Commit 8511074c authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: remove unused btrfs_folio_start_writer_lock() 



This function is not really suitable to lock a folio, as it lacks the
proper mapping checks, thus the locked folio may not even belong to
btrfs.

And due to the above reason, the last user inside lock_delalloc_folios()
is already removed, and we can remove this function.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 70958a94

fs/btrfs/subpage.c

+0 −47
Original line number Diff line number Diff line
@@ -295,26 +295,6 @@ static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len) 
			     orig_start + orig_len) - *start;

}



static void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,

				       struct folio *folio, u64 start, u32 len)

{

	struct btrfs_subpage *subpage = folio_get_private(folio);

	const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);

	const int nbits = (len >> fs_info->sectorsize_bits);

	unsigned long flags;

	int ret;



	btrfs_subpage_assert(fs_info, folio, start, len);



	spin_lock_irqsave(&subpage->lock, flags);

	ASSERT(atomic_read(&subpage->readers) == 0);

	ASSERT(bitmap_test_range_all_zero(subpage->bitmaps, start_bit, nbits));

	bitmap_set(subpage->bitmaps, start_bit, nbits);

	ret = atomic_add_return(nbits, &subpage->writers);

	ASSERT(ret == nbits);

	spin_unlock_irqrestore(&subpage->lock, flags);

}



static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,

					      struct folio *folio, u64 start, u32 len)

{
@@ -351,33 +331,6 @@ static bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_inf 
	return last;

}



/*

 * Lock a folio for delalloc page writeback.

 *

 * Return -EAGAIN if the page is not properly initialized.

 * Return 0 with the page locked, and writer counter updated.

 *

 * Even with 0 returned, the page still need extra check to make sure

 * it's really the correct page, as the caller is using

 * filemap_get_folios_contig(), which can race with page invalidating.

 */

int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,

				  struct folio *folio, u64 start, u32 len)

{

	if (unlikely(!fs_info) || !btrfs_is_subpage(fs_info, folio->mapping)) {

		folio_lock(folio);

		return 0;

	}

	folio_lock(folio);

	if (!folio_test_private(folio) || !folio_get_private(folio)) {

		folio_unlock(folio);

		return -EAGAIN;

	}

	btrfs_subpage_clamp_range(folio, &start, &len);

	btrfs_subpage_start_writer(fs_info, folio, start, len);

	return 0;

}



/*

 * Handle different locked folios:

 *

fs/btrfs/subpage.h

+0 −2
Original line number Diff line number Diff line
@@ -100,8 +100,6 @@ void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, 
void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,

			      struct folio *folio, u64 start, u32 len);



int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,

				  struct folio *folio, u64 start, u32 len);

void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,

				 struct folio *folio, u64 start, u32 len);

void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,