[PATCH 12/13] bdi: invert BDI_CAP_NO_ACCT_WB

Christoph Hellwig
2020-09-24T06:52:52Z

Replace BDI_CAP_NO_ACCT_WB with a positive BDI_CAP_WRITEBACK_ACCT to
make the checks more obvious. Also remove the pointless
bdi_cap_account_writeback wrapper that just obsfucates the check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/fuse/inode.c | 3 ++-
include/linux/backing-dev.h | 13 +++----------
mm/backing-dev.c | 1 +
mm/page-writeback.c | 4 ++--
4 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 17b00670fb539e..581329203d6860 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1050,7 +1050,8 @@ static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
return err;

/* fuse does it's own writeback accounting */
- sb->s_bdi->capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
+ sb->s_bdi->capabilities &= ~BDI_CAP_WRITEBACK_ACCT;
+ sb->s_bdi->capabilities |= BDI_CAP_STRICTLIMIT;

/*
* For a single fuse filesystem use max 1% of dirty +
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 5da4ea3dd0cc5c..b217344a2c63be 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -120,17 +120,17 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
*
* BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
* BDI_CAP_NO_WRITEBACK: Don't write pages back
- * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
+ * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages
* BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
*/
#define BDI_CAP_NO_ACCT_DIRTY 0x00000001
#define BDI_CAP_NO_WRITEBACK 0x00000002
-#define BDI_CAP_NO_ACCT_WB 0x00000004
+#define BDI_CAP_WRITEBACK_ACCT 0x00000004
#define BDI_CAP_STRICTLIMIT 0x00000010
#define BDI_CAP_CGROUP_WRITEBACK 0x00000020

#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
- (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
+ (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY)

extern struct backing_dev_info noop_backing_dev_info;

@@ -179,13 +179,6 @@ static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
}

-static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
-{
- /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
- return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
- BDI_CAP_NO_WRITEBACK));
-}
-
static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
{
return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8e3802bf03a968..df18f0088dd3f5 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -745,6 +745,7 @@ struct backing_dev_info *bdi_alloc(int node_id)
kfree(bdi);
return NULL;
}
+ bdi->capabilities = BDI_CAP_WRITEBACK_ACCT;
bdi->ra_pages = VM_READAHEAD_PAGES;
bdi->io_pages = VM_READAHEAD_PAGES;
return bdi;
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index e9c36521461aaa..0139f9622a92da 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2738,7 +2738,7 @@ int test_clear_page_writeback(struct page *page)
if (ret) {
__xa_clear_mark(&mapping->i_pages, page_index(page),
PAGECACHE_TAG_WRITEBACK);
- if (bdi_cap_account_writeback(bdi)) {
+ if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT) {
struct bdi_writeback *wb = inode_to_wb(inode);

dec_wb_stat(wb, WB_WRITEBACK);
@@ -2791,7 +2791,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
PAGECACHE_TAG_WRITEBACK);

xas_set_mark(&xas, PAGECACHE_TAG_WRITEBACK);
- if (bdi_cap_account_writeback(bdi))
+ if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT)
inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);

/*
--
2.28.0