diff --git a/include/linux/writeback.h b/include/linux/writeback.h
@@ -28,6 +28,7 @@ static inline int task_is_pdflush(struct task_struct *task)
*/
enum writeback_sync_modes {
WB_SYNC_NONE, /* Don't wait on anything */
+ WB_SYNC_NONE_PG,/* Don't wait on anything, don't touch locked pages */
WB_SYNC_ALL, /* Wait on every mapping */
WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */
};
It would be simpler/safer/saner to add a new bitflag to writeback_control
and use that directly. The WB_SYNC_foo flags are a holdover from an
earlier time and really should be made to go away, in favour of directly
setting up an appropriate writeback_control.
The code you have there looks racy: if someone else locks the page in that
little window after the PageLocked() test we'll still block in lock_page().
That's unlikely to happen in your application (apart from a remaining
ab/ba scenario) but we should make it robust:
if (wbc->skip_locked_pages) {
if (TestSetPageLocked(page))
continue;
} else {
lock_page(page);
}