new file mode 100644
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
+ */
+
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/buffer_head.h>
+
+#include "exfat_raw.h"
+#include "exfat_fs.h"
+
+static int exfat_cont_expand(struct inode *inode, loff_t size)
+{
+ struct address_space *mapping = inode->i_mapping;
+ loff_t start = i_size_read(inode), count = size - i_size_read(inode);
+ int err, err2;
+
+ err = generic_cont_expand_simple(inode, size);
+ if (err)
+ return err;
+
+ inode->i_ctime = inode->i_mtime = current_time(inode);
+ mark_inode_dirty(inode);
+
+ if (!IS_SYNC(inode))
+ return 0;
+
+ err = filemap_fdatawrite_range(mapping, start, start + count - 1);
+ err2 = sync_mapping_buffers(mapping);
+ if (!err)
+ err = err2;
+ err2 = write_inode_now(inode, 1);
+ if (!err)
+ err = err2;
+ if (err)
+ return err;
+
+ return filemap_fdatawait_range(mapping, start, start + count - 1);
+}
+
+static int exfat_allow_set_time(struct exfat_sb_info *sbi, struct inode *inode)
+{
+ mode_t allow_utime = sbi->options.allow_utime;
+
+ if (!uid_eq(current_fsuid(), inode->i_uid)) {
+ if (in_group_p(inode->i_gid))
+ allow_utime >>= 3;
+ if (allow_utime & MAY_WRITE)
+ return 1;
+ }
+
+ /* use a default check */
+ return 0;
+}
+
+static int exfat_sanitize_mode(const struct exfat_sb_info *sbi,
+ struct inode *inode, umode_t *mode_ptr)
+{
+ mode_t i_mode, mask, perm;
+
+ i_mode = inode->i_mode;
+
+ if (S_ISREG(i_mode) || S_ISLNK(i_mode))
+ mask = sbi->options.fs_fmask;
+ else
+ mask = sbi->options.fs_dmask;
+
+ perm = *mode_ptr & ~(S_IFMT | mask);
+
+ /* Of the r and x bits, all (subject to umask) must be present.*/
+ if ((perm & 0555) != (i_mode & 0555))
+ return -EPERM;
+
+ if (exfat_mode_can_hold_ro(inode)) {
+ /*
+ * Of the w bits, either all (subject to umask) or none must
+ * be present.
+ */
+ if ((perm & 0222) && ((perm & 0222) != (0222 & ~mask)))
+ return -EPERM;
+ } else {
+ /*
+ * If exfat_mode_can_hold_ro(inode) is false, can't change
+ * w bits.
+ */
+ if ((perm & 0222) != (0222 & ~mask))
+ return -EPERM;
+ }
+
+ *mode_ptr &= S_IFMT | perm;
+
+ return 0;
+}
+
+/* resize the file length */
+int __exfat_truncate(struct inode *inode, loff_t new_size)
+{
+ unsigned int num_clusters_new, num_clusters_phys;
+ unsigned int last_clu = FREE_CLUSTER;
+ struct exfat_chain clu;
+ struct exfat_timestamp tm;
+ struct exfat_dentry *ep, *ep2;
+ struct super_block *sb = inode->i_sb;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct exfat_inode_info *ei = EXFAT_I(inode);
+ struct exfat_entry_set_cache *es = NULL;
+ int evict = (ei->dir.dir == DIR_DELETED) ? 1 : 0;
+
+ /* check if the given file ID is opened */
+ if (ei->type != TYPE_FILE && ei->type != TYPE_DIR)
+ return -EPERM;
+
+ exfat_set_vol_flags(sb, VOL_DIRTY);
+
+ num_clusters_new = EXFAT_B_TO_CLU_ROUND_UP(i_size_read(inode), sbi);
+ num_clusters_phys =
+ EXFAT_B_TO_CLU_ROUND_UP(EXFAT_I(inode)->i_size_ondisk, sbi);
