LXR linux/fs/erofs/data.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2017-2018 HUAWEI, Inc.
   4 *             https://www.huawei.com/
   5 * Created by Gao Xiang <gaoxiang25@huawei.com>
   6 */
   7#include "internal.h"
   8#include <linux/prefetch.h>
   9
  10#include <trace/events/erofs.h>
  11
  12static void erofs_readendio(struct bio *bio)
  13{
  14        struct bio_vec *bvec;
  15        blk_status_t err = bio->bi_status;
  16        struct bvec_iter_all iter_all;
  17
  18        bio_for_each_segment_all(bvec, bio, iter_all) {
  19                struct page *page = bvec->bv_page;
  20
  21                /* page is already locked */
  22                DBG_BUGON(PageUptodate(page));
  23
  24                if (err)
  25                        SetPageError(page);
  26                else
  27                        SetPageUptodate(page);
  28
  29                unlock_page(page);
  30                /* page could be reclaimed now */
  31        }
  32        bio_put(bio);
  33}
  34
  35struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr)
  36{
  37        struct address_space *const mapping = sb->s_bdev->bd_inode->i_mapping;
  38        struct page *page;
  39
  40        page = read_cache_page_gfp(mapping, blkaddr,
  41                                   mapping_gfp_constraint(mapping, ~__GFP_FS));
  42        /* should already be PageUptodate */
  43        if (!IS_ERR(page))
  44                lock_page(page);
  45        return page;
  46}
  47
  48static int erofs_map_blocks_flatmode(struct inode *inode,
  49                                     struct erofs_map_blocks *map,
  50                                     int flags)
  51{
  52        int err = 0;
  53        erofs_blk_t nblocks, lastblk;
  54        u64 offset = map->m_la;
  55        struct erofs_inode *vi = EROFS_I(inode);
  56        bool tailendpacking = (vi->datalayout == EROFS_INODE_FLAT_INLINE);
  57
  58        trace_erofs_map_blocks_flatmode_enter(inode, map, flags);
  59
  60        nblocks = DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
  61        lastblk = nblocks - tailendpacking;
  62
  63        if (offset >= inode->i_size) {
  64                /* leave out-of-bound access unmapped */
  65                map->m_flags = 0;
  66                map->m_plen = 0;
  67                goto out;
  68        }
  69
  70        /* there is no hole in flatmode */
  71        map->m_flags = EROFS_MAP_MAPPED;
  72
  73        if (offset < blknr_to_addr(lastblk)) {
  74                map->m_pa = blknr_to_addr(vi->raw_blkaddr) + map->m_la;
  75                map->m_plen = blknr_to_addr(lastblk) - offset;
  76        } else if (tailendpacking) {
  77                /* 2 - inode inline B: inode, [xattrs], inline last blk... */
  78                struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
  79
  80                map->m_pa = iloc(sbi, vi->nid) + vi->inode_isize +
  81                        vi->xattr_isize + erofs_blkoff(map->m_la);
  82                map->m_plen = inode->i_size - offset;
  83
  84                /* inline data should be located in one meta block */
  85                if (erofs_blkoff(map->m_pa) + map->m_plen > PAGE_SIZE) {
  86                        erofs_err(inode->i_sb,
  87                                  "inline data cross block boundary @ nid %llu",
  88                                  vi->nid);
  89                        DBG_BUGON(1);
  90                        err = -EFSCORRUPTED;
  91                        goto err_out;
  92                }
  93
  94                map->m_flags |= EROFS_MAP_META;
  95        } else {
  96                erofs_err(inode->i_sb,
  97                          "internal error @ nid: %llu (size %llu), m_la 0x%llx",
  98                          vi->nid, inode->i_size, map->m_la);
  99                DBG_BUGON(1);
 100                err = -EIO;
 101                goto err_out;
 102        }
 103
 104out:
 105        map->m_llen = map->m_plen;
 106
 107err_out:
 108        trace_erofs_map_blocks_flatmode_exit(inode, map, flags, 0);
 109        return err;
 110}
 111
 112int erofs_map_blocks(struct inode *inode,
 113                     struct erofs_map_blocks *map, int flags)
 114{
 115        if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout)) {
