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Subject: [PATCH 3/7] cifs: Add some helper functions
From:   David Howells <dhowells@redhat.com>
To:     Steve French <smfrench@gmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>
Cc:     Steve French <sfrench@samba.org>,
        Shyam Prasad N <nspmangalore@gmail.com>,
        Rohith Surabattula <rohiths.msft@gmail.com>,
        linux-cifs@vger.kernel.org, dhowells@redhat.com,
        Shyam Prasad N <nspmangalore@gmail.com>,
        Rohith Surabattula <rohiths.msft@gmail.com>,
        Jeff Layton <jlayton@kernel.org>, linux-cifs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 23 Aug 2022 15:12:28 +0100
Message-ID: <166126394799.708021.10637797063862600488.stgit@warthog.procyon.org.uk>
In-Reply-To: <166126392703.708021.14465850073772688008.stgit@warthog.procyon.org.uk>
References: <166126392703.708021.14465850073772688008.stgit@warthog.procyon.org.uk>
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Precedence: bulk

Add some helper functions to manipulate the folio marks by iterating
through a list of folios held in an xarray rather than using a page list.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: linux-cifs@vger.kernel.org
---

 fs/cifs/cifsfs.h |    3 ++
 fs/cifs/file.c   |   93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 81f4c15936d0..bbc7aa31cc94 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -110,6 +110,9 @@ extern int cifs_file_strict_mmap(struct file * , struct vm_area_struct *);
 extern const struct file_operations cifs_dir_ops;
 extern int cifs_dir_open(struct inode *inode, struct file *file);
 extern int cifs_readdir(struct file *file, struct dir_context *ctx);
+extern void cifs_pages_written_back(struct inode *inode, loff_t start, unsigned int len);
+extern void cifs_pages_write_failed(struct inode *inode, loff_t start, unsigned int len);
+extern void cifs_pages_write_redirty(struct inode *inode, loff_t start, unsigned int len);
 
 /* Functions related to dir entries */
 extern const struct dentry_operations cifs_dentry_ops;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index fa738adc031f..6dfd96715274 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -36,6 +36,99 @@
 #include "cifs_ioctl.h"
 #include "cached_dir.h"
 
+/*
+ * Completion of write to server.
+ */
+void cifs_pages_written_back(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		folio_detach_private(folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
+/*
+ * Failure of write to server.
+ */
+void cifs_pages_write_failed(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		folio_set_error(folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
+/*
+ * Redirty pages after a temporary failure.
+ */
+void cifs_pages_write_redirty(struct inode *inode, loff_t start, unsigned int len)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	pgoff_t end;
+
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
+
+	if (!len)
+		return;
+
+	rcu_read_lock();
+
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, folio, end) {
+		if (!folio_test_writeback(folio)) {
+			WARN_ONCE(1, "bad %x @%llx page %lx %lx\n",
+				  len, start, folio_index(folio), end);
+			continue;
+		}
+
+		filemap_dirty_folio(folio->mapping, folio);
+		folio_end_writeback(folio);
+	}
+
+	rcu_read_unlock();
+}
+
 /*
  * Mark as invalid, all open files on tree connections since they
  * were closed when session to server was lost.