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/extent_io.c b/fs/btrfs/extent_io.c
index 970190c..0dfcef3 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -109,7 +109,6 @@ struct extent_page_data {
struct bio *bio;
struct extent_io_tree *tree;
get_extent_t *get_extent;
- unsigned long bio_flags;
/* tells writepage not to lock the state bits for this range
* it still does the unlocking
@@ -3715,7 +3714,6 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
u64 offset = eb->start;
u32 nritems;
unsigned long i, num_pages;
- unsigned long bio_flags = 0;
unsigned long start, end;
unsigned int write_flags = wbc_to_write_flags(wbc) | REQ_META;
int ret = 0;
@@ -3723,8 +3721,6 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
num_pages = num_extent_pages(eb->start, eb->len);
atomic_set(&eb->io_pages, num_pages);
- if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)
- bio_flags = EXTENT_BIO_TREE_LOG;
/* set btree blocks beyond nritems with 0 to avoid stale content. */
nritems = btrfs_header_nritems(eb);
@@ -3751,8 +3747,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
p, offset >> 9, PAGE_SIZE, 0, bdev,
&epd->bio,
end_bio_extent_buffer_writepage,
- 0, epd->bio_flags, bio_flags, false);
- epd->bio_flags = bio_flags;
+ 0, 0, 0, false);
if (ret) {
set_btree_ioerr(p);
if (PageWriteback(p))
@@ -3789,7 +3784,6 @@ int btree_write_cache_pages(struct address_space *mapping,
.tree = tree,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
- .bio_flags = 0,
};
int ret = 0;
int done = 0;
@@ -4062,7 +4056,7 @@ static void flush_epd_write_bio(struct extent_page_data *epd)
if (epd->bio) {
int ret;
- ret = submit_one_bio(epd->bio, 0, epd->bio_flags);
+ ret = submit_one_bio(epd->bio, 0, 0);
BUG_ON(ret < 0); /* -ENOMEM */
epd->bio = NULL;
}
@@ -4085,7 +4079,6 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
.get_extent = get_extent,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
- .bio_flags = 0,
};
ret = __extent_writepage(page, wbc, &epd);
@@ -4110,7 +4103,6 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode,
.get_extent = get_extent,
.extent_locked = 1,
.sync_io = mode == WB_SYNC_ALL,
- .bio_flags = 0,
};
struct writeback_control wbc_writepages = {
.sync_mode = mode,
@@ -4150,7 +4142,6 @@ int extent_writepages(struct extent_io_tree *tree,
.get_extent = get_extent,
.extent_locked = 0,
.sync_io = wbc->sync_mode == WB_SYNC_ALL,
- .bio_flags = 0,
};
ret = extent_write_cache_pages(mapping, wbc, __extent_writepage, &epd,