[PATCH] cifs: create a helper to find a writeable handle by path name

[Ronnie Sahlberg <lsahlber@redhat.com>]

rename() takes a path for old_file and in SMB2 we used to just create
a compound for create(old_path)/rename/close().
If we already have a writable handle we can avoid the create() and close()
altogether and just use the existing handle.

For this situation, as we avoid doing the create()
we also avoid triggering an oplock break for the existing handle.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
---
 fs/cifs/cifsproto.h |  2 ++
 fs/cifs/connect.c   |  2 +-
 fs/cifs/dir.c       |  2 +-
 fs/cifs/file.c      | 35 ++++++++++++++++++++
 fs/cifs/smb2inode.c | 94 ++++++++++++++++++++++++++++++++++++++---------------
 5 files changed, 107 insertions(+), 28 deletions(-)

diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 592a6cea2b79..be206744407c 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -137,6 +137,8 @@ extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *, bool);
 extern int cifs_get_writable_file(struct cifsInodeInfo *cifs_inode,
 				  bool fsuid_only,
 				  struct cifsFileInfo **ret_file);
+extern int cifs_get_writable_path(struct cifs_tcon *tcon, const char *name,
+				  struct cifsFileInfo **ret_file);
 extern struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *, bool);
 extern unsigned int smbCalcSize(void *buf, struct TCP_Server_Info *server);
 extern int decode_negTokenInit(unsigned char *security_blob, int length,
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1ed449f4a8ec..c5dc8265b671 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -4232,7 +4232,7 @@ build_unc_path_to_root(const struct smb_vol *vol,
 	unsigned int unc_len = strnlen(vol->UNC, MAX_TREE_SIZE + 1);
 
 	if (unc_len > MAX_TREE_SIZE)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
 	if (full_path == NULL)
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index be424e81e3ad..dd5ac841aefa 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -125,7 +125,7 @@ build_path_from_dentry_optional_prefix(struct dentry *direntry, bool prefix)
 	}
 	rcu_read_unlock();
 
-	full_path = kmalloc(namelen+1, GFP_KERNEL);
+	full_path = kmalloc(namelen+1, GFP_ATOMIC);
 	if (full_path == NULL)
 		return full_path;
 	full_path[namelen] = 0;	/* trailing null */
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 97090693d182..885740496dae 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1980,6 +1980,41 @@ find_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only)
 	return cfile;
 }
 
+int
+cifs_get_writable_path(struct cifs_tcon *tcon, const char *name,
+		       struct cifsFileInfo **ret_file)
+{
+	struct list_head *tmp;
+	struct cifsFileInfo *cfile;
+	struct cifsInodeInfo *cinode;
+	char *full_path;
+
+	*ret_file = NULL;
+
+	spin_lock(&tcon->open_file_lock);
+	list_for_each(tmp, &tcon->openFileList) {
+		cfile = list_entry(tmp, struct cifsFileInfo,
+			     tlist);
+		full_path = build_path_from_dentry(cfile->dentry);
+		if (full_path == NULL) {
+			spin_unlock(&tcon->open_file_lock);
+			return -ENOMEM;
+		}
+		if (strcmp(full_path, name)) {
+			kfree(full_path);
+			continue;
+		}
+
+		kfree(full_path);
+		cinode = CIFS_I(d_inode(cfile->dentry));
+		spin_unlock(&tcon->open_file_lock);
+		return cifs_get_writable_file(cinode, 0, ret_file);
+	}
+
+	spin_unlock(&tcon->open_file_lock);
+	return -ENOENT;
+}
+
 static int cifs_partialpagewrite(struct page *page, unsigned from, unsigned to)
 {
 	struct address_space *mapping = page->mapping;
diff --git a/fs/cifs/smb2inode.c b/fs/cifs/smb2inode.c
index d8d9cdfa30b6..939fc7b2234c 100644
--- a/fs/cifs/smb2inode.c
+++ b/fs/cifs/smb2inode.c
@@ -51,7 +51,8 @@ static int
 smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		 struct cifs_sb_info *cifs_sb, const char *full_path,
 		 __u32 desired_access, __u32 create_disposition,
-		 __u32 create_options, void *ptr, int command)
+		 __u32 create_options, void *ptr, int command,
+		 struct cifsFileInfo *cfile)
 {
 	int rc;
 	__le16 *utf16_path = NULL;
@@ -83,10 +84,16 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	resp_buftype[0] = resp_buftype[1] = resp_buftype[2] = CIFS_NO_BUFFER;
 	memset(rsp_iov, 0, sizeof(rsp_iov));
 
