nfs: fix DIO good bytes calculation (1ccbad9f) · Commits · 戴 / test

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 ("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>

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

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