Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

[linux-2.6] / fs / ecryptfs / mmap.c

diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 16a7a555f39264a829ce70a9d2e8c9ba954c87c3..32c5711d79a320593e9a536590f3b347905055bd 100644 (file)
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -263,14 +263,13 @@ out:
        return 0;
 }
 
+/* This function must zero any hole we create */
 static int ecryptfs_prepare_write(struct file *file, struct page *page,
                                  unsigned from, unsigned to)
 {
        int rc = 0;
+       loff_t prev_page_end_size;
 
-       if (from == 0 && to == PAGE_CACHE_SIZE)
-               goto out;       /* If we are writing a full page, it will be
-                                  up to date. */
        if (!PageUptodate(page)) {
                rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
                                                      PAGE_CACHE_SIZE,
@@ -283,22 +282,32 @@ static int ecryptfs_prepare_write(struct file *file, struct page *page,
                } else
                        SetPageUptodate(page);
        }
-       if (page->index != 0) {
-               loff_t end_of_prev_pg_pos =
-                       (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1);
 
-               if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) {
+       prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
+
+       /*
+        * If creating a page or more of holes, zero them out via truncate.
+        * Note, this will increase i_size.
+        */
+       if (page->index != 0) {
+               if (prev_page_end_size > i_size_read(page->mapping->host)) {
                        rc = ecryptfs_truncate(file->f_path.dentry,
-                                              end_of_prev_pg_pos);
+                                              prev_page_end_size);
                        if (rc) {
                                printk(KERN_ERR "Error on attempt to "
                                       "truncate to (higher) offset [%lld];"
-                                      " rc = [%d]\n", end_of_prev_pg_pos, rc);
+                                      " rc = [%d]\n", prev_page_end_size, rc);
                                goto out;
                        }
                }
-               if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host))
-                       zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
+       }
+       /*
+        * Writing to a new page, and creating a small hole from start of page?
+        * Zero it out.
+        */
+       if ((i_size_read(page->mapping->host) == prev_page_end_size) &&
+           (from != 0)) {
+               zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
        }
 out:
        return rc;