[PATCH] libext2fs: When truncating file, punch out blocks at end

[PATCH] libext2fs: When truncating file, punch out blocks at end

[Darrick J. Wong]

Currently, ext2fs_file_set_size2 punches out data blocks between the end of the
file and infinity when truncate_block <= old_truncate (i.e. when you've made
the file longer).  This is not a useful behavior, particularly since it *fails*
to punch out the data blocks when the file is shortened (i.e. truncate_block <
old_truncate).  This seems to be the result of the test being backwards, so fix
the code to punch only when the file is getting shorter.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---
 lib/ext2fs/fileio.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index d56f5b5..8751635 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -389,7 +389,7 @@ errcode_t ext2fs_file_set_size2(ext2_file_t file, ext2_off64_t size)
 			return retval;
 	}
 
-	if (truncate_block <= old_truncate)
+	if (truncate_block >= old_truncate)
 		return 0;
 
 	return ext2fs_punch(file->fs, file->ino, &file->inode, 0,

Re: [PATCH] libext2fs: When truncating file, punch out blocks at end

[Ted Ts'o]

On Fri, Jan 06, 2012 at 08:47:37PM -0800, Darrick J. Wong wrote:
> Currently, ext2fs_file_set_size2 punches out data blocks between the
> end of the file and infinity when truncate_block <= old_truncate
> (i.e. when you've made the file longer).  This is not a useful
> behavior, particularly since it *fails* to punch out the data blocks
> when the file is shortened (i.e. truncate_block < old_truncate).
> This seems to be the result of the test being backwards, so fix the
> code to punch only when the file is getting shorter.
> 
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>

Thanks, applied.

						- Ted