[PATCH] reiserfs: Truncate blocks not used by a write

[Jan Kara]

It can happen that write does not use all the blocks allocated in write_begin
either because of some filesystem error (like ENOSPC) or because page with
data to write has been removed from memory. We truncate these blocks so that
we don't have dangling blocks beyond i_size.

Signed-off-by: Jan Kara <jack@...>
---

Andrew, would you merge the patch please? Thanks.

diff -rupX /home/jack/.kerndiffexclude linux-2.6.27-SLE11_BRANCH/fs/reiserfs/inode.c linux-2.6.27-SLE11_BRANCH-1-reiserfs_corruption//fs/reiserfs/inode.c
--- linux-2.6.27-SLE11_BRANCH/fs/reiserfs/inode.c 2009-06-02 17:14:29.000000000 +0200
+++ linux-2.6.27-SLE11_BRANCH-1-reiserfs_corruption//fs/reiserfs/inode.c 2009-06-24 14:39:44.000000000 +0200
@@ -2606,6 +2610,8 @@ static int reiserfs_write_begin(struct f
  if (ret) {
  unlock_page(page);
  page_cache_release(page);
+ /* Truncate allocated blocks */
+ vmtruncate(inode, inode->i_size);
  }
  return ret;
 }
@@ -2698,8 +2705,7 @@ static int reiserfs_write_end(struct fil
  ** transaction tracking stuff when the size changes.  So, we have
  ** to do the i_size updates here.
  */
- pos += copied;
- if (pos > inode->i_size) {
+ if (pos + copied > inode->i_size) {
  struct reiserfs_transaction_handle myth;
  reiserfs_write_lock(inode->i_sb);
  /* If the file have grown beyond the border where it
@@ -2717,7 +2723,7 @@ static int reiserfs_write_end(struct fil
  goto journal_error;
  }
  reiserfs_update_inode_transaction(inode);
- inode->i_size = pos;
+ inode->i_size = pos + copied;
  /*
  * this will just nest into our transaction.  It's important
  * to use mark_inode_dirty so the inode gets pushed around on the
@@ -2744,6 +2750,10 @@ static int reiserfs_write_end(struct fil
       out:
  unlock_page(page);
  page_cache_release(page);
+
+ if (pos + len > inode->i_size)
+ vmtruncate(inode, inode->i_size);
+
  return ret == 0 ? copied : ret;
 
       journal_error:
--
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[Christoph Hellwig]

On Tue, Sep 01, 2009 at 05:55:54PM +0200, Jan Kara wrote:
> It can happen that write does not use all the blocks allocated in write_begin
> either because of some filesystem error (like ENOSPC) or because page with
> data to write has been removed from memory. We truncate these blocks so that
> we don't have dangling blocks beyond i_size.

vmtruncate is in the process of going away for 2.6.32.  Please use a
filesystems-specific routine to just trim the blocks, similar to what
the vmtruncate call in the generic write_begin helper is beeing replaced
with in Nick's truncate patch series.

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[Jan Kara]

On Tue 01-09-09 13:42:56, Christoph Hellwig wrote:

> On Tue, Sep 01, 2009 at 05:55:54PM +0200, Jan Kara wrote:
> > It can happen that write does not use all the blocks allocated in write_begin
> > either because of some filesystem error (like ENOSPC) or because page with
> > data to write has been removed from memory. We truncate these blocks so that
> > we don't have dangling blocks beyond i_size.
>
> vmtruncate is in the process of going away for 2.6.32.  Please use a
> filesystems-specific routine to just trim the blocks, similar to what
> the vmtruncate call in the generic write_begin helper is beeing replaced
> with in Nick's truncate patch series.

  Reiserfs does not have such helper (yet), that's why I've used
vmtruncate. But OK, I'll try to convert reiserfs to the new truncate
sequence and then make this fix use it...

                                                                Honza
--
Jan Kara <jack@...>
SUSE Labs, CR
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