On Tue, 2024-12-24 at 12:56 +0000, Matthew Wilcox wrote:
> On Mon, Dec 23, 2024 at 11:13:47PM +0000, Viacheslav Dubeyko wrote:
> > * On writeback, we must submit writes to the osd IN SNAP ORDER.
> > So,
> > * we look for the first capsnap in i_cap_snaps and write out pages
> > in
> > * that snap context _only_. Then we move on to the next capsnap,
> > * eventually reaching the "live" or "head" context (i.e., pages
> > that
> > * are not yet snapped) and are writing the most recently dirtied
> > * pages
>
> Speaking of writeback, ceph doesn't need a writepage operation.
> We're
> removing ->writepage from filesystems in favour of using -
> >migrate_folio
> for migration and ->writepages for writeback. As far as I can tell,
> filemap_migrate_folio() will be perfect for ceph (as the
> ceph_snap_context
> contains no references to the address of the memory). And ceph
> already
> has a ->writepages. So I think this patch should work. Can you give
> it
> a try?
>
Sure. Let me spend some time for testing it.
Thanks,
Slava.
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 85936f6d2bf7..5a5a870b6aee 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -810,32 +810,6 @@ static int writepage_nounlock(struct page *page,
> struct writeback_control *wbc)
> return err;
> }
>
> -static int ceph_writepage(struct page *page, struct
> writeback_control *wbc)
> -{
> - int err;
> - struct inode *inode = page->mapping->host;
> - BUG_ON(!inode);
> - ihold(inode);
> -
> - if (wbc->sync_mode == WB_SYNC_NONE &&
> - ceph_inode_to_fs_client(inode)->write_congested) {
> - redirty_page_for_writepage(wbc, page);
> - return AOP_WRITEPAGE_ACTIVATE;
> - }
> -
> - folio_wait_private_2(page_folio(page)); /* [DEPRECATED] */
> -
> - err = writepage_nounlock(page, wbc);
> - if (err == -ERESTARTSYS) {
> - /* direct memory reclaimer was killed by SIGKILL.
> return 0
> - * to prevent caller from setting mapping/page error
> */
> - err = 0;
> - }
> - unlock_page(page);
> - iput(inode);
> - return err;
> -}
> -
> /*
> * async writeback completion handler.
> *
> @@ -1584,7 +1558,6 @@ static int ceph_write_end(struct file *file,
> struct address_space *mapping,
> const struct address_space_operations ceph_aops = {
> .read_folio = netfs_read_folio,
> .readahead = netfs_readahead,
> - .writepage = ceph_writepage,
> .writepages = ceph_writepages_start,
> .write_begin = ceph_write_begin,
> .write_end = ceph_write_end,
> @@ -1592,6 +1565,7 @@ const struct address_space_operations ceph_aops
> = {
> .invalidate_folio = ceph_invalidate_folio,
> .release_folio = netfs_release_folio,
> .direct_IO = noop_direct_IO,
> + .migrate_folio = filemap_migrate_folio,
> };
>
> static void ceph_block_sigs(sigset_t *oldset)
