From: Christoph Hellwig hch@lst.de
commit 7833b865953c8e62abc76a3261c04132b2fb69de upstream.
can_nocow_extent can reduce the len passed in, which needs to be propagated to btrfs_dio_iomap_begin so that iomap does not submit more data then is mapped.
This problems exists since the btrfs_get_blocks_direct helper was added in commit c5794e51784a ("btrfs: Factor out write portion of btrfs_get_blocks_direct"), but the ordered_extent splitting added in commit b73a6fd1b1ef ("btrfs: split partial dio bios before submit") added a WARN_ON that made a syzkaller test fail.
Reported-by: syzbot+ee90502d5c8fd1d0dd93@syzkaller.appspotmail.com Fixes: c5794e51784a ("btrfs: Factor out write portion of btrfs_get_blocks_direct") CC: stable@vger.kernel.org # 6.1+ Tested-by: syzbot+ee90502d5c8fd1d0dd93@syzkaller.appspotmail.com Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/inode.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7324,7 +7324,7 @@ static struct extent_map *create_io_em(s static int btrfs_get_blocks_direct_write(struct extent_map **map, struct inode *inode, struct btrfs_dio_data *dio_data, - u64 start, u64 len, + u64 start, u64 *lenp, unsigned int iomap_flags) { const bool nowait = (iomap_flags & IOMAP_NOWAIT); @@ -7335,6 +7335,7 @@ static int btrfs_get_blocks_direct_write struct btrfs_block_group *bg; bool can_nocow = false; bool space_reserved = false; + u64 len = *lenp; u64 prev_len; int ret = 0;
@@ -7405,15 +7406,19 @@ static int btrfs_get_blocks_direct_write free_extent_map(em); *map = NULL;
- if (nowait) - return -EAGAIN; + if (nowait) { + ret = -EAGAIN; + goto out; + }
/* * If we could not allocate data space before locking the file * range and we can't do a NOCOW write, then we have to fail. */ - if (!dio_data->data_space_reserved) - return -ENOSPC; + if (!dio_data->data_space_reserved) { + ret = -ENOSPC; + goto out; + }
/* * We have to COW and we have already reserved data space before, @@ -7454,6 +7459,7 @@ out: btrfs_delalloc_release_extents(BTRFS_I(inode), len); btrfs_delalloc_release_metadata(BTRFS_I(inode), len, true); } + *lenp = len; return ret; }
@@ -7630,7 +7636,7 @@ static int btrfs_dio_iomap_begin(struct
if (write) { ret = btrfs_get_blocks_direct_write(&em, inode, dio_data, - start, len, flags); + start, &len, flags); if (ret < 0) goto unlock_err; unlock_extents = true;