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Commit 1ccbad9f authored by Peng Tao's avatar Peng Tao Committed by Trond Myklebust
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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: default avatarJean Spector <jean@primarydata.com>
Cc: <stable@vger.kernel.org> # v3.19+
Signed-off-by: default avatarPeng Tao <tao.peng@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent ea96d1ec

fs/nfs/direct.c

+17 −12
Original line number Diff line number Diff line
@@ -131,12 +131,16 @@ nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) 


	WARN_ON_ONCE(hdr->pgio_mirror_idx >= dreq->mirror_count);



	if (dreq->mirror_count == 1) {

		dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;

		dreq->count += hdr->good_bytes;

	} else {

		/* mirrored writes */

		count = dreq->mirrors[hdr->pgio_mirror_idx].count;

		if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {

			count = hdr->io_start + hdr->good_bytes - dreq->io_start;

			dreq->mirrors[hdr->pgio_mirror_idx].count = count;

		}



		/* update the dreq->count by finding the minimum agreed count from all

		 * mirrors */

		count = dreq->mirrors[0].count;
@@ -146,6 +150,7 @@ nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) 


		dreq->count = count;

	}

}



/*

 * nfs_direct_select_verf - select the right verifier