> On Sep 1, 2022, at 3:44 PM, Anna Schumaker <anna@xxxxxxxxxx> wrote:
>
> On Thu, Sep 1, 2022 at 3:05 PM Chuck Lever III <chuck.lever@xxxxxxxxxx> wrote:
>>
>> Good to see this! I'll study it over the next few days.
>>
>>
>>> On Sep 1, 2022, at 2:33 PM, Anna Schumaker <anna@xxxxxxxxxx> wrote:
>>>
>>> From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
>>>
>>> Change the implementation to return a single DATA segment covering the
>>> requested read range.
>>
>> The discussion in your cover letter should go in this patch
>> description. A good patch description explains "why"; the diff
>> below already explains "what".
>>
>> I harp on that because the patch description is important
>> information that I often consult when conducting archaeology
>> during troubleshooting. "Why the f... did we do that?"
>
> Makes sense! Do you want me to resubmit now as a v2 with some of this
> moved over to the patch description?
Let me have a careful look at the diff -- give me a couple days --
so you can incorporate any review comments in v2.
Also I'll try to answer the splice question you posed in 0/1.
> Anna
>>
>>
>>> Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
>>> ---
>>> fs/nfsd/nfs4xdr.c | 122 ++++++++--------------------------------------
>>> 1 file changed, 20 insertions(+), 102 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
>>> index 1e9690a061ec..adbff7737c14 100644
>>> --- a/fs/nfsd/nfs4xdr.c
>>> +++ b/fs/nfsd/nfs4xdr.c
>>> @@ -4731,79 +4731,30 @@ nfsd4_encode_offload_status(struct nfsd4_compoundres *resp, __be32 nfserr,
>>>
>>> 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)
>>> {
>>> + unsigned long maxcount;
>>> struct xdr_stream *xdr = resp->xdr;
>>> 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));
>>> + __be32 *p;
>>>
>>> /* Content type, offset, byte count */
>>> p = xdr_reserve_space(xdr, 4 + 8 + 4);
>>> if (!p)
>>> return nfserr_resource;
>>>
>>> - 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);
>>> + 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;
>>> }
>>>
>>> @@ -4811,20 +4762,14 @@ static __be32
>>> nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
>>> struct nfsd4_read *read)
>>> {
>>> - unsigned long maxcount, count;
>>> struct xdr_stream *xdr = resp->xdr;
>>> - struct file *file;
>>> + struct file *file = read->rd_nf->nf_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;
>>> + __be32 *p;
>>>
>>> if (nfserr)
>>> return nfserr;
>>> - file = read->rd_nf->nf_file;
>>>
>>> /* eof flag, segment count */
>>> p = xdr_reserve_space(xdr, 4 + 4);
>>> @@ -4832,48 +4777,21 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
>>> return nfserr_resource;
>>> 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;
>>> }
>>>
>>> --
>>> 2.37.2
>>>
>>
>> --
>> Chuck Lever
--
Chuck Lever
