ext4: Convert truncate_mutex to read write semaphore.

We are currently taking the truncate_mutex for every read. This would have
performance impact on large CPU configuration. Convert the lock to read write
semaphore and take read lock when we are trying to read the file.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index d460223b8e1d..7ae223ed152f 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -526,7 +526,7 @@ static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
  * when setting the reservation window size through ioctl before the file
  * is open for write (needs block allocation).
  *
- * Needs truncate_mutex protection prior to call this function.
+ * Needs down_write(i_data_sem) protection prior to call this function.
  */
 void ext4_init_block_alloc_info(struct inode *inode)
 {