+ /*
+ * Check each quota to cap the prealloc size and provide a shift
+ * value to throttle with.
+ */
+ if (xfs_quota_need_throttle(ip, XFS_DQ_USER, alloc_blocks))
+ xfs_quota_calc_throttle(ip, XFS_DQ_USER, &qblocks, &qshift);
+ if (xfs_quota_need_throttle(ip, XFS_DQ_GROUP, alloc_blocks))
+ xfs_quota_calc_throttle(ip, XFS_DQ_GROUP, &qblocks, &qshift);
+ if (xfs_quota_need_throttle(ip, XFS_DQ_PROJ, alloc_blocks))
+ xfs_quota_calc_throttle(ip, XFS_DQ_PROJ, &qblocks, &qshift);
+
+ /*
+ * The final prealloc size is set to the minimum of free space available
+ * in each of the quotas and the overall filesystem.
+ *
+ * The shift throttle value is set to the maximum value as determined by
+ * the global low free space values and per-quota low free space values.
+ */
+ alloc_blocks = MIN(alloc_blocks, qblocks);
+ shift = MAX(shift, qshift);
+
+ if (shift)
+ alloc_blocks >>= shift;
+ /*
+ * rounddown_pow_of_two() returns an undefined result if we pass in
+ * alloc_blocks = 0.
+ */
+ if (alloc_blocks)
+ alloc_blocks = rounddown_pow_of_two(alloc_blocks);
+ if (alloc_blocks > MAXEXTLEN)
+ alloc_blocks = MAXEXTLEN;
+
+ /*
+ * If we are still trying to allocate more space than is
+ * available, squash the prealloc hard. This can happen if we
+ * have a large file on a small filesystem and the above
+ * lowspace thresholds are smaller than MAXEXTLEN.
+ */
+ while (alloc_blocks && alloc_blocks >= freesp)
+ alloc_blocks >>= 4;
+
+check_writeio: