Re: [PATCH 1/1] xfs: fix overlapping extents returned for pNFS LAYOUTGET

[Christoph Hellwig <hch@infradead.org>]

[adding Sergey, who wrote the code to allow multiple mappings]

On Tue, May 19, 2026 at 07:59:49AM -0700, Darrick J. Wong wrote:
> 1) xfs_fs_map_blocks only takes i_rwsem and XFS_ILOCK; it doesn't take
> the mmap invalidation lock.  Does that mean that pagefaults could wander
> in and mess with the layout?

Looks like it.

> 2) Now that NFS apparently can serve up multiple mappings at once,
> should ->map_blocks pass in an array element count so that we can do
> multiple iomaps in a single lock cycle?

I guess we need to do that, or revert the code to provide multiple maps
for now.

> 3) Do the reflink and realtime inode checks need to be re-assessed after
> grabbing the ilock since they can change?

Yes.