[PATCH] v9fs: remove additional buffer allocation from v9fs_file_read and v9fs_file_write

v9fs_file_read and v9fs_file_write use kmalloc to allocate buffers as big as the data buffer received as parameter. kmalloc cannot be used to allocate buffers bigger than 128K, so reading/writing data in chunks bigger than 128k fails. This patch reorganizes v9fs_file_read and v9fs_file_write to allocate only buffers as big as the maximum data that can be sent in one 9P message. Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Cc: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] v9fs: remove additional buffer allocation from v9fs_file_read and v9fs_file_write
v9fs_file_read and v9fs_file_write use kmalloc to allocate buffers as big as the data buffer received as parameter. kmalloc cannot be used to allocate buffers bigger than 128K, so reading/writing data in chunks bigger than 128k fails. This patch reorganizes v9fs_file_read and v9fs_file_write to allocate only buffers as big as the maximum data that can be sent in one 9P message. Signed-off-by: Latchesar Ionkov <lucho@ionkov.net> Cc: Eric Van Hensbergen <ericvh@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Latchesar Ionkov · Linus Torvalds
1 parent ad6ce87e5b
Showing 1 changed file with 33 additions and 81 deletions Side-by-side Diff
fs/9p/vfs_file.c
@@ -175,16 +175,16 @@
 }
  
 /**
- * v9fs_read - read from a file (internal)
+ * v9fs_file_read - read from a file
  * @filep: file pointer to read
  * @data: data buffer to read data into
  * @count: size of buffer
  * @offset: offset at which to read data
  *
  */
-
 static ssize_t
-v9fs_read(struct file *filp, char *buffer, size_t count, loff_t * offset)
+v9fs_file_read(struct file *filp, char __user * data, size_t count,
+	       loff_t * offset)
 {
 	struct inode *inode = filp->f_dentry->d_inode;
 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
@@ -194,6 +194,7 @@
 	int rsize = 0;
 	int result = 0;
 	int total = 0;
+	int n;
  
 	dprintk(DEBUG_VFS, "\n");
  
  
@@ -216,10 +217,15 @@
 		} else
 			*offset += result;
  
-		/* XXX - extra copy */
-		memcpy(buffer, fcall->params.rread.data, result);
+		n = copy_to_user(data, fcall->params.rread.data, result);
+		if (n) {
+			dprintk(DEBUG_ERROR, "Problem copying to user %d\n", n);
+			kfree(fcall);
+			return -EFAULT;
+		}
+
 		count -= result;
-		buffer += result;
+		data += result;
 		total += result;
  
 		kfree(fcall);
@@ -232,42 +238,7 @@
 }
  
 /**
- * v9fs_file_read - read from a file
- * @filep: file pointer to read
- * @data: data buffer to read data into
- * @count: size of buffer
- * @offset: offset at which to read data
- *
- */
-
-static ssize_t
-v9fs_file_read(struct file *filp, char __user * data, size_t count,
-	       loff_t * offset)
-{
-	int retval = -1;
-	int ret = 0;
-	char *buffer;
-
-	buffer = kmalloc(count, GFP_KERNEL);
-	if (!buffer)
-		return -ENOMEM;
-
-	retval = v9fs_read(filp, buffer, count, offset);
-	if (retval > 0) {
-		if ((ret = copy_to_user(data, buffer, retval)) != 0) {
-			dprintk(DEBUG_ERROR, "Problem copying to user %d\n",
-				ret);
-			retval = ret;
-		}
-	}
-
-	kfree(buffer);
-
-	return retval;
-}
-
-/**
- * v9fs_write - write to a file
+ * v9fs_file_write - write to a file
  * @filep: file pointer to write
  * @data: data buffer to write data from
  * @count: size of buffer
@@ -276,7 +247,8 @@
  */
  
 static ssize_t
-v9fs_write(struct file *filp, char *buffer, size_t count, loff_t * offset)
+v9fs_file_write(struct file *filp, const char __user * data,
+		size_t count, loff_t * offset)
 {
 	struct inode *inode = filp->f_dentry->d_inode;
 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
  
  
  
  
  
@@ -286,30 +258,42 @@
 	int result = -EIO;
 	int rsize = 0;
 	int total = 0;
+	char *buf;
  
-	dprintk(DEBUG_VFS, "data %p count %d offset %x\n", buffer, (int)count,
+	dprintk(DEBUG_VFS, "data %p count %d offset %x\n", data, (int)count,
 		(int)*offset);
 	rsize = v9ses->maxdata - V9FS_IOHDRSZ;
 	if (v9fid->iounit != 0 && rsize > v9fid->iounit)
 		rsize = v9fid->iounit;
  
