nfsd: use vfs_iter_read/write

Instead of messing with the address limit to use vfs_read/vfs_writev.

Note that this requires that exported file implement ->read_iter and
->write_iter.  All currently exportable file systems do this.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 10 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 2be32955d7f2..37a03c456b38 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -911,13 +911,12 @@ __be32 nfsd_splice_read(struct svc_rqst *rqstp,
 __be32 nfsd_readv(struct file *file, loff_t offset, struct kvec *vec, int vlen,
                 unsigned long *count)
 {
-        mm_segment_t oldfs;
+        struct iov_iter iter;
         int host_err;
 
-        oldfs = get_fs();
-        set_fs(KERNEL_DS);
-        host_err = vfs_readv(file, (struct iovec __user *)vec, vlen, &offset, 0);
-        set_fs(oldfs);
+        iov_iter_kvec(&iter, READ | ITER_KVEC, vec, vlen, *count);
+        host_err = vfs_iter_read(file, &iter, &offset, 0);
+
         return nfsd_finish_read(file, count, host_err);
 }
 
@@ -974,7 +973,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
                                 unsigned long *cnt, int stable)
 {
         struct svc_export       *exp;
-        mm_segment_t            oldfs;
+        struct iov_iter         iter;
         __be32                  err = 0;
         int                     host_err;
         int                     use_wgather;
@@ -1000,10 +999,8 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         if (stable && !use_wgather)
                 flags |= RWF_SYNC;
 
-        /* Write the data. */
-        oldfs = get_fs(); set_fs(KERNEL_DS);
-        host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &pos, flags);
-        set_fs(oldfs);
+        iov_iter_kvec(&iter, WRITE | ITER_KVEC, vec, vlen, *cnt);
+        host_err = vfs_iter_write(file, &iter, &pos, flags);
         if (host_err < 0)
                 goto out_nfserr;
         *cnt = host_err;