On Fri, 18 Nov 2011 18:39:50 +0800 Cong Wang <amwang@xxxxxxxxxx> wrote: > It seems that systemd needs tmpfs to support fallocate, > see http://lkml.org/lkml/2011/10/20/275. This patch adds > fallocate support to tmpfs. > > As we already have shmem_truncate_range(), it is also easy > to add FALLOC_FL_PUNCH_HOLE support too. > > > ... > > +static long shmem_fallocate(struct file *file, int mode, > + loff_t offset, loff_t len) > +{ > + struct inode *inode = file->f_path.dentry->d_inode; > + pgoff_t start = offset >> PAGE_CACHE_SHIFT; > + pgoff_t end = DIV_ROUND_UP((offset + len), PAGE_CACHE_SIZE); > + pgoff_t index = start; > + loff_t i_size = i_size_read(inode); > + struct page *page = NULL; > + int ret = 0; > + > + mutex_lock(&inode->i_mutex); It would be saner and less racy-looking to read i_size _after_ taking i_mutex. And if you do that, there's no need to use i_size_read() - just a plain old i_size = inode->i_size; is OK. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>