From: Zhaoyang Huang <[email protected]>
According to the comments of readahead_page[3], the refcnt which
represents page cache dropped in [1] makes sense for two reasons, '1.
The folio is going to do IO and is locked until IO done;2. The refcnt
will be added back when found again from the page cache and then serve
for PTE or vfs' while it doesn't make sense in [2] as the refcnt of
page cache will be dropped in filemap_remove_folio.
read_pages()
{
aops->readahead
{
[1]
folio = readahead_folio();
}
..
[2]
while (folio = readahead_folio())
filemap_remove_folio(folio);
}
[3]
* Context: The page is locked and has an elevated refcount. The caller
* should decreases the refcount once the page has been submitted for I/O
* and unlock the page once all I/O to that page has completed.
* Return: A pointer to the next page, or %NULL if we are done.
Signed-off-by: Zhaoyang Huang <[email protected]>
---
mm/readahead.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/readahead.c b/mm/readahead.c
index 130c0e7df99f..657736200a92 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -163,7 +163,7 @@ static void read_pages(struct readahead_control *rac)
* may be used to size the next readahead, so make sure
* they accurately reflect what happened.
*/
- while ((folio = readahead_folio(rac)) != NULL) {
+ while ((folio = __readahead_folio(rac)) != NULL) {
unsigned long nr = folio_nr_pages(folio);
folio_get(folio);
--
2.25.1
On Wed, Mar 27, 2024 at 01:54:06PM +0800, zhaoyang.huang wrote:
> From: Zhaoyang Huang <[email protected]>
>
> According to the comments of readahead_page[3], the refcnt which
> represents page cache dropped in [1] makes sense for two reasons, '1.
> The folio is going to do IO and is locked until IO done;2. The refcnt
> will be added back when found again from the page cache and then serve
> for PTE or vfs' while it doesn't make sense in [2] as the refcnt of
> page cache will be dropped in filemap_remove_folio.
NAK, per previous email.