The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 77b0b98bb743f5d04d8f995ba1936e1143689d4a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024100117-venture-unloving-3135@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

77b0b98bb743 ("btrfs: subpage: fix the bitmap dump which can cause bitmap corruption")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 77b0b98bb743f5d04d8f995ba1936e1143689d4a Mon Sep 17 00:00:00 2001 From: Qu Wenruo wqu@suse.com Date: Fri, 30 Aug 2024 16:35:48 +0930 Subject: [PATCH] btrfs: subpage: fix the bitmap dump which can cause bitmap corruption

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

diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index 631d96f1e905..f8795c3d2270 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -902,8 +902,14 @@ void btrfs_folio_end_all_writers(const struct btrfs_fs_info *fs_info, struct fol }

#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)