tao.ma@oracle.com
2007-Sep-05 17:12 UTC
[Ocfs2-devel] [patch] Fix a wrong cluster calculation.
In ocfs2_alloc_write_write_ctxt, the written clusters length is calculated
by the byte length only. This may cause some problems if we start to write
at some position in the end of one cluster and last to a second cluster
while the "len" is smaller than a cluster size. In that case, we have
to
write 2 clusters actually.
So we have to take the start position into consideration also.
Signed-off-by: Tao Ma <tao.ma@oracle.com>
---
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 460d440..50cd8a2 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -855,6 +855,7 @@ static int ocfs2_alloc_write_ctxt(struct
struct ocfs2_super *osb, loff_t pos,
unsigned len, struct buffer_head *di_bh)
{
+ u32 cend;
struct ocfs2_write_ctxt *wc;
wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
@@ -862,7 +863,8 @@ static int ocfs2_alloc_write_ctxt(struct
return -ENOMEM;
wc->w_cpos = pos >> osb->s_clustersize_bits;
- wc->w_clen = ocfs2_clusters_for_bytes(osb->sb, len);
+ cend = (pos + len - 1) >> osb->s_clustersize_bits;
+ wc->w_clen = cend - wc->w_cpos + 1;
get_bh(di_bh);
wc->w_di_bh = di_bh;
--
On Thu, Sep 06, 2007 at 08:02:25AM +0800, tao.ma wrote:> In ocfs2_alloc_write_write_ctxt, the written clusters length is calculated > by the byte length only. This may cause some problems if we start to write > at some position in the end of one cluster and last to a second cluster > while the "len" is smaller than a cluster size. In that case, we have to > write 2 clusters actually. > So we have to take the start position into consideration also.Good catch Tao, thanks. --Mark -- Mark Fasheh Senior Software Developer, Oracle mark.fasheh@oracle.com