---- 在 星期二, 2020-11-10 21:45:51 Jan Kara <jack@xxxxxxx> 撰写 ----
> On Sun 08-11-20 22:03:04, Chengguang Xu wrote:
> > +static int ovl_write_inode(struct inode *inode,
> > + struct writeback_control *wbc)
> > +{
> > + struct ovl_fs *ofs = inode->i_sb->s_fs_info;
> > + struct inode *upper = ovl_inode_upper(inode);
> > + unsigned long iflag = 0;
> > + int ret = 0;
> > +
> > + if (!upper)
> > + return 0;
> > +
> > + if (!ovl_should_sync(ofs))
> > + return 0;
> > +
> > + if (upper->i_sb->s_op->write_inode)
> > + ret = upper->i_sb->s_op->write_inode(inode, wbc);
> > +
> > + iflag |= upper->i_state & I_DIRTY_ALL;
> > +
> > + if (mapping_writably_mapped(upper->i_mapping) ||
> > + mapping_tagged(upper->i_mapping, PAGECACHE_TAG_WRITEBACK))
> > + iflag |= I_DIRTY_PAGES;
> > +
> > + if (iflag)
> > + ovl_mark_inode_dirty(inode);
>
> I think you didn't incorporate feedback we were speaking about in the last
> version of the series. May comment in [1] still applies - you can miss
> inodes dirtied through mmap when you decide to clean the inode here. So
> IMHO you need something like:
>
> if (inode_is_open_for_write(inode))
> ovl_mark_inode_dirty(inode);
>
> here to keep inode dirty while it is open for write (and not based on upper
> inode state which is unreliable).
Hi Jan,
I not only checked upper inode state but also checked upper inode mmap(shared) state
using mapping_writably_mapped(upper->i_mapping). Maybe it's better to move i_state check
after mmap check but isn't above checks enough for mmapped file?
Below code is the definition of mmapping_writably_mapped(), I think it will check shared mmap
regardless write or read permission though the function name is quite confusable.
static inline int mapping_writably_mapped(struct address_space *mapping)
{
return atomic_read(&mapping->i_mmap_writable) > 0;
}
Thanks,
Chengguang
>
> Honza
>
> [1] https://lore.kernel.org/linux-fsdevel/20201105140332.GG32718@xxxxxxxxxxxxxx/
>
> > +
> > + return ret;
> > +}
> > +
> > static void ovl_evict_inode(struct inode *inode)
> > {
> > struct ovl_fs *ofs = inode->i_sb->s_fs_info;
> > @@ -411,6 +440,7 @@ static const struct super_operations ovl_super_operations = {
> > .destroy_inode = ovl_destroy_inode,
> > .drop_inode = generic_delete_inode,
> > .evict_inode = ovl_evict_inode,
> > + .write_inode = ovl_write_inode,
> > .put_super = ovl_put_super,
> > .sync_fs = ovl_sync_fs,
> > .statfs = ovl_statfs,
> > --
> > 2.26.2
> >
> >
> --
> Jan Kara <jack@xxxxxxxx>
> SUSE Labs, CR
>
