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_vol_flags(sb, VOL_DIRTY);
 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
 158                es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,
 159                                ES_ALL_ENTRIES);
 160                if (!es)
 161                        return -EIO;
 162                ep = exfat_get_dentry_cached(es, 0);
 163                ep2 = exfat_get_dentry_cached(es, 1);
 164
 165                ts = current_time(inode);
 166                exfat_set_entry_time(sbi, &ts,
 167                                &ep->dentry.file.modify_tz,
 168                                &ep->dentry.file.modify_time,
 169                                &ep->dentry.file.modify_date,
 170                                &ep->dentry.file.modify_time_cs);
 171                ep->dentry.file.attr = cpu_to_le16(ei->attr);
 172
 173                /* File size should be zero if there is no cluster allocated */
 174                if (ei->start_clu == EXFAT_EOF_CLUSTER) {
 175                        ep2->dentry.stream.valid_size = 0;
 176                        ep2->dentry.stream.size = 0;
 177                } else {
 178                        ep2->dentry.stream.valid_size = cpu_to_le64(new_size);
 179                        ep2->dentry.stream.size = ep2->dentry.stream.valid_size;
 180                }
 181
 182                if (new_size == 0) {
 183                        /* Any directory can not be truncated to zero */
 184                        WARN_ON(ei->type != TYPE_FILE);
 185
 186                        ep2->dentry.stream.flags = ALLOC_FAT_CHAIN;
 187                        ep2->dentry.stream.start_clu = EXFAT_FREE_CLUSTER;
 188                }
 189
 190                exfat_update_dir_chksum_with_entry_set(es);
 191                exfat_free_dentry_set(es, inode_needs_sync(inode));
 192        }
 193
 194        /* cut off from the FAT chain */
 195        if (ei->flags == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
 196                        last_clu != EXFAT_EOF_CLUSTER) {
 197                if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
 198                        return -EIO;
 199        }
 200
 201        /* invalidate cache and free the clusters */
 202        /* clear exfat cache */
 203        exfat_cache_inval_inode(inode);
 204
 205        /* hint information */
 206        ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
 207        ei->hint_bmap.clu = EXFAT_EOF_CLUSTER;
 208        if (ei->rwoffset > new_size)
 209                ei->rwoffset = new_size;
 210
 211        /* hint_stat will be used if this is directory. */
 212        ei->hint_stat.eidx = 0;
 213        ei->hint_stat.clu = ei->start_clu;
 214        ei->hint_femp.eidx = EXFAT_HINT_NONE;
 215
 216        /* free the clusters */
 217        if (exfat_free_cluster(inode, &clu))
 218                return -EIO;
 219
 220        exfat_set_vol_flags(sb, VOL_CLEAN);
 221
 222        return 0;
 223}
 224
 225void exfat_truncate(struct inode *inode, loff_t size)
 226{
 227        struct super_block *sb = inode->i_sb;
 228        struct exfat_sb_info *sbi = EXFAT_SB(sb);
 229        unsigned int blocksize = 1 << inode->i_blkbits;
 230        loff_t aligned_size;
 231        int err;
 232
 233        mutex_lock(&sbi->s_lock);
 234        if (EXFAT_I(inode)->start_clu == 0) {
 235                /*
 236                 * Empty start_clu != ~0 (not allocated)
 237                 */
 238                exfat_fs_error(sb, "tried to truncate zeroed cluster.");
 239                goto write_size;
 240        }
 241
 242        err = __exfat_truncate(inode, i_size_read(inode));
 243        if (err)
 244                goto write_size;
 245
 246        inode->i_ctime = inode->i_mtime = current_time(inode);
 247        if (IS_DIRSYNC(inode))
 248                exfat_sync_inode(inode);
 249        else
 250                mark_inode_dirty(inode);
 251
 252        inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
 253                        ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
 254write_size:
 255        aligned_size = i_size_read(inode);
 256        if (aligned_size & (blocksize - 1)) {
 257                aligned_size |= (blocksize - 1);
 258                aligned_size++;
 259        }
 260
 261        if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))
 262                EXFAT_I(inode)->i_size_ondisk = aligned_size;
