On Tue, Sep 17, 2024 at 02:29:35PM -0700, Darrick J. Wong wrote: > 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? gfs2 does not hold invalidate_lock over iomap_zero_range. But it also does not use iomap_file_buffered_write_punch_delalloc at all, which is what requires the lock (and asserts that it is held).
