6.10-stable review patch. If anyone has any objections, please let me know.
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From: Qu Wenruo wqu@suse.com
commit 77b0b98bb743f5d04d8f995ba1936e1143689d4a upstream.
In commit 75258f20fb70 ("btrfs: subpage: dump extra subpage bitmaps for debug") an internal macro GET_SUBPAGE_BITMAP() is introduced to grab the bitmap of each attribute.
But that commit is using bitmap_cut() which will do the left shift of the larger bitmap, causing incorrect values.
Thankfully this bitmap_cut() is only called for debug usage, and so far it's not yet causing problem.
Fix it to use bitmap_read() to only grab the desired sub-bitmap.
Fixes: 75258f20fb70 ("btrfs: subpage: dump extra subpage bitmaps for debug") CC: stable@vger.kernel.org # 6.6+ Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/subpage.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -766,8 +766,14 @@ void btrfs_folio_unlock_writer(struct bt }
#define GET_SUBPAGE_BITMAP(subpage, subpage_info, name, dst) \ - bitmap_cut(dst, subpage->bitmaps, 0, \ - subpage_info->name##_offset, subpage_info->bitmap_nr_bits) +{ \ + const int bitmap_nr_bits = subpage_info->bitmap_nr_bits; \ + \ + ASSERT(bitmap_nr_bits < BITS_PER_LONG); \ + *dst = bitmap_read(subpage->bitmaps, \ + subpage_info->name##_offset, \ + bitmap_nr_bits); \ +}
void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info, struct folio *folio, u64 start, u32 len)