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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
NFSD: Insulate nfsd4_encode_fattr4() from page boundaries in the encode buffer
Commit ab04de60ae1c ("NFSD: Optimize nfsd4_encode_fattr()") replaced
the use of write_bytes_to_xdr_buf() because it's expensive and the
data items to be encoded are already properly aligned.
However, there's no guarantee that the pointer returned from
xdr_reserve_space() will still point to the correct reserved space
in the encode buffer after one or more intervening calls to
xdr_reserve_space(). It just happens to work with the current
implementation of xdr_reserve_space().
This commit effectively reverts the optimization.
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
+5
-5
+5
-5
fs/nfsd/nfs4xdr.c
+5
-5
fs/nfsd/nfs4xdr.c
···
3507
3507
struct nfsd4_fattr_args args;
3508
3508
struct svc_fh *tempfh = NULL;
3509
3509
int starting_len = xdr->buf->len;
3510
-
__be32 *attrlen_p, status;
3511
-
int attrlen_offset;
3510
+
unsigned int attrlen_offset;
3511
+
__be32 attrlen, status;
3512
3512
u32 attrmask[3];
3513
3513
int err;
3514
3514
struct nfsd4_compoundres *resp = rqstp->rq_resp;
···
3629
3629
3630
3630
/* attr_vals */
3631
3631
attrlen_offset = xdr->buf->len;
3632
-
attrlen_p = xdr_reserve_space(xdr, XDR_UNIT);
3633
-
if (!attrlen_p)
3632
+
if (unlikely(!xdr_reserve_space(xdr, XDR_UNIT)))
3634
3633
goto out_resource;
3635
3634
bitmap_from_arr32(attr_bitmap, attrmask,
3636
3635
ARRAY_SIZE(nfsd4_enc_fattr4_encode_ops));
···
3639
3640
if (status != nfs_ok)
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3641
goto out;
3641
3642
}
3642
-
*attrlen_p = cpu_to_be32(xdr->buf->len - attrlen_offset - XDR_UNIT);
3643
+
attrlen = cpu_to_be32(xdr->buf->len - attrlen_offset - XDR_UNIT);
3644
+
write_bytes_to_xdr_buf(xdr->buf, attrlen_offset, &attrlen, XDR_UNIT);
3643
3645
status = nfs_ok;
3644
3646
3645
3647
out: