ocfs2: shared writeable mmap
Implement cluster consistent shared writeable mappings using the
->page_mkwrite() callback.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index fc723fb..b8869fd 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1034,7 +1034,8 @@
*/
static int ocfs2_grab_pages_for_write(struct address_space *mapping,
struct ocfs2_write_ctxt *wc,
- u32 cpos, loff_t user_pos, int new)
+ u32 cpos, loff_t user_pos, int new,
+ struct page *mmap_page)
{
int ret = 0, i;
unsigned long start, target_index, index;
@@ -1058,11 +1059,36 @@
for(i = 0; i < wc->w_num_pages; i++) {
index = start + i;
- wc->w_pages[i] = find_or_create_page(mapping, index, GFP_NOFS);
- if (!wc->w_pages[i]) {
- ret = -ENOMEM;
- mlog_errno(ret);
- goto out;
+ if (index == target_index && mmap_page) {
+ /*
+ * ocfs2_pagemkwrite() is a little different
+ * and wants us to directly use the page
+ * passed in.
+ */
+ lock_page(mmap_page);
+
+ if (mmap_page->mapping != mapping) {
+ unlock_page(mmap_page);
+ /*
+ * Sanity check - the locking in
+ * ocfs2_pagemkwrite() should ensure
+ * that this code doesn't trigger.
+ */
+ ret = -EINVAL;
+ mlog_errno(ret);
+ goto out;
+ }
+
+ page_cache_get(mmap_page);
+ wc->w_pages[i] = mmap_page;
+ } else {
+ wc->w_pages[i] = find_or_create_page(mapping, index,
+ GFP_NOFS);
+ if (!wc->w_pages[i]) {
+ ret = -ENOMEM;
+ mlog_errno(ret);
+ goto out;
+ }
}
if (index == target_index)
@@ -1213,10 +1239,10 @@
}
}
-static int ocfs2_write_begin_nolock(struct address_space *mapping,
- loff_t pos, unsigned len, unsigned flags,
- struct page **pagep, void **fsdata,
- struct buffer_head *di_bh)
+int ocfs2_write_begin_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ struct buffer_head *di_bh, struct page *mmap_page)
{
int ret, i, credits = OCFS2_INODE_UPDATE_CREDITS;
unsigned int num_clusters = 0, clusters_to_alloc = 0;
@@ -1318,7 +1344,7 @@
* extent.
*/
ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
- clusters_to_alloc);
+ clusters_to_alloc, mmap_page);
if (ret) {
mlog_errno(ret);
goto out_commit;
@@ -1386,7 +1412,7 @@
}
ret = ocfs2_write_begin_nolock(mapping, pos, len, flags, pagep,
- fsdata, di_bh);
+ fsdata, di_bh, NULL);
if (ret) {
mlog_errno(ret);
goto out_fail_data;
@@ -1407,9 +1433,9 @@
return ret;
}
-static int ocfs2_write_end_nolock(struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
+int ocfs2_write_end_nolock(struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
{
int i;
unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);