Qu Wenruo fe1c6c7acc btrfs: fix wrong block_start calculation for btrfs_drop_extent_map_range() ... [BUG] During my extent_map cleanup/refactor, with extra sanity checks, extent-map-tests::test_case_7() would not pass the checks. The problem is, after btrfs_drop_extent_map_range(), the resulted extent_map has a @block_start way too large. Meanwhile my btrfs_file_extent_item based members are returning a correct @disk_bytenr/@offset combination. The extent map layout looks like this: 0 16K 32K 48K | PINNED | | Regular | The regular em at [32K, 48K) also has 32K @block_start. Then drop range [0, 36K), which should shrink the regular one to be [36K, 48K). However the @block_start is incorrect, we expect 32K + 4K, but got 52K. [CAUSE] Inside btrfs_drop_extent_map_range() function, if we hit an extent_map that covers the target range but is still beyond it, we need to split that extent map into half: |<-- drop range -->| |<----- existing extent_map --->| And if the extent map is not compressed, we need to forward extent_map::block_start by the difference between the end of drop range and the extent map start. However in that particular case, the difference is calculated using (start + len - em->start). The problem is @start can be modified if the drop range covers any pinned extent. This leads to wrong calculation, and would be caught by my later extent_map sanity checks, which checks the em::block_start against btrfs_file_extent_item::disk_bytenr + btrfs_file_extent_item::offset. This is a regression caused by commit c962098ca4 ("btrfs: fix incorrect splitting in btrfs_drop_extent_map_range"), which removed the @len update for pinned extents. [FIX] Fix it by avoiding using @start completely, and use @end - em->start instead, which @end is exclusive bytenr number. And update the test case to verify the @block_start to prevent such problem from happening. Thankfully this is not going to lead to any data corruption, as IO path does not utilize btrfs_drop_extent_map_range() with @skip_pinned set. So this fix is only here for the sake of consistency/correctness. CC: stable@vger.kernel.org # 6.5+ Fixes: c962098ca4 ("btrfs: fix incorrect splitting in btrfs_drop_extent_map_range") Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>		2024-04-18 18:18:50 +02:00
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btrfs-tests.c	btrfs: always set extent_io_tree::inode and drop fs_info	2023-12-15 20:27:02 +01:00
btrfs-tests.h	btrfs: use a dedicated data structure for chunk maps	2023-12-15 20:27:02 +01:00
extent-buffer-tests.c	btrfs: abort transaction on generation mismatch when marking eb as dirty	2023-10-12 16:44:07 +02:00
extent-io-tests.c	btrfs: tests: allocate dummy fs_info and root in test_find_delalloc()	2024-03-04 16:24:49 +01:00
extent-map-tests.c	btrfs: fix wrong block_start calculation for btrfs_drop_extent_map_range()	2024-04-18 18:18:50 +02:00
free-space-tests.c	btrfs: remove use btrfs_remove_free_space_cache instead of variant	2022-09-26 12:27:58 +02:00
free-space-tree-tests.c	btrfs: convert btrfs_block_group::needs_free_space to runtime flag	2022-12-05 18:00:51 +01:00
inode-tests.c	btrfs: remove the pg_offset parameter from btrfs_get_extent()	2024-03-04 16:24:45 +01:00
qgroup-tests.c	btrfs: use a structure to pass arguments to backref walking functions	2022-12-05 18:00:50 +01:00