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authorEric Sandeen <sandeen@redhat.com>2010-07-27 11:56:06 -0400
committerTheodore Ts'o <tytso@mit.edu>2010-07-27 11:56:06 -0400
commit506bf2d82165c09b179a5077e01037f6270a4db3 (patch)
tree9e0a92d5da86f8f402032a408148cb8676ade715 /fs/ext4
parent5b3ff237bef43b9e7fb7d1eb858e29b73fd664f9 (diff)
downloadop-kernel-dev-506bf2d82165c09b179a5077e01037f6270a4db3.zip
op-kernel-dev-506bf2d82165c09b179a5077e01037f6270a4db3.tar.gz
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>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/mballoc.c7
1 files changed, 3 insertions, 4 deletions
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 @@ 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);
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