NFS: Optimise away unnecessary setattrs for open(O_TRUNC);
Currently, we will correctly optimise away a truncate that doesn't
change the file size. However, in the case of open(O_TRUNC), we
also want to optimise away the time changes.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index fd9a872..bb132a8 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1429,6 +1429,7 @@
}
open_flags = nd->intent.open.flags;
+ attr.ia_valid = 0;
ctx = create_nfs_open_context(dentry, open_flags);
res = ERR_CAST(ctx);
@@ -1437,11 +1438,14 @@
if (nd->flags & LOOKUP_CREATE) {
attr.ia_mode = nd->intent.open.create_mode;
- attr.ia_valid = ATTR_MODE;
+ attr.ia_valid |= ATTR_MODE;
attr.ia_mode &= ~current_umask();
- } else {
+ } else
open_flags &= ~(O_EXCL | O_CREAT);
- attr.ia_valid = 0;
+
+ if (open_flags & O_TRUNC) {
+ attr.ia_valid |= ATTR_SIZE;
+ attr.ia_size = 0;
}
/* Open the file on the server */
@@ -1495,6 +1499,7 @@
struct inode *inode;
struct inode *dir;
struct nfs_open_context *ctx;
+ struct iattr attr;
int openflags, ret = 0;
if (nd->flags & LOOKUP_RCU)
@@ -1523,19 +1528,27 @@
/* We cannot do exclusive creation on a positive dentry */
if ((openflags & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
goto no_open_dput;
- /* We can't create new files, or truncate existing ones here */
- openflags &= ~(O_CREAT|O_EXCL|O_TRUNC);
+ /* We can't create new files here */
+ openflags &= ~(O_CREAT|O_EXCL);
ctx = create_nfs_open_context(dentry, openflags);
ret = PTR_ERR(ctx);
if (IS_ERR(ctx))
goto out;
+
+ attr.ia_valid = 0;
+ if (openflags & O_TRUNC) {
+ attr.ia_valid |= ATTR_SIZE;
+ attr.ia_size = 0;
+ nfs_wb_all(inode);
+ }
+
/*
* Note: we're not holding inode->i_mutex and so may be racing with
* operations that change the directory. We therefore save the
* change attribute *before* we do the RPC call.
*/
- inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, NULL);
+ inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr);
if (IS_ERR(inode)) {
ret = PTR_ERR(inode);
switch (ret) {