9p: switch p9_client_read() to passing struct iov_iter *

... and make it loop

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/9p/v9fs_vfs.h

@@ -68,8 +68,6 @@ int v9fs_file_open(struct inode *inode, struct file *file);
 void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat);
 int v9fs_uflags2omode(int uflags, int extended);
 
-ssize_t v9fs_file_readn(struct file *, char *, char __user *, u32, u64);
-ssize_t v9fs_fid_readn(struct p9_fid *, char *, char __user *, u32, u64);
 void v9fs_blank_wstat(struct p9_wstat *wstat);
 int v9fs_vfs_setattr_dotl(struct dentry *, struct iattr *);
 int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,

fs/9p/vfs_addr.c

@@ -51,12 +51,11 @@
  */
 static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
 {
-	int retval;
-	loff_t offset;
-	char *buffer;
-	struct inode *inode;
+	struct inode *inode = page->mapping->host;
+	struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
+	struct iov_iter to;
+	int retval, err;
 
-	inode = page->mapping->host;
 	p9_debug(P9_DEBUG_VFS, "\n");
 
 	BUG_ON(!PageLocked(page));
@@ -65,24 +64,23 @@ static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
 	if (retval == 0)
 		return retval;
 
-	buffer = kmap(page);
-	offset = page_offset(page);
+	iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE);
 
-	retval = v9fs_fid_readn(fid, buffer, NULL, PAGE_CACHE_SIZE, offset);
-	if (retval < 0) {
+	retval = p9_client_read(fid, page_offset(page), &to, &err);
+	if (err) {
 		v9fs_uncache_page(inode, page);
+		retval = err;
 		goto done;
 	}
 
-	memset(buffer + retval, 0, PAGE_CACHE_SIZE - retval);
+	zero_user(page, retval, PAGE_SIZE - retval);
 	flush_dcache_page(page);
 	SetPageUptodate(page);
 
 	v9fs_readpage_to_fscache(inode, page);
 	retval = 0;
 
 done:
-	kunmap(page);
 	unlock_page(page);
 	return retval;
 }

fs/9p/vfs_dir.c

@@ -33,6 +33,7 @@
 #include <linux/inet.h>
 #include <linux/idr.h>
 #include <linux/slab.h>
+#include <linux/uio.h>
 #include <net/9p/9p.h>
 #include <net/9p/client.h>
 
@@ -115,6 +116,7 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 	int buflen;
 	int reclen = 0;
 	struct p9_rdir *rdir;
+	struct kvec kvec;
 
 	p9_debug(P9_DEBUG_VFS, "name %pD\n", file);
 	fid = file->private_data;
@@ -124,16 +126,21 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
 	rdir = v9fs_alloc_rdir_buf(file, buflen);
 	if (!rdir)
 		return -ENOMEM;
+	kvec.iov_base = rdir->buf;
+	kvec.iov_len = buflen;
 
 	while (1) {
 		if (rdir->tail == rdir->head) {
-			err = v9fs_file_readn(file, rdir->buf, NULL,
-							buflen, ctx->pos);
-			if (err <= 0)
+			struct iov_iter to;
+			int n;
+			iov_iter_kvec(&to, READ | ITER_KVEC, &kvec, 1, buflen);
+			n = p9_client_read(file->private_data, ctx->pos, &to,
+					   &err);
+			if (err)
 				return err;
 
 			rdir->head = 0;
-			rdir->tail = err;
+			rdir->tail = n;
 		}
 		while (rdir->head < rdir->tail) {
 			p9stat_init(&st);

fs/9p/vfs_file.c

@@ -364,63 +364,6 @@ static int v9fs_file_flock_dotl(struct file *filp, int cmd,
 	return ret;
 }
 
