From e98bf64f7aaca09d5e6780f60ca79fda3003aecb Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Wed, 3 Apr 2024 10:30:06 +1030 Subject: [PATCH] btrfs: add extra sanity checks for create_io_em() The function create_io_em() is called before we submit an IO, to update the in-memory extent map for the involved range. This patch changes the following aspects: - Does not allow BTRFS_ORDERED_NOCOW type For real NOCOW (excluding NOCOW writes into preallocated ranges) writes, we never call create_io_em(), as we does not need to update the extent map at all. So remove the sanity check allowing BTRFS_ORDERED_NOCOW type. - Add extra sanity checks * PREALLOC - @block_len == len For uncompressed writes. * REGULAR - @block_len == @orig_block_len == @ram_bytes == @len We're creating a new uncompressed extent, and referring all of it. - @orig_start == @start We haven no offset inside the extent. * COMPRESSED - valid @compress_type - @len <= @ram_bytes This is to co-operate with encoded writes, which can cause a new file extent referring only part of a uncompressed extent. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index eb0dc913c33b..3d587b517809 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7258,11 +7258,49 @@ static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start, struct extent_map *em; int ret; + /* + * Note the missing NOCOW type. + * + * For pure NOCOW writes, we should not create an io extent map, but + * just reusing the existing one. + * Only PREALLOC writes (NOCOW write into preallocated range) can + * create an io extent map. + */ ASSERT(type == BTRFS_ORDERED_PREALLOC || type == BTRFS_ORDERED_COMPRESSED || - type == BTRFS_ORDERED_NOCOW || type == BTRFS_ORDERED_REGULAR); + switch (type) { + case BTRFS_ORDERED_PREALLOC: + /* Uncompressed extents. */ + ASSERT(block_len == len); + + /* We're only referring part of a larger preallocated extent. */ + ASSERT(block_len <= ram_bytes); + break; + case BTRFS_ORDERED_REGULAR: + /* Uncompressed extents. */ + ASSERT(block_len == len); + + /* COW results a new extent matching our file extent size. */ + ASSERT(orig_block_len == len); + ASSERT(ram_bytes == len); + + /* Since it's a new extent, we should not have any offset. */ + ASSERT(orig_start == start); + break; + case BTRFS_ORDERED_COMPRESSED: + /* Must be compressed. */ + ASSERT(compress_type != BTRFS_COMPRESS_NONE); + + /* + * Encoded write can make us to refer to part of the + * uncompressed extent. + */ + ASSERT(len <= ram_bytes); + break; + } + em = alloc_extent_map(); if (!em) return ERR_PTR(-ENOMEM);