1 files changed, 20 insertions, 10 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 30dbbd1df511..27f3e787faca 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -857,6 +857,7 @@ do_holes:
 			/* Handle holes */
 			if (!buffer_mapped(map_bh)) {
 				char *kaddr;
+				loff_t i_size_aligned;
 
 				/* AKPM: eargh, -ENOTBLK is a hack */
 				if (dio->rw == WRITE) {
@@ -864,8 +865,14 @@ do_holes:
 					return -ENOTBLK;
 				}
 
+				/*
+				 * Be sure to account for a partial block as the
+				 * last block in the file
+				 */
+				i_size_aligned = ALIGN(i_size_read(dio->inode),
+							1 << blkbits);
 				if (dio->block_in_file >=
-					i_size_read(dio->inode)>>blkbits) {
+						i_size_aligned >> blkbits) {
 					/* We hit eof */
 					page_cache_release(page);
 					goto out;
@@ -1148,15 +1155,16 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
  * For writes, i_mutex is not held on entry; it is never taken.
  *
  * DIO_LOCKING (simple locking for regular files)
- * For writes we are called under i_mutex and return with i_mutex held, even though
- * it is internally dropped.
+ * For writes we are called under i_mutex and return with i_mutex held, even
+ * though it is internally dropped.
  * For reads, i_mutex is not held on entry, but it is taken and dropped before
  * returning.
  *
  * DIO_OWN_LOCKING (filesystem provides synchronisation and handling of
  *	uninitialised data, allowing parallel direct readers and writers)
  * For writes we are called without i_mutex, return without it, never touch it.
- * For reads, i_mutex is held on entry and will be released before returning.
+ * For reads we are called under i_mutex and return with i_mutex held, even
+ * though it may be internally dropped.
  *
  * Additional i_alloc_sem locking requirements described inline below.
  */
@@ -1175,7 +1183,8 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 	ssize_t retval = -EINVAL;
 	loff_t end = offset;
 	struct dio *dio;
-	int reader_with_isem = (rw == READ && dio_lock_type == DIO_OWN_LOCKING);
+	int release_i_mutex = 0;
+	int acquire_i_mutex = 0;
 
 	if (rw & WRITE)
 		current->flags |= PF_SYNCWRITE;
@@ -1218,7 +1227,6 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 	 *	writers need to grab i_alloc_sem only (i_mutex is already held)
 	 * For regular files using DIO_OWN_LOCKING,
 	 *	neither readers nor writers take any locks here
-	 *	(i_mutex is already held and release for writers here)
 	 */
 	dio->lock_type = dio_lock_type;
 	if (dio_lock_type != DIO_NO_LOCKING) {
@@ -1229,7 +1237,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 			mapping = iocb->ki_filp->f_mapping;
 			if (dio_lock_type != DIO_OWN_LOCKING) {
 				mutex_lock(&inode->i_mutex);
-				reader_with_isem = 1;
+				release_i_mutex = 1;
 			}
 
 			retval = filemap_write_and_wait_range(mapping, offset,
@@ -1241,7 +1249,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 
 			if (dio_lock_type == DIO_OWN_LOCKING) {
 				mutex_unlock(&inode->i_mutex);
-				reader_with_isem = 0;
+				acquire_i_mutex = 1;
 			}
 		}
 
@@ -1262,11 +1270,13 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
 				nr_segs, blkbits, get_blocks, end_io, dio);
 
 	if (rw == READ && dio_lock_type == DIO_LOCKING)
-		reader_with_isem = 0;
+		release_i_mutex = 0;
 
 out:
-	if (reader_with_isem)
+	if (release_i_mutex)
 		mutex_unlock(&inode->i_mutex);
+	else if (acquire_i_mutex)
+		mutex_lock(&inode->i_mutex);
 	if (rw & WRITE)
 		current->flags &= ~PF_SYNCWRITE;
 	return retval;