linux-kernel - [PATCH v2 2/6] shmem: return freed pages in shmem_free

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Message-ID: <20230919135536.2165715-3-da.gomez@samsung.com>
Date:   Tue, 19 Sep 2023 13:55:47 +0000
From:   Daniel Gomez <da.gomez@...sung.com>
To:     "minchan@...nel.org" <minchan@...nel.org>,
        "senozhatsky@...omium.org" <senozhatsky@...omium.org>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "djwong@...nel.org" <djwong@...nel.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "hughd@...gle.com" <hughd@...gle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
CC:     "gost.dev@...sung.com" <gost.dev@...sung.com>,
        Pankaj Raghav <p.raghav@...sung.com>,
        Daniel Gomez <da.gomez@...sung.com>
Subject: [PATCH v2 2/6] shmem: return freed pages in shmem_free_swap

Both shmem_free_swap callers require to get the number of pages in the
folio after calling shmem_free_swap. Make shmem_free_swap return the
expected value directly and return 0 number of pages being freed
to avoid error handling in the external accounting.

Suggested-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: Daniel Gomez <da.gomez@...sung.com>
---
 mm/shmem.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index de0d0fa0349e..5c9e80207cbf 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -846,16 +846,18 @@ static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
 /*
  * Remove swap entry from page cache, free the swap and its page cache.
  */
-static int shmem_free_swap(struct address_space *mapping,
+static long shmem_free_swap(struct address_space *mapping,
 			   pgoff_t index, void *radswap)
 {
 	void *old;
 
 	old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
 	if (old != radswap)
-		return -ENOENT;
+		return 0;
+
 	free_swap_and_cache(radix_to_swp_entry(radswap));
-	return 0;
+
+	return folio_nr_pages((struct folio *)radswap);
 }
 
 /*
@@ -1008,7 +1010,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			if (xa_is_value(folio)) {
 				if (unfalloc)
 					continue;
-				nr_swaps_freed += !shmem_free_swap(mapping,
+				nr_swaps_freed += shmem_free_swap(mapping,
 							indices[i], folio);
 				continue;
 			}
@@ -1077,12 +1079,12 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			if (xa_is_value(folio)) {
 				if (unfalloc)
 					continue;
-				if (shmem_free_swap(mapping, indices[i], folio)) {
+				nr_swaps_freed += shmem_free_swap(mapping, indices[i], folio);
+				if (!nr_swaps_freed) {
 					/* Swap was replaced by page: retry */
 					index = indices[i];
 					break;
 				}
-				nr_swaps_freed++;
 				continue;
 			}
 
-- 
2.39.2