The patch below does not apply to the 4.19-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-4.19.y git checkout FETCH_HEAD git cherry-pick -x c962098ca4af146f2625ed64399926a098752c9c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023082000-sincerity-outsource-e807@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..
Possible dependencies:
c962098ca4af ("btrfs: fix incorrect splitting in btrfs_drop_extent_map_range") db21370bffbc ("btrfs: drop extent map range more efficiently") f3109e33bb0a ("btrfs: use extent_map_end() at btrfs_drop_extent_map_range()") 4c0c8cfc8433 ("btrfs: move btrfs_drop_extent_cache() to extent_map.c") cef7820d6abf ("btrfs: fix missed extent on fsync after dropping extent maps") 570eb97bace8 ("btrfs: unify the lock/unlock extent variants") dbbf49928f2e ("btrfs: remove the wake argument from clear_extent_bits") e3974c669472 ("btrfs: move core extent_io_tree functions to extent-io-tree.c") 38830018387e ("btrfs: move a few exported extent_io_tree helpers to extent-io-tree.c") 04eba8932392 ("btrfs: temporarily export and then move extent state helpers") 91af24e48474 ("btrfs: temporarily export and move core extent_io_tree tree functions") 6962541e964f ("btrfs: move btrfs_debug_check_extent_io_range into extent-io-tree.c") ec39e39bbf97 ("btrfs: export wait_extent_bit") a66318872c41 ("btrfs: move simple extent bit helpers out of extent_io.c") ad795329574c ("btrfs: convert BUG_ON(EXTENT_BIT_LOCKED) checks to ASSERT's") 83cf709a89fb ("btrfs: move extent state init and alloc functions to their own file") c45379a20fbc ("btrfs: temporarily export alloc_extent_state helpers") a40246e8afc0 ("btrfs: separate out the eb and extent state leak helpers") a62a3bd9546b ("btrfs: separate out the extent state and extent buffer init code") 87c11705cc94 ("btrfs: convert the io_failure_tree to a plain rb_tree")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From c962098ca4af146f2625ed64399926a098752c9c Mon Sep 17 00:00:00 2001 From: Josef Bacik josef@toxicpanda.com Date: Thu, 17 Aug 2023 16:57:30 -0400 Subject: [PATCH] btrfs: fix incorrect splitting in btrfs_drop_extent_map_range
In production we were seeing a variety of WARN_ON()'s in the extent_map code, specifically in btrfs_drop_extent_map_range() when we have to call add_extent_mapping() for our second split.
Consider the following extent map layout
PINNED [0 16K) [32K, 48K)
and then we call btrfs_drop_extent_map_range for [0, 36K), with skip_pinned == true. The initial loop will have
start = 0 end = 36K len = 36K
we will find the [0, 16k) extent, but since we are pinned we will skip it, which has this code
start = em_end; if (end != (u64)-1) len = start + len - em_end;
em_end here is 16K, so now the values are
start = 16K len = 16K + 36K - 16K = 36K
len should instead be 20K. This is a problem when we find the next extent at [32K, 48K), we need to split this extent to leave [36K, 48k), however the code for the split looks like this
split->start = start + len; split->len = em_end - (start + len);
In this case we have
em_end = 48K split->start = 16K + 36K // this should be 16K + 20K split->len = 48K - (16K + 36K) // this overflows as 16K + 36K is 52K
and now we have an invalid extent_map in the tree that potentially overlaps other entries in the extent map. Even in the non-overlapping case we will have split->start set improperly, which will cause problems with any block related calculations.
We don't actually need len in this loop, we can simply use end as our end point, and only adjust start up when we find a pinned extent we need to skip.
Adjust the logic to do this, which keeps us from inserting an invalid extent map.
We only skip_pinned in the relocation case, so this is relatively rare, except in the case where you are running relocation a lot, which can happen with auto relocation on.
Fixes: 55ef68990029 ("Btrfs: Fix btrfs_drop_extent_cache for skip pinned case") CC: stable@vger.kernel.org # 4.14+ Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Josef Bacik josef@toxicpanda.com Signed-off-by: David Sterba dsterba@suse.com
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 0cdb3e86f29b..a6d8368ed0ed 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -760,8 +760,6 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end,
if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) { start = em_end; - if (end != (u64)-1) - len = start + len - em_end; goto next; }
@@ -829,8 +827,8 @@ void btrfs_drop_extent_map_range(struct btrfs_inode *inode, u64 start, u64 end, if (!split) goto remove_em; } - split->start = start + len; - split->len = em_end - (start + len); + split->start = end; + split->len = em_end - end; split->block_start = em->block_start; split->flags = flags; split->compress_type = em->compress_type;