On Tue, Apr 30, 2024 at 3:21 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Tue, Apr 30, 2024 at 03:11:34AM +0800, Kairui Song wrote: > > +++ b/fs/nfs/file.c > > @@ -588,7 +588,7 @@ static vm_fault_t nfs_vm_page_mkwrite(struct vm_fault *vmf) > > > > dfprintk(PAGECACHE, "NFS: vm_page_mkwrite(%pD2(%lu), offset %lld)\n", > > filp, filp->f_mapping->host->i_ino, > > - (long long)folio_file_pos(folio)); > > + (long long)folio_pos(folio)); > > Yes, we can't call page_mkwrite() on a swapcache page. > > > +++ b/fs/nfs/nfstrace.h > > @@ -960,7 +960,7 @@ DECLARE_EVENT_CLASS(nfs_folio_event, > > __entry->fileid = nfsi->fileid; > > __entry->fhandle = nfs_fhandle_hash(&nfsi->fh); > > __entry->version = inode_peek_iversion_raw(inode); > > - __entry->offset = folio_file_pos(folio); > > + __entry->offset = folio_pos(folio); > > __entry->count = nfs_folio_length(folio); > > ), > > > > @@ -1008,7 +1008,7 @@ DECLARE_EVENT_CLASS(nfs_folio_event_done, > > __entry->fileid = nfsi->fileid; > > __entry->fhandle = nfs_fhandle_hash(&nfsi->fh); > > __entry->version = inode_peek_iversion_raw(inode); > > - __entry->offset = folio_file_pos(folio); > > + __entry->offset = folio_pos(folio); > > These two I don't know about. I can add a more detailed call chain for this in the commit message to make it look more convincing. > > +++ b/fs/nfs/write.c > > @@ -281,7 +281,7 @@ static void nfs_grow_file(struct folio *folio, unsigned int offset, > > end_index = ((i_size - 1) >> folio_shift(folio)) << folio_order(folio); > > if (i_size > 0 && folio_index(folio) < end_index) > > goto out; > > - end = folio_file_pos(folio) + (loff_t)offset + (loff_t)count; > > + end = folio_pos(folio) + (loff_t)offset + (loff_t)count; > > This one concerns me. Are we sure we can't call nfs_grow_file() > for a swapfile? Right, I did a audit of the code, all callers of nfs_grow_file are listed below: .write_end -> nfs_write_end -> nfs_update_folio -> nfs_writepage_setup -> nfs_grow_file .page_mkwrite -> nfs_vm_page_mkwrite -> nfs_update_folio -> nfs_writepage_setup -> nfs_grow_file > > > @@ -2073,7 +2073,7 @@ int nfs_wb_folio_cancel(struct inode *inode, struct folio *folio) > > */ > > int nfs_wb_folio(struct inode *inode, struct folio *folio) > > { > > - loff_t range_start = folio_file_pos(folio); > > + loff_t range_start = folio_pos(folio); > > loff_t range_end = range_start + (loff_t)folio_size(folio) - 1; > > Likewise here. Are we absolutely certain that swap I/O can't call this > function? Similar above: .release_folio -> nfs_release_folio -> nfs_wb_folio .launder_folio -> nfs_launder_folio -> nfs_wb_folio .write_begin -> nfs_write_begin -> nfs_read_folio -> nfs_wb_folio .read_folio -> nfs_read_folio -> nfs_wb_folio nfs_update_folio (listed above) -> nfs_writepage_setup -> nfs_setup_write_request -> nfs_try_to_update_request -> nfs_wb_folio-- .write_begin -> nfs_write_begin -> nfs_flush_incompatible -> nfs_wb_folio .page_mkwrite -> nfs_vm_page_mkwrite -> nfs_flush_incompatible -> nfs_wb_folio And nothing from the swap mapping side can call into fs, except swap_rw, none of the helpers are called by that.