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    Subject[PATCH v7 05/13] exfat: add file operations
    Date
    This adds the implementation of file operations for exfat.

    Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
    Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
    ---
    fs/exfat/file.c | 343 ++++++++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 343 insertions(+)
    create mode 100644 fs/exfat/file.c

    diff --git a/fs/exfat/file.c b/fs/exfat/file.c
    new file mode 100644
    index 000000000000..3baa46c09c99
    --- /dev/null
    +++ b/fs/exfat/file.c
    @@ -0,0 +1,343 @@
    +// 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 bool 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 true;
    + }
    +
    + /* use a default check */
    + return false;
    +}
    +
    +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;
    +
    + mask = (S_ISREG(i_mode) || S_ISLNK(i_mode)) ?
    + sbi->options.fs_fmask : 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 = EXFAT_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 == ALLOC_NO_FAT_CHAIN) {
    + 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 = ALLOC_NO_FAT_CHAIN;
    + ei->start_clu = EXFAT_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 == EXFAT_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 = ALLOC_FAT_CHAIN;
    + ep2->stream_start_clu = EXFAT_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 == ALLOC_FAT_CHAIN && last_clu != EXFAT_FREE_CLUSTER &&
    + last_clu != EXFAT_EOF_CLUSTER) {
    + if (exfat_ent_set(sb, last_clu, EXFAT_EOF_CLUSTER))
    + return -EIO;
    + }
    +
    + /* invalidate cache and free the clusters */
    + /* clear exfat cache */
    + exfat_cache_inval_inode(inode);
    +
    + /* hint information */
    + ei->hint_bmap.off = EXFAT_EOF_CLUSTER;
    + ei->hint_bmap.clu = EXFAT_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 write_size;
    + }
    +
    + err = __exfat_truncate(inode, i_size_read(inode));
    + if (err)
    + goto write_size;
    +
    + 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;
    +write_size:
    + 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,
    +};
    --
    2.17.1
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      Last update: 2019-12-13 06:55    [W:3.931 / U:0.044 seconds]
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