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	nfs: fix DIO good bytes calculation
For direct read that has IO size larger than rsize, we'll split
it into several READ requests and nfs_direct_good_bytes() would
count completed bytes incorrectly by eating last zero count reply.
Fix it by handling mirror and non-mirror cases differently such that
we only count mirrored writes differently.
This fixes 5fadeb47("nfs: count DIO good bytes correctly with mirroring").
Reported-by: Jean Spector <jean@primarydata.com>
Cc: <stable@vger.kernel.org> # v3.19+
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
			
			
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					 1 changed files with 18 additions and 13 deletions
				
			
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			@ -131,20 +131,25 @@ nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
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	WARN_ON_ONCE(hdr->pgio_mirror_idx >= dreq->mirror_count);
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	count = dreq->mirrors[hdr->pgio_mirror_idx].count;
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	if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
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		count = hdr->io_start + hdr->good_bytes - dreq->io_start;
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		dreq->mirrors[hdr->pgio_mirror_idx].count = count;
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	if (dreq->mirror_count == 1) {
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		dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;
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		dreq->count += hdr->good_bytes;
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	} else {
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		/* mirrored writes */
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		count = dreq->mirrors[hdr->pgio_mirror_idx].count;
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		if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
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			count = hdr->io_start + hdr->good_bytes - dreq->io_start;
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			dreq->mirrors[hdr->pgio_mirror_idx].count = count;
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		}
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		/* update the dreq->count by finding the minimum agreed count from all
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		 * mirrors */
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		count = dreq->mirrors[0].count;
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		for (i = 1; i < dreq->mirror_count; i++)
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			count = min(count, dreq->mirrors[i].count);
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		dreq->count = count;
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	}
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	/* update the dreq->count by finding the minimum agreed count from all
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	 * mirrors */
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	count = dreq->mirrors[0].count;
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	for (i = 1; i < dreq->mirror_count; i++)
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		count = min(count, dreq->mirrors[i].count);
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	dreq->count = count;
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}
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/*
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