From: Khalid Aziz <khalid@xxxxxxxxxx>
Make msharefs filesystem writable and allow creating directories
to support better access control to mshare'd regions defined in
msharefs.
Signed-off-by: Khalid Aziz <khalid@xxxxxxxxxx>
Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
---
mm/mshare.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 116 insertions(+), 1 deletion(-)
diff --git a/mm/mshare.c b/mm/mshare.c
index 6562000545e1..f718b8934cdf 100644
--- a/mm/mshare.c
+++ b/mm/mshare.c
@@ -21,11 +21,126 @@ struct msharefs_info {
struct dentry *info_dentry;
};
+static const struct inode_operations msharefs_dir_inode_ops;
+static const struct inode_operations msharefs_file_inode_ops;
+
static const struct file_operations msharefs_file_operations = {
.open = simple_open,
.llseek = no_llseek,
};
+static struct inode
+*msharefs_get_inode(struct mnt_idmap *idmap, struct super_block *sb,
+ const struct inode *dir, umode_t mode)
+{
+ struct inode *inode = new_inode(sb);
+
+ if (!inode)
+ return ERR_PTR(-ENOMEM);
+
+ inode->i_ino = get_next_ino();
+ inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
+ simple_inode_init_ts(inode);
+
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ inode->i_op = &msharefs_file_inode_ops;
+ inode->i_fop = &msharefs_file_operations;
+ break;
+ case S_IFDIR:
+ inode->i_op = &msharefs_dir_inode_ops;
+ inode->i_fop = &simple_dir_operations;
+ inc_nlink(inode);
+ break;
+ default:
+ discard_new_inode(inode);
+ return ERR_PTR(-EINVAL);
+ }
+
+ return inode;
+}
+
+static int
+msharefs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+ struct dentry *dentry, umode_t mode)
+{
+ struct inode *inode;
+
+ inode = msharefs_get_inode(idmap, dir->i_sb, dir, mode);
+ if (IS_ERR(inode))
+ return PTR_ERR(inode);
+
+ d_instantiate(dentry, inode);
+ dget(dentry);
+ inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+
+ return 0;
+}
+
+static int
+msharefs_create(struct mnt_idmap *idmap, struct inode *dir,
+ struct dentry *dentry, umode_t mode, bool excl)
+{
+ return msharefs_mknod(idmap, dir, dentry, mode | S_IFREG);
+}
+
+static int
+msharefs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+ struct dentry *dentry, umode_t mode)
+{
+ int ret = msharefs_mknod(idmap, dir, dentry, mode | S_IFDIR);
+
+ if (!ret)
+ inc_nlink(dir);
+ return ret;
+}
+
+static inline bool
+is_msharefs_info_file(const struct dentry *dentry)
+{
+ struct msharefs_info *info = dentry->d_sb->s_fs_info;
+
+ return info->info_dentry == dentry;
+}
+
+static int
+msharefs_rename(struct mnt_idmap *idmap,
+ struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry,
+ unsigned int flags)
+{
+ if (is_msharefs_info_file(old_dentry) ||
+ is_msharefs_info_file(new_dentry))
+ return -EPERM;
+
+ return simple_rename(idmap, old_dir, old_dentry, new_dir,
+ new_dentry, flags);
+}
+
+static int
+msharefs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ if (is_msharefs_info_file(dentry))
+ return -EPERM;
+
+ return simple_unlink(dir, dentry);
+}
+
+static const struct inode_operations msharefs_file_inode_ops = {
+ .setattr = simple_setattr,
+ .getattr = simple_getattr,
+};
+
+static const struct inode_operations msharefs_dir_inode_ops = {
+ .create = msharefs_create,
+ .lookup = simple_lookup,
+ .link = simple_link,
+ .unlink = msharefs_unlink,
+ .mkdir = msharefs_mkdir,
+ .rmdir = simple_rmdir,
+ .rename = msharefs_rename,
+};
+
static ssize_t
mshare_info_read(struct file *file, char __user *buf, size_t nbytes,
loff_t *ppos)
@@ -104,7 +219,7 @@ msharefs_fill_super(struct super_block *sb, struct fs_context *fc)
inode->i_ino = 1;
inode->i_mode = S_IFDIR | 0777;
simple_inode_init_ts(inode);
- inode->i_op = &simple_dir_inode_operations;
+ inode->i_op = &msharefs_dir_inode_ops;
inode->i_fop = &simple_dir_operations;
set_nlink(inode, 2);
--
2.43.5
