From 506bf2d82165c09b179a5077e01037f6270a4db3 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Tue, 27 Jul 2010 11:56:06 -0400 Subject: [PATCH] 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 Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- fs/ext4/mballoc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 5338b1ca64bb..a75de7d44dc9 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1822,8 +1822,7 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac, /* * 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 @@ repeat: 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); -- 2.39.5