[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>

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index a4799e9..bbc3cc6 100644 (file)
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -175,16 +175,16 @@ static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
 }
 
 /**
- * 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 @@ v9fs_read(struct file *filp, char *buffer, size_t count, loff_t * offset)
        int rsize = 0;
        int result = 0;
        int total = 0;
+       int n;
 
        dprintk(DEBUG_VFS, "\n");
 
@@ -216,10 +217,15 @@ v9fs_read(struct file *filp, char *buffer, size_t count, loff_t * offset)
                } 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_read(struct file *filp, char *buffer, size_t count, loff_t * offset)
 }
 
 /**
- * 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 @@ v9fs_file_read(struct file *filp, char __user * data, size_t count,
  */
 
 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 @@ v9fs_write(struct file *filp, char *buffer, size_t count, loff_t * offset)
        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,
@@ -319,46 +303,14 @@ v9fs_write(struct file *filp, char *buffer, size_t count, loff_t * offset)
                }
 
                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 = {
        .llseek = generic_file_llseek,
        .read = v9fs_file_read,