-/**
- * v9fs_fid_readn - read from a fid
- * @fid: fid to read
- * @data: data buffer to read data into
- * @udata: user data buffer to read data into
- * @count: size of buffer
- * @offset: offset at which to read data
- *
- */
-ssize_t
-v9fs_fid_readn(struct p9_fid *fid, char *data, char __user *udata, u32 count,
-	       u64 offset)
-{
-	int n, total, size;
-
-	p9_debug(P9_DEBUG_VFS, "fid %d offset %llu count %d\n",
-		 fid->fid, (long long unsigned)offset, count);
-	n = 0;
-	total = 0;
-	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
-	do {
-		n = p9_client_read(fid, data, udata, offset, count);
-		if (n <= 0)
-			break;
-
-		if (data)
-			data += n;
-		if (udata)
-			udata += n;
-
-		offset += n;
-		count -= n;
-		total += n;
-	} while (count > 0 && n == size);
-
-	if (n < 0)
-		total = n;
-
-	return total;
-}
-
-/**
- * v9fs_file_readn - read from a file
- * @filp: file pointer to read
- * @data: data buffer to read data into
- * @udata: user data buffer to read data into
- * @count: size of buffer
- * @offset: offset at which to read data
- *
- */
-ssize_t
-v9fs_file_readn(struct file *filp, char *data, char __user *udata, u32 count,
-	       u64 offset)
-{
-	return v9fs_fid_readn(filp->private_data, data, udata, count, offset);
-}
-
 /**
  * v9fs_file_read - read from a file
  * @filp: file pointer to read
@@ -434,22 +377,20 @@ static ssize_t
 v9fs_file_read(struct file *filp, char __user *udata, size_t count,
 	       loff_t * offset)
 {
-	int ret;
-	struct p9_fid *fid;
-	size_t size;
+	struct p9_fid *fid = filp->private_data;
+	struct iovec iov = {.iov_base = udata, .iov_len = count};
+	struct iov_iter to;
+	int ret, err;
 
-	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
-	fid = filp->private_data;
+	iov_iter_init(&to, READ, &iov, 1, count);
 
-	size = fid->iounit ? fid->iounit : fid->clnt->msize - P9_IOHDRSZ;
-	if (count > size)
-		ret = v9fs_file_readn(filp, NULL, udata, count, *offset);
-	else
-		ret = p9_client_read(fid, NULL, udata, *offset, count);
+	p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n", count, *offset);
 
-	if (ret > 0)
-		*offset += ret;
+	ret = p9_client_read(fid, *offset, &to, &err);
+	if (!ret)
+		return err;
 
+	*offset += ret;
 	return ret;
 }
 

fs/9p/xattr.c

@@ -26,50 +26,34 @@ ssize_t v9fs_fid_xattr_get(struct p9_fid *fid, const char *name,
 			   void *buffer, size_t buffer_size)
 {
 	ssize_t retval;
-	int msize, read_count;
-	u64 offset = 0, attr_size;
+	u64 attr_size;
 	struct p9_fid *attr_fid;
+	struct kvec kvec = {.iov_base = buffer, .iov_len = buffer_size};
+	struct iov_iter to;
+	int err;
+
+	iov_iter_kvec(&to, READ | ITER_KVEC, &kvec, 1, buffer_size);
 
 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
 	if (IS_ERR(attr_fid)) {
 		retval = PTR_ERR(attr_fid);
 		p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
 			 retval);
-		attr_fid = NULL;
-		goto error;
-	}
-	if (!buffer_size) {
-		/* request to get the attr_size */
-		retval = attr_size;
-		goto error;
+		return retval;
 	}
 	if (attr_size > buffer_size) {
-		retval = -ERANGE;
-		goto error;
-	}
-	msize = attr_fid->clnt->msize;
-	while (attr_size) {
-		if (attr_size > (msize - P9_IOHDRSZ))
-			read_count = msize - P9_IOHDRSZ;
+		if (!buffer_size) /* request to get the attr_size */
+			retval = attr_size;
 		else
-			read_count = attr_size;
-		read_count = p9_client_read(attr_fid, ((char *)buffer)+offset,
-					NULL, offset, read_count);
-		if (read_count < 0) {
-			/* error in xattr read */
-			retval = read_count;
-			goto error;
-		}
-		offset += read_count;
-		attr_size -= read_count;
+			retval = -ERANGE;
+	} else {
+		iov_iter_truncate(&to, attr_size);
+		retval = p9_client_read(attr_fid, 0, &to, &err);
+		if (err)
+			retval = err;
 	}
-	/* Total read xattr bytes */
-	retval = offset;
-error:
-	if (attr_fid)
-		p9_client_clunk(attr_fid);
+	p9_client_clunk(attr_fid);
 	return retval;
-
 }
 
 

include/net/9p/client.h

@@ -238,8 +238,7 @@ int p9_client_clunk(struct p9_fid *fid);
 int p9_client_fsync(struct p9_fid *fid, int datasync);
 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_read(struct p9_fid *fid, u64 offset, struct iov_iter *to, int *err);
 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,