Commit 031d73ed authored by Trond Myklebust's avatar Trond Myklebust Committed by Anna Schumaker
Browse files

NFS: Fix O_DIRECT accounting of number of bytes read/written 



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: default avatarSu Yanjun <suyj.fnst@cn.fujitsu.com>
Fixes: 1ccbad9f ("nfs: fix DIO good bytes calculation")
Cc: stable@vger.kernel.org # 4.1+
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 33ea5aaa

fs/nfs/direct.c

+43 −35
Original line number Diff line number Diff line
@@ -123,32 +123,49 @@ 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];



	WARN_ON_ONCE(dreq->count >= dreq->max_count);

	if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||

	      test_bit(NFS_IOHDR_EOF, &hdr->flags)))

		return;

	if (dreq->max_count >= dreq_len) {

		dreq->max_count = dreq_len;

		if (dreq->count > dreq_len)

			dreq->count = dreq_len;



	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;

		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags))

			dreq->error = hdr->error;

		else /* Clear outstanding error if this is EOF */

			dreq->error = 0;

	}

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

		 * mirrors */

		count = dreq->mirrors[0].count;

	if (mirror->count > dreq_len)

		mirror->count = dreq_len;

}



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;



		for (i = 1; i < dreq->mirror_count; i++)

			count = min(count, dreq->mirrors[i].count);

	if (hdr_end > dreq->io_start)

		dreq_len = hdr_end - dreq->io_start;



		dreq->count = count;

	}

	nfs_direct_handle_truncated(dreq, hdr, dreq_len);



	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 +419,12 @@ 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 +661,9 @@ 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 +803,13 @@ 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;

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