ocfs2: return real error code in ocfs2_dio_wr_get_block

Patch series "ocfs2 bugs fixes exposed by fstests", v3.

The patchset is to fix some wrong behavior of ocfs2 exposed by fstests.

Patch 1 makes userspace happy when some error happens when doing direct
io.  Before the patch, DIO always return -EIO in case of error.  After the
patch, it returns real error code such like -ENOSPC, EDQUOT...

Patch 2 fixes an error case when doing AIO+DIO and hole punching at same
file position in parallel.  generic/300

Patch 3 fixes inode link count mismatch after power failure.  Without the
patch, inode link would be wrong even fync was called on the file. 
tests/generic/040,041,104,107,336

patch 4 fixes wrong atime with mount option realtime.  Without the patch,
atime of new created file won't be updated in right time. 
tests/generic/192

For stable kernels, I added fixes to patch 2,3,4.  The patch 1 is not
recommended to be backported since ocfs2_dio_wr_get_block calls too many
functions.  It's diffcult to check every git history of ocfs2 for every
LTS kernel.  


This patch (of 4):

ocfs2_dio_wr_get_block always returns -EIO in case of errors.  However,
some programs expect right exit codes while doing dio.  For example, tools
like fio treat -ENOSPC as expected code while doing stress jobs.  And
quota tools expect -EDQUOT when disk quota exceeds.

-EIO is too strong return code in the dio path.  The caller of
ocfs2_dio_wr_get_block is __blockdev_direct_IO which is widely used and it
handles error codes well.  I have checked functions called by
ocfs2_dio_wr_get_block and their return codes look good and clear.  So I
think it's safe to let ocfs2_dio_wr_get_block return real error code.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Su Yue <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Cc: Changwei Ge <[email protected]>
Cc: Gang He <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Jun Piao <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Mark Fasheh <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Damenly

fs/ocfs2/aops.c

@@ -2283,8 +2283,6 @@ static int ocfs2_dio_wr_get_block(struct inode *inode, sector_t iblock,
 	ocfs2_inode_unlock(inode, 1);
 	brelse(di_bh);
 out:
-	if (ret < 0)
-		ret = -EIO;
 	return ret;
 }