| Message ID | 1358510446-19174-12-git-send-email-jack@suse.cz |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Fri, Jan 18, 2013 at 01:00:45PM +0100, Jan Kara wrote: > So far ext4_bio_writepage() unconditionally cleared dirty bit on all buffers > underlying the page. That implicitely assumes we can write all buffers. So > far that is true because callers call into ext4_bio_writepage() make sure > all buffers in the page are mapped but > a) it's a data corruption bug waiting to happen > b) in data=ordered mode when blocksize < pagesize we do need to write pages > that may have only some of dirty buffers mapped. > > So change ext4_bio_writepage() to skip buffers that cannot be written without > clearing their dirty bit. > > Signed-off-by: Jan Kara <jack@suse.cz> Thanks, applied. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 3fb385c..0290bf8 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -350,14 +350,6 @@ static int io_submit_add_bh(struct ext4_io_submit *io, unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); } - if (!buffer_mapped(bh) || buffer_delay(bh)) { - if (!buffer_mapped(bh)) - clear_buffer_dirty(bh); - if (io->io_bio) - ext4_io_submit(io); - return 0; - } - if (io->io_bio && bh->b_blocknr != io->io_next_block) { submit_and_retry: ext4_io_submit(io); @@ -436,6 +428,15 @@ int ext4_bio_write_page(struct ext4_io_submit *io, set_buffer_uptodate(bh); continue; } + if (!buffer_dirty(bh) || buffer_delay(bh) || + !buffer_mapped(bh) || buffer_unwritten(bh)) { + /* A hole? We can safely clear the dirty bit */ + if (!buffer_mapped(bh)) + clear_buffer_dirty(bh); + if (io->io_bio) + ext4_io_submit(io); + continue; + } ret = io_submit_add_bh(io, io_page, inode, wbc, bh); if (ret) { /*
So far ext4_bio_writepage() unconditionally cleared dirty bit on all buffers underlying the page. That implicitely assumes we can write all buffers. So far that is true because callers call into ext4_bio_writepage() make sure all buffers in the page are mapped but a) it's a data corruption bug waiting to happen b) in data=ordered mode when blocksize < pagesize we do need to write pages that may have only some of dirty buffers mapped. So change ext4_bio_writepage() to skip buffers that cannot be written without clearing their dirty bit. Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/page-io.c | 17 +++++++++-------- 1 files changed, 9 insertions(+), 8 deletions(-)