 116                int err = z_erofs_map_blocks_iter(inode, map, flags);
 117
 118                if (map->mpage) {
 119                        put_page(map->mpage);
 120                        map->mpage = NULL;
 121                }
 122                return err;
 123        }
 124        return erofs_map_blocks_flatmode(inode, map, flags);
 125}
 126
 127static inline struct bio *erofs_read_raw_page(struct bio *bio,
 128                                              struct address_space *mapping,
 129                                              struct page *page,
 130                                              erofs_off_t *last_block,
 131                                              unsigned int nblocks,
 132                                              bool ra)
 133{
 134        struct inode *const inode = mapping->host;
 135        struct super_block *const sb = inode->i_sb;
 136        erofs_off_t current_block = (erofs_off_t)page->index;
 137        int err;
 138
 139        DBG_BUGON(!nblocks);
 140
 141        if (PageUptodate(page)) {
 142                err = 0;
 143                goto has_updated;
 144        }
 145
 146        /* note that for readpage case, bio also equals to NULL */
 147        if (bio &&
 148            /* not continuous */
 149            *last_block + 1 != current_block) {
 150submit_bio_retry:
 151                submit_bio(bio);
 152                bio = NULL;
 153        }
 154
 155        if (!bio) {
 156                struct erofs_map_blocks map = {
 157                        .m_la = blknr_to_addr(current_block),
 158                };
 159                erofs_blk_t blknr;
 160                unsigned int blkoff;
 161
 162                err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
 163                if (err)
 164                        goto err_out;
 165
 166                /* zero out the holed page */
 167                if (!(map.m_flags & EROFS_MAP_MAPPED)) {
 168                        zero_user_segment(page, 0, PAGE_SIZE);
 169                        SetPageUptodate(page);
 170
 171                        /* imply err = 0, see erofs_map_blocks */
 172                        goto has_updated;
 173                }
 174
 175                /* for RAW access mode, m_plen must be equal to m_llen */
 176                DBG_BUGON(map.m_plen != map.m_llen);
 177
 178                blknr = erofs_blknr(map.m_pa);
 179                blkoff = erofs_blkoff(map.m_pa);
 180
 181                /* deal with inline page */
 182                if (map.m_flags & EROFS_MAP_META) {
 183                        void *vsrc, *vto;
 184                        struct page *ipage;
 185
 186                        DBG_BUGON(map.m_plen > PAGE_SIZE);
 187
 188                        ipage = erofs_get_meta_page(inode->i_sb, blknr);
 189
 190                        if (IS_ERR(ipage)) {
 191                                err = PTR_ERR(ipage);
 192                                goto err_out;
 193                        }
 194
 195                        vsrc = kmap_atomic(ipage);
 196                        vto = kmap_atomic(page);
 197                        memcpy(vto, vsrc + blkoff, map.m_plen);
 198                        memset(vto + map.m_plen, 0, PAGE_SIZE - map.m_plen);
 199                        kunmap_atomic(vto);
 200                        kunmap_atomic(vsrc);
 201                        flush_dcache_page(page);
 202
 203                        SetPageUptodate(page);
 204                        /* TODO: could we unlock the page earlier? */
 205                        unlock_page(ipage);
 206                        put_page(ipage);
 207
 208                        /* imply err = 0, see erofs_map_blocks */
 209                        goto has_updated;
 210                }
 211
 212                /* pa must be block-aligned for raw reading */
 213                DBG_BUGON(erofs_blkoff(map.m_pa));
 214
 215                /* max # of continuous pages */
 216                if (nblocks > DIV_ROUND_UP(map.m_plen, PAGE_SIZE))
 217                        nblocks = DIV_ROUND_UP(map.m_plen, PAGE_SIZE);
 218                if (nblocks > BIO_MAX_PAGES)
 219                        nblocks = BIO_MAX_PAGES;
 220
 221                bio = bio_alloc(GFP_NOIO, nblocks);
 222
 223                bio->bi_end_io = erofs_readendio;
