On Thu, Jan 04, 2024 at 01:06:10PM -0800, Randy Dunlap wrote: > > +/** > > + * block_dirty_folio - Mark a folio as dirty. > > + * @mapping: The address space containing this folio. > > + * @folio: The folio to mark dirty. > > + * > > + * Filesystems which use buffer_heads can use this function as their > > + * ->dirty_folio implementation. Some filesystems need to do a little > > + * work before calling this function. Filesystems which do not use > > + * buffer_heads should call filemap_dirty_folio() instead. > > + * > > + * If the folio has buffers, the uptodate buffers are set dirty, to > > + * preserve dirty-state coherency between the folio and the buffers. > > + * It the folio does not have buffers then when they are later attached > > + * they will all be set dirty. > > + * > > + * The buffers are dirtied before the folio is dirtied. There's a small > > + * race window in which writeback may see the folio cleanness but not the > > + * buffer dirtiness. That's fine. If this code were to set the folio > > + * dirty before the buffers, writeback could clear the folio dirty flag, > > + * see a bunch of clean buffers and we'd end up with dirty buffers/clean > > + * folio on the dirty folio list. > > + * > > + * We use private_lock to lock against try_to_free_buffers() while > > + * using the folio's buffer list. This also prevents clean buffers > > + * being added to the folio after it was set dirty. > > + * > > + * Context: May only be called from process context. Does not sleep. > > + * Caller must ensure that @folio cannot be truncated during this call, > > + * typically by holding the folio lock or having a page in the folio > > + * mapped and holding the page table lock. > > * Return: tbd + * + * Return: True if the folio was dirtied; false if it was already dirtied.
