[PATCH 13/13] bdi: replace BDI_CAP_NO_{WRITEBACK,ACCT_DIRTY} with a single flag

Christoph Hellwig
2020-09-24T06:52:46Z

Replace the two negative flags that are always used together with a
single positive flag that indicates the writeback capability instead
of two related non-capabilities. Also remove the pointless wrappers
to just check the flag.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
fs/9p/vfs_file.c | 2 +-
fs/fs-writeback.c | 7 +++---
include/linux/backing-dev.h | 48 ++++++++-----------------------------
mm/backing-dev.c | 6 ++---
mm/filemap.c | 4 ++--
mm/memcontrol.c | 2 +-
mm/memory-failure.c | 2 +-
mm/migrate.c | 2 +-
mm/mmap.c | 2 +-
mm/page-writeback.c | 12 +++++-----
10 files changed, 29 insertions(+), 58 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3576123d82990e..6ecf863bfa2f4b 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -625,7 +625,7 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma)

inode = file_inode(vma->vm_file);

- if (!mapping_cap_writeback_dirty(inode->i_mapping))
+ if (!mapping_can_writeback(inode->i_mapping))
wbc.nr_to_write = 0;

might_sleep();
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 149227160ff0b0..d4f84a2fe0878e 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2321,7 +2321,7 @@ void __mark_inode_dirty(struct inode *inode, int flags)

wb = locked_inode_to_wb_and_lock_list(inode);

- WARN(bdi_cap_writeback_dirty(wb->bdi) &&
+ WARN((wb->bdi->capabilities & BDI_CAP_WRITEBACK) &&
!test_bit(WB_registered, &wb->state),
"bdi-%s not registered\n", bdi_dev_name(wb->bdi));

@@ -2346,7 +2346,8 @@ void __mark_inode_dirty(struct inode *inode, int flags)
* to make sure background write-back happens
* later.
*/
- if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi)
+ if (wakeup_bdi &&
+ (wb->bdi->capabilities & BDI_CAP_WRITEBACK))
wb_wakeup_delayed(wb);
return;
}
@@ -2581,7 +2582,7 @@ int write_inode_now(struct inode *inode, int sync)
.range_end = LLONG_MAX,
};

- if (!mapping_cap_writeback_dirty(inode->i_mapping))
+ if (!mapping_can_writeback(inode->i_mapping))
wbc.nr_to_write = 0;

might_sleep();
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index b217344a2c63be..44df4fcef65c1e 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -110,27 +110,14 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
/*
* Flags in backing_dev_info::capability
*
- * The first three flags control whether dirty pages will contribute to the
- * VM's accounting and whether writepages() should be called for dirty pages
- * (something that would not, for example, be appropriate for ramfs)
- *
- * WARNING: these flags are closely related and should not normally be
- * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
- * three flags into a single convenience macro.
- *
- * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
- * BDI_CAP_NO_WRITEBACK: Don't write pages back
- * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages
- * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
+ * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages
+ * should contribute to accounting
+ * 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_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)
+#define BDI_CAP_WRITEBACK (1 << 0)
+#define BDI_CAP_WRITEBACK_ACCT (1 << 1)
+#define BDI_CAP_STRICTLIMIT (1 << 2)

extern struct backing_dev_info noop_backing_dev_info;

@@ -169,24 +156,9 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
long congestion_wait(int sync, long timeout);
long wait_iff_congested(int sync, long timeout);

-static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
-{
- return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
-}
-
-static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
-{
- return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
-}
-
-static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
-{
- return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
-}
-
-static inline bool mapping_cap_account_dirty(struct address_space *mapping)
+static inline bool mapping_can_writeback(struct address_space *mapping)
{
- return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
+ return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;
}

static inline int bdi_sched_wait(void *word)
@@ -223,7 +195,7 @@ static inline bool inode_cgwb_enabled(struct inode *inode)

return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
cgroup_subsys_on_dfl(io_cgrp_subsys) &&
- bdi_cap_account_dirty(bdi) &&
+ (bdi->capabilities & BDI_CAP_WRITEBACK) &&
(inode->i_sb->s_iflags & SB_I_CGROUPWB);
}

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index df18f0088dd3f5..408d5051d05b3d 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -14,9 +14,7 @@
#include <linux/device.h>
#include <trace/events/writeback.h>

-struct backing_dev_info noop_backing_dev_info = {
- .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
+struct backing_dev_info noop_backing_dev_info;
EXPORT_SYMBOL_GPL(noop_backing_dev_info);

static struct class *bdi_class;
@@ -745,7 +743,7 @@ struct backing_dev_info *bdi_alloc(int node_id)
kfree(bdi);
return NULL;
}
- bdi->capabilities = BDI_CAP_WRITEBACK_ACCT;
+ bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
bdi->ra_pages = VM_READAHEAD_PAGES;
bdi->io_pages = VM_READAHEAD_PAGES;
return bdi;
diff --git a/mm/filemap.c b/mm/filemap.c
index 1aaea26556cc7e..6c2a0139e22fa3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -414,7 +414,7 @@ int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
.range_end = end,
};

