| From | Paul Gortmaker <> | Subject | [34-longterm 038/196] Treat writes as new when holes span across page boundaries | Date | Mon, 12 Mar 2012 20:12:46 -0400 |
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From: Goldwyn Rodrigues <rgoldwyn@gmail.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
commit 272b62c1f0f6f742046e45b50b6fec98860208a0 upstream.
When a hole spans across page boundaries, the next write forces a read of the block. This could end up reading existing garbage data from the disk in ocfs2_map_page_blocks. This leads to non-zero holes. In order to avoid this, mark the writes as new when the holes span across page boundaries.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.de> Signed-off-by: jlbec <jlbec@evilplan.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- fs/ocfs2/aops.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c index e504ab7..3de08db 100644 --- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -1035,6 +1035,12 @@ static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno, ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos, &cluster_start, &cluster_end); + /* treat the write as new if the a hole/lseek spanned across + * the page boundary. + */ + new = new | ((i_size_read(inode) <= page_offset(page)) && + (page_offset(page) <= user_pos)); + if (page == wc->w_target_page) { map_from = user_pos & (PAGE_CACHE_SIZE - 1); map_to = map_from + user_len; -- 1.7.9.3
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