X-Git-Url: http://pilppa.org/gitweb/?a=blobdiff_plain;f=fs%2Fecryptfs%2Fread_write.c;h=948f57624c05dd2bb1750ff05628f7931f44f2b7;hb=88fb61e4ba263685a0d5b82c7e9cd6f22a9e6a9d;hp=2150edf9a58e6db662adcb12bb9ae279ad306c2d;hpb=16a72c455a67bb23eed7292a31c6ba17729e78e6;p=linux-2.6-omap-h63xx.git

diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index 2150edf9a58..948f57624c0 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -87,7 +87,7 @@ int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
 	loff_t offset;
 	int rc;
 
-	offset = ((((off_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
+	offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
 		  + offset_in_page);
 	virt = kmap(page_for_lower);
 	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
@@ -124,6 +124,10 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
 	loff_t pos;
 	int rc = 0;
 
+	/*
+	 * if we are writing beyond current size, then start pos
+	 * at the current size - we'll fill in zeros from there.
+	 */
 	if (offset > ecryptfs_file_size)
 		pos = ecryptfs_file_size;
 	else
@@ -137,6 +141,7 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
 		if (num_bytes > total_remaining_bytes)
 			num_bytes = total_remaining_bytes;
 		if (pos < offset) {
+			/* remaining zeros to write, up to destination offset */
 			size_t total_remaining_zeros = (offset - pos);
 
 			if (num_bytes > total_remaining_zeros)
@@ -167,17 +172,27 @@ int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
 			}
 		}
 		ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
+
+		/*
+		 * pos: where we're now writing, offset: where the request was
+		 * If current pos is before request, we are filling zeros
+		 * If we are at or beyond request, we are writing the *data*
+		 * If we're in a fresh page beyond eof, zero it in either case
+		 */
+		if (pos < offset || !start_offset_in_page) {
+			/* We are extending past the previous end of the file.
+			 * Fill in zero values to the end of the page */
+			memset(((char *)ecryptfs_page_virt
+				+ start_offset_in_page), 0,
+				PAGE_CACHE_SIZE - start_offset_in_page);
+		}
+
+		/* pos >= offset, we are now writing the data request */
 		if (pos >= offset) {
 			memcpy(((char *)ecryptfs_page_virt
 				+ start_offset_in_page),
 			       (data + data_offset), num_bytes);
 			data_offset += num_bytes;
-		} else {
-			/* We are extending past the previous end of the file.
-			 * Fill in zero values up to the start of where we
-			 * will be writing data. */
-			memset(((char *)ecryptfs_page_virt
-				+ start_offset_in_page), 0, num_bytes);
 		}
 		kunmap_atomic(ecryptfs_page_virt, KM_USER0);
 		flush_dcache_page(ecryptfs_page);