LXR linux/fs/exfat/file.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   4 */
   5
   6#include <linux/slab.h>
   7#include <linux/cred.h>
   8#include <linux/buffer_head.h>
   9#include <linux/blkdev.h>
  10
  11#include "exfat_raw.h"
  12#include "exfat_fs.h"
  13
  14static int exfat_cont_expand(struct inode *inode, loff_t size)
  15{
  16        struct address_space *mapping = inode->i_mapping;
  17        loff_t start = i_size_read(inode), count = size - i_size_read(inode);
  18        int err, err2;
  19
  20        err = generic_cont_expand_simple(inode, size);
  21        if (err)
  22                return err;
  23
  24        inode->i_ctime = inode->i_mtime = current_time(inode);
  25        mark_inode_dirty(inode);
  26
  27        if (!IS_SYNC(inode))
  28                return 0;
  29
  30        err = filemap_fdatawrite_range(mapping, start, start + count - 1);
  31        err2 = sync_mapping_buffers(mapping);
  32        if (!err)
  33                err = err2;
  34        err2 = write_inode_now(inode, 1);
  35        if (!err)
  36                err = err2;
  37        if (err)
  38                return err;
  39
  40        return filemap_fdatawait_range(mapping, start, start + count - 1);
  41}
  42
  43static bool exfat_allow_set_time(struct exfat_sb_info *sbi, struct inode *inode)
  44{
  45        mode_t allow_utime = sbi->options.allow_utime;
  46
  47        if (!uid_eq(current_fsuid(), inode->i_uid)) {
  48                if (in_group_p(inode->i_gid))
  49                        allow_utime >>= 3;
  50                if (allow_utime & MAY_WRITE)
  51                        return true;
  52        }
  53
  54        /* use a default check */
  55        return false;
  56}
  57
  58static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
  59                struct inode *inode, umode_t *mode_ptr)
  60{
  61        mode_t i_mode, mask, perm;
  62
  63        i_mode = inode->i_mode;
  64
  65        mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
  66                sbi->options.fs_fmask : sbi->options.fs_dmask;
  67        perm = *mode_ptr & ~(S_IFMT | mask);
  68
  69        /* Of the r and x bits, all (subject to umask) must be present.*/
  70        if ((perm & 0555) != (i_mode & 0555))
  71                return -EPERM;
  72
  73        if (exfat_mode_can_hold_ro(inode)) {
  74                /*
  75                 * Of the w bits, either all (subject to umask) or none must
  76                 * be present.
  77                 */
  78                if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
  79                        return -EPERM;
  80        } else {
  81                /*
  82                 * If exfat_mode_can_hold_ro(inode) is false, can't change
  83                 * w bits.
  84                 */
  85                if ((perm & 0222) != (0222 & ~mask))
  86                        return -EPERM;
  87        }
  88
  89        *mode_ptr &= S_IFMT | perm;
  90
  91        return 0;
  92}
  93
  94/* resize the file length */
  95int __exfat_truncate(struct inode *inode, loff_t new_size)
  96{
  97        unsigned int num_clusters_new, num_clusters_phys;
  98        unsigned int last_clu = EXFAT_FREE_CLUSTER;
  99        struct exfat_chain clu;
 100        struct super_block *sb = inode->i_sb;
 101        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 102        struct exfat_inode_info *ei = EXFAT_I(inode);
 103        int evict = (ei->dir.dir == DIR_DELETED) ? 1 : 0;
 104
 105        /* check if the given file ID is opened */
 106        if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
 107                return -EPERM;
 108
 109        exfat_set_volume_dirty(sb);
 110
 111        num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
 112        num_clusters_phys =
 113                EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk, sbi);
 114
 115        exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);
 116
 117        if (new_size > 0) {
 118                /*
 119                 * Truncate FAT chain num_clusters after the first cluster
 120                 * num_clusters = min(new, phys);
 121                 */
 122                unsigned int num_clusters =
 123                        min(num_clusters_new, num_clusters_phys);
 124
 125                /*
 126                 * Follow FAT chain
 127                 * (defensive coding - works fine even with corrupted FAT table
 128                 */
 129                if (clu.flags == ALLOC_NO_FAT_CHAIN) {
 130                        clu.dir += num_clusters;
 131                        clu.size -= num_clusters;
 132                } else {
 133                        while (num_clusters > 0) {
 134                                last_clu = clu.dir;
