| Date | Tue, 12 Apr 2011 07:35:06 -0700 | From | Greg KH <> | Subject | [077/105] Treat writes as new when holes span across page boundaries |
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2.6.38-stable review patch. If anyone has any objections, please let us know.
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From: Goldwyn Rodrigues <rgoldwyn@gmail.com>
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: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/ocfs2/aops.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -1026,6 +1026,12 @@ static int ocfs2_prepare_page_for_write( 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;
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