[PATCH 17/37] libext2fs: file IO routines should handle uninit blocks

Darrick J. Wong
2014-05-01T23:14:18Z

The file IO routines do not handle uninit blocks at all. The read
method should check for the uninit flag and return a buffer of zeroes,
and the write routine should convert unwritten extents.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
lib/ext2fs/fileio.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index 14eaed3..1e386f8 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -123,6 +123,8 @@ errcode_t ext2fs_file_flush(ext2_file_t file)
{
errcode_t retval;
ext2_filsys fs;
+ int ret_flags;
+ blk64_t dontcare;

EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
fs = file->fs;
@@ -131,6 +133,22 @@ errcode_t ext2fs_file_flush(ext2_file_t file)
!(file->flags & EXT2_FILE_BUF_DIRTY))
return 0;

+ /* Is this an uninit block? */
+ if (file->physblock && file->inode.i_flags & EXT4_EXTENTS_FL) {
+ retval = ext2fs_bmap2(fs, file->ino, &file->inode, BMAP_BUFFER,
+ 0, file->blockno, &ret_flags, &dontcare);
+ if (retval)
+ return retval;
+ if (ret_flags & BMAP_RET_UNINIT) {
+ retval = ext2fs_bmap2(fs, file->ino, &file->inode,
+ BMAP_BUFFER, BMAP_SET,
+ file->blockno, 0,
+ &file->physblock);
+ if (retval)
+ return retval;
+ }
+ }
+
/*
* OK, the physical block hasn't been allocated yet.
* Allocate it.
@@ -185,15 +203,17 @@ static errcode_t load_buffer(ext2_file_t file, int dontfill)
{
ext2_filsys fs = file->fs;
errcode_t retval;
+ int ret_flags;

if (!(file->flags & EXT2_FILE_BUF_VALID)) {
retval = ext2fs_bmap2(fs, file->ino, &file->inode,
- BMAP_BUFFER, 0, file->blockno, 0,
+ BMAP_BUFFER, 0, file->blockno, &ret_flags,
&file->physblock);
if (retval)
return retval;
if (!dontfill) {
- if (file->physblock) {
+ if (file->physblock &&
+ !(ret_flags & BMAP_RET_UNINIT)) {
retval = io_channel_read_blk64(fs->io,
file->physblock,
1, file->buf);