diff mbox

nfsd: use short read rather than i_size to set eof

Message ID 82e4c7a9756b21a4645421d04735ccf491b4296a.1458571329.git.bcodding@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Benjamin Coddington March 21, 2016, 2:42 p.m. UTC 
Use the result of a local read to determine when to set the eof flag.  This
allows us to return the location of the end of the file atomically at the
time of the read.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/nfsd/nfs3proc.c |   10 ++++------
 fs/nfsd/nfs4xdr.c  |    9 +++++----
 2 files changed, 9 insertions(+), 10 deletions(-)

Comments

J. Bruce Fields March 21, 2016, 9:36 p.m. UTC | #1 
On Mon, Mar 21, 2016 at 10:42:25AM -0400, Benjamin Coddington wrote:
> Use the result of a local read to determine when to set the eof flag.  This
> allows us to return the location of the end of the file atomically at the
> time of the read.

My only question is whether we should instead do something like:

	eof = (res > cnt) || (offset + cnt >= i_size)

That'd fix the reported bug without changing existing behavior
otherwise.

But maybe it's unlikely any client depends on existing behavior.

The only test failure I'm seeing is on pynfs WRT13, which literally just
checks that a 6-byte read of a 6-byte file returns with eof set.  The
test is correct (the spec does clearly require eof to be set in that
case), but maybe it's not important.

--b.

> 
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
>  fs/nfsd/nfs3proc.c |   10 ++++------
>  fs/nfsd/nfs4xdr.c  |    9 +++++----
>  2 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index 7b755b7..6be6092 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -147,6 +147,7 @@ nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
>  {
>  	__be32	nfserr;
>  	u32	max_blocksize = svc_max_payload(rqstp);
> +	unsigned long cnt = min(argp->count, max_blocksize);
>  
>  	dprintk("nfsd: READ(3) %s %lu bytes at %Lu\n",
>  				SVCFH_fmt(&argp->fh),
> @@ -157,7 +158,7 @@ nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
>  	 * 1 (status) + 22 (post_op_attr) + 1 (count) + 1 (eof)
>  	 * + 1 (xdr opaque byte count) = 26
>  	 */
> -	resp->count = min(argp->count, max_blocksize);
> +	resp->count = cnt;
>  	svc_reserve_auth(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);
>  
>  	fh_copy(&resp->fh, &argp->fh);
> @@ -165,11 +166,8 @@ nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
>  				  argp->offset,
>  			   	  rqstp->rq_vec, argp->vlen,
>  				  &resp->count);
> -	if (nfserr == 0) {
> -		struct inode	*inode = d_inode(resp->fh.fh_dentry);
> -
> -		resp->eof = (argp->offset + resp->count) >= inode->i_size;
> -	}
> +	if (nfserr == 0)
> +		resp->eof = cnt > resp->count;
>  
>  	RETURN_STATUS(nfserr);
>  }
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index d6ef095..2e14839 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3362,6 +3362,7 @@ static __be32 nfsd4_encode_splice_read(
>  	struct xdr_stream *xdr = &resp->xdr;
>  	struct xdr_buf *buf = xdr->buf;
>  	u32 eof;
> +	long len;
>  	int space_left;
>  	__be32 nfserr;
>  	__be32 *p = xdr->p - 2;
> @@ -3370,6 +3371,7 @@ static __be32 nfsd4_encode_splice_read(
>  	if (xdr->end - xdr->p < 1)
>  		return nfserr_resource;
>  
> +	len = maxcount;
>  	nfserr = nfsd_splice_read(read->rd_rqstp, file,
>  				  read->rd_offset, &maxcount);
>  	if (nfserr) {
> @@ -3382,8 +3384,7 @@ static __be32 nfsd4_encode_splice_read(
>  		return nfserr;
>  	}
>  
> -	eof = (read->rd_offset + maxcount >=
> -	       d_inode(read->rd_fhp->fh_dentry)->i_size);
> +	eof = len > maxcount;
>  
>  	*(p++) = htonl(eof);
>  	*(p++) = htonl(maxcount);
> @@ -3453,14 +3454,14 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
>  	}
>  	read->rd_vlen = v;
>  
> +	len = maxcount;
>  	nfserr = nfsd_readv(file, read->rd_offset, resp->rqstp->rq_vec,
>  			read->rd_vlen, &maxcount);
>  	if (nfserr)
>  		return nfserr;
>  	xdr_truncate_encode(xdr, starting_len + 8 + ((maxcount+3)&~3));
>  
> -	eof = (read->rd_offset + maxcount >=
> -	       d_inode(read->rd_fhp->fh_dentry)->i_size);
> +	eof = len > maxcount;
>  
>  	tmp = htonl(eof);
>  	write_bytes_to_xdr_buf(xdr->buf, starting_len    , &tmp, 4);
> -- 
> 1.7.1
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diff mbox

