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NFSD: Update NFSv3 READDIR entry encoders to use struct xdr_stream 

The benefit of the xdr_stream helpers is that they transparently
handle encoding an XDR data item that crosses page boundaries.
Most of the open-coded logic to do that here can be eliminated.

A sub-buffer and sub-stream are set up as a sink buffer for the
directory entry encoder. As an entry is encoded, it is added to
the end of the content in this buffer/stream. The total length of
the directory list is tracked in the buffer's @len field.

When it comes time to encode the Reply, the sub-buffer is merged
into rq_res's page array at the correct place using
xdr_write_pages().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2020-10-22 19:46:58 -04:00
parent e4ccfe3014
commit 7f87fc2d34
3 changed files with 185 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
fs/nfsd/nfs3proc.c
View File

@ -441,18 +441,30 @@ static void nfsd3_init_dirlist_pages(struct svc_rqst *rqstp,
struct nfsd3_readdirres *resp,
int count)
{
struct xdr_buf *buf = &resp->dirlist;
struct xdr_stream *xdr = &resp->xdr;
count = min_t(u32, count, svc_max_payload(rqstp));
/* Convert byte count to number of words (i.e. >> 2),
* and reserve room for the NULL ptr & eof flag (-2 words) */
resp->buflen = (count >> 2) - 2;
memset(buf, 0, sizeof(*buf));
resp->pages = rqstp->rq_next_page;
resp->buffer = page_address(*resp->pages);
/* Reserve room for the NULL ptr & eof flag (-2 words) */
buf->buflen = count - XDR_UNIT * 2;
buf->pages = rqstp->rq_next_page;
while (count > 0) {
rqstp->rq_next_page++;
count -= PAGE_SIZE;
}
/* This is xdr_init_encode(), but it assumes that
* the head kvec has already been consumed. */
xdr_set_scratch_buffer(xdr, NULL, 0);
xdr->buf = buf;
xdr->page_ptr = buf->pages;
xdr->iov = NULL;
xdr->p = page_address(*buf->pages);
xdr->end = xdr->p + (PAGE_SIZE >> 2);
xdr->rqst = NULL;
}
/*
@ -471,16 +483,13 @@ nfsd3_proc_readdir(struct svc_rqst *rqstp)
nfsd3_init_dirlist_pages(rqstp, resp, argp->count);
/* Read directory and encode entries on the fly */
fh_copy(&resp->fh, &argp->fh);
resp->count = 0;
resp->common.err = nfs_ok;
resp->cookie_offset = 0;
resp->rqstp = rqstp;
offset = argp->cookie;
resp->status = nfsd_readdir(rqstp, &resp->fh, &offset,
&resp->common, nfs3svc_encode_entry);
&resp->common, nfs3svc_encode_entry3);
memcpy(resp->verf, argp->verf, 8);
nfs3svc_encode_cookie3(resp, offset);
@ -504,11 +513,9 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
nfsd3_init_dirlist_pages(rqstp, resp, argp->count);
/* Read directory and encode entries on the fly */
fh_copy(&resp->fh, &argp->fh);
resp->count = 0;
resp->common.err = nfs_ok;
resp->cookie_offset = 0;
resp->rqstp = rqstp;
offset = argp->cookie;
@ -522,7 +529,7 @@ nfsd3_proc_readdirplus(struct svc_rqst *rqstp)
}
resp->status = nfsd_readdir(rqstp, &resp->fh, &offset,
&resp->common, nfs3svc_encode_entry_plus);
&resp->common, nfs3svc_encode_entryplus3);
memcpy(resp->verf, argp->verf, 8);
nfs3svc_encode_cookie3(resp, offset);