-	dump_data(buffer, count);
+	buf = kmalloc(v9ses->maxdata - V9FS_IOHDRSZ, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
  
 	do {
 		if (count < rsize)
 			rsize = count;
  
-		result =
-		    v9fs_t_write(v9ses, fid, *offset, rsize, buffer, &fcall);
+		result = copy_from_user(buf, data, rsize);
+		if (result) {
+			dprintk(DEBUG_ERROR, "Problem copying from user\n");
+			kfree(buf);
+			return -EFAULT;
+		}
+
+		dump_data(buf, rsize);
+		result = v9fs_t_write(v9ses, fid, *offset, rsize, buf, &fcall);
 		if (result < 0) {
 			eprintk(KERN_ERR, "error while writing: %s(%d)\n",
 				FCALL_ERROR(fcall), result);
 			kfree(fcall);
+			kfree(buf);
 			return result;
 		} else
 			*offset += result;
  
 		kfree(fcall);
+		fcall = NULL;
  
 		if (result != rsize) {
 			eprintk(KERN_ERR,
  
  
@@ -319,44 +303,12 @@
 		}
  
 		count -= result;
-		buffer += result;
+		data += result;
 		total += result;
 	} while (count);
  
+	kfree(buf);
 	return total;
-}
-
-/**
- * v9fs_file_write - write to a file
- * @filep: file pointer to write
- * @data: data buffer to write data from
- * @count: size of buffer
- * @offset: offset at which to write data
- *
- */
-
-static ssize_t
-v9fs_file_write(struct file *filp, const char __user * data,
-		size_t count, loff_t * offset)
-{
-	int ret = -1;
-	char *buffer;
-
-	buffer = kmalloc(count, GFP_KERNEL);
-	if (buffer == NULL)
-		return -ENOMEM;
-
-	ret = copy_from_user(buffer, data, count);
-	if (ret) {
-		dprintk(DEBUG_ERROR, "Problem copying from user\n");
-		ret = -EFAULT;
-	} else {
-		ret = v9fs_write(filp, buffer, count, offset);
-	}
-
-	kfree(buffer);
-
-	return ret;
 }
  