 263
 264        if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))
 265                EXFAT_I(inode)->i_size_aligned = aligned_size;
 266        mutex_unlock(&sbi->s_lock);
 267}
 268
 269int exfat_getattr(const struct path *path, struct kstat *stat,
 270                unsigned int request_mask, unsigned int query_flags)
 271{
 272        struct inode *inode = d_backing_inode(path->dentry);
 273        struct exfat_inode_info *ei = EXFAT_I(inode);
 274
 275        generic_fillattr(inode, stat);
 276        exfat_truncate_atime(&stat->atime);
 277        stat->result_mask |= STATX_BTIME;
 278        stat->btime.tv_sec = ei->i_crtime.tv_sec;
 279        stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
 280        stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
 281        return 0;
 282}
 283
 284int exfat_setattr(struct dentry *dentry, struct iattr *attr)
 285{
 286        struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
 287        struct inode *inode = dentry->d_inode;
 288        unsigned int ia_valid;
 289        int error;
 290
 291        if ((attr->ia_valid & ATTR_SIZE) &&
 292            attr->ia_size > i_size_read(inode)) {
 293                error = exfat_cont_expand(inode, attr->ia_size);
 294                if (error || attr->ia_valid == ATTR_SIZE)
 295                        return error;
 296                attr->ia_valid &= ~ATTR_SIZE;
 297        }
 298
 299        /* Check for setting the inode time. */
 300        ia_valid = attr->ia_valid;
 301        if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
 302            exfat_allow_set_time(sbi, inode)) {
 303                attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
 304                                ATTR_TIMES_SET);
 305        }
 306
 307        error = setattr_prepare(dentry, attr);
 308        attr->ia_valid = ia_valid;
 309        if (error)
 310                goto out;
 311
 312        if (((attr->ia_valid & ATTR_UID) &&
 313             !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||
 314            ((attr->ia_valid & ATTR_GID) &&
 315             !gid_eq(attr->ia_gid, sbi->options.fs_gid)) ||
 316            ((attr->ia_valid & ATTR_MODE) &&
 317             (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777)))) {
 318                error = -EPERM;
 319                goto out;
 320        }
 321
 322        /*
 323         * We don't return -EPERM here. Yes, strange, but this is too
 324         * old behavior.
 325         */
 326        if (attr->ia_valid & ATTR_MODE) {
 327                if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 328                        attr->ia_valid &= ~ATTR_MODE;
 329        }
 330
 331        if (attr->ia_valid & ATTR_SIZE) {
 332                error = exfat_block_truncate_page(inode, attr->ia_size);
 333                if (error)
 334                        goto out;
 335
 336                down_write(&EXFAT_I(inode)->truncate_lock);
 337                truncate_setsize(inode, attr->ia_size);
 338                exfat_truncate(inode, attr->ia_size);
 339                up_write(&EXFAT_I(inode)->truncate_lock);
 340        }
 341
 342        setattr_copy(inode, attr);
 343        exfat_truncate_atime(&inode->i_atime);
 344        mark_inode_dirty(inode);
 345
 346out:
 347        return error;
 348}
 349
 350int exfat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 351{
 352        struct inode *inode = filp->f_mapping->host;
 353        int err;
 354
 355        err = __generic_file_fsync(filp, start, end, datasync);
 356        if (err)
 357                return err;
 358
 359        err = sync_blockdev(inode->i_sb->s_bdev);
 360        if (err)
 361                return err;
 362
 363        return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL);
 364}
 365
 366const struct file_operations exfat_file_operations = {
 367        .llseek         = generic_file_llseek,
 368        .read_iter      = generic_file_read_iter,
 369        .write_iter     = generic_file_write_iter,
 370        .mmap           = generic_file_mmap,
 371        .fsync          = exfat_file_fsync,
 372        .splice_read    = generic_file_splice_read,
 373        .splice_write   = iter_file_splice_write,
 374};
 375
 376const struct inode_operations exfat_file_inode_operations = {
 377        .setattr     = exfat_setattr,
 378        .getattr     = exfat_getattr,
 379};
 380