[PATCH] v9fs: zero copy implementation

Performance enhancement reducing the number of copies in the data and
stat paths.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@ericvh.myip.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 21 deletions

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index e13577da913..6852f0eb96e 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -32,6 +32,7 @@
 #include <linux/string.h>
 #include <linux/smp_lock.h>
 #include <linux/inet.h>
+#include <linux/version.h>
 #include <linux/list.h>
 #include <asm/uaccess.h>
 #include <linux/idr.h>
@@ -117,9 +118,7 @@ int v9fs_file_open(struct inode *inode, struct file *file)
 
                 result = v9fs_t_open(v9ses, newfid, open_mode, &fcall);
                 if (result < 0) {
-                        dprintk(DEBUG_ERROR,
-                                "open failed, open_mode 0x%x: %s\n", open_mode,
-                                FCALL_ERROR(fcall));
+                        PRINT_FCALL_ERROR("open failed", fcall);
                         kfree(fcall);
                         return result;
                 }
@@ -256,7 +255,6 @@ v9fs_file_write(struct file *filp, const char __user * data,
         int result = -EIO;
         int rsize = 0;
         int total = 0;
-        char *buf;
 
         dprintk(DEBUG_VFS, "data %p count %d offset %x\n", data, (int)count,
                 (int)*offset);
@@ -264,28 +262,14 @@ v9fs_file_write(struct file *filp, const char __user * data,
         if (v9fid->iounit != 0 && rsize > v9fid->iounit)
                 rsize = v9fid->iounit;
 
-        buf = kmalloc(v9ses->maxdata - V9FS_IOHDRSZ, GFP_KERNEL);
-        if (!buf)
-                return -ENOMEM;
-
         do {
                 if (count < rsize)
                         rsize = count;
 
-                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);
+                result = v9fs_t_write(v9ses, fid, *offset, rsize, data, &fcall);
                 if (result < 0) {
-                        eprintk(KERN_ERR, "error while writing: %s(%d)\n",
-                                FCALL_ERROR(fcall), result);
+                        PRINT_FCALL_ERROR("error while writing", fcall);
                         kfree(fcall);
-                        kfree(buf);
                         return result;
                 } else
                         *offset += result;
@@ -305,7 +289,6 @@ v9fs_file_write(struct file *filp, const char __user * data,
                 total += result;
         } while (count);
 
-        kfree(buf);
         return total;
 }