On Thu, Jun 11, 2020 at 01:37:26AM +0100, Al Viro wrote: > On Wed, Jun 10, 2020 at 05:13:52PM -0700, Mike Kravetz wrote: > > > To address this issue, > > - Add a new file operation f_real while will return the underlying file. > > Only overlayfs provides a function for this operation. > > - Add a new routine real_file() which can be used by core code get an > > underlying file. > > - Update is_file_hugepages to get the real file. > > Egads... So to find out whether it's a hugetlb you would > * check if a method is NULL > * if not, call it > * ... and check if the method table of the result is hugetlbfs one? > > Here's a radical suggestion: FMODE_HUGEPAGES. Just have it set by > ->open() and let is_file_hugepages() check it. In ->f_mode. And > make the bloody hugetlbfs_file_operations static, while we are at it. ITYM FMODE_OVL_UPPER. To quote Mike: > while (file->f_op == &ovl_file_operations) > file = file->private_data; > return file; which would be transformed into: while (file->f_mode & FMODE_OVL_UPPER) file = file->private_data; return file; Or are you proposing that overlayfs copy FMODE_HUGEPAGES from the underlying fs to the overlaying fs?
