[patch 49/60] ext4: Fix discard of inode prealloc space with delayed allocation.

[Greg KH]

-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>

(cherry picked from commit d6014301b5599fba395c42a1e96a7fe86f7d0b2d)

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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 fs/ext4/file.c  |    3 ++-
 fs/ext4/inode.c |    8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -39,7 +39,8 @@ static int ext4_release_file (struct ino
 	}
 	/* 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_reservation(inode);
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1046,6 +1046,14 @@ static void ext4_da_update_reserve_space
 	EXT4_I(inode)->i_reserved_meta_blocks = mdb;
 	EXT4_I(inode)->i_allocated_meta_blocks = 0;
 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+	/*
+	 * 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_reservation(inode);
 }
 
 /*


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