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@xxxxxxx>
---
fs/ext4/page-io.c | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)
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) {
/*
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