166
fs/nfsd/nfs3xdr.c
View File

@ -1139,6 +1139,7 @@ nfs3svc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
{
struct xdr_stream *xdr = &rqstp->rq_res_stream;
struct nfsd3_readdirres *resp = rqstp->rq_resp;
struct xdr_buf *dirlist = &resp->dirlist;
if (!svcxdr_encode_nfsstat3(xdr, resp->status))
return 0;
@ -1148,7 +1149,7 @@ nfs3svc_encode_readdirres(struct svc_rqst *rqstp, __be32 *p)
return 0;
if (!svcxdr_encode_cookieverf3(xdr, resp->verf))
return 0;
xdr_write_pages(xdr, resp->pages, 0, resp->count << 2);
xdr_write_pages(xdr, dirlist->pages, 0, dirlist->len);
/* no more entries */
if (xdr_stream_encode_item_absent(xdr) < 0)
return 0;
@ -1240,21 +1241,18 @@ static __be32 *encode_entryplus_baggage(struct nfsd3_readdirres *cd, __be32 *p,
* @resp: readdir result context
* @offset: offset cookie to encode
*
* The buffer space for the offset cookie has already been reserved
* by svcxdr_encode_entry3_common().
*/
void nfs3svc_encode_cookie3(struct nfsd3_readdirres *resp, u64 offset)
{
if (!resp->offset)
return;
__be64 cookie = cpu_to_be64(offset);
if (resp->offset1) {
/* we ended up with offset on a page boundary */
*resp->offset = cpu_to_be32(offset >> 32);
*resp->offset1 = cpu_to_be32(offset & 0xffffffff);
resp->offset1 = NULL;
} else {
xdr_encode_hyper(resp->offset, offset);
}
resp->offset = NULL;
if (!resp->cookie_offset)
return;
write_bytes_to_xdr_buf(&resp->dirlist, resp->cookie_offset, &cookie,
sizeof(cookie));
resp->cookie_offset = 0;
}
/*
@ -1403,6 +1401,150 @@ nfs3svc_encode_entry_plus(void *cd, const char *name,
return encode_entry(cd, name, namlen, offset, ino, d_type, 1);
}
static bool
svcxdr_encode_entry3_common(struct nfsd3_readdirres *resp, const char *name,
int namlen, loff_t offset, u64 ino)
{
struct xdr_buf *dirlist = &resp->dirlist;
struct xdr_stream *xdr = &resp->xdr;
if (xdr_stream_encode_item_present(xdr) < 0)
return false;
/* fileid */
if (xdr_stream_encode_u64(xdr, ino) < 0)
return false;
/* name */
if (xdr_stream_encode_opaque(xdr, name, min(namlen, NFS3_MAXNAMLEN)) < 0)
return false;
/* cookie */
resp->cookie_offset = dirlist->len;
if (xdr_stream_encode_u64(xdr, NFS_OFFSET_MAX) < 0)
return false;
return true;
}
/**
* nfs3svc_encode_entry3 - encode one NFSv3 READDIR entry
* @data: directory context
* @name: name of the object to be encoded
* @namlen: length of that name, in bytes
* @offset: the offset of the previous entry
* @ino: the fileid of this entry
* @d_type: unused
*
* Return values:
* %0: Entry was successfully encoded.
* %-EINVAL: An encoding problem occured, secondary status code in resp->common.err
*
* On exit, the following fields are updated:
* - resp->xdr
* - resp->common.err
* - resp->cookie_offset
*/
int nfs3svc_encode_entry3(void *data, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
struct readdir_cd *ccd = data;
struct nfsd3_readdirres *resp = container_of(ccd,
struct nfsd3_readdirres,
common);
unsigned int starting_length = resp->dirlist.len;
/* The offset cookie for the previous entry */
nfs3svc_encode_cookie3(resp, offset);
if (!svcxdr_encode_entry3_common(resp, name, namlen, offset, ino))
goto out_toosmall;
xdr_commit_encode(&resp->xdr);
resp->common.err = nfs_ok;
return 0;
out_toosmall:
resp->cookie_offset = 0;
resp->common.err = nfserr_toosmall;
resp->dirlist.len = starting_length;
return -EINVAL;
}
static bool
svcxdr_encode_entry3_plus(struct nfsd3_readdirres *resp, const char *name,
int namlen, u64 ino)
{
struct xdr_stream *xdr = &resp->xdr;
struct svc_fh *fhp = &resp->scratch;
bool result;
result = false;
fh_init(fhp, NFS3_FHSIZE);
if (compose_entry_fh(resp, fhp, name, namlen, ino) != nfs_ok)
goto out_noattrs;
if (!svcxdr_encode_post_op_attr(resp->rqstp, xdr, fhp))
goto out;
if (!svcxdr_encode_post_op_fh3(xdr, fhp))
goto out;
result = true;
out:
fh_put(fhp);
return result;
out_noattrs:
if (xdr_stream_encode_item_absent(xdr) < 0)
return false;
if (xdr_stream_encode_item_absent(xdr) < 0)
return false;
return true;
}
/**
* nfs3svc_encode_entryplus3 - encode one NFSv3 READDIRPLUS entry
* @data: directory context
* @name: name of the object to be encoded
* @namlen: length of that name, in bytes
* @offset: the offset of the previous entry
* @ino: the fileid of this entry
* @d_type: unused
*
* Return values:
* %0: Entry was successfully encoded.
* %-EINVAL: An encoding problem occured, secondary status code in resp->common.err
*
* On exit, the following fields are updated:
* - resp->xdr
* - resp->common.err
* - resp->cookie_offset
*/
int nfs3svc_encode_entryplus3(void *data, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type)
{
struct readdir_cd *ccd = data;
struct nfsd3_readdirres *resp = container_of(ccd,
struct nfsd3_readdirres,
common);
unsigned int starting_length = resp->dirlist.len;
/* The offset cookie for the previous entry */
nfs3svc_encode_cookie3(resp, offset);
if (!svcxdr_encode_entry3_common(resp, name, namlen, offset, ino))
goto out_toosmall;
if (!svcxdr_encode_entry3_plus(resp, name, namlen, ino))
goto out_toosmall;
xdr_commit_encode(&resp->xdr);
resp->common.err = nfs_ok;
return 0;
out_toosmall:
resp->cookie_offset = 0;
resp->common.err = nfserr_toosmall;
resp->dirlist.len = starting_length;
return -EINVAL;
}
static bool
svcxdr_encode_fsstat3resok(struct xdr_stream *xdr,
const struct nfsd3_fsstatres *resp)