 struct file_operations v9fs_file_operations = {
...	...	@@ -175,16 +175,16 @@
175	175	}
176	176
177	177	/**
178		- * v9fs_read - read from a file (internal)
	178	+ * v9fs_file_read - read from a file
179	179	* @filep: file pointer to read
180	180	* @data: data buffer to read data into
181	181	* @count: size of buffer
182	182	* @offset: offset at which to read data
183	183	*
184	184	*/
185		-
186	185	static ssize_t
187		-v9fs_read(struct file filp, char buffer, size_t count, loff_t * offset)
	186	+v9fs_file_read(struct file filp, char __user data, size_t count,
	187	+ loff_t * offset)
188	188	{
189	189	struct inode *inode = filp->f_dentry->d_inode;
190	190	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
...	...	@@ -194,6 +194,7 @@
194	194	int rsize = 0;
195	195	int result = 0;
196	196	int total = 0;
	197	+ int n;
197	198
198	199	dprintk(DEBUG_VFS, "\n");
199	200
200	201
...	...	@@ -216,10 +217,15 @@
216	217	} else
217	218	*offset += result;
218	219
219		- /* XXX - extra copy */
220		- memcpy(buffer, fcall->params.rread.data, result);
	220	+ n = copy_to_user(data, fcall->params.rread.data, result);
	221	+ if (n) {
	222	+ dprintk(DEBUG_ERROR, "Problem copying to user %d\n", n);
	223	+ kfree(fcall);
	224	+ return -EFAULT;
	225	+ }
	226	+
221	227	count -= result;
222		- buffer += result;
	228	+ data += result;
223	229	total += result;
224	230
225	231	kfree(fcall);
...	...	@@ -232,42 +238,7 @@
232	238	}
233	239
234	240	/**
235		- * v9fs_file_read - read from a file
236		- * @filep: file pointer to read
237		- * @data: data buffer to read data into
238		- * @count: size of buffer
239		- * @offset: offset at which to read data
240		- *
241		- */
242		-
243		-static ssize_t
244		-v9fs_file_read(struct file filp, char __user data, size_t count,
245		- loff_t * offset)
246		-{
247		- int retval = -1;
248		- int ret = 0;
249		- char *buffer;
250		-
251		- buffer = kmalloc(count, GFP_KERNEL);
252		- if (!buffer)
253		- return -ENOMEM;
254		-
255		- retval = v9fs_read(filp, buffer, count, offset);
256		- if (retval > 0) {
257		- if ((ret = copy_to_user(data, buffer, retval)) != 0) {
258		- dprintk(DEBUG_ERROR, "Problem copying to user %d\n",
259		- ret);
260		- retval = ret;
261		- }
262		- }
263		-
264		- kfree(buffer);
265		-
266		- return retval;
267		-}
268		-
269		-/**
270		- * v9fs_write - write to a file
	241	+ * v9fs_file_write - write to a file
271	242	* @filep: file pointer to write
272	243	* @data: data buffer to write data from
273	244	* @count: size of buffer
...	...	@@ -276,7 +247,8 @@
276	247	*/
277	248
278	249	static ssize_t
279		-v9fs_write(struct file filp, char buffer, size_t count, loff_t * offset)
	250	+v9fs_file_write(struct file filp, const char __user data,
	251	+ size_t count, loff_t * offset)
280	252	{
281	253	struct inode *inode = filp->f_dentry->d_inode;
282	254	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
283	255
284	256
285	257
286	258
287	259
...	...	@@ -286,30 +258,42 @@
286	258	int result = -EIO;
287	259	int rsize = 0;
288	260	int total = 0;
	261	+ char *buf;
289	262
290		- dprintk(DEBUG_VFS, "data %p count %d offset %x\n", buffer, (int)count,
	263	+ dprintk(DEBUG_VFS, "data %p count %d offset %x\n", data, (int)count,
291	264	(int)*offset);
292	265	rsize = v9ses->maxdata - V9FS_IOHDRSZ;
293	266	if (v9fid->iounit != 0 && rsize > v9fid->iounit)
294	267	rsize = v9fid->iounit;
295	268
296		- dump_data(buffer, count);
	269	+ buf = kmalloc(v9ses->maxdata - V9FS_IOHDRSZ, GFP_KERNEL);
	270	+ if (!buf)
	271	+ return -ENOMEM;
297	272
298	273	do {
299	274	if (count < rsize)
300	275	rsize = count;
301	276
302		- result =
303		- v9fs_t_write(v9ses, fid, *offset, rsize, buffer, &fcall);
	277	+ result = copy_from_user(buf, data, rsize);
	278	+ if (result) {
	279	+ dprintk(DEBUG_ERROR, "Problem copying from user\n");
	280	+ kfree(buf);
	281	+ return -EFAULT;
	282	+ }
	283	+
	284	+ dump_data(buf, rsize);
	285	+ result = v9fs_t_write(v9ses, fid, *offset, rsize, buf, &fcall);
304	286	if (result < 0) {
305	287	eprintk(KERN_ERR, "error while writing: %s(%d)\n",
306	288	FCALL_ERROR(fcall), result);
307	289	kfree(fcall);
	290	+ kfree(buf);
308	291	return result;
309	292	} else
310	293	*offset += result;
311	294
312	295	kfree(fcall);
	296	+ fcall = NULL;
313	297
314	298	if (result != rsize) {
315	299	eprintk(KERN_ERR,
316	300
317	301
...	...	@@ -319,44 +303,12 @@
319	303	}
320	304
321	305	count -= result;
322		- buffer += result;
	306	+ data += result;
323	307	total += result;
324	308	} while (count);
325	309
	310	+ kfree(buf);
326	311	return total;
327		-}
328		-
329		-/**
330		- * v9fs_file_write - write to a file
331		- * @filep: file pointer to write
332		- * @data: data buffer to write data from
333		- * @count: size of buffer
334		- * @offset: offset at which to write data
335		- *
336		- */
337		-
338		-static ssize_t
339		-v9fs_file_write(struct file filp, const char __user data,
340		- size_t count, loff_t * offset)
341		-{
342		- int ret = -1;
343		- char *buffer;
344		-
345		- buffer = kmalloc(count, GFP_KERNEL);
346		- if (buffer == NULL)
347		- return -ENOMEM;
348		-
349		- ret = copy_from_user(buffer, data, count);
350		- if (ret) {
351		- dprintk(DEBUG_ERROR, "Problem copying from user\n");
352		- ret = -EFAULT;
353		- } else {
354		- ret = v9fs_write(filp, buffer, count, offset);
355		- }
356		-
357		- kfree(buffer);
358		-
359		- return ret;
360	312	}
361	313
362	314	struct file_operations v9fs_file_operations = {