Patch

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 7b755b7..6be6092 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -147,6 +147,7 @@  nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
 {
 	__be32	nfserr;
 	u32	max_blocksize = svc_max_payload(rqstp);
+	unsigned long cnt = min(argp->count, max_blocksize);
 
 	dprintk("nfsd: READ(3) %s %lu bytes at %Lu\n",
 				SVCFH_fmt(&argp->fh),
@@ -157,7 +158,7 @@  nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
 	 * 1 (status) + 22 (post_op_attr) + 1 (count) + 1 (eof)
 	 * + 1 (xdr opaque byte count) = 26
 	 */
-	resp->count = min(argp->count, max_blocksize);
+	resp->count = cnt;
 	svc_reserve_auth(rqstp, ((1 + NFS3_POST_OP_ATTR_WORDS + 3)<<2) + resp->count +4);
 
 	fh_copy(&resp->fh, &argp->fh);
@@ -165,11 +166,8 @@  nfsd3_proc_read(struct svc_rqst *rqstp, struct nfsd3_readargs *argp,
 				  argp->offset,
 			   	  rqstp->rq_vec, argp->vlen,
 				  &resp->count);
-	if (nfserr == 0) {
-		struct inode	*inode = d_inode(resp->fh.fh_dentry);
-
-		resp->eof = (argp->offset + resp->count) >= inode->i_size;
-	}
+	if (nfserr == 0)
+		resp->eof = cnt > resp->count;
 
 	RETURN_STATUS(nfserr);
 }
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index d6ef095..2e14839 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3362,6 +3362,7 @@  static __be32 nfsd4_encode_splice_read(
 	struct xdr_stream *xdr = &resp->xdr;
 	struct xdr_buf *buf = xdr->buf;
 	u32 eof;
+	long len;
 	int space_left;
 	__be32 nfserr;
 	__be32 *p = xdr->p - 2;
@@ -3370,6 +3371,7 @@  static __be32 nfsd4_encode_splice_read(
 	if (xdr->end - xdr->p < 1)
 		return nfserr_resource;
 
+	len = maxcount;
 	nfserr = nfsd_splice_read(read->rd_rqstp, file,
 				  read->rd_offset, &maxcount);
 	if (nfserr) {
@@ -3382,8 +3384,7 @@  static __be32 nfsd4_encode_splice_read(
 		return nfserr;
 	}
 
-	eof = (read->rd_offset + maxcount >=
-	       d_inode(read->rd_fhp->fh_dentry)->i_size);
+	eof = len > maxcount;
 
 	*(p++) = htonl(eof);
 	*(p++) = htonl(maxcount);
@@ -3453,14 +3454,14 @@  static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
 	}
 	read->rd_vlen = v;
 
+	len = maxcount;
 	nfserr = nfsd_readv(file, read->rd_offset, resp->rqstp->rq_vec,
 			read->rd_vlen, &maxcount);
 	if (nfserr)
 		return nfserr;
 	xdr_truncate_encode(xdr, starting_len + 8 + ((maxcount+3)&~3));
 
-	eof = (read->rd_offset + maxcount >=
-	       d_inode(read->rd_fhp->fh_dentry)->i_size);
+	eof = len > maxcount;
 
 	tmp = htonl(eof);
 	write_bytes_to_xdr_buf(xdr->buf, starting_len    , &tmp, 4);