Btrfs: remove bio_flags which indicates a meta block of log-tree
Since both committing transaction and writing log-tree are doing
plugging on metadata IO, we can unify to use %sync_writers to benefit
both cases, instead of checking bio_flags while writing meta blocks of
log-tree.
We can remove this bio_flags because in order to write dirty blocks,
log tree also uses btrfs_write_marked_extents(), inside which we
have enabled %sync_writers, therefore, every write goes in a
synchronous way, so does checksuming.
Please also note that, bio_flags is applied per-context while
%sync_writers is applied per-inode, so this might incur some overhead, ie.
1) while log tree is flushing its dirty blocks via
btrfs_write_marked_extents(), in which %sync_writers is increased
by one.
2) in the meantime, some writeback operations may happen upon btrfs's
metadata inode, so these writes go synchronously, too.
However, AFAICS, the overhead is not a big one while the win is that
we unify the two places that needs synchronous way and remove a
special hack/flag.
This removes the bio_flags related stuff for writing log-tree.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2344274..90310d9 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1005,12 +1005,10 @@ static blk_status_t __btree_submit_bio_done(void *private_data, struct bio *bio,
return ret;
}
-static int check_async_write(struct btrfs_inode *bi, unsigned long bio_flags)
+static int check_async_write(struct btrfs_inode *bi)
{
if (atomic_read(&bi->sync_writers))
return 0;
- if (bio_flags & EXTENT_BIO_TREE_LOG)
- return 0;
#ifdef CONFIG_X86
if (static_cpu_has(X86_FEATURE_XMM4_2))
return 0;
@@ -1024,7 +1022,7 @@ static blk_status_t btree_submit_bio_hook(void *private_data, struct bio *bio,
{
struct inode *inode = private_data;
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
- int async = check_async_write(BTRFS_I(inode), bio_flags);
+ int async = check_async_write(BTRFS_I(inode));
blk_status_t ret;
if (bio_op(bio) != REQ_OP_WRITE) {