[CIFS] file create with acl support enabled is slow

Shirish Pargaonkar noted:
With cifsacl mount option, when a file is created on the Windows server,
exclusive oplock is broken right away because the get cifs acl code
again opens the file to obtain security descriptor.
The client does not have the newly created file handle or inode in any
of its lists yet so it does not respond to oplock break and server waits for
its duration and then responds to the second open. This slows down file
creation signficantly.  The fix is to pass the file descriptor to the get
cifsacl code wherever available so that get cifs acl code does not send
second open (NT Create ANDX) and oplock is not broken.

CC: Shirish Pargaonkar <shirishp@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 15 insertions, 10 deletions

diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index f93932c..1f5a428 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -1,7 +1,7 @@
 /*
  *   fs/cifs/cifsacl.c
  *
- *   Copyright (C) International Business Machines  Corp., 2007
+ *   Copyright (C) International Business Machines  Corp., 2007,2008
  *   Author(s): Steve French (sfrench@us.ibm.com)
  *
  *   Contains the routines for mapping CIFS/NTFS ACLs
@@ -556,9 +556,9 @@ static int build_sec_desc(struct cifs_ntsd *pntsd, struct cifs_ntsd *pnntsd,
 
 /* Retrieve an ACL from the server */
 static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
-				       const char *path)
+				       const char *path, const __u16 *pfid)
 {
-	struct cifsFileInfo *open_file;
+	struct cifsFileInfo *open_file = NULL;
 	int unlock_file = FALSE;
 	int xid;
 	int rc = -EIO;
@@ -573,7 +573,11 @@ static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
 		return NULL;
 
 	xid = GetXid();
-	open_file = find_readable_file(CIFS_I(inode));
+	if (pfid == NULL)
+		open_file = find_readable_file(CIFS_I(inode));
+	else
+		fid = *pfid;
+
 	sb = inode->i_sb;
 	if (sb == NULL) {
 		FreeXid(xid);
@@ -584,7 +588,7 @@ static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
 	if (open_file) {
 		unlock_file = TRUE;
 		fid = open_file->netfid;
-	} else {
+	} else if (pfid == NULL) {
 		int oplock = FALSE;
 		/* open file */
 		rc = CIFSSMBOpen(xid, cifs_sb->tcon, path, FILE_OPEN,
@@ -600,10 +604,11 @@ static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
 
 	rc = CIFSSMBGetCIFSACL(xid, cifs_sb->tcon, fid, &pntsd, pacllen);
 	cFYI(1, ("GetCIFSACL rc = %d ACL len %d", rc, *pacllen));
-	if (unlock_file == TRUE)
+	if (unlock_file == TRUE) /* find_readable_file increments ref count */
 		atomic_dec(&open_file->wrtPending);
-	else
+	else if (pfid == NULL) /* if opened above we have to close the handle */
 		CIFSSMBClose(xid, cifs_sb->tcon, fid);
+	/* else handle was passed in by caller */
 
 	FreeXid(xid);
 	return pntsd;
@@ -664,14 +669,14 @@ static int set_cifs_acl(struct cifs_ntsd *pnntsd, __u32 acllen,
 }
 
 /* Translate the CIFS ACL (simlar to NTFS ACL) for a file into mode bits */
-void acl_to_uid_mode(struct inode *inode, const char *path)
+void acl_to_uid_mode(struct inode *inode, const char *path, const __u16 *pfid)
 {
 	struct cifs_ntsd *pntsd = NULL;
 	u32 acllen = 0;
 	int rc = 0;
 
 	cFYI(DBG2, ("converting ACL to mode for %s", path));
-	pntsd = get_cifs_acl(&acllen, inode, path);
+	pntsd = get_cifs_acl(&acllen, inode, path, pfid);
 
 	/* if we can retrieve the ACL, now parse Access Control Entries, ACEs */
 	if (pntsd)
@@ -694,7 +699,7 @@ int mode_to_acl(struct inode *inode, const char *path, __u64 nmode)
 	cFYI(DBG2, ("set ACL from mode for %s", path));
 
 	/* Get the security descriptor */
-	pntsd = get_cifs_acl(&acllen, inode, path);
+	pntsd = get_cifs_acl(&acllen, inode, path, NULL);
 
 	/* Add three ACEs for owner, group, everyone getting rid of
 	   other ACEs as chmod disables ACEs and set the security descriptor */