On Wed, Jan 3, 2018 at 8:48 AM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > On Wed, Jan 3, 2018 at 12:54 AM, J . Bruce Fields <bfields@xxxxxxxxxxxx> wrote: >> On Tue, Jan 02, 2018 at 02:26:49PM +0200, Amir Goldstein wrote: >>> Instead of looking for all the places that update inode's m_time, >>> update overlay inode i_mtime just before nfsd needs to read it. >>> >>> The non uptodate mtime issue was found and verified with the >>> nfstest_posix test when run over NFS exported overlayfs: >>> >>> $ nfstest_posix --runtest=link,write >>> ... >>> FAIL: link - parent directory st_mtime should be updated >>> FAIL: write - file st_mtime should be updated >> >> Grepping for users of i_mtime in fs/nfsd/.... >> >> Looks like we might need something similar for fill_pre_wcc() ? (And >> maybe nfsd4_block_commit_blocks() ?) >> >> I don't think it's necessary for do_nfsd_create(), but it should be >> harmless if we want to just make it a rule that nfsd shouldn't be >> accessing i_mtime directly. >> > > All right. I'll do that. > While at it, do you think it will be fine to call vfs_getattr() from a helper > nfsd_get_inode_mtime() instead of having to special case overlayfs? > Or is there some reason why accessing i_mtime is a requirement? > Looking closer... in the callers of lease_get_mtime() vfs_getattr() is already called before accessing i_mtime, but stat->mtime is ignored, so I will change lease_get_mtime() to only *update* mtime for the has_lease case and leave it at the stat->mtime value otherwise. Regarding fill_pre_wcc() it is quite unbalanced that fill_pre_wcc() reads i_mtime, while fill_post_wcc() reads stat->mtime. I will change fill_pre_wcc() to use stat->mtime as well. Regarding nfsd4_block_commit_blocks(), there is no concern with respect to overlayfs and I have no means to test it, so I rather leave it be. Patches to follow... Thanks for your inputs, Amir.
