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authorJan Kara <jack@suse.cz>2013-01-28 20:53:28 -0500
committerTheodore Ts'o <tytso@mit.edu>2013-01-28 20:53:28 -0500
commit8a850c3fb8d0f204eabc1a32b502f47d3c16eac4 (patch)
tree7178b6117c8d559e4de519bfc17e792f6456bdd8
parentb6a8e62f8b0aec7607c947ba0d37d30fef65440f (diff)
downloadop-kernel-dev-8a850c3fb8d0f204eabc1a32b502f47d3c16eac4.zip
op-kernel-dev-8a850c3fb8d0f204eabc1a32b502f47d3c16eac4.tar.gz
ext4: Make ext4_bio_writepage() handle unprepared buffers
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> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/page-io.c17
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) {
/*
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