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NFSD: Clean up nfsd4_encode_readdir()

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Untangle nfsd4_encode_readdir() so it is more clear what XDR data
item is being encoded by which piece of code.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2023-10-04 09:42:10 -04:00
parent a1aee9aa35
commit 25c307acc8
1 changed files with 65 additions and 67 deletions
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132
fs/nfsd/nfs4xdr.c
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@ -4452,85 +4452,83 @@ out_err:
return nfserr;
}
static __be32 nfsd4_encode_dirlist4(struct xdr_stream *xdr,
struct nfsd4_readdir *readdir,
u32 max_payload)
{
int bytes_left, maxcount, starting_len = xdr->buf->len;
loff_t offset;
__be32 status;
/*
* Number of bytes left for directory entries allowing for the
* final 8 bytes of the readdir and a following failed op.
*/
bytes_left = xdr->buf->buflen - xdr->buf->len -
COMPOUND_ERR_SLACK_SPACE - XDR_UNIT * 2;
if (bytes_left < 0)
return nfserr_resource;
maxcount = min_t(u32, readdir->rd_maxcount, max_payload);
/*
* The RFC defines rd_maxcount as the size of the
* READDIR4resok structure, which includes the verifier
* and the 8 bytes encoded at the end of this function.
*/
if (maxcount < XDR_UNIT * 4)
return nfserr_toosmall;
maxcount = min_t(int, maxcount - XDR_UNIT * 4, bytes_left);
/* RFC 3530 14.2.24 allows us to ignore dircount when it's 0 */
if (!readdir->rd_dircount)
readdir->rd_dircount = max_payload;
/* *entries */
readdir->xdr = xdr;
readdir->rd_maxcount = maxcount;
readdir->common.err = 0;
readdir->cookie_offset = 0;
offset = readdir->rd_cookie;
status = nfsd_readdir(readdir->rd_rqstp, readdir->rd_fhp, &offset,
&readdir->common, nfsd4_encode_entry4);
if (status)
return status;
if (readdir->common.err == nfserr_toosmall &&
xdr->buf->len == starting_len) {
/* No entries were encoded. Which limit did we hit? */
if (maxcount - XDR_UNIT * 4 < bytes_left)
/* It was the fault of rd_maxcount */
return nfserr_toosmall;
/* We ran out of buffer space */
return nfserr_resource;
}
/* Encode the final entry's cookie value */
nfsd4_encode_entry4_nfs_cookie4(readdir, offset);
/* No entries follow */
if (xdr_stream_encode_item_absent(xdr) != XDR_UNIT)
return nfserr_resource;
/* eof */
return nfsd4_encode_bool(xdr, readdir->common.err == nfserr_eof);
}
static __be32
nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr,
union nfsd4_op_u *u)
{
struct nfsd4_readdir *readdir = &u->readdir;
int maxcount;
int bytes_left;
loff_t offset;
struct xdr_stream *xdr = resp->xdr;
int starting_len = xdr->buf->len;
__be32 *p;
/* cookieverf */
nfserr = nfsd4_encode_verifier4(xdr, &readdir->rd_verf);
if (nfserr != nfs_ok)
return nfserr;
/*
* Number of bytes left for directory entries allowing for the
* final 8 bytes of the readdir and a following failed op:
*/
bytes_left = xdr->buf->buflen - xdr->buf->len
- COMPOUND_ERR_SLACK_SPACE - 8;
if (bytes_left < 0) {
nfserr = nfserr_resource;
goto err_no_verf;
}
maxcount = svc_max_payload(resp->rqstp);
maxcount = min_t(u32, readdir->rd_maxcount, maxcount);
/*
* Note the rfc defines rd_maxcount as the size of the
* READDIR4resok structure, which includes the verifier above
* and the 8 bytes encoded at the end of this function:
*/
if (maxcount < 16) {
nfserr = nfserr_toosmall;
goto err_no_verf;
}
maxcount = min_t(int, maxcount-16, bytes_left);
/* RFC 3530 14.2.24 allows us to ignore dircount when it's 0: */
if (!readdir->rd_dircount)
readdir->rd_dircount = svc_max_payload(resp->rqstp);
readdir->xdr = xdr;
readdir->rd_maxcount = maxcount;
readdir->common.err = 0;
readdir->cookie_offset = 0;
offset = readdir->rd_cookie;
nfserr = nfsd_readdir(readdir->rd_rqstp, readdir->rd_fhp, &offset,
&readdir->common, nfsd4_encode_entry4);
if (nfserr == nfs_ok &&
readdir->common.err == nfserr_toosmall &&
xdr->buf->len == starting_len + 8) {
/* nothing encoded; which limit did we hit?: */
if (maxcount - 16 < bytes_left)
/* It was the fault of rd_maxcount: */
nfserr = nfserr_toosmall;
else
/* We ran out of buffer space: */
nfserr = nfserr_resource;
}
if (nfserr)
goto err_no_verf;
/* Encode the final entry's cookie value */
nfsd4_encode_entry4_nfs_cookie4(readdir, offset);
p = xdr_reserve_space(xdr, 8);
if (!p) {
WARN_ON_ONCE(1);
goto err_no_verf;
}
*p++ = 0; /* no more entries */
*p++ = htonl(readdir->common.err == nfserr_eof);
return 0;
err_no_verf:
xdr_truncate_encode(xdr, starting_len);
/* reply */
nfserr = nfsd4_encode_dirlist4(xdr, readdir, svc_max_payload(resp->rqstp));
if (nfserr != nfs_ok)
xdr_truncate_encode(xdr, starting_len);
return nfserr;
}