[PATCH 6.4 054/800] btrfs: submit a writeback bio per extent_buffer

Greg Kroah-Hartman
2023-07-16T19:56:10Z

From: Christoph Hellwig <hch@lst.de>

[ Upstream commit 50b21d7a066f9a702b1d54ca11fc577302e875cb ]

Stop trying to cluster writes of multiple extent_buffers into a single
bio. There is no need for that as the blk_plug mechanism used all the
way up in writeback_inodes_wb gives us the same I/O pattern even with
multiple bios. Removing the clustering simplifies
lock_extent_buffer_for_io a lot and will also allow passing the eb
as private data to the end I/O handler.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 7027f87108ce ("btrfs: don't treat zoned writeback as being from an async helper thread")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/extent_io.c | 102 ++++++++++++++++---------------------------
1 file changed, 37 insertions(+), 65 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 28d0792359968..0c9538bb3c852 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1669,41 +1669,24 @@ static void end_extent_buffer_writeback(struct extent_buffer *eb)
/*
* Lock extent buffer status and pages for writeback.
*
- * May try to flush write bio if we can't get the lock.
- *
* Return %false if the extent buffer doesn't need to be submitted (e.g. the
* extent buffer is not dirty)
* Return %true is the extent buffer is submitted to bio.
*/
static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb,
- struct btrfs_bio_ctrl *bio_ctrl)
+ struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
- int i, num_pages;
- int flush = 0;
bool ret = false;
+ int i;

- if (!btrfs_try_tree_write_lock(eb)) {
- submit_write_bio(bio_ctrl, 0);
- flush = 1;
- btrfs_tree_lock(eb);
- }
-
- if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
+ btrfs_tree_lock(eb);
+ while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
btrfs_tree_unlock(eb);
- if (bio_ctrl->wbc->sync_mode != WB_SYNC_ALL)
+ if (wbc->sync_mode != WB_SYNC_ALL)
return false;
- if (!flush) {
- submit_write_bio(bio_ctrl, 0);
- flush = 1;
- }
- while (1) {
- wait_on_extent_buffer_writeback(eb);
- btrfs_tree_lock(eb);
- if (!test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags))
- break;
- btrfs_tree_unlock(eb);
- }
+ wait_on_extent_buffer_writeback(eb);
+ btrfs_tree_lock(eb);
}

/*
@@ -1735,19 +1718,8 @@ static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *e
if (!ret || fs_info->nodesize < PAGE_SIZE)
return ret;

- num_pages = num_extent_pages(eb);
- for (i = 0; i < num_pages; i++) {
- struct page *p = eb->pages[i];
-
- if (!trylock_page(p)) {
- if (!flush) {
- submit_write_bio(bio_ctrl, 0);
- flush = 1;
- }
- lock_page(p);
- }
- }
-
+ for (i = 0; i < num_extent_pages(eb); i++)
+ lock_page(eb->pages[i]);
return ret;
}

@@ -1977,11 +1949,16 @@ static void prepare_eb_write(struct extent_buffer *eb)
* Page locking is only utilized at minimum to keep the VMM code happy.
*/
static void write_one_subpage_eb(struct extent_buffer *eb,
- struct btrfs_bio_ctrl *bio_ctrl)
+ struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
struct page *page = eb->pages[0];
bool no_dirty_ebs = false;
+ struct btrfs_bio_ctrl bio_ctrl = {
+ .wbc = wbc,
+ .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
+ .end_io_func = end_bio_subpage_eb_writepage,
+ };

prepare_eb_write(eb);

@@ -1995,40 +1972,43 @@ static void write_one_subpage_eb(struct extent_buffer *eb,
if (no_dirty_ebs)
clear_page_dirty_for_io(page);

- bio_ctrl->end_io_func = end_bio_subpage_eb_writepage;
-
- submit_extent_page(bio_ctrl, eb->start, page, eb->len,
+ submit_extent_page(&bio_ctrl, eb->start, page, eb->len,
eb->start - page_offset(page));
unlock_page(page);
+ submit_one_bio(&bio_ctrl);
/*
* Submission finished without problem, if no range of the page is
* dirty anymore, we have submitted a page. Update nr_written in wbc.
*/
if (no_dirty_ebs)
- bio_ctrl->wbc->nr_to_write--;
+ wbc->nr_to_write--;
}

static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
- struct btrfs_bio_ctrl *bio_ctrl)
+ struct writeback_control *wbc)
{
u64 disk_bytenr = eb->start;
int i, num_pages;
+ struct btrfs_bio_ctrl bio_ctrl = {
+ .wbc = wbc,
+ .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
+ .end_io_func = end_bio_extent_buffer_writepage,
+ };

prepare_eb_write(eb);

