lkml.org 
[lkml]   [2020]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 01/35] fs: introduce dmemfs module
    On Thu, Oct 08, 2020 at 03:53:51PM +0800, yulei.kernel@gmail.com wrote:

    > +static struct inode *
    > +dmemfs_get_inode(struct super_block *sb, const struct inode *dir, umode_t mode,
    > + dev_t dev);

    WTF is 'dev' for?

    > +static int
    > +dmemfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
    > +{
    > + struct inode *inode = dmemfs_get_inode(dir->i_sb, dir, mode, dev);
    > + int error = -ENOSPC;
    > +
    > + if (inode) {
    > + d_instantiate(dentry, inode);
    > + dget(dentry); /* Extra count - pin the dentry in core */
    > + error = 0;
    > + dir->i_mtime = dir->i_ctime = current_time(inode);
    > + }
    > + return error;
    > +}

    ... same here, seeing that you only call that thing from the next two functions
    and you do *not* provide ->mknod() as a method (unsurprisingly - what would
    device nodes do there?)

    > +static int dmemfs_create(struct inode *dir, struct dentry *dentry,
    > + umode_t mode, bool excl)
    > +{
    > + return dmemfs_mknod(dir, dentry, mode | S_IFREG, 0);
    > +}
    > +
    > +static int dmemfs_mkdir(struct inode *dir, struct dentry *dentry,
    > + umode_t mode)
    > +{
    > + int retval = dmemfs_mknod(dir, dentry, mode | S_IFDIR, 0);
    > +
    > + if (!retval)
    > + inc_nlink(dir);
    > + return retval;
    > +}

    > +int dmemfs_file_mmap(struct file *file, struct vm_area_struct *vma)
    > +{
    > + return 0;
    > +}
    > +
    > +static const struct file_operations dmemfs_file_operations = {
    > + .mmap = dmemfs_file_mmap,
    > +};

    Er... Is that a placeholder for later in the series? Because as it is,
    it makes no sense whatsoever - "it can be mmapped, but any access to the
    mapped area will segfault".

    > +struct inode *dmemfs_get_inode(struct super_block *sb,
    > + const struct inode *dir, umode_t mode, dev_t dev)
    > +{
    > + struct inode *inode = new_inode(sb);
    > +
    > + if (inode) {
    > + inode->i_ino = get_next_ino();
    > + inode_init_owner(inode, dir, mode);
    > + inode->i_mapping->a_ops = &empty_aops;
    > + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
    > + mapping_set_unevictable(inode->i_mapping);
    > + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
    > + switch (mode & S_IFMT) {
    > + default:
    > + init_special_inode(inode, mode, dev);
    > + break;
    > + case S_IFREG:
    > + inode->i_op = &dmemfs_file_inode_operations;
    > + inode->i_fop = &dmemfs_file_operations;
    > + break;
    > + case S_IFDIR:
    > + inode->i_op = &dmemfs_dir_inode_operations;
    > + inode->i_fop = &simple_dir_operations;
    > +
    > + /*
    > + * directory inodes start off with i_nlink == 2
    > + * (for "." entry)
    > + */
    > + inc_nlink(inode);
    > + break;
    > + case S_IFLNK:
    > + inode->i_op = &page_symlink_inode_operations;
    > + break;

    Where would symlinks come from? Or anything other than regular files and
    directories, for that matter...

    \
     
     \ /
      Last update: 2020-11-10 21:05    [W:4.944 / U:0.332 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site