 135                                if (exfat_get_next_cluster(sb, &(clu.dir)))
 136                                        return -EIO;
 137
 138                                num_clusters--;
 139                                clu.size--;
 140                        }
 141                }
 142        } else {
 143                ei->flags = ALLOC_NO_FAT_CHAIN;
 144                ei->start_clu = EXFAT_EOF_CLUSTER;
 145        }
 146
 147        i_size_write(inode, new_size);
 148
 149        if (ei->type == TYPE_FILE)
 150                ei->attr |= ATTR_ARCHIVE;
 151
 152        /* update the directory entry */
 153        if (!evict) {
 154                struct timespec64 ts;
 155                struct exfat_dentry *ep, *ep2;
 156                struct exfat_entry_set_cache *es;
 157                int err;
 158
 159                es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,
 160                                ES_ALL_ENTRIES);
 161                if (!es)
 162                        return -EIO;
 163                ep = exfat_get_dentry_cached(es, 0);
 164                ep2 = exfat_get_dentry_cached(es, 1);
 165
 166                ts = current_time(inode);
 167                exfat_set_entry_time(sbi, &ts,
 168                                &ep->dentry.file.modify_tz,
 169                                &ep->dentry.file.modify_time,
 170                                &ep->dentry.file.modify_date,
 171                                &ep->dentry.file.modify_time_cs);
 172                ep->dentry.file.attr = cpu_to_le16(ei->attr);
 173
 174                /* File size should be zero if there is no cluster allocated */
 175                if (ei->start_clu == EXFAT_EOF_CLUSTER) {
 176                        ep2->dentry.stream.valid_size = 0;
 177                        ep2->dentry.stream.size = 0;
 178                } else {
 179                        ep2->dentry.stream.valid_size = cpu_to_le64(new_size);
 180                        ep2->dentry.stream.size = ep2->dentry.stream.valid_size;
 181                }
 182
 183                if (new_size == 0) {
 184                        /* Any directory can not be truncated to zero */
 185                        WARN_ON(ei->type != TYPE_FILE);
 186
 187                        ep2->dentry.stream.flags = ALLOC_FAT_CHAIN;
 188                        ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;
 189                }
 190
 191                exfat_update_dir_chksum_with_entry_set(es);
 192                err = exfat_free_dentry_set(es, inode_needs_sync(inode));
 193                if (err)
 194                        return err;
 195        }
 196
 197        /* cut off from the FAT chain */
 198        if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
 199                        last_clu != EXFAT_EOF_CLUSTER) {
 200                if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
 201                        return -EIO;
 202        }
 203
 204        /* invalidate cache and free the clusters */
 205        /* clear exfat cache */
 206        exfat_cache_inval_inode(inode);
 207
 208        /* hint information */
 209        ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
 210        ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;
 211        if (ei->rwoffset > new_size)
 212                ei->rwoffset = new_size;
 213
 214        /* hint_stat will be used if this is directory. */
 215        ei->hint_stat.eidx = 0;
 216        ei->hint_stat.clu = ei->start_clu;
 217        ei->hint_femp.eidx = EXFAT_HINT_NONE;
 218
 219        /* free the clusters */
 220        if (exfat_free_cluster(inode, &clu))
 221                return -EIO;
 222
 223        exfat_clear_volume_dirty(sb);
 224
 225        return 0;
 226}
 227
 228void exfat_truncate(struct inode *inode, loff_t size)
 229{
 230        struct super_block *sb = inode->i_sb;
 231        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 232        unsigned int blocksize = 1 << inode->i_blkbits;
 233        loff_t aligned_size;
 234        int err;
 235
 236        mutex_lock(&sbi->s_lock);
 237        if (EXFAT_I(inode)->start_clu == 0) {
 238                /*
 239                 * Empty start_clu != ~0 (not allocated)
 240                 */
 241                exfat_fs_error(sb, "tried to truncate zeroed cluster.");
 242                goto write_size;
 243        }
 244
 245        err = __exfat_truncate(inode, i_size_read(inode));
 246        if (err)
 247                goto write_size;
 248
 249        inode->i_ctime = inode->i_mtime = current_time(inode);
 250        if (IS_DIRSYNC(inode))
 251                exfat_sync_inode(inode);
 252        else
 253                mark_inode_dirty(inode);
 254
 255        inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