+	/* We already have a handle so we can skip the open */
+	if (cfile)
+		goto after_open;
+
 	/* Open */
 	utf16_path = cifs_convert_path_to_utf16(full_path, cifs_sb);
-	if (!utf16_path)
-		return -ENOMEM;
+	if (!utf16_path) {
+		rc = -ENOMEM;
+		goto finished;
+	}
 
 	oparms.tcon = tcon;
 	oparms.desired_access = desired_access;
@@ -106,7 +113,10 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	if (rc)
 		goto finished;
 
-	smb2_set_next_command(tcon, &rqst[num_rqst++]);
+	smb2_set_next_command(tcon, &rqst[num_rqst]);
+ after_open:
+	num_rqst++;
+	rc = 0;
 
 	/* Operation */
 	switch (command) {
@@ -210,14 +220,23 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 		size[1] = len + 2 /* null */;
 		data[1] = (__le16 *)ptr;
 
-		rc = SMB2_set_info_init(tcon, &rqst[num_rqst], COMPOUND_FID,
-					COMPOUND_FID, current->tgid,
-					FILE_RENAME_INFORMATION,
+		if (cfile)
+			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+						cfile->fid.persistent_fid,
+						cfile->fid.volatile_fid,
+					current->tgid, FILE_RENAME_INFORMATION,
+					SMB2_O_INFO_FILE, 0, data, size);
+		else {
+			rc = SMB2_set_info_init(tcon, &rqst[num_rqst],
+					COMPOUND_FID, COMPOUND_FID,
+					current->tgid, FILE_RENAME_INFORMATION,
 					SMB2_O_INFO_FILE, 0, data, size);
+			smb2_set_next_command(tcon, &rqst[num_rqst]);
+			smb2_set_related(&rqst[num_rqst]);
+		}
 		if (rc)
 			goto finished;
-		smb2_set_next_command(tcon, &rqst[num_rqst]);
-		smb2_set_related(&rqst[num_rqst++]);
+		num_rqst++;
 		trace_smb3_rename_enter(xid, ses->Suid, tcon->tid, full_path);
 		break;
 	case SMB2_OP_HARDLINK:
@@ -254,20 +273,36 @@ smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 	if (rc)
 		goto finished;
 
+	/* We already have a handle so we can skip the close */
+	if (cfile)
+		goto after_close;
 	/* Close */
 	memset(&close_iov, 0, sizeof(close_iov));
 	rqst[num_rqst].rq_iov = close_iov;
 	rqst[num_rqst].rq_nvec = 1;
 	rc = SMB2_close_init(tcon, &rqst[num_rqst], COMPOUND_FID,
 			     COMPOUND_FID);
-	smb2_set_related(&rqst[num_rqst++]);
+	smb2_set_related(&rqst[num_rqst]);
 	if (rc)
 		goto finished;
-
-	rc = compound_send_recv(xid, ses, flags, num_rqst, rqst,
-				resp_buftype, rsp_iov);
+ after_close:
+	num_rqst++;
+
+	if (cfile) {
+		cifsFileInfo_put(cfile);
+		cfile = NULL;
+		rc = compound_send_recv(xid, ses, flags, num_rqst - 2,
+					&rqst[1], &resp_buftype[1],
+					&rsp_iov[1]);
+	} else
+		rc = compound_send_recv(xid, ses, flags, num_rqst,
+					rqst, resp_buftype,
+					rsp_iov);
 
  finished:
+	if (cfile)
+		cifsFileInfo_put(cfile);
+
 	SMB2_open_free(&rqst[0]);
 	switch (command) {
 	case SMB2_OP_QUERY_INFO:
@@ -404,7 +439,7 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,
 			      FILE_READ_ATTRIBUTES, FILE_OPEN, create_options,
-			      smb2_data, SMB2_OP_QUERY_INFO);
+			      smb2_data, SMB2_OP_QUERY_INFO, NULL);
 	if (rc == -EOPNOTSUPP) {
 		*symlink = true;
 		create_options |= OPEN_REPARSE_POINT;
@@ -413,7 +448,7 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 		rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,
 				      FILE_READ_ATTRIBUTES, FILE_OPEN,
 				      create_options, smb2_data,
-				      SMB2_OP_QUERY_INFO);
+				      SMB2_OP_QUERY_INFO, NULL);
 	}
 	if (rc)
 		goto out;
@@ -430,7 +465,7 @@ smb2_mkdir(const unsigned int xid, struct cifs_tcon *tcon, const char *name,
 {
 	return smb2_compound_op(xid, tcon, cifs_sb, name,
 				FILE_WRITE_ATTRIBUTES, FILE_CREATE,
-				CREATE_NOT_FILE, NULL, SMB2_OP_MKDIR);
+				CREATE_NOT_FILE, NULL, SMB2_OP_MKDIR, NULL);
 }
 
