fs: Make wbc_to_tag() inline and use it in fs.

The logic in wbc_to_tag() is widely used in file systems, so modify this
function to be inline and use it in file systems.

This patch has only passed compilation tests, but it should be fine.

Signed-off-by: Julian Sun <[e-mail]>
Reviewed-by: Qu Wenruo <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/btrfs/extent_io.c

···
 			       &BTRFS_I(inode)->runtime_flags))
 		wbc->tagged_writepages = 1;
 
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag = PAGECACHE_TAG_TOWRITE;
-	else
-		tag = PAGECACHE_TAG_DIRTY;
+	tag = wbc_to_tag(wbc);
 retry:
 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
 		tag_pages_for_writeback(mapping, index, end);

fs/ceph/addr.c

···
 	ceph_wbc->index = ceph_wbc->start_index;
 	ceph_wbc->end = -1;
 
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {
-		ceph_wbc->tag = PAGECACHE_TAG_TOWRITE;
-	} else {
-		ceph_wbc->tag = PAGECACHE_TAG_DIRTY;
-	}
+	ceph_wbc->tag = wbc_to_tag(wbc);
 
 	ceph_wbc->op_idx = -1;
 	ceph_wbc->num_ops = 0;

fs/ext4/inode.c

···
 	handle_t *handle = NULL;
 	int bpp = ext4_journal_blocks_per_folio(mpd->inode);
 
-	if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
-		tag = PAGECACHE_TAG_TOWRITE;
-	else
-		tag = PAGECACHE_TAG_DIRTY;
+	tag = wbc_to_tag(mpd->wbc);
 
 	mpd->map.m_len = 0;
 	mpd->next_pos = mpd->start_pos;

fs/f2fs/data.c

···
 		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
 			range_whole = 1;
 	}
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag = PAGECACHE_TAG_TOWRITE;
-	else
-		tag = PAGECACHE_TAG_DIRTY;
+	tag = wbc_to_tag(wbc);
 retry:
 	retry = 0;
 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)

fs/gfs2/aops.c

···
 			range_whole = 1;
 		cycled = 1; /* ignore range_cyclic tests */
 	}
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		tag = PAGECACHE_TAG_TOWRITE;
-	else
-		tag = PAGECACHE_TAG_DIRTY;
+	tag = wbc_to_tag(wbc);
 
 retry:
 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)

include/linux/writeback.h

···
 		       !(READ_ONCE(inode->i_state) & I_NEW));
 }
 
+static inline xa_mark_t wbc_to_tag(struct writeback_control *wbc)
+{
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		return PAGECACHE_TAG_TOWRITE;
+	return PAGECACHE_TAG_DIRTY;
+}
+
 #ifdef CONFIG_CGROUP_WRITEBACK
 
 #include <linux/cgroup.h>

mm/page-writeback.c

···
 	return true;
 }
 
-static xa_mark_t wbc_to_tag(struct writeback_control *wbc)
-{
-	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
-		return PAGECACHE_TAG_TOWRITE;
-	return PAGECACHE_TAG_DIRTY;
-}
 
 static pgoff_t wbc_end(struct writeback_control *wbc)
 {