kernel.git/fs/fuse/file.c, branch linux-6.15.y

fuse: fix dax truncate/punch_hole fault path

2025-03-18T05:06:36Z

Patch series "fs/dax: Fix ZONE_DEVICE page reference counts", v9. Device and FS DAX pages have always maintained their own page reference counts without following the normal rules for page reference counting. In particular pages are considered free when the refcount hits one rather than zero and refcounts are not added when mapping the page. Tracking this requires special PTE bits (PTE_DEVMAP) and a secondary mechanism for allowing GUP to hold references on the page (see get_dev_pagemap). However there doesn't seem to be any reason why FS DAX pages need their own reference counting scheme. By treating the refcounts on these pages the same way as normal pages we can remove a lot of special checks. In particular pXd_trans_huge() becomes the same as pXd_leaf(), although I haven't made that change here. It also frees up a valuable SW define PTE bit on architectures that have devmap PTE bits defined. It also almost certainly allows further clean-up of the devmap managed functions, but I have left that as a future improvment. It also enables support for compound ZONE_DEVICE pages which is one of my primary motivators for doing this work. This patch (of 20): FS DAX requires file systems to call into the DAX layout prior to unlinking inodes to ensure there is no ongoing DMA or other remote access to the direct mapped page. The fuse file system implements fuse_dax_break_layouts() to do this which includes a comment indicating that passing dmap_end == 0 leads to unmapping of the whole file. However this is not true - passing dmap_end == 0 will not unmap anything before dmap_start, and further more dax_layout_busy_page_range() will not scan any of the range to see if there maybe ongoing DMA access to the range. Fix this by passing -1 for dmap_end to fuse_dax_break_layouts() which will invalidate the entire file range to dax_layout_busy_page_range(). Link: https://lkml.kernel.org/r/cover.8068ad144a7eea4a813670301f4d2a86a8e68ec4.1740713401.git-series.apopple@nvidia.com Link: https://lkml.kernel.org/r/f09a34b6c40032022e4ddee6fadb7cc676f08867.1740713401.git-series.apopple@nvidia.com Fixes: 6ae330cad6ef ("virtiofs: serialize truncate/punch_hole and dax fault path") Signed-off-by: Alistair Popple Co-developed-by: Dan Williams Signed-off-by: Dan Williams Reviewed-by: Balbir Singh Tested-by: Alison Schofield Cc: Vivek Goyal Cc: Alexander Gordeev Cc: Asahi Lina Cc: Bjorn Helgaas Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christoph Hellwig Cc: Chunyan Zhang Cc: "Darrick J. Wong" Cc: Dave Chinner Cc: Dave Hansen Cc: Dave Jiang Cc: David Hildenbrand Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Huacai Chen Cc: Ira Weiny Cc: Jan Kara Cc: Jason Gunthorpe Cc: Jason Gunthorpe Cc: John Hubbard Cc: linmiaohe Cc: Logan Gunthorpe Cc: Matthew Wilcow (Oracle) Cc: Michael "Camp Drill Sergeant" Ellerman Cc: Nicholas Piggin Cc: Peter Xu Cc: Sven Schnelle Cc: Ted Ts'o Cc: Vasily Gorbik Cc: Vishal Verma Cc: WANG Xuerui Cc: Will Deacon Signed-off-by: Andrew Morton

fuse: revert back to __readahead_folio() for readahead

2025-02-14T09:49:23Z

In commit 3eab9d7bc2f4 ("fuse: convert readahead to use folios"), the logic was converted to using the new folio readahead code, which drops the reference on the folio once it is locked, using an inferred reference on the folio. Previously we held a reference on the folio for the entire duration of the readpages call. This is fine, however for the case for splice pipe responses where we will remove the old folio and splice in the new folio (see fuse_try_move_page()), we assume that there is a reference held on the folio for ap->folios, which is no longer the case. To fix this, revert back to __readahead_folio() which allows us to hold the reference on the folio for the duration of readpages until either we drop the reference ourselves in fuse_readpages_end() or the reference is dropped after it's replaced in the page cache in the splice case. This will fix the UAF bug that was reported. Link: https://lore.kernel.org/linux-fsdevel/2f681f48-00f5-4e09-8431-2b3dbfaa881e@heusel.eu/ Fixes: 3eab9d7bc2f4 ("fuse: convert readahead to use folios") Reported-by: Christian Heusel Closes: https://lore.kernel.org/all/2f681f48-00f5-4e09-8431-2b3dbfaa881e@heusel.eu/ Closes: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/110 Reported-by: Mantas Mikulėnas Closes: https://lore.kernel.org/all/34feb867-09e2-46e4-aa31-d9660a806d1a@gmail.com/ Closes: https://bugzilla.opensuse.org/show_bug.cgi?id=1236660 Cc: # v6.13 Signed-off-by: Joanne Koong Reviewed-by: Jeff Layton Signed-off-by: Miklos Szeredi

fuse: Set *nbytesp=0 in fuse_get_user_pages on allocation failure

2024-12-13T15:43:36Z

In fuse_get_user_pages(), set *nbytesp to 0 when struct page **pages allocation fails. This prevents the caller (fuse_direct_io) from making incorrect assumptions that could lead to NULL pointer dereferences when processing the request reply. Previously, *nbytesp was left unmodified on allocation failure, which could cause issues if the caller assumed pages had been added to ap->descs[] when they hadn't. Reported-by: syzbot+87b8e6ed25dbc41759f7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=87b8e6ed25dbc41759f7 Fixes: 3b97c3652d91 ("fuse: convert direct io to use folios") Signed-off-by: Bernd Schubert Reviewed-by: Joanne Koong Tested-by: Dmitry Antipov Tested-by: David Howells Signed-off-by: Miklos Szeredi

fuse: fix direct io folio offset and length calculation

2024-12-12T08:27:42Z

For the direct io case, the pages from userspace may be part of a huge folio, even if all folios in the page cache for fuse are small. Fix the logic for calculating the offset and length of the folio for the direct io case, which currently incorrectly assumes that all folios encountered are one page size. Fixes: 3b97c3652d91 ("fuse: convert direct io to use folios") Signed-off-by: Joanne Koong Reviewed-by: Jingbo Xu Reviewed-by: Bernd Schubert Signed-off-by: Miklos Szeredi

fuse: remove pages for requests and exclusively use folios

2024-11-05T13:08:35Z

All fuse requests use folios instead of pages for transferring data. Remove pages from the requests and exclusively use folios. No functional changes. [SzM: rename back folio_descs -> descs, etc.] