On Wed, Jun 24, 2020 at 3:53 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > On Wed, Jun 24, 2020 at 1:23 PM Chengguang Xu <cgxu519@xxxxxxxxxxxx> wrote: > > > > In metacopy case, we should use ovl_inode_realdata() instead of > > ovl_inode_real() to get real inode which has data, so that > > we can get correct information of extentes in ->fiemap operation. > > > > Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx> > > looks right Miklos, Not related to this patch, I noticed something that could be odd with ovl_fiemap(). When passed the flag FIEMAP_FLAG_SYNC, ->fiemap() will trigger writeback of lower inode pages. This behavior is border line for overlayfs. I did not check if filemap_write_and_wait() ends up being a noop on read-only fs or if it can return an error. Following ovl_fsync() practice, we may want to silently drop the FIEMAP_FLAG_SYNC flag? but that could result in unexpected results. Am I overthinking this? Thanks, Amir.
