On Sat, Dec 23, 2023 at 05:31:55PM +0000, Matthew Wilcox wrote: > On Thu, Dec 21, 2023 at 04:57:04PM +0800, Yu Kuai wrote: > > @@ -3674,16 +3670,17 @@ struct btrfs_super_block > > *btrfs_read_dev_one_super(struct block_device *bdev, > > * Drop the page of the primary superblock, so later read will > > * always read from the device. > > */ > > - invalidate_inode_pages2_range(mapping, > > - bytenr >> PAGE_SHIFT, > > + invalidate_bdev_range(bdev, bytenr >> PAGE_SHIFT, > > (bytenr + BTRFS_SUPER_INFO_SIZE) >> PAGE_SHIFT); > > } > > > > - page = read_cache_page_gfp(mapping, bytenr >> PAGE_SHIFT, GFP_NOFS); > > - if (IS_ERR(page)) > > - return ERR_CAST(page); > > + nofs_flag = memalloc_nofs_save(); > > + folio = bdev_read_folio(bdev, bytenr); > > + memalloc_nofs_restore(nofs_flag); > > This is the wrong way to use memalloc_nofs_save/restore. They should be > used at the point that the filesystem takes/releases whatever lock is > also used during reclaim. I don't know btrfs well enough to suggest > what lock is missing these annotations.
Yes, but considering this is a cross-filesystem cleanup I wouldn't want to address that in this patchset. And the easier, more incremental approach for the conversion would be to first convert every GFP_NOFS usage to memalloc_nofs_save() like this patch does, as small local changes, and then let the btrfs people combine them and move them to the approproate location in a separate patchstet.
