diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 73c95466c225..2ae55db8c977 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -4795,34 +4795,59 @@ xfs_bmap_split_indlen( xfs_filblks_t len2 = *indlen2; xfs_filblks_t nres = len1 + len2; /* new total res. */ xfs_filblks_t stolen = 0; + xfs_filblks_t resfactor; /* * Steal as many blocks as we can to try and satisfy the worst case * indlen for both new extents. */ - while (nres > ores && avail) { - nres--; - avail--; - stolen++; - } + if (ores < nres && avail) + stolen = XFS_FILBLKS_MIN(nres - ores, avail); + ores += stolen; + + /* nothing else to do if we've satisfied the new reservation */ + if (ores >= nres) + return stolen; /* - * The only blocks available are those reserved for the original - * extent and what we can steal from the extent being removed. - * If this still isn't enough to satisfy the combined - * requirements for the two new extents, skim blocks off of each - * of the new reservations until they match what is available. + * We can't meet the total required reservation for the two extents. + * Calculate the percent of the overall shortage between both extents + * and apply this percentage to each of the requested indlen values. + * This distributes the shortage fairly and reduces the chances that one + * of the two extents is left with nothing when extents are repeatedly + * split. */ - while (nres > ores) { - if (len1) { - len1--; - nres--; + resfactor = (ores * 100); + do_div(resfactor, nres); + len1 *= resfactor; + do_div(len1, 100); + len2 *= resfactor; + do_div(len2, 100); + ASSERT(len1 + len2 <= ores); + ASSERT(len1 < *indlen1 && len2 < *indlen2); + + /* + * Hand out the remainder to each extent. If one of the two reservations + * is zero, we want to make sure that one gets a block first. The loop + * below starts with len1, so hand len2 a block right off the bat if it + * is zero. + */ + ores -= (len1 + len2); + ASSERT((*indlen1 - len1) + (*indlen2 - len2) >= ores); + if (ores && !len2 && *indlen2) { + len2++; + ores--; + } + while (ores) { + if (len1 < *indlen1) { + len1++; + ores--; } - if (nres == ores) + if (!ores) break; - if (len2) { - len2--; - nres--; + if (len2 < *indlen2) { + len2++; + ores--; } }