2020-08-17 17:34:47

by Anna Schumaker

[permalink] [raw]
Subject: [PATCH v4 3/5] NFSD: Add READ_PLUS hole segment encoding

From: Anna Schumaker <[email protected]>

However, we still only reply to the READ_PLUS call with a single segment
at this time.

Signed-off-by: Anna Schumaker <[email protected]>
---
fs/nfsd/nfs4proc.c | 2 +-
fs/nfsd/nfs4xdr.c | 40 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 9630d33211f2..36305b846f5a 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -2528,7 +2528,7 @@ static inline u32 nfsd4_read_plus_rsize(struct svc_rqst *rqstp, struct nfsd4_op
u32 maxcount = svc_max_payload(rqstp);
u32 rlen = min(op->u.read.rd_length, maxcount);
/* enough extra xdr space for encoding either a hole or data segment. */
- u32 segments = 1 + 2 + 2;
+ u32 segments = 2 * (1 + 2 + 2);

return (op_encode_hdr_size + 2 + segments + XDR_QUADLEN(rlen)) * sizeof(__be32);
}
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 9af92f538000..2fa39217c256 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4378,10 +4378,14 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
struct xdr_stream *xdr = &resp->xdr;
struct file *file = read->rd_nf->nf_file;
int starting_len = xdr->buf->len;
+ loff_t hole_pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE);
__be32 nfserr;
__be32 *p, tmp;
__be64 tmp64;

+ if (hole_pos > read->rd_offset)
+ maxcount = min_t(unsigned long, maxcount, hole_pos - read->rd_offset);
+
/* Content type, offset, byte count */
p = xdr_reserve_space(xdr, 4 + 8 + 4);
if (!p)
@@ -4405,6 +4409,27 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
return nfs_ok;
}

+static __be32
+nfsd4_encode_read_plus_hole(struct nfsd4_compoundres *resp,
+ struct nfsd4_read *read,
+ unsigned long maxcount, u32 *eof)
+{
+ struct file *file = read->rd_nf->nf_file;
+ __be32 *p;
+
+ /* Content type, offset, byte count */
+ p = xdr_reserve_space(&resp->xdr, 4 + 8 + 8);
+ if (!p)
+ return nfserr_resource;
+
+ *p++ = htonl(NFS4_CONTENT_HOLE);
+ p = xdr_encode_hyper(p, read->rd_offset);
+ p = xdr_encode_hyper(p, maxcount);
+
+ *eof = (read->rd_offset + maxcount) >= i_size_read(file_inode(file));
+ return nfs_ok;
+}
+
static __be32
nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
struct nfsd4_read *read)
@@ -4415,6 +4440,7 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
int starting_len = xdr->buf->len;
int segments = 0;
__be32 *p, tmp;
+ loff_t pos;
u32 eof;

if (nfserr)
@@ -4433,11 +4459,23 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
maxcount = min_t(unsigned long, maxcount, read->rd_length);

eof = read->rd_offset >= i_size_read(file_inode(file));
- if (!eof) {
+ if (eof)
+ goto out;
+
+ pos = vfs_llseek(file, read->rd_offset, SEEK_DATA);
+ if (pos == -ENXIO)
+ pos = i_size_read(file_inode(file));
+
+ if (pos > read->rd_offset) {
+ maxcount = pos - read->rd_offset;
+ nfserr = nfsd4_encode_read_plus_hole(resp, read, maxcount, &eof);
+ segments++;
+ } else {
nfserr = nfsd4_encode_read_plus_data(resp, read, maxcount, &eof);
segments++;
}

+out:
if (nfserr)
xdr_truncate_encode(xdr, starting_len);
else {
--
2.28.0