9p: switch p9_client_write() to passing it struct iov_iter *

... and make it loop until it's done
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/9p/vfs_file.c

@@ -36,6 +36,7 @@
 #include <linux/utsname.h>
 #include <asm/uaccess.h>
 #include <linux/idr.h>
+#include <linux/uio.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -457,24 +458,20 @@ v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
 			 const char __user *data, size_t count,
 			 loff_t *offset, int invalidate)
 {
-	int n;
-	loff_t i_size;
-	size_t total = 0;
 	loff_t origin = *offset;
-	unsigned long pg_start, pg_end;
+	struct iovec iov = {.iov_base = (void __user *)data, .iov_len = count};
+	struct iov_iter from;
+	int total, err = 0;
 
 	p9_debug(P9_DEBUG_VFS, "data %p count %d offset %x\n",
 		 data, (int)count, (int)*offset);
 
-	do {
-		n = p9_client_write(fid, NULL, data+total, origin+total, count);
-		if (n <= 0)
-			break;
-		count -= n;
-		total += n;
-	} while (count > 0);
+	iov_iter_init(&from, WRITE, &iov, 1, count);
 
+	total = p9_client_write(fid, origin, &from, &err);
 	if (invalidate && (total > 0)) {
+		loff_t i_size;
+		unsigned long pg_start, pg_end;
 		pg_start = origin >> PAGE_CACHE_SHIFT;
 		pg_end = (origin + total - 1) >> PAGE_CACHE_SHIFT;
 		if (inode->i_mapping && inode->i_mapping->nrpages)
@@ -487,10 +484,7 @@ v9fs_file_write_internal(struct inode *inode, struct p9_fid *fid,
 			i_size_write(inode, *offset);
 		}
 	}
-	if (n < 0)
-		return n;
-
-	return total;
+	return total ? total : err;
 }
 
 /**

fs/9p/xattr.c

@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
+#include <linux/uio.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -120,8 +121,11 @@ int v9fs_xattr_set(struct dentry *dentry, const char *name,
 int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 		   const void *value, size_t value_len, int flags)
 {
-	u64 offset = 0;
-	int retval, msize, write_count;
+	struct kvec kvec = {.iov_base = (void *)value, .iov_len = value_len};
+	struct iov_iter from;
+	int retval;
+
+	iov_iter_kvec(&from, WRITE | ITER_KVEC, &kvec, 1, value_len);
 
 	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
 		 name, value_len, flags);
@@ -135,29 +139,11 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
 	 * On success fid points to xattr
 	 */
 	retval = p9_client_xattrcreate(fid, name, value_len, flags);
-	if (retval < 0) {
+	if (retval < 0)
 		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
 			 retval);
-		goto err;
-	}
-	msize = fid->clnt->msize;
-	while (value_len) {
-		if (value_len > (msize - P9_IOHDRSZ))
-			write_count = msize - P9_IOHDRSZ;
 	else
-			write_count = value_len;
-		write_count = p9_client_write(fid, ((char *)value)+offset,
-					NULL, offset, write_count);
-		if (write_count < 0) {
-			/* error in xattr write */
-			retval = write_count;
-			goto err;
-		}
-		offset += write_count;
-		value_len -= write_count;
-	}
-	retval = 0;
-err:
+		p9_client_write(fid, 0, &from, &retval);
 	p9_client_clunk(fid);
 	return retval;
 }

include/net/9p/client.h

@@ -211,6 +211,8 @@ struct p9_dirent {
 	char d_name[256];
 };
 
+struct iov_iter;
+
 int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb);
 int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid,
 		     const char *name);
@@ -238,8 +240,7 @@ int p9_client_remove(struct p9_fid *fid);
 int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags);
 int p9_client_read(struct p9_fid *fid, char *data, char __user *udata,
 							u64 offset, u32 count);
-int p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
-							u64 offset, u32 count);
+int p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err);
 int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset);
 int p9dirent_read(struct p9_client *clnt, char *buf, int len,
 		  struct p9_dirent *dirent);

net/9p/client.c

@@ -1611,34 +1611,19 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
 EXPORT_SYMBOL(p9_client_read);
 
 int
-p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
-							u64 offset, u32 count)
+p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
 {
-	int err, rsize;
-	struct p9_client *clnt;
+	struct p9_client *clnt = fid->clnt;
 	struct p9_req_t *req;
-	struct iov_iter from;
-	union {
-		struct kvec kv;
-		struct iovec iov;
-	} v;
+	int total = 0;
 
-	if (data) {
-		v.kv.iov_base = data;
-		v.kv.iov_len = count;
-		iov_iter_kvec(&from, ITER_KVEC | WRITE, &v.kv, 1, count);
-	} else {
-		v.iov.iov_base = udata;
-		v.iov.iov_len = count;
-		iov_iter_init(&from, WRITE, &v.iov, 1, count);
-	}
-
-	p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %d\n",
-				fid->fid, (unsigned long long) offset, count);
-	err = 0;
-	clnt = fid->clnt;
+	p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %zd\n",
+				fid->fid, (unsigned long long) offset,
+				iov_iter_count(from));
 
-	rsize = fid->iounit;
+	while (iov_iter_count(from)) {
+		int count = iov_iter_count(from);
+		int rsize = fid->iounit;
 		if (!rsize || rsize > clnt->msize-P9_IOHDRSZ)
 			rsize = clnt->msize - P9_IOHDRSZ;
 
@@ -1647,33 +1632,32 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
 
 		/* Don't bother zerocopy for small IO (< 1024) */
 		if (clnt->trans_mod->zc_request && rsize > 1024) {
-		req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, &from, 0, rsize,
-				       P9_ZC_HDR_SZ, "dqd",
+			req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, from, 0,
+					       rsize, P9_ZC_HDR_SZ, "dqd",
 					       fid->fid, offset, rsize);
 		} else {
 			req = p9_client_rpc(clnt, P9_TWRITE, "dqV", fid->fid,
-					    offset, rsize, &from);
+						    offset, rsize, from);
 		}
 		if (IS_ERR(req)) {
-		err = PTR_ERR(req);
-		goto error;
+			*err = PTR_ERR(req);
+			break;
 		}
 
-	err = p9pdu_readf(req->rc, clnt->proto_version, "d", &count);
-	if (err) {
+		*err = p9pdu_readf(req->rc, clnt->proto_version, "d", &count);
+		if (*err) {
 			trace_9p_protocol_dump(clnt, req->rc);
-		goto free_and_error;
+			p9_free_req(clnt, req);
 		}
 
 		p9_debug(P9_DEBUG_9P, "<<< RWRITE count %d\n", count);
 
 		p9_free_req(clnt, req);
-	return count;
-
-free_and_error:
-	p9_free_req(clnt, req);
-error:
-	return err;
+		iov_iter_advance(from, count);
+		total += count;
+		offset += count;
+	}
+	return total;
 }
 EXPORT_SYMBOL(p9_client_write);