| Message ID | 164299611274.26253.3394253485576079921.stgit@noble.brown (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Repair SWAP-over_NFS | expand |
On Mon, Jan 24, 2022 at 02:48:32PM +1100, NeilBrown wrote: > Pages that are written to swap are owned by the MM subsystem - not any > filesystem. > > When such a page is passed to a filesystem to be written out to a > swap-file, the filesystem handles the data, but the page itself does not > belong to the filesystem. So calling the filesystem's set_page_dirty > address_space operation makes no sense. This is for pages in the given > address space, and a page to be written to swap does not exist in the > given address space. > > So drop swap_set_page_dirty() which calls the address-space's > set_page_dirty, and alway use __set_page_dirty_no_writeback, which is > appropriate for pages being swapped out. Yes, this looks sane to me: Reviewed-by: Christoph Hellwig <hch@lst.de> > > Fixes-no-auto-backport: 62c230bc1790 ("mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages") > Signed-off-by: NeilBrown <neilb@suse.de> > --- > include/linux/swap.h | 1 - > mm/page_io.c | 14 -------------- > mm/swap_state.c | 2 +- > 3 files changed, 1 insertion(+), 16 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 3f54a8941c9d..a43929f7033e 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -419,7 +419,6 @@ extern void kswapd_stop(int nid); > > #ifdef CONFIG_SWAP > > -extern int swap_set_page_dirty(struct page *page); > int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, > unsigned long nr_pages, sector_t start_block); > int generic_swapfile_activate(struct swap_info_struct *, struct file *, > diff --git a/mm/page_io.c b/mm/page_io.c > index f8c26092e869..34b12d6f94d7 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -438,17 +438,3 @@ int swap_readpage(struct page *page, bool synchronous) > delayacct_swapin_end(); > return ret; > } > - > -int swap_set_page_dirty(struct page *page) > -{ > - struct swap_info_struct *sis = page_swap_info(page); > - > - if (data_race(sis->flags & SWP_FS_OPS)) { > - struct address_space *mapping = sis->swap_file->f_mapping; > - > - VM_BUG_ON_PAGE(!PageSwapCache(page), page); > - return mapping->a_ops->set_page_dirty(page); > - } else { > - return __set_page_dirty_no_writeback(page); > - } > -} > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 093ecf864200..d541594be1c3 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -31,7 +31,7 @@ > */ > static const struct address_space_operations swap_aops = { > .writepage = swap_writepage, > - .set_page_dirty = swap_set_page_dirty, > + .set_page_dirty = __set_page_dirty_no_writeback, > #ifdef CONFIG_MIGRATION > .migratepage = migrate_page, > #endif > > ---end quoted text---
diff --git a/include/linux/swap.h b/include/linux/swap.h index 3f54a8941c9d..a43929f7033e 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -419,7 +419,6 @@ extern void kswapd_stop(int nid); #ifdef CONFIG_SWAP -extern int swap_set_page_dirty(struct page *page); int add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, unsigned long nr_pages, sector_t start_block); int generic_swapfile_activate(struct swap_info_struct *, struct file *, diff --git a/mm/page_io.c b/mm/page_io.c index f8c26092e869..34b12d6f94d7 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -438,17 +438,3 @@ int swap_readpage(struct page *page, bool synchronous) delayacct_swapin_end(); return ret; } - -int swap_set_page_dirty(struct page *page) -{ - struct swap_info_struct *sis = page_swap_info(page); - - if (data_race(sis->flags & SWP_FS_OPS)) { - struct address_space *mapping = sis->swap_file->f_mapping; - - VM_BUG_ON_PAGE(!PageSwapCache(page), page); - return mapping->a_ops->set_page_dirty(page); - } else { - return __set_page_dirty_no_writeback(page); - } -} diff --git a/mm/swap_state.c b/mm/swap_state.c index 093ecf864200..d541594be1c3 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -31,7 +31,7 @@ */ static const struct address_space_operations swap_aops = { .writepage = swap_writepage, - .set_page_dirty = swap_set_page_dirty, + .set_page_dirty = __set_page_dirty_no_writeback, #ifdef CONFIG_MIGRATION .migratepage = migrate_page, #endif
Pages that are written to swap are owned by the MM subsystem - not any filesystem. When such a page is passed to a filesystem to be written out to a swap-file, the filesystem handles the data, but the page itself does not belong to the filesystem. So calling the filesystem's set_page_dirty address_space operation makes no sense. This is for pages in the given address space, and a page to be written to swap does not exist in the given address space. So drop swap_set_page_dirty() which calls the address-space's set_page_dirty, and alway use __set_page_dirty_no_writeback, which is appropriate for pages being swapped out. Fixes-no-auto-backport: 62c230bc1790 ("mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages") Signed-off-by: NeilBrown <neilb@suse.de> --- include/linux/swap.h | 1 - mm/page_io.c | 14 -------------- mm/swap_state.c | 2 +- 3 files changed, 1 insertion(+), 16 deletions(-)