[PATCH 3/6] CIFS: Make write call work with strict cache mode (try #3)

[Pavel Shilovsky <piastryyy-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On strict cache mode if we don't have Exclusive oplock we write a data to
the server through cifs_user_write. Also set inode invalid_mapping flag if
we have written anything to the server.

Signed-off-by: Pavel Shilovsky <piastryyy-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 fs/cifs/cifsfs.c |   49 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 431c46e..0732538 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -609,12 +609,51 @@ static ssize_t cifs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
 static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 				   unsigned long nr_segs, loff_t pos)
 {
-	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
-	ssize_t written;
+	struct inode *inode;
+	struct cifs_sb_info *cifs_sb;
+	ssize_t written = 0, retval;
+	unsigned long i;
+
+	inode = iocb->ki_filp->f_path.dentry->d_inode;
+
+	if (CIFS_I(inode)->clientCanCacheAll)
+		return generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+	cifs_sb = CIFS_SB(iocb->ki_filp->f_path.dentry->d_sb);
+
+	if ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) == 0) {
+		int rc;
+
+		written = generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+		rc = filemap_fdatawrite(inode->i_mapping);
+		if (rc)
+			cFYI(1, "cifs_file_aio_write: %d rc on %p inode",
+			     rc, inode);
+		return written;
+	}
+
+	/* In strict cache mode we need to write the data to the server exactly
+	 * from the pos to pos+len-1 rather than flush all affected pages
+	 * because it may cause a error with mandatory locks on these pages but
+	 * not on the region from pos to ppos+len-1. */
+
+	for (i = 0; i < nr_segs; i++) {
+		retval = cifs_user_write(iocb->ki_filp, iov[i].iov_base,
+					 iov[i].iov_len, &pos);
+		if (retval < 0) {
+			written = written ? written : retval;
+			break;
+		}
+
+		written += retval;
+	}
+
+	iocb->ki_pos = pos;
+
+	if (written > 0)
+		CIFS_I(inode)->invalid_mapping = true;
 
-	written = generic_file_aio_write(iocb, iov, nr_segs, pos);
-	if (!CIFS_I(inode)->clientCanCacheAll)
-		filemap_fdatawrite(inode->i_mapping);
 	return written;
 }
 
-- 
1.7.3.2