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mm: warn on deleting redirtied only if accounted

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filemap_unaccount_folio() has a WARN_ON_ONCE(folio_test_dirty(folio)).  It
is good to warn of late dirtying on a persistent filesystem, but late
dirtying on tmpfs can only lose data which is expected to be thrown away;
and it's a pity if that warning comes ONCE on tmpfs, then hides others
which really matter.  Make it conditional on mapping_cap_writeback().

Cleanup: then folio_account_cleaned() no longer needs to check that for
itself, and so no longer needs to know the mapping.

Link: https://lkml.kernel.org/r/b5a1106c-7226-a5c6-ad41-ad4832cae1f@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jan Kara <jack@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2022-03-24 18:13:59 -07:00 committed by Linus Torvalds
parent 7f7609175f
commit 566d336288
3 changed files with 18 additions and 17 deletions
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3
include/linux/pagemap.h
View File

@ -1009,8 +1009,7 @@ static inline void __set_page_dirty(struct page *page,
{
__folio_mark_dirty(page_folio(page), mapping, warn);
}
void folio_account_cleaned(struct folio *folio, struct address_space *mapping,
struct bdi_writeback *wb);
void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb);
void __folio_cancel_dirty(struct folio *folio);
static inline void folio_cancel_dirty(struct folio *folio)
{

14
mm/filemap.c
View File

@ -193,16 +193,20 @@ static void filemap_unaccount_folio(struct address_space *mapping,
/*
* At this point folio must be either written or cleaned by
* truncate. Dirty folio here signals a bug and loss of
* unwritten data.
* unwritten data - on ordinary filesystems.
*
* This fixes dirty accounting after removing the folio entirely
* But it's harmless on in-memory filesystems like tmpfs; and can
* occur when a driver which did get_user_pages() sets page dirty
* before putting it, while the inode is being finally evicted.
*
* Below fixes dirty accounting after removing the folio entirely
* but leaves the dirty flag set: it has no effect for truncated
* folio and anyway will be cleared before returning folio to
* buddy allocator.
*/
if (WARN_ON_ONCE(folio_test_dirty(folio)))
folio_account_cleaned(folio, mapping,
inode_to_wb(mapping->host));
if (WARN_ON_ONCE(folio_test_dirty(folio) &&
mapping_can_writeback(mapping)))
folio_account_cleaned(folio, inode_to_wb(mapping->host));
}
/*

18
mm/page-writeback.c
View File

@ -2465,16 +2465,14 @@ static void folio_account_dirtied(struct folio *folio,
*
* Caller must hold lock_page_memcg().
*/
void folio_account_cleaned(struct folio *folio, struct address_space *mapping,
struct bdi_writeback *wb)
void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb)
{
if (mapping_can_writeback(mapping)) {
long nr = folio_nr_pages(folio);
lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr);
zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
wb_stat_mod(wb, WB_RECLAIMABLE, -nr);
task_io_account_cancelled_write(nr * PAGE_SIZE);
}
long nr = folio_nr_pages(folio);
lruvec_stat_mod_folio(folio, NR_FILE_DIRTY, -nr);
zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
wb_stat_mod(wb, WB_RECLAIMABLE, -nr);
task_io_account_cancelled_write(nr * PAGE_SIZE);
}
/*
@ -2683,7 +2681,7 @@ void __folio_cancel_dirty(struct folio *folio)
wb = unlocked_inode_to_wb_begin(inode, &cookie);
if (folio_test_clear_dirty(folio))
folio_account_cleaned(folio, mapping, wb);
folio_account_cleaned(folio, wb);
unlocked_inode_to_wb_end(inode, &cookie);
folio_memcg_unlock(folio);