Commit 535c5d9d authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

pagevec: add ability to iterate a queue 

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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Acked-by: default avatarDave Chinner <dchinner@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 807d1fe3

include/linux/pagevec.h

+18 −0
Original line number Diff line number Diff line
@@ -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)