[RFC PATCH] staging: exfat: remove symlink feature.

From: Tetsuhiro Kohada
Date: Wed Feb 19 2020 - 00:58:01 EST

Remove symlink feature completely.

Becouse
-Uses reserved areas(defined in the Microsoft exfat specification), causing future incompatibilities.
-Not described in Microsoft exfat specifications or SD standards.
-For REMOVABLE media, causes incompatibility with other implementations.
-Not supported by other major exfat drivers.
-Not implemented symlink feature in linux FAT/VFAT.

Remove this feature completely because of serious media compatibility issues.
(Can't enable even with CONFIG)

If you have any questions about this patch, please let me know.

Reviewed-by: Takahiro Mori <Mori.Takahiro@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tetsuhiro Kohada <Kohada.Tetsuhiro@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
---
drivers/staging/exfat/exfat_super.c | 450 ----------------------------
1 file changed, 450 deletions(-)

diff --git a/drivers/staging/exfat/exfat_super.c b/drivers/staging/exfat/exfat_super.c
index b398114c2604..c7bc07e91c45 100644
--- a/drivers/staging/exfat/exfat_super.c
+++ b/drivers/staging/exfat/exfat_super.c
@@ -660,375 +660,6 @@ static int ffsCreateFile(struct inode *inode, char *path, u8 mode,
return ret;
}

