ext4: allocate stripe-multiple IOs on stripe boundaries
For some reason, today mballoc only allocates IOs which are exactly
stripe-sized on a stripe boundary. If you have a multiple (say, a
128k IO on a 64k stripe) you may end up unaligned.
It seems to me that a simple change to align stripe-multiple IOs
on stripe boundaries would be a very good idea, unless this breaks
some other mballoc heuristic for some reason...
Reported-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 5338b1c..a75de7d 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1822,8 +1822,7 @@
/*
* This is a special case for storages like raid5
- * we try to find stripe-aligned chunks for stripe-size requests
- * XXX should do so at least for multiples of stripe size as well
+ * we try to find stripe-aligned chunks for stripe-size-multiple requests
*/
static noinline_for_stack
void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
@@ -2092,8 +2091,8 @@
ac->ac_groups_scanned++;
if (cr == 0)
ext4_mb_simple_scan_group(ac, &e4b);
- else if (cr == 1 &&
- ac->ac_g_ex.fe_len == sbi->s_stripe)
+ else if (cr == 1 && sbi->s_stripe &&
+ !(ac->ac_g_ex.fe_len % sbi->s_stripe))
ext4_mb_scan_aligned(ac, &e4b);
else
ext4_mb_complex_scan_group(ac, &e4b);