 224                bio_set_dev(bio, sb->s_bdev);
 225                bio->bi_iter.bi_sector = (sector_t)blknr <<
 226                        LOG_SECTORS_PER_BLOCK;
 227                bio->bi_opf = REQ_OP_READ;
 228        }
 229
 230        err = bio_add_page(bio, page, PAGE_SIZE, 0);
 231        /* out of the extent or bio is full */
 232        if (err < PAGE_SIZE)
 233                goto submit_bio_retry;
 234
 235        *last_block = current_block;
 236
 237        /* shift in advance in case of it followed by too many gaps */
 238        if (bio->bi_iter.bi_size >= bio->bi_max_vecs * PAGE_SIZE) {
 239                /* err should reassign to 0 after submitting */
 240                err = 0;
 241                goto submit_bio_out;
 242        }
 243
 244        return bio;
 245
 246err_out:
 247        /* for sync reading, set page error immediately */
 248        if (!ra) {
 249                SetPageError(page);
 250                ClearPageUptodate(page);
 251        }
 252has_updated:
 253        unlock_page(page);
 254
 255        /* if updated manually, continuous pages has a gap */
 256        if (bio)
 257submit_bio_out:
 258                submit_bio(bio);
 259        return err ? ERR_PTR(err) : NULL;
 260}
 261
 262/*
 263 * since we dont have write or truncate flows, so no inode
 264 * locking needs to be held at the moment.
 265 */
 266static int erofs_raw_access_readpage(struct file *file, struct page *page)
 267{
 268        erofs_off_t last_block;
 269        struct bio *bio;
 270
 271        trace_erofs_readpage(page, true);
 272
 273        bio = erofs_read_raw_page(NULL, page->mapping,
 274                                  page, &last_block, 1, false);
 275
 276        if (IS_ERR(bio))
 277                return PTR_ERR(bio);
 278
 279        DBG_BUGON(bio); /* since we have only one bio -- must be NULL */
 280        return 0;
 281}
 282
 283static void erofs_raw_access_readahead(struct readahead_control *rac)
 284{
 285        erofs_off_t last_block;
 286        struct bio *bio = NULL;
 287        struct page *page;
 288
 289        trace_erofs_readpages(rac->mapping->host, readahead_index(rac),
 290                        readahead_count(rac), true);
 291
 292        while ((page = readahead_page(rac))) {
 293                prefetchw(&page->flags);
 294
 295                bio = erofs_read_raw_page(bio, rac->mapping, page, &last_block,
 296                                readahead_count(rac), true);
 297
 298                /* all the page errors are ignored when readahead */
 299                if (IS_ERR(bio)) {
 300                        pr_err("%s, readahead error at page %lu of nid %llu\n",
 301                               __func__, page->index,
 302                               EROFS_I(rac->mapping->host)->nid);
 303
 304                        bio = NULL;
 305                }
 306
 307                put_page(page);
 308        }
 309
 310        /* the rare case (end in gaps) */
 311        if (bio)
 312                submit_bio(bio);
 313}
 314
 315static int erofs_get_block(struct inode *inode, sector_t iblock,
 316                           struct buffer_head *bh, int create)
 317{
 318        struct erofs_map_blocks map = {
 319                .m_la = iblock << 9,
 320        };
 321        int err;
 322
 323        err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
 324        if (err)
 325                return err;
 326
 327        if (map.m_flags & EROFS_MAP_MAPPED)
 328                bh->b_blocknr = erofs_blknr(map.m_pa);
 329
 330        return err;
 331}
 332
 333static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
 334{
 335        struct inode *inode = mapping->host;
 336
 337        if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE) {
 338                erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
 339
 340                if (block >> LOG_SECTORS_PER_BLOCK >= blks)
 341                        return 0;
 342        }
 343
 344        return generic_block_bmap(mapping, block, erofs_get_block);
 345}
 346
 347/* for uncompressed (aligned) files and raw access for other files */
 348const struct address_space_operations erofs_raw_access_aops = {
 349        .readpage = erofs_raw_access_readpage,
 350        .readahead = erofs_raw_access_readahead,
 351        .bmap = erofs_bmap,
 352};
 353
 354