-static int ffsReadFile(struct inode *inode, struct file_id_t *fid, void *buffer,
- u64 count, u64 *rcount)
-{
- s32 offset, sec_offset, clu_offset;
- u32 clu;
- int ret = 0;
- sector_t LogSector;
- u64 oneblkread, read_bytes;
- struct buffer_head *tmp_bh = NULL;
- struct super_block *sb = inode->i_sb;
- struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
- struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
-
- /* check the validity of the given file id */
- if (!fid)
- return -EINVAL;
-
- /* check the validity of pointer parameters */
- if (!buffer)
- return -EINVAL;
-
- /* acquire the lock for file system critical section */
- mutex_lock(&p_fs->v_mutex);
-
- /* check if the given file ID is opened */
- if (fid->type != TYPE_FILE) {
- ret = -EPERM;
- goto out;
- }
-
- if (fid->rwoffset > fid->size)
- fid->rwoffset = fid->size;
-
- if (count > (fid->size - fid->rwoffset))
- count = fid->size - fid->rwoffset;
-
- if (count == 0) {
- if (rcount)
- *rcount = 0;
- ret = 0;
- goto out;
- }
-
- read_bytes = 0;
-
- while (count > 0) {
- clu_offset = (s32)(fid->rwoffset >> p_fs->cluster_size_bits);
- clu = fid->start_clu;
-
- if (fid->flags == 0x03) {
- clu += clu_offset;
- } else {
- /* hint information */
- if ((clu_offset > 0) && (fid->hint_last_off > 0) &&
- (clu_offset >= fid->hint_last_off)) {
- clu_offset -= fid->hint_last_off;
- clu = fid->hint_last_clu;
- }
-
- while (clu_offset > 0) {
- /* clu = exfat_fat_read(sb, clu); */
- if (exfat_fat_read(sb, clu, &clu) == -1) {
- ret = -EIO;
- goto out;
- }
-
- clu_offset--;
- }
- }
-
- /* hint information */
- fid->hint_last_off = (s32)(fid->rwoffset >>
- p_fs->cluster_size_bits);
- fid->hint_last_clu = clu;
-
- /* byte offset in cluster */
- offset = (s32)(fid->rwoffset & (p_fs->cluster_size - 1));
-
- /* sector offset in cluster */
- sec_offset = offset >> p_bd->sector_size_bits;
-
- /* byte offset in sector */
- offset &= p_bd->sector_size_mask;
-
- LogSector = START_SECTOR(clu) + sec_offset;
-
- oneblkread = (u64)(p_bd->sector_size - offset);
- if (oneblkread > count)
- oneblkread = count;
-
- if ((offset == 0) && (oneblkread == p_bd->sector_size)) {
- if (sector_read(sb, LogSector, &tmp_bh, 1) !=
- 0)
- goto err_out;
- memcpy((char *)buffer + read_bytes,
- (char *)tmp_bh->b_data, (s32)oneblkread);
- } else {
- if (sector_read(sb, LogSector, &tmp_bh, 1) !=
- 0)
- goto err_out;
- memcpy((char *)buffer + read_bytes,
- (char *)tmp_bh->b_data + offset,
- (s32)oneblkread);
- }
- count -= oneblkread;
- read_bytes += oneblkread;
- fid->rwoffset += oneblkread;
- }
- brelse(tmp_bh);
-
-/* How did this ever work and not leak a brlse()?? */
-err_out:
- /* set the size of read bytes */
- if (rcount)
- *rcount = read_bytes;
-
- if (p_fs->dev_ejected)
- ret = -EIO;
-
-out:
- /* release the lock for file system critical section */
- mutex_unlock(&p_fs->v_mutex);
-
- return ret;
-}
-
-static int ffsWriteFile(struct inode *inode, struct file_id_t *fid,
- void *buffer, u64 count, u64 *wcount)
-{
- bool modified = false;
- s32 offset, sec_offset, clu_offset;
- s32 num_clusters, num_alloc, num_alloced = (s32)~0;
- int ret = 0;
- u32 clu, last_clu;
- sector_t LogSector;
- u64 oneblkwrite, write_bytes;
- struct chain_t new_clu;
- struct timestamp_t tm;
- struct dentry_t *ep, *ep2;
- struct entry_set_cache_t *es = NULL;
- struct buffer_head *tmp_bh = NULL;
- struct super_block *sb = inode->i_sb;
- struct fs_info_t *p_fs = &(EXFAT_SB(sb)->fs_info);
- struct bd_info_t *p_bd = &(EXFAT_SB(sb)->bd_info);
-
- /* check the validity of the given file id */
- if (!fid)
- return -EINVAL;
-
- /* check the validity of pointer parameters */
- if (!buffer)
- return -EINVAL;
-
- /* acquire the lock for file system critical section */
- mutex_lock(&p_fs->v_mutex);
-
- /* check if the given file ID is opened */
- if (fid->type != TYPE_FILE) {
- ret = -EPERM;
- goto out;
- }
-
- if (fid->rwoffset > fid->size)
- fid->rwoffset = fid->size;
-
- if (count == 0) {
- if (wcount)
- *wcount = 0;
- ret = 0;
- goto out;
- }
-
- fs_set_vol_flags(sb, VOL_DIRTY);
-
- if (fid->size == 0)
- num_clusters = 0;
- else
- num_clusters = (s32)((fid->size - 1) >>
- p_fs->cluster_size_bits) + 1;
-
- write_bytes = 0;
-
- while (count > 0) {
- clu_offset = (s32)(fid->rwoffset >> p_fs->cluster_size_bits);
- clu = fid->start_clu;
- last_clu = fid->start_clu;
