diff mbox

block_invalidatepage: only release page if the full page was invalidated

Message ID x49fu5rtnzs.fsf@segfault.boston.devel.redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jeff Moyer Feb. 23, 2018, 9:06 p.m. UTC
Prior to commit d47992f86b307 ("mm: change invalidatepage prototype to
accept length"), an offset of 0 meant that the full page was being
invalidated.  After that commit, we need to instead check the length.

Fixes: d47992f86b307 ("mm: change invalidatepage prototype to accept length")
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>

---
Note that I found this via code inspection.  I'm not sure if this causes
issues in the wild.

Comments

Jan Kara Feb. 26, 2018, 10:18 a.m. UTC | #1
On Fri 23-02-18 16:06:15, Jeff Moyer wrote:
> Prior to commit d47992f86b307 ("mm: change invalidatepage prototype to
> accept length"), an offset of 0 meant that the full page was being
> invalidated.  After that commit, we need to instead check the length.
> 
> Fixes: d47992f86b307 ("mm: change invalidatepage prototype to accept length")
> Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
> 
> ---
> Note that I found this via code inspection.  I'm not sure if this causes
> issues in the wild.

The only possible issue is that try_to_release_page() was called more often
than necessary. Otherwise the issue is harmless but still it's good to have
this fixed. The patch looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 9a73924db22f..6b98609356ed 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1511,7 +1511,7 @@ void block_invalidatepage(struct page *page, unsigned int offset,
>  	 * The get_block cached value has been unconditionally invalidated,
>  	 * so real IO is not possible anymore.
>  	 */
> -	if (offset == 0)
> +	if (length == PAGE_SIZE)
>  		try_to_release_page(page, 0);
>  out:
>  	return;
diff mbox

Patch

diff --git a/fs/buffer.c b/fs/buffer.c
index 9a73924db22f..6b98609356ed 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1511,7 +1511,7 @@  void block_invalidatepage(struct page *page, unsigned int offset,
 	 * The get_block cached value has been unconditionally invalidated,
 	 * so real IO is not possible anymore.
 	 */
-	if (offset == 0)
+	if (length == PAGE_SIZE)
 		try_to_release_page(page, 0);
 out:
 	return;