[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, 13 insertions, 18 deletions

diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
index 3893dd307ddb..ae6d032b9b59 100644
--- a/fs/9p/vfs_dir.c
+++ b/fs/9p/vfs_dir.c
@@ -37,8 +37,8 @@
 #include "debug.h"
 #include "v9fs.h"
 #include "9p.h"
-#include "v9fs_vfs.h"
 #include "conv.h"
+#include "v9fs_vfs.h"
 #include "fid.h"
 
 /**
@@ -77,17 +77,13 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
         unsigned int i, n, s;
         int fid = -1;
         int ret = 0;
-        struct v9fs_stat *mi = NULL;
+        struct v9fs_stat stat;
         int over = 0;
 
         dprintk(DEBUG_VFS, "name %s\n", filp->f_dentry->d_name.name);
 
         fid = file->fid;
 
-        mi = kmalloc(v9ses->maxdata, GFP_KERNEL);
-        if (!mi)
-                return -ENOMEM;
-
         if (file->rdir_fcall && (filp->f_pos != file->rdir_pos)) {
                 kfree(file->rdir_fcall);
                 file->rdir_fcall = NULL;
@@ -99,18 +95,18 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
                 while (i < n) {
                         s = v9fs_deserialize_stat(
                                 file->rdir_fcall->params.rread.data + i,
-                                n - i, mi, v9ses->maxdata, v9ses->extended);
+                                n - i, &stat, v9ses->extended);
 
                         if (s == 0) {
                                 dprintk(DEBUG_ERROR,
-                                        "error while deserializing mistat\n");
+                                        "error while deserializing stat\n");
                                 ret = -EIO;
                                 goto FreeStructs;
                         }
 
-                        over = filldir(dirent, mi->name, strlen(mi->name),
-                                    filp->f_pos, v9fs_qid2ino(&mi->qid),
-                                    dt_type(mi));
+                        over = filldir(dirent, stat.name.str, stat.name.len,
+                                    filp->f_pos, v9fs_qid2ino(&stat.qid),
+                                    dt_type(&stat));
 
                         if (over) {
                                 file->rdir_fpos = i;
@@ -130,7 +126,7 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 
         while (!over) {
                 ret = v9fs_t_read(v9ses, fid, filp->f_pos,
-                                            v9ses->maxdata-V9FS_IOHDRSZ, &fcall);
+                        v9ses->maxdata-V9FS_IOHDRSZ, &fcall);
                 if (ret < 0) {
                         dprintk(DEBUG_ERROR, "error while reading: %d: %p\n",
                                 ret, fcall);
@@ -142,17 +138,17 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
                 i = 0;
                 while (i < n) {
                         s = v9fs_deserialize_stat(fcall->params.rread.data + i,
-                                n - i, mi, v9ses->maxdata, v9ses->extended);
+                                n - i, &stat, v9ses->extended);
 
                         if (s == 0) {
                                 dprintk(DEBUG_ERROR,
-                                        "error while deserializing mistat\n");
+                                        "error while deserializing stat\n");
                                 return -EIO;
                         }
 
-                        over = filldir(dirent, mi->name, strlen(mi->name),
-                                    filp->f_pos, v9fs_qid2ino(&mi->qid),
-                                    dt_type(mi));
+                        over = filldir(dirent, stat.name.str, stat.name.len,
+                                    filp->f_pos, v9fs_qid2ino(&stat.qid),
+                                    dt_type(&stat));
 
                         if (over) {
                                 file->rdir_fcall = fcall;
@@ -171,7 +167,6 @@ static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 
       FreeStructs:
         kfree(fcall);
-        kfree(mi);
         return ret;
 }