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mm/filemap: drop streaming/uncached pages when writeback completes

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If the folio is marked as streaming, drop pages when writeback completes. 
Intended to be used with RWF_DONTCACHE, to avoid needing sync writes for
uncached IO.

Link: https://lkml.kernel.org/r/20241220154831.1086649-10-axboe@kernel.dk
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Brian Foster <bfoster@redhat.com>
Cc: Chris Mason <clm@meta.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jens Axboe 2024-12-20 08:47:47 -07:00 • committed by Andrew Morton
parent 8026e49bff
commit fb7d3bc414
1 changed files with 28 additions and 0 deletions
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28
mm/filemap.c
View file

@ -1571,6 +1571,27 @@ int folio_wait_private_2_killable(struct folio *folio)
}
EXPORT_SYMBOL(folio_wait_private_2_killable);
/*
* If folio was marked as dropbehind, then pages should be dropped when writeback
* completes. Do that now. If we fail, it's likely because of a big folio -
* just reset dropbehind for that case and latter completions should invalidate.
*/
static void folio_end_dropbehind_write(struct folio *folio)
{
/*
* Hitting !in_task() should not happen off RWF_DONTCACHE writeback,
* but can happen if normal writeback just happens to find dirty folios
* that were created as part of uncached writeback, and that writeback
* would otherwise not need non-IRQ handling. Just skip the
* invalidation in that case.
*/
if (in_task() && folio_trylock(folio)) {
if (folio->mapping)
folio_unmap_invalidate(folio->mapping, folio, 0);
folio_unlock(folio);
}
}
/**
* folio_end_writeback - End writeback against a folio.
* @folio: The folio.
@ -1581,6 +1602,8 @@ EXPORT_SYMBOL(folio_wait_private_2_killable);
*/
void folio_end_writeback(struct folio *folio)
{
bool folio_dropbehind = false;
VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);
/*
@ -1602,9 +1625,14 @@ void folio_end_writeback(struct folio *folio)
* reused before the folio_wake_bit().
*/
folio_get(folio);
if (!folio_test_dirty(folio))
folio_dropbehind = folio_test_clear_dropbehind(folio);
if (__folio_end_writeback(folio))
folio_wake_bit(folio, PG_writeback);
acct_reclaim_writeback(folio);
if (folio_dropbehind)
folio_end_dropbehind_write(folio);
folio_put(folio);
}
EXPORT_SYMBOL(folio_end_writeback);