+
+ exfat_chain_set(&clu, ei->start_clu, num_clusters_phys, ei->flags);
+
+ if (new_size > 0) {
+ /*
+ * Truncate FAT chain num_clusters after the first cluster
+ * num_clusters = min(new, phys);
+ */
+ unsigned int num_clusters =
+ min(num_clusters_new, num_clusters_phys);
+
+ /*
+ * Follow FAT chain
+ * (defensive coding - works fine even with corrupted FAT table
+ */
+ if (clu.flags == 0x03) {
+ clu.dir += num_clusters;
+ clu.size -= num_clusters;
+ } else {
+ while (num_clusters > 0) {
+ last_clu = clu.dir;
+ if (exfat_get_next_cluster(sb, &(clu.dir)))
+ return -EIO;
+
+ num_clusters--;
+ clu.size--;
+ }
+ }
+ } else {
+ ei->flags = 0x03;
+ ei->start_clu = EOF_CLUSTER;
+ }
+
+ i_size_write(inode, new_size);
+
+ if (ei->type == TYPE_FILE)
+ ei->attr |= ATTR_ARCHIVE;
+
+ /* update the directory entry */
+ if (!evict) {
+ es = exfat_get_dentry_set(sb, &(ei->dir), ei->entry,
+ ES_ALL_ENTRIES, &ep);
+ if (!es)
+ return -EIO;
+ ep2 = ep + 1;
+
+ exfat_set_entry_time(ep, exfat_tm_now(EXFAT_SB(sb), &tm),
+ TM_MODIFY);
+ ep->file_attr = cpu_to_le16(ei->attr);
+
+ /* File size should be zero if there is no cluster allocated */
+ if (ei->start_clu == EOF_CLUSTER)
+ ep->stream_valid_size = ep->stream_size = 0;
+ else {
+ ep->stream_valid_size = cpu_to_le64(new_size);
+ ep->stream_size = ep->stream_valid_size;
+ }
+
+ if (new_size == 0) {
+ /* Any directory can not be truncated to zero */
+ WARN_ON(ei->type != TYPE_FILE);
+
+ ep2->stream_flags = 0x01;
+ ep2->stream_start_clu = FREE_CLUSTER;
+ }
+
+ if (exfat_update_dir_chksum_with_entry_set(sb, es,
+ inode_needs_sync(inode)))
+ return -EIO;
+ kfree(es);
+ }
+
+ /* cut off from the FAT chain */
+ if (ei->flags == 0x01 && last_clu != FREE_CLUSTER &&
+ last_clu != EOF_CLUSTER) {
+ if (exfat_ent_set(sb, last_clu, EOF_CLUSTER))
+ return -EIO;
+ }
+
+ /* invalidate cache and free the clusters */
+ /* clear exfat cache */
+ exfat_cache_inval_inode(inode);
+
+ /* hint information */
+ ei->hint_bmap.off = EOF_CLUSTER;
+ ei->hint_bmap.clu = EOF_CLUSTER;
+ if (ei->rwoffset > new_size)
+ ei->rwoffset = new_size;
+
+ /* hint_stat will be used if this is directory. */
+ ei->hint_stat.eidx = 0;
+ ei->hint_stat.clu = ei->start_clu;
+ ei->hint_femp.eidx = EXFAT_HINT_NONE;
+
+ /* free the clusters */
+ if (exfat_free_cluster(inode, &clu))
+ return -EIO;
+
+ exfat_set_vol_flags(sb, VOL_CLEAN);
+
+ return 0;
+}
+
+void exfat_truncate(struct inode *inode, loff_t size)
+{
+ struct super_block *sb = inode->i_sb;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ unsigned int blocksize = 1 << inode->i_blkbits;
+ loff_t aligned_size;
+ int err;
+
+ mutex_lock(&sbi->s_lock);
+ if (EXFAT_I(inode)->start_clu == 0) {
+ /*
+ * Empty start_clu != ~0 (not allocated)
+ */
+ exfat_fs_error(sb, "tried to truncate zeroed cluster.");
+ goto out;
+ }
+
+ err = __exfat_truncate(inode, i_size_read(inode));
+ if (err)
+ goto out;
+
