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[68.40.189.247]) by smtp.gmail.com with ESMTPSA id c65sm8038648ilg.26.2019.10.01.13.22.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Oct 2019 13:22:08 -0700 (PDT) From: Trond Myklebust X-Google-Original-From: Trond Myklebust To: Su Yanjun , Anna Schumaker Cc: linux-nfs@vger.kernel.org Subject: [PATCH v2 1/2] NFS: Fix O_DIRECT accounting of number of bytes read/written Date: Tue, 1 Oct 2019 16:19:59 -0400 Message-Id: <20191001202000.13248-2-trond.myklebust@hammerspace.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20191001202000.13248-1-trond.myklebust@hammerspace.com> References: <20191001202000.13248-1-trond.myklebust@hammerspace.com> MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org When a series of O_DIRECT reads or writes are truncated, either due to eof or due to an error, then we should return the number of contiguous bytes that were received/sent starting at the offset specified by the application. Currently, we are failing to correctly check contiguity, and so we're failing the generic/465 in xfstests when the race between the read and write RPCs causes the file to get extended while the 2 reads are outstanding. If the first read RPC call wins the race and returns with eof set, we should treat the second read RPC as being truncated. Reported-by: Su Yanjun Fixes: 1ccbad9f9f9bd ("nfs: fix DIO good bytes calculation") Cc: stable@vger.kernel.org # 4.1+ Signed-off-by: Trond Myklebust --- fs/nfs/direct.c | 82 ++++++++++++++++++++++++++++--------------------- 1 file changed, 47 insertions(+), 35 deletions(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index 222d7115db71..62cb4a1a87f0 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -123,32 +123,53 @@ static inline int put_dreq(struct nfs_direct_req *dreq) } static void -nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) +nfs_direct_handle_truncated(struct nfs_direct_req *dreq, + const struct nfs_pgio_header *hdr, + ssize_t dreq_len) { - int i; - ssize_t count; + struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx]; + loff_t hdr_arg = hdr->io_start + hdr->args.count; + ssize_t expected = 0; + + if (hdr_arg > dreq->io_start) + expected = hdr_arg - dreq->io_start; + + if (dreq_len == expected) + return; + if (dreq->max_count > dreq_len) { + dreq->max_count = dreq_len; + if (dreq->count > dreq_len) + dreq->count = dreq_len; + + if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) + dreq->error = hdr->error; + else if (hdr->good_bytes > 0) + dreq->error = 0; + } + if (mirror->count > dreq_len) + mirror->count = dreq_len; +} - WARN_ON_ONCE(dreq->count >= dreq->max_count); +static void +nfs_direct_count_bytes(struct nfs_direct_req *dreq, + const struct nfs_pgio_header *hdr) +{ + struct nfs_direct_mirror *mirror = &dreq->mirrors[hdr->pgio_mirror_idx]; + loff_t hdr_end = hdr->io_start + hdr->good_bytes; + ssize_t dreq_len = 0; - 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; + if (hdr_end > dreq->io_start) + dreq_len = hdr_end - dreq->io_start; - for (i = 1; i < dreq->mirror_count; i++) - count = min(count, dreq->mirrors[i].count); + nfs_direct_handle_truncated(dreq, hdr, dreq_len); - dreq->count = count; - } + if (dreq_len > dreq->max_count) + dreq_len = dreq->max_count; + + if (mirror->count < dreq_len) + mirror->count = dreq_len; + if (dreq->count < dreq_len) + dreq->count = dreq_len; } /* @@ -402,20 +423,12 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr) struct nfs_direct_req *dreq = hdr->dreq; spin_lock(&dreq->lock); - if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) - dreq->error = hdr->error; - if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { spin_unlock(&dreq->lock); goto out_put; } - if (hdr->good_bytes != 0) - nfs_direct_good_bytes(dreq, hdr); - - if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) - dreq->error = 0; - + nfs_direct_count_bytes(dreq, hdr); spin_unlock(&dreq->lock); while (!list_empty(&hdr->pages)) { @@ -652,6 +665,9 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq) nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo); dreq->count = 0; + dreq->max_count = 0; + list_for_each_entry(req, &reqs, wb_list) + dreq->max_count += req->wb_bytes; dreq->verf.committed = NFS_INVALID_STABLE_HOW; nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo); for (i = 0; i < dreq->mirror_count; i++) @@ -791,17 +807,13 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr) nfs_init_cinfo_from_dreq(&cinfo, dreq); spin_lock(&dreq->lock); - - if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) - dreq->error = hdr->error; - if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) { spin_unlock(&dreq->lock); goto out_put; } + nfs_direct_count_bytes(dreq, hdr); if (hdr->good_bytes != 0) { - nfs_direct_good_bytes(dreq, hdr); if (nfs_write_need_commit(hdr)) { if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) request_commit = true;