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

(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@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 06df8272c63964c39330367ca791a0d32bbbe62d..588af8c77246f71b9a2b088602dba33b88c43f52 100644 (file)
--- 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 afb3ea2d1cf335b8c808f8457bbd96f98c06d16e..9abf8c12c67ddb2a24583be9dc027a7b059c06c2 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1036,8 +1036,15 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
        /* update per-inode reservations */
        BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
        EXT4_I(inode)->i_reserved_data_blocks -= used;
-
        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_preallocations(inode);
 }
 
 /*