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Commit 5fadeb47 authored by Peng Tao's avatar Peng Tao Committed by Tom Haynes
Browse files

nfs: count DIO good bytes correctly with mirroring 



When resending to MDS, we might resend multiple mirroring
requests to MDS. As a result, nfs_direct_good_bytes() ends
up counting bytes multiple times, causing application to
get wrong return results in read/write syscalls.

Fix it by tracking start of a dreq and checking the range of
pgio header.

Cc: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: default avatarPeng Tao <tao.peng@primarydata.com>
parent aa8a45ee

fs/nfs/direct.c

+8 −4
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ struct nfs_direct_req { 


	ssize_t			count,		/* bytes actually processed */

				bytes_left,	/* bytes left to be sent */

				io_start,	/* start of IO */

				error;		/* any reported error */

	struct completion	completion;	/* wait for i/o completion */
@@ -130,10 +131,11 @@ nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr) 


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



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



	if (hdr->pgio_mirror_idx == 0)

		dreq->count += hdr->good_bytes;

	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 */
@@ -594,6 +596,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter, 


	dreq->inode = inode;

	dreq->bytes_left = count;

	dreq->io_start = pos;

	dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));

	l_ctx = nfs_get_lock_context(dreq->ctx);

	if (IS_ERR(l_ctx)) {
@@ -1002,6 +1005,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter, 


	dreq->inode = inode;

	dreq->bytes_left = count;

	dreq->io_start = pos;

	dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));

	l_ctx = nfs_get_lock_context(dreq->ctx);

	if (IS_ERR(l_ctx)) {