Re: [PATCH v2 26/30] fuse: Add logic to free up a memory range

Hi, @@ -1784,8 +1822,23 @@ static int fuse_iomap_begin(struct inode *inode, > loff_t pos, loff_t length, > if (pos >= i_size_read(inode)) > goto iomap_hole; > > - alloc_dmap = alloc_dax_mapping(fc); > - if (!alloc_dmap) > + /* Can't do reclaim in fault path yet due to lock ordering. > + * Read path takes shared inode lock and that's not > sufficient > + * for inline range reclaim. Caller needs to drop lock, > wait > + * and retry. > + */ > + if (flags & IOMAP_FAULT || !(flags & IOMAP_WRITE)) { > + alloc_dmap = alloc_dax_mapping(fc); > + if (!alloc_dmap) > + return -ENOSPC; > + } else { > + alloc_dmap = alloc_dax_mapping_reclaim(fc, inode); > alloc_dmap could be NULL as follows: alloc_dax_mapping_reclaim -->fuse_dax_reclaim_first_mapping -->fuse_dax_reclaim_first_mapping_locked --> fuse_dax_interval_tree_iter_first ==> return NULL and IS_ERR(NULL) is false, so we may miss that error case.