Merge tag '5.16-rc-part2-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull more cifs updates from Steve French:

 - improvements to reconnect and multichannel

 - a performance improvement (additional use of SMB3 compounding)

 - DFS code cleanup and improvements

 - various trivial Coverity fixes

 - two fscache fixes

 - an fsync fix

* tag '5.16-rc-part2-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6: (23 commits)
  cifs: do not duplicate fscache cookie for secondary channels
  cifs: connect individual channel servers to primary channel server
  cifs: protect session channel fields with chan_lock
  cifs: do not negotiate session if session already exists
  smb3: do not setup the fscache_super_cookie until fsinfo initialized
  cifs: fix potential use-after-free bugs
  cifs: fix memory leak of smb3_fs_context_dup::server_hostname
  smb3: add additional null check in SMB311_posix_mkdir
  cifs: release lock earlier in dequeue_mid error case
  smb3: add additional null check in SMB2_tcon
  smb3: add additional null check in SMB2_open
  smb3: add additional null check in SMB2_ioctl
  smb3: remove trivial dfs compile warning
  cifs: support nested dfs links over reconnect
  smb3: do not error on fsync when readonly
  cifs: for compound requests, use open handle if possible
  cifs: set a minimum of 120s for next dns resolution
  cifs: split out dfs code from cifs_reconnect()
  cifs: convert list_for_each to entry variant
  cifs: introduce new helper for cifs_reconnect()
  ...

1 files changed, 29 insertions, 6 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1b855fcb179e..9fee3af83a73 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2692,12 +2692,23 @@ int cifs_strict_fsync(struct file *file, loff_t start, loff_t end,
 	tcon = tlink_tcon(smbfile->tlink);
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
 		server = tcon->ses->server;
-		if (server->ops->flush)
-			rc = server->ops->flush(xid, tcon, &smbfile->fid);
-		else
+		if (server->ops->flush == NULL) {
 			rc = -ENOSYS;
+			goto strict_fsync_exit;
+		}
+
+		if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) {
+			smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY);
+			if (smbfile) {
+				rc = server->ops->flush(xid, tcon, &smbfile->fid);
+				cifsFileInfo_put(smbfile);
+			} else
+				cifs_dbg(FYI, "ignore fsync for file not open for write\n");
+		} else
+			rc = server->ops->flush(xid, tcon, &smbfile->fid);
 	}
 
+strict_fsync_exit:
 	free_xid(xid);
 	return rc;
 }
@@ -2709,6 +2720,7 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	struct cifs_tcon *tcon;
 	struct TCP_Server_Info *server;
 	struct cifsFileInfo *smbfile = file->private_data;
+	struct inode *inode = file_inode(file);
 	struct cifs_sb_info *cifs_sb = CIFS_FILE_SB(file);
 
 	rc = file_write_and_wait_range(file, start, end);
@@ -2725,12 +2737,23 @@ int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	tcon = tlink_tcon(smbfile->tlink);
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOSSYNC)) {
 		server = tcon->ses->server;
-		if (server->ops->flush)
-			rc = server->ops->flush(xid, tcon, &smbfile->fid);
-		else
+		if (server->ops->flush == NULL) {
 			rc = -ENOSYS;
+			goto fsync_exit;
+		}
+
+		if ((OPEN_FMODE(smbfile->f_flags) & FMODE_WRITE) == 0) {
+			smbfile = find_writable_file(CIFS_I(inode), FIND_WR_ANY);
+			if (smbfile) {
+				rc = server->ops->flush(xid, tcon, &smbfile->fid);
+				cifsFileInfo_put(smbfile);
+			} else
+				cifs_dbg(FYI, "ignore fsync for file not open for write\n");
+		} else
+			rc = server->ops->flush(xid, tcon, &smbfile->fid);
 	}
 
+fsync_exit:
 	free_xid(xid);
 	return rc;
 }