diff mbox series

[v2,3/8] fs/mpage: avoid negative shift for large blocksize

Message ID 20250204231209.429356-4-mcgrof@kernel.org (mailing list archive)
State New
Headers show
Series enable bs > ps for block devices | expand

Commit Message

Luis Chamberlain Feb. 4, 2025, 11:12 p.m. UTC 
From: Hannes Reinecke <hare@kernel.org>

For large blocksizes the number of block bits is larger than PAGE_SHIFT,
so use instead use folio_pos(folio) >> blkbits to calculate the sector
number. This is required to enable large folios with buffer-heads.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
 fs/mpage.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Matthew Wilcox Feb. 17, 2025, 9:48 p.m. UTC | #1 
On Tue, Feb 04, 2025 at 03:12:04PM -0800, Luis Chamberlain wrote:
> From: Hannes Reinecke <hare@kernel.org>
> 
> For large blocksizes the number of block bits is larger than PAGE_SHIFT,
> so use instead use folio_pos(folio) >> blkbits to calculate the sector

"so calculate the sector number from the byte offset instead"

> number. This is required to enable large folios with buffer-heads.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> Signed-off-by: Hannes Reinecke <hare@kernel.org>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
diff mbox series

Patch

diff --git a/fs/mpage.c b/fs/mpage.c
index 82aecf372743..a3c82206977f 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -181,7 +181,7 @@  static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
 	if (folio_buffers(folio))
 		goto confused;
 
-	block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);
+	block_in_file = folio_pos(folio) >> blkbits;
 	last_block = block_in_file + args->nr_pages * blocks_per_page;
 	last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits;
 	if (last_block > last_block_in_file)
@@ -527,7 +527,7 @@  static int __mpage_writepage(struct folio *folio, struct writeback_control *wbc,
 	 * The page has no buffers: map it to disk
 	 */
 	BUG_ON(!folio_test_uptodate(folio));
-	block_in_file = (sector_t)folio->index << (PAGE_SHIFT - blkbits);
+	block_in_file = folio_pos(folio) >> blkbits;
 	/*
 	 * Whole page beyond EOF? Skip allocating blocks to avoid leaking
 	 * space.