[PATCH 6.1 143/215] NFSD: Simplify READ_PLUS

Greg Kroah-Hartman
2024-03-04T21:49:10Z

From: Anna Schumaker <Anna.Schumaker@Netapp.com>

[ Upstream commit eeadcb75794516839078c28b3730132aeb700ce6 ]

Chuck had suggested reverting READ_PLUS so it returns a single DATA
segment covering the requested read range. This prepares the server for
a future "sparse read" function so support can easily be added without
needing to rip out the old READ_PLUS code at the same time.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfsd/nfs4xdr.c | 139 ++++++++++++------------------------------------------
1 file changed, 32 insertions(+), 107 deletions(-)

--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4777,79 +4777,37 @@ nfsd4_encode_offload_status(struct nfsd4

static __be32
nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
- struct nfsd4_read *read,
- unsigned long *maxcount, u32 *eof,
- loff_t *pos)
+ struct nfsd4_read *read)
{
- struct xdr_stream *xdr = resp->xdr;
+ bool splice_ok = test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags);
struct file *file = read->rd_nf->nf_file;
- int starting_len = xdr->buf->len;
- loff_t hole_pos;
- __be32 nfserr;
- __be32 *p, tmp;
- __be64 tmp64;
-
- hole_pos = pos ? *pos : vfs_llseek(file, read->rd_offset, SEEK_HOLE);
- if (hole_pos > read->rd_offset)
- *maxcount = min_t(unsigned long, *maxcount, hole_pos - read->rd_offset);
- *maxcount = min_t(unsigned long, *maxcount, (xdr->buf->buflen - xdr->buf->len));
+ struct xdr_stream *xdr = resp->xdr;
+ unsigned long maxcount;
+ __be32 nfserr, *p;

/* Content type, offset, byte count */
p = xdr_reserve_space(xdr, 4 + 8 + 4);
if (!p)
- return nfserr_resource;
+ return nfserr_io;
+ if (resp->xdr->buf->page_len && splice_ok) {
+ WARN_ON_ONCE(splice_ok);
+ return nfserr_serverfault;
+ }

- read->rd_vlen = xdr_reserve_space_vec(xdr, resp->rqstp->rq_vec, *maxcount);
- if (read->rd_vlen < 0)
- return nfserr_resource;
+ maxcount = min_t(unsigned long, read->rd_length,
+ (xdr->buf->buflen - xdr->buf->len));

- nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, file, read->rd_offset,
- resp->rqstp->rq_vec, read->rd_vlen, maxcount, eof);
+ if (file->f_op->splice_read && splice_ok)
+ nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);
+ else
+ nfserr = nfsd4_encode_readv(resp, read, file, maxcount);
if (nfserr)
return nfserr;
- xdr_truncate_encode(xdr, starting_len + 16 + xdr_align_size(*maxcount));
-
- tmp = htonl(NFS4_CONTENT_DATA);
- write_bytes_to_xdr_buf(xdr->buf, starting_len, &tmp, 4);
- tmp64 = cpu_to_be64(read->rd_offset);
- write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp64, 8);
- tmp = htonl(*maxcount);
- write_bytes_to_xdr_buf(xdr->buf, starting_len + 12, &tmp, 4);
-
- tmp = xdr_zero;
- write_bytes_to_xdr_buf(xdr->buf, starting_len + 16 + *maxcount, &tmp,
- xdr_pad_size(*maxcount));
- 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;
- loff_t data_pos = vfs_llseek(file, read->rd_offset, SEEK_DATA);
- loff_t f_size = i_size_read(file_inode(file));
- unsigned long count;
- __be32 *p;
-
- if (data_pos == -ENXIO)
- data_pos = f_size;
- else if (data_pos <= read->rd_offset || (data_pos < f_size && data_pos % PAGE_SIZE))
- return nfsd4_encode_read_plus_data(resp, read, maxcount, eof, &f_size);
- count = data_pos - read->rd_offset;

- /* 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++ = cpu_to_be32(NFS4_CONTENT_DATA);
p = xdr_encode_hyper(p, read->rd_offset);
- p = xdr_encode_hyper(p, count);
+ *p = cpu_to_be32(read->rd_length);

- *eof = (read->rd_offset + count) >= f_size;
- *maxcount = min_t(unsigned long, count, *maxcount);
return nfs_ok;
}

@@ -4857,69 +4815,36 @@ static __be32
nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
struct nfsd4_read *read)
{
- unsigned long maxcount, count;
+ struct file *file = read->rd_nf->nf_file;
struct xdr_stream *xdr = resp->xdr;
- struct file *file;
int starting_len = xdr->buf->len;
- int last_segment = xdr->buf->len;
- int segments = 0;
- __be32 *p, tmp;
- bool is_data;
- loff_t pos;
- u32 eof;
+ u32 segments = 0;
+ __be32 *p;

if (nfserr)
return nfserr;
- file = read->rd_nf->nf_file;

/* eof flag, segment count */
p = xdr_reserve_space(xdr, 4 + 4);
if (!p)
- return nfserr_resource;
+ return nfserr_io;
xdr_commit_encode(xdr);

- maxcount = min_t(unsigned long, read->rd_length,
- (xdr->buf->buflen - xdr->buf->len));
- count = maxcount;
-
- eof = read->rd_offset >= i_size_read(file_inode(file));
- if (eof)
+ read->rd_eof = read->rd_offset >= i_size_read(file_inode(file));
+ if (read->rd_eof)
goto out;

- pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE);
- is_data = pos > read->rd_offset;
-
- while (count > 0 && !eof) {
- maxcount = count;
- if (is_data)
- nfserr = nfsd4_encode_read_plus_data(resp, read, &maxcount, &eof,
- segments == 0 ? &pos : NULL);
- else
- nfserr = nfsd4_encode_read_plus_hole(resp, read, &maxcount, &eof);
- if (nfserr)
- goto out;
- count -= maxcount;
- read->rd_offset += maxcount;
- is_data = !is_data;
- last_segment = xdr->buf->len;
- segments++;
- }
-
-out:
- if (nfserr && segments == 0)
+ nfserr = nfsd4_encode_read_plus_data(resp, read);
+ if (nfserr) {
xdr_truncate_encode(xdr, starting_len);
- else {
- if (nfserr) {
- xdr_truncate_encode(xdr, last_segment);
- nfserr = nfs_ok;
- eof = 0;
- }
- tmp = htonl(eof);
- write_bytes_to_xdr_buf(xdr->buf, starting_len, &tmp, 4);
- tmp = htonl(segments);
- write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp, 4);
+ return nfserr;
}

+ segments++;
+
+out:
+ p = xdr_encode_bool(p, read->rd_eof);
+ *p = cpu_to_be32(segments);
return nfserr;
}