Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx2.netapp.com ([216.240.18.37]:47143 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750949AbaLQWfP (ORCPT ); Wed, 17 Dec 2014 17:35:15 -0500 From: To: CC: Subject: [PATCH 3/4] NFSD: Add support for encoding holes in files Date: Wed, 17 Dec 2014 17:35:03 -0500 Message-ID: <1418855704-14127-4-git-send-email-Anna.Schumaker@Netapp.com> In-Reply-To: <1418855704-14127-1-git-send-email-Anna.Schumaker@Netapp.com> References: <1418855704-14127-1-git-send-email-Anna.Schumaker@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-nfs-owner@vger.kernel.org List-ID: From: Anna Schumaker This patch adds support for returning NFS4_CONTENT_HOLE segments to the client. I did notice a race condition where the same offset can be reported as both a hole and as data, and this patch gets around this without a lock by encoding questionable regions as data. Signed-off-by: Anna Schumaker --- fs/nfsd/nfs4xdr.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 6ed22ca..2ec9860 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3800,7 +3800,7 @@ nfsd4_encode_test_stateid(struct nfsd4_compoundres *resp, __be32 nfserr, static __be32 nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp, struct nfsd4_read *read, - struct file *file) + struct file *file, loff_t hole_pos) { __be32 *p, err; unsigned long maxcount; @@ -3814,6 +3814,7 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp, struct nfsd4_read *r maxcount = svc_max_payload(resp->rqstp); maxcount = min_t(unsigned long, maxcount, (xdr->buf->buflen - xdr->buf->len)); maxcount = min_t(unsigned long, maxcount, read->rd_length); + maxcount = min_t(unsigned long, maxcount, hole_pos - read->rd_offset); err = nfsd4_encode_readv(resp, read, file, &maxcount); @@ -3826,6 +3827,22 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp, struct nfsd4_read *r } static __be32 +nfsd4_encode_read_plus_hole(struct nfsd4_compoundres *resp, struct nfsd4_read *read, + struct file *file, loff_t data_pos) +{ + __be32 *p; + unsigned long maxcount = data_pos - read->rd_offset; + + p = xdr_reserve_space(&resp->xdr, 4 + 8 + 8); + *p++ = cpu_to_be32(NFS4_CONTENT_HOLE); + p = xdr_encode_hyper(p, read->rd_offset); + p = xdr_encode_hyper(p, maxcount); + + read->rd_offset += maxcount; + return nfs_ok; +} + +static __be32 nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_read *read) { @@ -3833,6 +3850,7 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr, struct file *file = read->rd_filp; int starting_len = xdr->buf->len; struct raparms *ra; + loff_t hole_pos, data_pos; __be32 *p; __be32 err; u32 eof, segments = 0; @@ -3853,10 +3871,20 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr, goto err_truncate; } - if (read->rd_offset >= i_size_read(file_inode(file))) + hole_pos = vfs_llseek(read->rd_filp, read->rd_offset, SEEK_HOLE); + if (hole_pos == -ENXIO) goto out_encode; - err = nfsd4_encode_read_plus_data(resp, read, file); + data_pos = vfs_llseek(read->rd_filp, read->rd_offset, SEEK_DATA); + if (data_pos == -ENXIO) + data_pos = i_size_read(file_inode(file)); + + if ((data_pos == read->rd_offset) && (hole_pos > data_pos)) + err = nfsd4_encode_read_plus_data(resp, read, file, hole_pos); + else if ((hole_pos == read->rd_offset) && (data_pos > hole_pos)) + err = nfsd4_encode_read_plus_hole(resp, read, file, data_pos); + else /* The file probably changed on us between seeks. */ + err = nfsd4_encode_read_plus_data(resp, read, file, i_size_read(file_inode(file))); segments++; out_encode: -- 2.1.3