- bio_ctrl->end_io_func = end_bio_extent_buffer_writepage;
-
num_pages = num_extent_pages(eb);
for (i = 0; i < num_pages; i++) {
struct page *p = eb->pages[i];

clear_page_dirty_for_io(p);
set_page_writeback(p);
- submit_extent_page(bio_ctrl, disk_bytenr, p, PAGE_SIZE, 0);
+ submit_extent_page(&bio_ctrl, disk_bytenr, p, PAGE_SIZE, 0);
disk_bytenr += PAGE_SIZE;
- bio_ctrl->wbc->nr_to_write--;
+ wbc->nr_to_write--;
unlock_page(p);
}
+ submit_one_bio(&bio_ctrl);
}

/*
@@ -2045,7 +2025,7 @@ static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
* Return >=0 for the number of submitted extent buffers.
* Return <0 for fatal error.
*/
-static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
+static int submit_eb_subpage(struct page *page, struct writeback_control *wbc)
{
struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
int submitted = 0;
@@ -2097,8 +2077,8 @@ static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
if (!eb)
continue;

- if (lock_extent_buffer_for_io(eb, bio_ctrl)) {
- write_one_subpage_eb(eb, bio_ctrl);
+ if (lock_extent_buffer_for_io(eb, wbc)) {
+ write_one_subpage_eb(eb, wbc);
submitted++;
}
free_extent_buffer(eb);
@@ -2126,7 +2106,7 @@ static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
* previous call.
* Return <0 for fatal error.
*/
-static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
+static int submit_eb_page(struct page *page, struct writeback_control *wbc,
struct extent_buffer **eb_context)
{
struct address_space *mapping = page->mapping;
@@ -2138,7 +2118,7 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
return 0;

if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE)
- return submit_eb_subpage(page, bio_ctrl);
+ return submit_eb_subpage(page, wbc);

spin_lock(&mapping->private_lock);
if (!PagePrivate(page)) {
@@ -2171,8 +2151,7 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
* If for_sync, this hole will be filled with
* trasnsaction commit.
*/
- if (bio_ctrl->wbc->sync_mode == WB_SYNC_ALL &&
- !bio_ctrl->wbc->for_sync)
+ if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
ret = -EAGAIN;
else
ret = 0;
@@ -2182,12 +2161,12 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,

*eb_context = eb;

- if (!lock_extent_buffer_for_io(eb, bio_ctrl)) {
+ if (!lock_extent_buffer_for_io(eb, wbc)) {
btrfs_revert_meta_write_pointer(cache, eb);
if (cache)
btrfs_put_block_group(cache);
free_extent_buffer(eb);
- return ret;
+ return 0;
}
if (cache) {
/*
@@ -2196,7 +2175,7 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
btrfs_schedule_zone_finish_bg(cache, eb);
btrfs_put_block_group(cache);
}
- write_one_eb(eb, bio_ctrl);
+ write_one_eb(eb, wbc);
free_extent_buffer(eb);
return 1;
}
@@ -2205,11 +2184,6 @@ int btree_write_cache_pages(struct address_space *mapping,
struct writeback_control *wbc)
{
struct extent_buffer *eb_context = NULL;
- struct btrfs_bio_ctrl bio_ctrl = {
- .wbc = wbc,
- .opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
- .extent_locked = 0,
- };
struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
int ret = 0;
int done = 0;
@@ -2251,7 +2225,7 @@ int btree_write_cache_pages(struct address_space *mapping,
for (i = 0; i < nr_folios; i++) {
struct folio *folio = fbatch.folios[i];

- ret = submit_eb_page(&folio->page, &bio_ctrl, &eb_context);
+ ret = submit_eb_page(&folio->page, wbc, &eb_context);
if (ret == 0)
continue;
if (ret < 0) {
@@ -2312,8 +2286,6 @@ int btree_write_cache_pages(struct address_space *mapping,
ret = 0;
if (!ret && BTRFS_FS_ERROR(fs_info))
ret = -EROFS;
- submit_write_bio(&bio_ctrl, ret);
-
btrfs_zoned_meta_io_unlock(fs_info);
return ret;
}
--
2.39.2