-
- if (fid->flags == 0x03) {
- if ((clu_offset > 0) && (clu != CLUSTER_32(~0))) {
- last_clu += clu_offset - 1;
-
- if (clu_offset == num_clusters)
- clu = CLUSTER_32(~0);
- else
- clu += clu_offset;
- }
- } else {
- /* hint information */
- if ((clu_offset > 0) && (fid->hint_last_off > 0) &&
- (clu_offset >= fid->hint_last_off)) {
- clu_offset -= fid->hint_last_off;
- clu = fid->hint_last_clu;
- }
-
- while ((clu_offset > 0) && (clu != CLUSTER_32(~0))) {
- last_clu = clu;
- /* clu = exfat_fat_read(sb, clu); */
- if (exfat_fat_read(sb, clu, &clu) == -1) {
- ret = -EIO;
- goto out;
- }
- clu_offset--;
- }
- }
-
- if (clu == CLUSTER_32(~0)) {
- num_alloc = (s32)((count - 1) >>
- p_fs->cluster_size_bits) + 1;
- new_clu.dir = (last_clu == CLUSTER_32(~0)) ?
- CLUSTER_32(~0) : last_clu + 1;
- new_clu.size = 0;
- new_clu.flags = fid->flags;
-
- /* (1) allocate a chain of clusters */
- num_alloced = exfat_alloc_cluster(sb,
- num_alloc,
- &new_clu);
- if (num_alloced == 0)
- break;
- if (num_alloced < 0) {
- ret = num_alloced;
- goto out;
- }
-
- /* (2) append to the FAT chain */
- if (last_clu == CLUSTER_32(~0)) {
- if (new_clu.flags == 0x01)
- fid->flags = 0x01;
- fid->start_clu = new_clu.dir;
- modified = true;
- } else {
- if (new_clu.flags != fid->flags) {
- exfat_chain_cont_cluster(sb,
- fid->start_clu,
- num_clusters);
- fid->flags = 0x01;
- modified = true;
- }
- if (new_clu.flags == 0x01)
- exfat_fat_write(sb, last_clu, new_clu.dir);
- }
-
- num_clusters += num_alloced;
- clu = new_clu.dir;
- }
-
- /* hint information */
- fid->hint_last_off = (s32)(fid->rwoffset >>
- p_fs->cluster_size_bits);
- fid->hint_last_clu = clu;
-
- /* byte offset in cluster */
- offset = (s32)(fid->rwoffset & (p_fs->cluster_size - 1));
-
- /* sector offset in cluster */
- sec_offset = offset >> p_bd->sector_size_bits;
-
- /* byte offset in sector */
- offset &= p_bd->sector_size_mask;
-
- LogSector = START_SECTOR(clu) + sec_offset;
-
- oneblkwrite = (u64)(p_bd->sector_size - offset);
- if (oneblkwrite > count)
- oneblkwrite = count;
-
- if ((offset == 0) && (oneblkwrite == p_bd->sector_size)) {
- if (sector_read(sb, LogSector, &tmp_bh, 0) !=
- 0)
- goto err_out;
- memcpy((char *)tmp_bh->b_data,
- (char *)buffer + write_bytes, (s32)oneblkwrite);
- if (sector_write(sb, LogSector, tmp_bh, 0) !=
- 0) {
- brelse(tmp_bh);
- goto err_out;
- }
- } else {
- if ((offset > 0) ||
- ((fid->rwoffset + oneblkwrite) < fid->size)) {
- if (sector_read(sb, LogSector, &tmp_bh, 1) !=
- 0)
- goto err_out;
- } else {
- if (sector_read(sb, LogSector, &tmp_bh, 0) !=
- 0)
- goto err_out;
- }
-
- memcpy((char *)tmp_bh->b_data + offset,
- (char *)buffer + write_bytes, (s32)oneblkwrite);
- if (sector_write(sb, LogSector, tmp_bh, 0) !=
- 0) {
- brelse(tmp_bh);
- goto err_out;
- }
- }
-
- count -= oneblkwrite;
- write_bytes += oneblkwrite;
- fid->rwoffset += oneblkwrite;
-
- fid->attr |= ATTR_ARCHIVE;
-
- if (fid->size < fid->rwoffset) {
- fid->size = fid->rwoffset;
- modified = true;
- }
- }
-
- brelse(tmp_bh);
-
- /* (3) update the direcoty entry */
- es = get_entry_set_in_dir(sb, &fid->dir, fid->entry,
- ES_ALL_ENTRIES, &ep);
- if (!es)
- goto err_out;
- ep2 = ep + 1;
-
- exfat_set_entry_time(ep, tm_current(&tm), TM_MODIFY);
- exfat_set_entry_attr(ep, fid->attr);
-
- if (modified) {
- if (exfat_get_entry_flag(ep2) != fid->flags)
- exfat_set_entry_flag(ep2, fid->flags);
-
- if (exfat_get_entry_size(ep2) != fid->size)
- exfat_set_entry_size(ep2, fid->size);
-
- if (exfat_get_entry_clu0(ep2) != fid->start_clu)
- exfat_set_entry_clu0(ep2, fid->start_clu);
- }
-
- update_dir_checksum_with_entry_set(sb, es);
- release_entry_set(es);
-
-#ifndef CONFIG_STAGING_EXFAT_DELAYED_SYNC
- fs_sync(sb, true);
- fs_set_vol_flags(sb, VOL_CLEAN);
-#endif
-
-err_out:
- /* set the size of written bytes */
- if (wcount)
- *wcount = write_bytes;
-
- if (num_alloced == 0)
- ret = -ENOSPC;
-
- else if (p_fs->dev_ejected)
- ret = -EIO;
-
-out:
- /* release the lock for file system critical section */
- mutex_unlock(&p_fs->v_mutex);
-
- return ret;
-}
-
static int ffsTruncateFile(struct inode *inode, u64 old_size, u64 new_size)
{
s32 num_clusters;
@@ -2273,7 +1904,6 @@ static struct dentry *exfat_lookup(struct inode *dir, struct dentry *dentry,
int err;
struct file_id_t fid;
loff_t i_pos;
- u64 ret;
mode_t i_mode;

