incorrect lock checks in cifs_writev()

[Steve French <smfrench@xxxxxxxxx>]

In file.c we are checking for Windows style lock conflicts (even
though this is Linux) for cached i/o which seems wrong (unless user
mouns with "forcemandatorylock" which today is ignored for non-POSIX
mounts)

One obvious way to fix this would be to do something like this change:

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 45459af5044d..a6c97af31cdf 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2789,9 +2789,6 @@ cifs_strict_writev(struct kiocb *iocb, struct
iov_iter *from)
        struct inode *inode = file_inode(iocb->ki_filp);
        struct cifsInodeInfo *cinode = CIFS_I(inode);
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-       struct cifsFileInfo *cfile = (struct cifsFileInfo *)
-                                               iocb->ki_filp->private_data;
-       struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
        ssize_t written;

        written = cifs_get_writer(cinode);
@@ -2799,9 +2796,7 @@ cifs_strict_writev(struct kiocb *iocb, struct
iov_iter *from)
                return written;

        if (CIFS_CACHE_WRITE(cinode)) {
-               if (cap_unix(tcon->ses) &&
-                   (CIFS_UNIX_FCNTL_CAP &
le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
-                   ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) {
+                   if ((cifs_sb->mnt_cifs_flags &
CIFS_MOUNT_NOPOSIXBRL) == 0) {
                        written = netfs_file_write_iter(iocb, from);
                        goto out;
                }


Another would be something like:
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 45459af5044d..57f9d934eb4e 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2753,6 +2753,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
        struct inode *inode = file->f_mapping->host;
        struct cifsInodeInfo *cinode = CIFS_I(inode);
        struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
+       struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
        ssize_t rc;

        rc = netfs_start_io_write(inode);
@@ -2769,12 +2770,16 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
        if (rc <= 0)
                goto out;

-       if (!cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from),
+       if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL))
+               if (cifs_find_lock_conflict(cfile, iocb->ki_pos,
iov_iter_count(from),
                                     server->vals->exclusive_lock_type, 0,
-                                    NULL, CIFS_WRITE_OP))
-               rc = netfs_buffered_write_iter_locked(iocb, from, NULL);
-       else
-               rc = -EACCES;
+                                    NULL, CIFS_WRITE_OP)) {
+                       rc = -EACCES;
+                       goto out;
+               }
+
+       rc = netfs_buffered_write_iter_locked(iocb, from, NULL);
+
 out:
        up_read(&cinode->lock_sem);
        netfs_end_io_write(inode);


Any opinions about which approach looks better?

-- 
Thanks,

Steve

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 45459af5044d..a6c97af31cdf 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2789,9 +2789,6 @@ cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *inode = file_inode(iocb->ki_filp);
 	struct cifsInodeInfo *cinode = CIFS_I(inode);
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
-	struct cifsFileInfo *cfile = (struct cifsFileInfo *)
-						iocb->ki_filp->private_data;
-	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	ssize_t written;
 
 	written = cifs_get_writer(cinode);
@@ -2799,9 +2796,7 @@ cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
 		return written;
 
 	if (CIFS_CACHE_WRITE(cinode)) {
-		if (cap_unix(tcon->ses) &&
-		    (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
-		    ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) {
+		    if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) {
 			written = netfs_file_write_iter(iocb, from);
 			goto out;
 		}

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 45459af5044d..57f9d934eb4e 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2753,6 +2753,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *inode = file->f_mapping->host;
 	struct cifsInodeInfo *cinode = CIFS_I(inode);
 	struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 	ssize_t rc;
 
 	rc = netfs_start_io_write(inode);
@@ -2769,12 +2770,16 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 	if (rc <= 0)
 		goto out;
 
-	if (!cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from),
+	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL))
+		if (cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from),
 				     server->vals->exclusive_lock_type, 0,
-				     NULL, CIFS_WRITE_OP))
-		rc = netfs_buffered_write_iter_locked(iocb, from, NULL);
-	else
-		rc = -EACCES;
+				     NULL, CIFS_WRITE_OP)) {
+			rc = -EACCES;
+			goto out;
+		}
+
+	rc = netfs_buffered_write_iter_locked(iocb, from, NULL);
+
 out:
 	up_read(&cinode->lock_sem);
 	netfs_end_io_write(inode);