From 68e0fcc3617b7a61ab93eeb6d8b935046d152685 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 9 Jul 2025 16:26:13 +0100 Subject: [PATCH] btrfs: assert we can NOCOW the range in btrfs_truncate_block() We call btrfs_check_nocow_lock() to see if we can NOCOW a block sized range but we don't check later if we can NOCOW the whole range. It's unexpected to be able to NOCOW a range smaller than blocksize, so add an assertion to check the NOCOW range matches the blocksize. Reviewed-by: Boris Burkov Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/inode.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index d7a2ea7d121f0..d79a95b3760cf 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4847,7 +4847,6 @@ int btrfs_truncate_block(struct btrfs_inode *inode, u64 offset, u64 start, u64 e pgoff_t index = (offset >> PAGE_SHIFT); struct folio *folio; gfp_t mask = btrfs_alloc_write_mask(mapping); - size_t write_bytes = blocksize; int ret = 0; const bool in_head_block = is_inside_block(offset, round_down(start, blocksize), blocksize); @@ -4899,8 +4898,12 @@ int btrfs_truncate_block(struct btrfs_inode *inode, u64 offset, u64 start, u64 e ret = btrfs_check_data_free_space(inode, &data_reserved, block_start, blocksize, false); if (ret < 0) { + size_t write_bytes = blocksize; + if (btrfs_check_nocow_lock(inode, block_start, &write_bytes, false) > 0) { - /* For nocow case, no need to reserve data space */ + /* For nocow case, no need to reserve data space. */ + ASSERT(write_bytes == blocksize, "write_bytes=%zu blocksize=%u", + write_bytes, blocksize); only_release_metadata = true; } else { goto out; -- 2.47.2