- if (!mapping_cap_writeback_dirty(mapping) ||
+ if (!mapping_can_writeback(mapping) ||
!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
return 0;

@@ -1702,7 +1702,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
no_page:
if (!page && (fgp_flags & FGP_CREAT)) {
int err;
- if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
+ if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
gfp_mask |= __GFP_WRITE;
if (fgp_flags & FGP_NOFS)
gfp_mask &= ~__GFP_FS;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b807952b4d431b..d2352f76d6519f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5643,7 +5643,7 @@ static int mem_cgroup_move_account(struct page *page,
if (PageDirty(page)) {
struct address_space *mapping = page_mapping(page);

- if (mapping_cap_account_dirty(mapping)) {
+ if (mapping_can_writeback(mapping)) {
__mod_lruvec_state(from_vec, NR_FILE_DIRTY,
-nr_pages);
__mod_lruvec_state(to_vec, NR_FILE_DIRTY,
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index f1aa6433f40416..a1e73943445e77 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1006,7 +1006,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
*/
mapping = page_mapping(hpage);
if (!(flags & MF_MUST_KILL) && !PageDirty(hpage) && mapping &&
- mapping_cap_writeback_dirty(mapping)) {
+ mapping_can_writeback(mapping)) {
if (page_mkclean(hpage)) {
SetPageDirty(hpage);
} else {
diff --git a/mm/migrate.c b/mm/migrate.c
index 34a842a8eb6a7b..9d2f42a3a16294 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -503,7 +503,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
__dec_lruvec_state(old_lruvec, NR_SHMEM);
__inc_lruvec_state(new_lruvec, NR_SHMEM);
}
- if (dirty && mapping_cap_account_dirty(mapping)) {
+ if (dirty && mapping_can_writeback(mapping)) {
__dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY);
__dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING);
__inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY);
diff --git a/mm/mmap.c b/mm/mmap.c
index 40248d84ad5fbd..1fc0e92be4ba9b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1666,7 +1666,7 @@ int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)

/* Can the mapping track the dirty pages? */
return vma->vm_file && vma->vm_file->f_mapping &&
- mapping_cap_account_dirty(vma->vm_file->f_mapping);
+ mapping_can_writeback(vma->vm_file->f_mapping);
}

/*
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0139f9622a92da..358d6f28c627b7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1882,7 +1882,7 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
int ratelimit;
int *p;

- if (!bdi_cap_account_dirty(bdi))
+ if (!(bdi->capabilities & BDI_CAP_WRITEBACK))
return;

if (inode_cgwb_enabled(inode))
@@ -2423,7 +2423,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)

trace_writeback_dirty_page(page, mapping);

- if (mapping_cap_account_dirty(mapping)) {
+ if (mapping_can_writeback(mapping)) {
struct bdi_writeback *wb;

inode_attach_wb(inode, page);
@@ -2450,7 +2450,7 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
void account_page_cleaned(struct page *page, struct address_space *mapping,
struct bdi_writeback *wb)
{
- if (mapping_cap_account_dirty(mapping)) {
+ if (mapping_can_writeback(mapping)) {
dec_lruvec_page_state(page, NR_FILE_DIRTY);
dec_zone_page_state(page, NR_ZONE_WRITE_PENDING);
dec_wb_stat(wb, WB_RECLAIMABLE);
@@ -2513,7 +2513,7 @@ void account_page_redirty(struct page *page)
{
struct address_space *mapping = page->mapping;

- if (mapping && mapping_cap_account_dirty(mapping)) {
+ if (mapping && mapping_can_writeback(mapping)) {
struct inode *inode = mapping->host;
struct bdi_writeback *wb;
struct wb_lock_cookie cookie = {};
@@ -2625,7 +2625,7 @@ void __cancel_dirty_page(struct page *page)
{
struct address_space *mapping = page_mapping(page);

- if (mapping_cap_account_dirty(mapping)) {
+ if (mapping_can_writeback(mapping)) {
struct inode *inode = mapping->host;
struct bdi_writeback *wb;
struct wb_lock_cookie cookie = {};
@@ -2665,7 +2665,7 @@ int clear_page_dirty_for_io(struct page *page)

VM_BUG_ON_PAGE(!PageLocked(page), page);

- if (mapping && mapping_cap_account_dirty(mapping)) {
+ if (mapping && mapping_can_writeback(mapping)) {
struct inode *inode = mapping->host;
struct bdi_writeback *wb;
struct wb_lock_cookie cookie = {};
--
2.28.0