__lock_super(sb);
@@ -2295,18 +1925,6 @@ static struct dentry *exfat_lookup(struct inode *dir, struct dentry *dentry,
}

i_mode = inode->i_mode;
- if (S_ISLNK(i_mode) && !EXFAT_I(inode)->target) {
- EXFAT_I(inode)->target = kmalloc(i_size_read(inode) + 1,
- GFP_KERNEL);
- if (!EXFAT_I(inode)->target) {
- err = -ENOMEM;
- goto error;
- }
- ffsReadFile(dir, &fid, EXFAT_I(inode)->target,
- i_size_read(inode), &ret);
- *(EXFAT_I(inode)->target + i_size_read(inode)) = '\0';
- }
-
alias = d_find_alias(inode);
if (alias && !exfat_d_anon_disconn(alias)) {
BUG_ON(d_unhashed(alias));
@@ -2398,73 +2016,6 @@ static int exfat_unlink(struct inode *dir, struct dentry *dentry)
return err;
}

-static int exfat_symlink(struct inode *dir, struct dentry *dentry,
- const char *target)
-{
- struct super_block *sb = dir->i_sb;
- struct timespec64 curtime;
- struct inode *inode;
- struct file_id_t fid;
- loff_t i_pos;
- int err;
- u64 len = (u64)strlen(target);
- u64 ret;
-
- __lock_super(sb);
-
- pr_debug("%s entered\n", __func__);
-
- err = ffsCreateFile(dir, (u8 *)dentry->d_name.name, FM_SYMLINK, &fid);
- if (err)
- goto out;
-
-
- err = ffsWriteFile(dir, &fid, (char *)target, len, &ret);
-
- if (err) {
- ffsRemoveFile(dir, &fid);
- goto out;
- }
-
- INC_IVERSION(dir);
- curtime = current_time(dir);
- dir->i_ctime = curtime;
- dir->i_mtime = curtime;
- dir->i_atime = curtime;
- if (IS_DIRSYNC(dir))
- (void)exfat_sync_inode(dir);
- else
- mark_inode_dirty(dir);
-
- i_pos = ((loff_t)fid.dir.dir << 32) | (fid.entry & 0xffffffff);
-
- inode = exfat_build_inode(sb, &fid, i_pos);
- if (IS_ERR(inode)) {
- err = PTR_ERR(inode);
- goto out;
- }
- INC_IVERSION(inode);
- curtime = current_time(inode);
- inode->i_mtime = curtime;
- inode->i_atime = curtime;
- inode->i_ctime = curtime;
- /* timestamp is already written, so mark_inode_dirty() is unneeded. */
-
- EXFAT_I(inode)->target = kmemdup(target, len + 1, GFP_KERNEL);
- if (!EXFAT_I(inode)->target) {
- err = -ENOMEM;
- goto out;
- }
-
- dentry->d_time = GET_IVERSION(dentry->d_parent->d_inode);
- d_instantiate(dentry, inode);
-
-out:
- __unlock_super(sb);
- pr_debug("%s exited\n", __func__);
- return err;
-}
-
static int exfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
struct super_block *sb = dir->i_sb;
@@ -2838,7 +2389,6 @@ static const struct inode_operations exfat_dir_inode_operations = {
.create = exfat_create,
.lookup = exfat_lookup,
.unlink = exfat_unlink,
- .symlink = exfat_symlink,
.mkdir = exfat_mkdir,
.rmdir = exfat_rmdir,
.rename = exfat_rename,
--
2.25.0