ext4: Fix discard of inode prealloc space with delayed allocation.

With delayed allocation we should not/cannot discard inode prealloc
space during file close. We would still have dirty pages for which we
haven't allocated blocks yet. With this fix after each get_blocks
request we check whether we have zero reserved blocks and if yes and
we don't have any writers on the file we discard inode prealloc space.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 10 insertions, 2 deletions

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 06df8272c639..588af8c77246 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -39,7 +39,8 @@ static int ext4_release_file(struct inode *inode, struct file *filp)
         }
         /* if we are the last writer on the inode, drop the block reservation */
         if ((filp->f_mode & FMODE_WRITE) &&
-                        (atomic_read(&inode->i_writecount) == 1))
+                        (atomic_read(&inode->i_writecount) == 1) &&
+                        !EXT4_I(inode)->i_reserved_data_blocks)
         {
                 down_write(&EXT4_I(inode)->i_data_sem);
                 ext4_discard_preallocations(inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 80ed6dc9c9d2..7dcac9d7e491 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1067,9 +1067,16 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
         /*
          * free those over-booking quota for metadata blocks
          */
-
         if (mdb_free)
                 vfs_dq_release_reservation_block(inode, mdb_free);
+
+        /*
+         * If we have done all the pending block allocations and if
+         * there aren't any writers on the inode, we can discard the
+         * inode's preallocations.
+         */
+        if (!total && (atomic_read(&inode->i_writecount) == 0))
+                ext4_discard_preallocations(inode);
 }
 
 /*