ext4: fix reserved cluster accounting at delayed write time

The code in ext4_da_map_blocks sometimes reserves space for more
delayed allocated clusters than it should, resulting in premature
ENOSPC, exceeded quota, and inaccurate free space reporting.

Fix this by checking for written and unwritten blocks shared in the
same cluster with the newly delayed allocated block.  A cluster
reservation should not be made for a cluster for which physical space
has already been allocated.

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index fc0f41dbf90b..d85fd5c8a2c4 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3155,6 +3155,7 @@ extern int ext4_swap_extents(handle_t *handle, struct inode *inode1,
                                 struct inode *inode2, ext4_lblk_t lblk1,
                              ext4_lblk_t lblk2,  ext4_lblk_t count,
                              int mark_unwritten,int *err);
+extern int ext4_clu_mapped(struct inode *inode, ext4_lblk_t lclu);
 
 /* move_extent.c */
 extern void ext4_double_down_write_data_sem(struct inode *first,