btrfs: use folio_contains() for EOF detection

Currently we use the following pattern to detect if the folio contains
the end of a file:

	if (folio->index == end_index)
		folio_zero_range();

But that only works if the folio is page sized.

For the following case, it will not work and leave the range beyond EOF
uninitialized:

  The page size is 4K, and the fs block size is also 4K.

	16K        20K       24K
        |          |     |   |
	                 |
                         EOF at 22K

And we have a large folio sized 8K at file offset 16K.

In that case, the old "folio->index == end_index" will not work, thus
the range [22K, 24K) will not be zeroed out.

Fix the following call sites which use the above pattern:

- add_ra_bio_pages()

- extent_writepage()

Reviewed-by: Filipe Manana <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 12a668dd5e5e..ba067d3461e6 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -221,7 +221,7 @@ static void __process_folios_contig(struct address_space *mapping,
 }
 
 static noinline void unlock_delalloc_folio(const struct inode *inode,
-					   const struct folio *locked_folio,
+					   struct folio *locked_folio,
 					   u64 start, u64 end)
 {
 	ASSERT(locked_folio);
@@ -231,7 +231,7 @@ static noinline void unlock_delalloc_folio(const struct inode *inode,
 }
 
 static noinline int lock_delalloc_folios(struct inode *inode,
-					 const struct folio *locked_folio,
+					 struct folio *locked_folio,
 					 u64 start, u64 end)
 {
 	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);
@@ -1707,7 +1707,7 @@ static int extent_writepage(struct folio *folio, struct btrfs_bio_ctrl *bio_ctrl
 		return 0;
 	}
 
-	if (folio->index == end_index)
+	if (folio_contains(folio, end_index))
 		folio_zero_range(folio, pg_offset, folio_size(folio) - pg_offset);
 
 	/*