On Tue, Sep 10, 2024 at 07:39:10AM +0300, Christoph Hellwig wrote:
> All callers of iomap_zero_range already hold invalidate_lock, so we can't
> take it again in iomap_file_buffered_write_punch_delalloc.
>
> Use the passed in flags argument to detect if we're called from a zeroing
> operation and don't take the lock again in this case.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/iomap/buffered-io.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 52f285ae4bddcb..3d7e69a542518a 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -1188,8 +1188,13 @@ static void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
> * folios and dirtying them via ->page_mkwrite whilst we walk the
> * cache and perform delalloc extent removal. Failing to do this can
> * leave dirty pages with no space reservation in the cache.
> + *
> + * For zeroing operations the callers already hold invalidate_lock.
> */
> - filemap_invalidate_lock(inode->i_mapping);
> + if (flags & IOMAP_ZERO)
> + rwsem_assert_held_write(&inode->i_mapping->invalidate_lock);
Does the other iomap_zero_range user (gfs2) take the invalidate lock?
AFAICT it doesn't. Shouldn't we annotate iomap_zero_range to say that
callers have to hold i_rwsem and the invalidate_lock?
--D
> + else
> + filemap_invalidate_lock(inode->i_mapping);
> while (start_byte < scan_end_byte) {
> loff_t data_end;
>
> @@ -1240,7 +1245,8 @@ static void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
> punch(inode, punch_start_byte, end_byte - punch_start_byte,
> iomap);
> out_unlock:
> - filemap_invalidate_unlock(inode->i_mapping);
> + if (!(flags & IOMAP_ZERO))
> + filemap_invalidate_unlock(inode->i_mapping);
> }
>
> /*
> --
> 2.45.2
>
>
