tem satisfies the search criteria in ext4_mb_good_group(). Scanning all the filesystem groups impacts performance. This was demonstrated by using a freshly created, 70GB, 1k block filesystem, with caches dropped write before the test via /proc/sys/vm/drop_caches, and with the filesystem mounted with nodelalloc and nodealloc,nomballoc. The time to write an 8 megabyte file using "dd if=/dev/zero of=/mnt/test/fo bs=8k count=1k conv=fsync" took 35.5091 seconds (236kB/s) with nodellaloc, and 0.233754 seconds (35.9 MB/s) with the nodelloc,nomballoc options. With a 1TB partition, it took several minutes to write 8MB! This patch modifies the algorithm in ext4_mb_normalize_group_request to calculate the number of blocks to allocate by taking into account the maximum size of free blocks chunks handled by the multiblock allocator. It has also been tested for filesystems with 2KB and 4KB block sizes to ensure that those cases don't regress. Reviewed-by: Aneesh Kumar K.V Signed-off-by: Valerie Clement Signed-off-by: Mingming Cao Signed-off-by: "Theodore Ts'o" Æ:Ä ™