 256                        ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
 257write_size:
 258        aligned_size = i_size_read(inode);
 259        if (aligned_size & (blocksize - 1)) {
 260                aligned_size |= (blocksize - 1);
 261                aligned_size++;
 262        }
 263
 264        if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))
 265                EXFAT_I(inode)->i_size_ondisk = aligned_size;
 266
 267        if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))
 268                EXFAT_I(inode)->i_size_aligned = aligned_size;
 269        mutex_unlock(&sbi->s_lock);
 270}
 271
 272int exfat_getattr(const struct path *path, struct kstat *stat,
 273                unsigned int request_mask, unsigned int query_flags)
 274{
 275        struct inode *inode = d_backing_inode(path->dentry);
 276        struct exfat_inode_info *ei = EXFAT_I(inode);
 277
 278        generic_fillattr(inode, stat);
 279        exfat_truncate_atime(&stat->atime);
 280        stat->result_mask |= STATX_BTIME;
 281        stat->btime.tv_sec = ei->i_crtime.tv_sec;
 282        stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
 283        stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
 284        return 0;
 285}
 286
 287int exfat_setattr(struct dentry *dentry, struct iattr *attr)
 288{
 289        struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
 290        struct inode *inode = dentry->d_inode;
 291        unsigned int ia_valid;
 292        int error;
 293
 294        if ((attr->ia_valid & ATTR_SIZE) &&
 295            attr->ia_size > i_size_read(inode)) {
 296                error = exfat_cont_expand(inode, attr->ia_size);
 297                if (error || attr->ia_valid == ATTR_SIZE)
 298                        return error;
 299                attr->ia_valid &= ~ATTR_SIZE;
 300        }
 301
 302        /* Check for setting the inode time. */
 303        ia_valid = attr->ia_valid;
 304        if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
 305            exfat_allow_set_time(sbi, inode)) {
 306                attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
 307                                ATTR_TIMES_SET);
 308        }
 309
 310        error = setattr_prepare(dentry, attr);
 311        attr->ia_valid = ia_valid;
 312        if (error)
 313                goto out;
 314
 315        if (((attr->ia_valid & ATTR_UID) &&
 316             !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||
 317            ((attr->ia_valid & ATTR_GID) &&
 318             !gid_eq(attr->ia_gid, sbi->options.fs_gid)) ||
 319            ((attr->ia_valid & ATTR_MODE) &&
 320             (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
 321                error = -EPERM;
 322                goto out;
 323        }
 324
 325        /*
 326         * We don't return -EPERM here. Yes, strange, but this is too
 327         * old behavior.
 328         */
 329        if (attr->ia_valid & ATTR_MODE) {
 330                if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 331                        attr->ia_valid &= ~ATTR_MODE;
 332        }
 333
 334        if (attr->ia_valid & ATTR_SIZE) {
 335                error = exfat_block_truncate_page(inode, attr->ia_size);
 336                if (error)
 337                        goto out;
 338
 339                down_write(&EXFAT_I(inode)->truncate_lock);
 340                truncate_setsize(inode, attr->ia_size);
 341                exfat_truncate(inode, attr->ia_size);
 342                up_write(&EXFAT_I(inode)->truncate_lock);
 343        }
 344
 345        setattr_copy(inode, attr);
 346        exfat_truncate_atime(&inode->i_atime);
 347        mark_inode_dirty(inode);
 348
 349out:
 350        return error;
 351}
 352
 353int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 354{
 355        struct inode *inode = filp->f_mapping->host;
 356        int err;
 357
 358        err = __generic_file_fsync(filp, start, end, datasync);
 359        if (err)
 360                return err;
 361
 362        err = sync_blockdev(inode->i_sb->s_bdev);
 363        if (err)
 364                return err;
 365
 366        return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
 367}
 368
 369const struct file_operations exfat_file_operations = {
 370        .llseek         = generic_file_llseek,
 371        .read_iter      = generic_file_read_iter,
 372        .write_iter     = generic_file_write_iter,
 373        .mmap           = generic_file_mmap,
 374        .fsync          = exfat_file_fsync,
 375        .splice_read    = generic_file_splice_read,
 376        .splice_write   = iter_file_splice_write,
 377};
 378
 379const struct inode_operations exfat_file_inode_operations = {
 380        .setattr     = exfat_setattr,
 381        .getattr     = exfat_getattr,
 382};
 383