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SubjectRe: [PATCH v6 05/13] exfat: add file operations
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On Mon, 2019-12-09 at 01:51 -0500, Namjae Jeon wrote:
> 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..1a32a88e2055
> --- /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))

What's about to use constants here instead of hardcoded values?

> + 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)))

Ditto.

> + return -EPERM;
> + } else {
> + /*
> + * If exfat_mode_can_hold_ro(inode) is false, can't
> change
> + * w bits.
> + */
> + if ((perm & 0222) != (0222 & ~mask))

Ditto.

> + 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 == 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 = 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;

The ep2 could point out on the garbage here. Maybe, it makes sense to
add some check here?

Thanks,
Viacheslav Dubeyko.

> +
> + 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 = ALLOC_FAT_CHAIN;
> + 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 == ALLOC_FAT_CHAIN && 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 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,
> +};

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