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authorJan Kara <jack@suse.cz>2013-06-04 13:17:40 -0400
committerTheodore Ts'o <tytso@mit.edu>2013-06-04 13:17:40 -0400
commit4e7ea81db53465ddd753678bc4cebf95369d0984 (patch)
tree39d71bab48ba0406c17410aa37d291485cd00b17 /fs/ext4/page-io.c
parentfffb273997cc52f255bde5f18e7f6b4686c914fb (diff)
downloadop-kernel-dev-4e7ea81db53465ddd753678bc4cebf95369d0984.zip
op-kernel-dev-4e7ea81db53465ddd753678bc4cebf95369d0984.tar.gz
ext4: restructure writeback path
There are two issues with current writeback path in ext4. For one we don't necessarily map complete pages when blocksize < pagesize and thus needn't do any writeback in one iteration. We always map some blocks though so we will eventually finish mapping the page. Just if writeback races with other operations on the file, forward progress is not really guaranteed. The second problem is that current code structure makes it hard to associate all the bios to some range of pages with one io_end structure so that unwritten extents can be converted after all the bios are finished. This will be especially difficult later when io_end will be associated with reserved transaction handle. We restructure the writeback path to a relatively simple loop which first prepares extent of pages, then maps one or more extents so that no page is partially mapped, and once page is fully mapped it is submitted for IO. We keep all the mapping and IO submission information in mpage_da_data structure to somewhat reduce stack usage. Resulting code is somewhat shorter than the old one and hopefully also easier to read. Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/page-io.c')
-rw-r--r--fs/ext4/page-io.c4
1 files changed, 0 insertions, 4 deletions
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 19599bd..3e58546 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -360,9 +360,6 @@ static int io_submit_init_bio(struct ext4_io_submit *io,
bio->bi_bdev = bh->b_bdev;
bio->bi_end_io = ext4_end_bio;
bio->bi_private = ext4_get_io_end(io->io_end);
- if (!io->io_end->size)
- io->io_end->offset = (bh->b_page->index << PAGE_CACHE_SHIFT)
- + bh_offset(bh);
io->io_bio = bio;
io->io_next_block = bh->b_blocknr;
return 0;
@@ -390,7 +387,6 @@ submit_and_retry:
io_end = io->io_end;
if (test_clear_buffer_uninit(bh))
ext4_set_io_unwritten_flag(inode, io_end);
- io_end->size += bh->b_size;
io->io_next_block++;
return 0;
}
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