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mm/writeback: Add folio_account_redirty()

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Account the number of pages in the folio that we're redirtying.
Turn account_page_dirty() into a wrapper around it.  Also turn
the comment on folio_account_redirty() into kernel-doc and
edit it slightly so it makes sense to its potential callers.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-05-03 10:06:55 -04:00
parent 9350f20a07
commit 25ff8b1553
2 changed files with 24 additions and 14 deletions
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6
include/linux/writeback.h
View File

@ -394,7 +394,11 @@ void tag_pages_for_writeback(struct address_space *mapping,
pgoff_t start, pgoff_t end);
bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio);
void account_page_redirty(struct page *page);
void folio_account_redirty(struct folio *folio);
static inline void account_page_redirty(struct page *page)
{
folio_account_redirty(page_folio(page));
}
void sb_mark_inode_writeback(struct inode *inode);
void sb_clear_inode_writeback(struct inode *inode);

32
mm/page-writeback.c
View File

@ -1084,7 +1084,7 @@ static void wb_update_write_bandwidth(struct bdi_writeback *wb,
* write_bandwidth = ---------------------------------------------------
* period
*
* @written may have decreased due to account_page_redirty().
* @written may have decreased due to folio_account_redirty().
* Avoid underflowing @bw calculation.
*/
bw = written - min(written, wb->written_stamp);
@ -2544,30 +2544,36 @@ bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio)
}
EXPORT_SYMBOL(filemap_dirty_folio);
/*
* Call this whenever redirtying a page, to de-account the dirty counters
* (NR_DIRTIED, WB_DIRTIED, tsk->nr_dirtied), so that they match the written
* counters (NR_WRITTEN, WB_WRITTEN) in long term. The mismatches will lead to
* systematic errors in balanced_dirty_ratelimit and the dirty pages position
* control.
/**
* folio_account_redirty - Manually account for redirtying a page.
* @folio: The folio which is being redirtied.
*
* Most filesystems should call folio_redirty_for_writepage() instead
* of this fuction. If your filesystem is doing writeback outside the
* context of a writeback_control(), it can call this when redirtying
* a folio, to de-account the dirty counters (NR_DIRTIED, WB_DIRTIED,
* tsk->nr_dirtied), so that they match the written counters (NR_WRITTEN,
* WB_WRITTEN) in long term. The mismatches will lead to systematic errors
* in balanced_dirty_ratelimit and the dirty pages position control.
*/
void account_page_redirty(struct page *page)
void folio_account_redirty(struct folio *folio)
{
struct address_space *mapping = page->mapping;
struct address_space *mapping = folio->mapping;
if (mapping && mapping_can_writeback(mapping)) {
struct inode *inode = mapping->host;
struct bdi_writeback *wb;
struct wb_lock_cookie cookie = {};
long nr = folio_nr_pages(folio);
wb = unlocked_inode_to_wb_begin(inode, &cookie);
current->nr_dirtied--;
dec_node_page_state(page, NR_DIRTIED);
dec_wb_stat(wb, WB_DIRTIED);
current->nr_dirtied -= nr;
node_stat_mod_folio(folio, NR_DIRTIED, -nr);
wb_stat_mod(wb, WB_DIRTIED, -nr);
unlocked_inode_to_wb_end(inode, &cookie);
}
}
EXPORT_SYMBOL(account_page_redirty);
EXPORT_SYMBOL(folio_account_redirty);
/*
* When a writepage implementation decides that it doesn't want to write this