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>
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1 changed files with 3 additions and 4 deletions
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@ -1822,8 +1822,7 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
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/*
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* This is a special case for storages like raid5
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* we try to find stripe-aligned chunks for stripe-size requests
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* XXX should do so at least for multiples of stripe size as well
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* we try to find stripe-aligned chunks for stripe-size-multiple requests
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*/
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static noinline_for_stack
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void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
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@ -2092,8 +2091,8 @@ repeat:
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ac->ac_groups_scanned++;
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if (cr == 0)
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ext4_mb_simple_scan_group(ac, &e4b);
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else if (cr == 1 &&
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ac->ac_g_ex.fe_len == sbi->s_stripe)
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else if (cr == 1 && sbi->s_stripe &&
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!(ac->ac_g_ex.fe_len % sbi->s_stripe))
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ext4_mb_scan_aligned(ac, &e4b);
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else
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ext4_mb_complex_scan_group(ac, &e4b);
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