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pagevec: add ability to iterate a queue

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Add a loop counter inside the folio_batch to let us iterate from 0-nr
instead of decrementing nr and treating the batch as a stack.  It would
generate some very weird and suboptimal I/O patterns for page writeback to
iterate over the batch as a stack.

Link: https://lkml.kernel.org/r/20240215063649.2164017-11-hch@lst.de
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-02-15 07:36:45 +01:00 committed by Andrew Morton
parent 807d1fe360
commit 535c5d9dad
1 changed files with 18 additions and 0 deletions
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18
include/linux/pagevec.h
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@ -27,6 +27,7 @@ struct folio;
*/
struct folio_batch {
unsigned char nr;
unsigned char i;
bool percpu_pvec_drained;
struct folio *folios[PAGEVEC_SIZE];
};
@ -40,12 +41,14 @@ struct folio_batch {
static inline void folio_batch_init(struct folio_batch *fbatch)
{
fbatch->nr = 0;
fbatch->i = 0;
fbatch->percpu_pvec_drained = false;
}
static inline void folio_batch_reinit(struct folio_batch *fbatch)
{
fbatch->nr = 0;
fbatch->i = 0;
}
static inline unsigned int folio_batch_count(struct folio_batch *fbatch)
@ -75,6 +78,21 @@ static inline unsigned folio_batch_add(struct folio_batch *fbatch,
return folio_batch_space(fbatch);
}
/**
* folio_batch_next - Return the next folio to process.
* @fbatch: The folio batch being processed.
*
* Use this function to implement a queue of folios.
*
* Return: The next folio in the queue, or NULL if the queue is empty.
*/
static inline struct folio *folio_batch_next(struct folio_batch *fbatch)
{
if (fbatch->i == fbatch->nr)
return NULL;
return fbatch->folios[fbatch->i++];
}
void __folio_batch_release(struct folio_batch *pvec);
static inline void folio_batch_release(struct folio_batch *fbatch)