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NFS: Optimise away unnecessary setattrs for open(O_TRUNC);

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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>
This commit is contained in:
Trond Myklebust
2012-01-17 22:04:26 -05:00
parent 48c22eb210
commit 536e43d12b
3 changed files with 28 additions and 11 deletions
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25
fs/nfs/dir.c
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@@ -1429,6 +1429,7 @@ static struct dentry *nfs_atomic_lookup(struct inode *dir, struct dentry *dentry
}
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 @@ static struct dentry *nfs_atomic_lookup(struct inode *dir, struct dentry *dentry
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 @@ static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
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 @@ static int nfs_open_revalidate(struct dentry *dentry, struct nameidata *nd)
/* 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) {