+ /*
+ * Figure out where the file ends, for pageout purposes. If
+ * ff_new_size > ff_size, then we're in the middle of extending the
+ * file via a write, so it is safe (and necessary) that we be able
+ * to pageout up to that point.
+ */
+ filesize = fp->ff_size;
+ if (fp->ff_new_size > filesize)
+ filesize = fp->ff_new_size;
+
+ a_flags = ap->a_flags;
+ a_pl_offset = ap->a_pl_offset;
+
+ /*
+ * we can tell if we're getting the new or old behavior from the UPL
+ */
+ if ((upl = ap->a_pl) == NULL) {
+ int request_flags;
+
+ is_pageoutv2 = 1;
+ /*
+ * we're in control of any UPL we commit
+ * make sure someone hasn't accidentally passed in UPL_NOCOMMIT
+ */
+ a_flags &= ~UPL_NOCOMMIT;
+ a_pl_offset = 0;
+
+ /*
+ * take truncate lock (shared) to guard against
+ * zero-fill thru fsync interfering, but only for v2
+ */
+ hfs_lock_truncate(cp, 0);
+
+ if (a_flags & UPL_MSYNC) {
+ request_flags = UPL_UBC_MSYNC | UPL_RET_ONLY_DIRTY;
+ }
+ else {
+ request_flags = UPL_UBC_PAGEOUT | UPL_RET_ONLY_DIRTY;
+ }
+ ubc_create_upl(vp, ap->a_f_offset, ap->a_size, &upl, &pl, request_flags);
+
+ if (upl == (upl_t) NULL) {
+ retval = EINVAL;
+ goto pageout_done;
+ }
+ }
+ /*
+ * from this point forward upl points at the UPL we're working with
+ * it was either passed in or we succesfully created it
+ */
+
+ /*
+ * Now that HFS is opting into VFC_VFSVNOP_PAGEOUTV2, we may need to operate on our own
+ * UPL instead of relying on the UPL passed into us. We go ahead and do that here,
+ * scanning for dirty ranges. We'll issue our own N cluster_pageout calls, for
+ * N dirty ranges in the UPL. Note that this is almost a direct copy of the
+ * logic in vnode_pageout except that we need to do it after grabbing the truncate
+ * lock in HFS so that we don't lock invert ourselves.
+ *
+ * Note that we can still get into this function on behalf of the default pager with
+ * non-V2 behavior (swapfiles). However in that case, we did not grab locks above
+ * since fsync and other writing threads will grab the locks, then mark the
+ * relevant pages as busy. But the pageout codepath marks the pages as busy,
+ * and THEN would attempt to grab the truncate lock, which would result in deadlock. So
+ * we do not try to grab anything for the pre-V2 case, which should only be accessed
+ * by the paging/VM system.
+ */
+
+ if (is_pageoutv2) {
+ off_t f_offset;
+ int offset;
+ int isize;
+ int pg_index;
+ int error;
+ int error_ret = 0;
+
+ isize = ap->a_size;
+ f_offset = ap->a_f_offset;
+
+ /*
+ * Scan from the back to find the last page in the UPL, so that we
+ * aren't looking at a UPL that may have already been freed by the
+ * preceding aborts/completions.
+ */
+ for (pg_index = ((isize) / PAGE_SIZE); pg_index > 0;) {
+ if (upl_page_present(pl, --pg_index))
+ break;
+ if (pg_index == 0) {
+ ubc_upl_abort_range(upl, 0, isize, UPL_ABORT_FREE_ON_EMPTY);
+ goto pageout_done;
projects / apple / xnu.git / blobdiff