14
fs/nfsd/xdr3.h
View File

@ -169,20 +169,22 @@ struct nfsd3_linkres {
};
struct nfsd3_readdirres {
/* Components of the reply */
__be32 status;
struct svc_fh fh;
/* Just to save kmalloc on every readdirplus entry (svc_fh is a
* little large for the stack): */
struct svc_fh scratch;
int count;
__be32 verf[2];
struct page **pages;
/* Used to encode the reply's entry list */
struct xdr_stream xdr;
struct xdr_buf dirlist;
struct svc_fh scratch;
struct readdir_cd common;
__be32 * buffer;
int buflen;
__be32 * offset;
__be32 * offset1;
unsigned int cookie_offset;
struct svc_rqst * rqstp;
};
@ -309,6 +311,10 @@ int nfs3svc_encode_entry(void *, const char *name,
int nfs3svc_encode_entry_plus(void *, const char *name,
int namlen, loff_t offset, u64 ino,
unsigned int);
int nfs3svc_encode_entry3(void *data, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type);
int nfs3svc_encode_entryplus3(void *data, const char *name, int namlen,
loff_t offset, u64 ino, unsigned int d_type);
/* Helper functions for NFSv3 ACL code */
__be32 *nfs3svc_encode_post_op_attr(struct svc_rqst *rqstp, __be32 *p,
struct svc_fh *fhp);