+ inode->i_ctime = inode->i_mtime = current_time(inode);
+ if (IS_DIRSYNC(inode))
+ exfat_sync_inode(inode);
+ else
+ mark_inode_dirty(inode);
+
+ inode->i_blocks = ((i_size_read(inode) + (sbi->cluster_size - 1)) &
+ ~(sbi->cluster_size - 1)) >> inode->i_blkbits;
+out:
+ aligned_size = i_size_read(inode);
+ if (aligned_size & (blocksize - 1)) {
+ aligned_size |= (blocksize - 1);
+ aligned_size++;
+ }
+
+ if (EXFAT_I(inode)->i_size_ondisk > i_size_read(inode))
+ EXFAT_I(inode)->i_size_ondisk = aligned_size;
+
+ if (EXFAT_I(inode)->i_size_aligned > i_size_read(inode))
+ EXFAT_I(inode)->i_size_aligned = aligned_size;
+ mutex_unlock(&sbi->s_lock);
+}
+
+int exfat_getattr(const struct path *path, struct kstat *stat,
+ unsigned int request_mask, unsigned int query_flags)
+{
+ struct inode *inode = d_backing_inode(path->dentry);
+
+ generic_fillattr(inode, stat);
+ stat->blksize = EXFAT_SB(inode->i_sb)->cluster_size;
+ return 0;
+}
+
+int exfat_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ struct exfat_sb_info *sbi = EXFAT_SB(dentry->d_sb);
+ struct inode *inode = dentry->d_inode;
+ unsigned int ia_valid;
+ int error;
+
+ if ((attr->ia_valid & ATTR_SIZE) &&
+ attr->ia_size > i_size_read(inode)) {
+ error = exfat_cont_expand(inode, attr->ia_size);
+ if (error || attr->ia_valid == ATTR_SIZE)
+ return error;
+ attr->ia_valid &= ~ATTR_SIZE;
+ }
+
+ /* Check for setting the inode time. */
+ ia_valid = attr->ia_valid;
+ if ((ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) &&
+ exfat_allow_set_time(sbi, inode)) {
+ attr->ia_valid &= ~(ATTR_MTIME_SET | ATTR_ATIME_SET |
+ ATTR_TIMES_SET);
+ }
+
+ error = setattr_prepare(dentry, attr);
+ attr->ia_valid = ia_valid;
+ if (error)
+ return error;
+
+ if (((attr->ia_valid & ATTR_UID) &&
+ !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||
+ ((attr->ia_valid & ATTR_GID) &&
+ !gid_eq(attr->ia_gid, sbi->options.fs_gid)) ||
+ ((attr->ia_valid & ATTR_MODE) &&
+ (attr->ia_mode & ~(S_IFREG | S_IFLNK | S_IFDIR | 0777))))
+ return -EPERM;
+
+ /*
+ * We don't return -EPERM here. Yes, strange, but this is too
+ * old behavior.
+ */
+ if (attr->ia_valid & ATTR_MODE) {
+ if (exfat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
+ attr->ia_valid &= ~ATTR_MODE;
+ }
+
+ if (attr->ia_valid & ATTR_SIZE) {
+ down_write(&EXFAT_I(inode)->truncate_lock);
+ truncate_setsize(inode, attr->ia_size);
+ exfat_truncate(inode, attr->ia_size);
+ up_write(&EXFAT_I(inode)->truncate_lock);
+ }
+
+ setattr_copy(inode, attr);
+ mark_inode_dirty(inode);
+
+ return error;
+}
+
+const struct file_operations exfat_file_operations = {
+ .llseek = generic_file_llseek,
+ .read_iter = generic_file_read_iter,
+ .write_iter = generic_file_write_iter,
+ .mmap = generic_file_mmap,
+ .fsync = generic_file_fsync,
+ .splice_read = generic_file_splice_read,
+};
+
+const struct inode_operations exfat_file_inode_operations = {
+ .setattr = exfat_setattr,
+ .getattr = exfat_getattr,
+};