 void
@@ -449,7 +484,8 @@ smb2_mkdir_setinfo(struct inode *inode, const char *name,
 	data.Attributes = cpu_to_le32(dosattrs);
 	tmprc = smb2_compound_op(xid, tcon, cifs_sb, name,
 				 FILE_WRITE_ATTRIBUTES, FILE_CREATE,
-				 CREATE_NOT_FILE, &data, SMB2_OP_SET_INFO);
+				 CREATE_NOT_FILE, &data, SMB2_OP_SET_INFO,
+				 NULL);
 	if (tmprc == 0)
 		cifs_i->cifsAttrs = dosattrs;
 }
@@ -460,7 +496,7 @@ smb2_rmdir(const unsigned int xid, struct cifs_tcon *tcon, const char *name,
 {
 	return smb2_compound_op(xid, tcon, cifs_sb, name, DELETE, FILE_OPEN,
 				CREATE_NOT_FILE,
-				NULL, SMB2_OP_RMDIR);
+				NULL, SMB2_OP_RMDIR, NULL);
 }
 
 int
@@ -469,13 +505,14 @@ smb2_unlink(const unsigned int xid, struct cifs_tcon *tcon, const char *name,
 {
 	return smb2_compound_op(xid, tcon, cifs_sb, name, DELETE, FILE_OPEN,
 				CREATE_DELETE_ON_CLOSE | OPEN_REPARSE_POINT,
-				NULL, SMB2_OP_DELETE);
+				NULL, SMB2_OP_DELETE, NULL);
 }
 
 static int
 smb2_set_path_attr(const unsigned int xid, struct cifs_tcon *tcon,
 		   const char *from_name, const char *to_name,
-		   struct cifs_sb_info *cifs_sb, __u32 access, int command)
+		   struct cifs_sb_info *cifs_sb, __u32 access, int command,
+		   struct cifsFileInfo *cfile)
 {
 	__le16 *smb2_to_name = NULL;
 	int rc;
@@ -486,7 +523,7 @@ smb2_set_path_attr(const unsigned int xid, struct cifs_tcon *tcon,
 		goto smb2_rename_path;
 	}
 	rc = smb2_compound_op(xid, tcon, cifs_sb, from_name, access,
-			      FILE_OPEN, 0, smb2_to_name, command);
+			      FILE_OPEN, 0, smb2_to_name, command, cfile);
 smb2_rename_path:
 	kfree(smb2_to_name);
 	return rc;
@@ -497,8 +534,12 @@ smb2_rename_path(const unsigned int xid, struct cifs_tcon *tcon,
 		 const char *from_name, const char *to_name,
 		 struct cifs_sb_info *cifs_sb)
 {
-	return smb2_set_path_attr(xid, tcon, from_name, to_name, cifs_sb,
-				  DELETE, SMB2_OP_RENAME);
+	struct cifsFileInfo *cfile;
+
+	cifs_get_writable_path(tcon, from_name, &cfile);
+
+	return smb2_set_path_attr(xid, tcon, from_name, to_name,
+				  cifs_sb, DELETE, SMB2_OP_RENAME, cfile);
 }
 
 int
@@ -507,7 +548,8 @@ smb2_create_hardlink(const unsigned int xid, struct cifs_tcon *tcon,
 		     struct cifs_sb_info *cifs_sb)
 {
 	return smb2_set_path_attr(xid, tcon, from_name, to_name, cifs_sb,
-				  FILE_READ_ATTRIBUTES, SMB2_OP_HARDLINK);
+				  FILE_READ_ATTRIBUTES, SMB2_OP_HARDLINK,
+				  NULL);
 }
 
 int
@@ -519,7 +561,7 @@ smb2_set_path_size(const unsigned int xid, struct cifs_tcon *tcon,
 
 	return smb2_compound_op(xid, tcon, cifs_sb, full_path,
 				FILE_WRITE_DATA, FILE_OPEN, 0, &eof,
-				SMB2_OP_SET_EOF);
+				SMB2_OP_SET_EOF, NULL);
 }
 
 int
@@ -541,7 +583,7 @@ smb2_set_file_info(struct inode *inode, const char *full_path,
 
 	rc = smb2_compound_op(xid, tlink_tcon(tlink), cifs_sb, full_path,
 			      FILE_WRITE_ATTRIBUTES, FILE_OPEN, 0, buf,
-			      SMB2_OP_SET_INFO);
+			      SMB2_OP_SET_INFO, NULL);
 	cifs_put_tlink(tlink);
 	return rc;
 }
-- 
2.13.6