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?
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)
