 - for partial page, >= 1 full page sub-index
 112  */
 113 typedef atomic_t z_erofs_onlinepage_t;
 114
 115 /* type punning */
 116 union z_erofs_onlinepage_converter {
 117         z_erofs_onlinepage_t *o;
 118         unsigned long *v;
 119 };
 120
 121 static inline unsigned int z_erofs_onlinepage_index(struct page *page)
 122 {
 123         union z_erofs_onlinepage_converter u;
 124
 125         DBG_BUGON(!PagePrivate(page));
 126         u.v = &page_private(page);
 127
 128         return atomic_read(u.o) >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
 129 }
 130
 131 static inline void z_erofs_onlinepage_init(struct page *page)
 132 {
 133         union {
 134                 z_erofs_onlinepage_t o;
 135                 unsigned long v;
 136         /* keep from being unlocked in advance */
 137         } u = { .o = ATOMIC_INIT(1) };
 138
 139         set_page_private(page, u.v);
 140         smp_wmb();
 141         SetPagePrivate(page);
 142 }
 143
 144 static inline void z_erofs_onlinepage_fixup(struct page *page,
 145         uintptr_t index, bool down)
 146 {
 147         unsigned long *p, o, v, id;
 148 repeat:
 149         p = &page_private(page);
 150         o = READ_ONCE(*p);
 151
 152         id = o >> Z_EROFS_ONLINEPAGE_INDEX_SHIFT;
 153         if (id) {
 154                 if (!index)
 155                         return;
 156
 157                 DBG_BUGON(id != index);
 158         }
 159
 160         v = (index << Z_EROFS_ONLINEPAGE_INDEX_SHIFT) |
 161                 ((o & Z_EROFS_ONLINEPAGE_COUNT_MASK) + (unsigned int)down);
 162         if (cmpxchg(p, o, v) != o)
 163                 goto repeat;
 164 }
 165
 166 static inline void z_erofs_onlinepage_endio(struct page *page)
 167 {
 168         union z_erofs_onlinepage_converter u;
 169         unsigned int v;
 170
 171         DBG_BUGON(!PagePrivate(page));
 172         u.v = &page_private(page);
 173
 174         v = atomic_dec_return(u.o);
 175         if (!(v & Z_EROFS_ONLINEPAGE_COUNT_MASK)) {
 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