bsd/vfs/vfs_cluster.c

2699 			 * never force zero valid pages - dirty or clean
2881 					 * written as dirty
3073 			 *    UPL has been automatically set to clear the dirty flags (both software and hardware)
3109 					 * cluster method of delaying dirty pages
5366 	 * - only pages that are currently dirty are returned... these are the ones we need to clean
5367 	 * - the hardware dirty bit is cleared when the page is gathered into the UPL... the software dirty bit is set
5368 	 * - if we have to abort the I/O for some reason, the software dirty bit is left set since we didn't clean the page
5369 	 * - when we commit the page, the software dirty bit is cleared... the hardware dirty bit is untouched so that if
5392 	 * since we only asked for the dirty pages back
5414 		 * find the next dirty page in the UPL
5423 				 * RET_ONLY_DIRTY will return non-dirty 'precious' pages
5431 			 * done... no more dirty pages to push
5436 			 * skipped over some non-dirty pages
5441 		 * find a range of dirty pages to write
5837  * dirty regions within a larger space (file).  It is primarily intended to
5838  * support clustering in large files with many dirty areas.
5840  * The implementation assumes that the dirty regions are pages.
5842  * To represent dirty pages within the file, we store bit vectors in a
5992 							    * dirty */
6015 	int		dirty);
6264  * Implementation of set dirty/clean.
6274 	int		dirty)
6283 	vfs_drt_trace(cmap, DRT_DEBUG_MARK | DBG_FUNC_START, (int)offset, (int)length, dirty, 0);
6291 		if (!dirty) {
6332 		 * Iterate over pages, dirty/clearing as we go.
6336 			if (dirty) {
6364  * Mark a set of pages as dirty/clean.
6376  *	Offset of the first page to be marked as dirty, in bytes.  Must be
6380  *	Length of dirty region, in bytes.  Must be a multiple of PAGE_SIZE.
6383  *	Number of pages newly marked dirty by this call (optional).
6403  * Get a cluster of dirty pages.
6415  *	Returns the length in bytes of the cluster of dirty pages.
6418  * are no dirty pages meeting the minmum size criteria.  Private storage will
6419  * be released if there are no more dirty pages left in the map