ext4: Add auto_da_alloc mount option

Add a mount option which allows the user to disable automatic
allocation of blocks whose allocation by delayed allocation when the
file was originally truncated or when the file is renamed over an
existing file.  This feature is intended to save users from the
effects of naive application writers, but it reduces the effectiveness
of the delayed allocation code.  This mount option disables this
safety feature, which may be desirable for prodcutions systems where
the risk of unclean shutdowns or unexpected system crashes is low.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 46aaaa2ed4c5..a004699e7296 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -549,7 +549,7 @@ do {									       \
 #define EXT4_MOUNT_NO_UID32             0x02000  /* Disable 32-bit UIDs */
 #define EXT4_MOUNT_XATTR_USER           0x04000 /* Extended user attributes */
 #define EXT4_MOUNT_POSIX_ACL            0x08000 /* POSIX Access Control Lists */
-#define EXT4_MOUNT_RESERVATION          0x10000 /* Preallocation */
+#define EXT4_MOUNT_NO_AUTO_DA_ALLOC     0x10000 /* No auto delalloc mapping */
 #define EXT4_MOUNT_BARRIER              0x20000 /* Use block barriers */
 #define EXT4_MOUNT_NOBH                 0x40000 /* No bufferheads */
 #define EXT4_MOUNT_QUOTA                0x80000 /* Some quota option set */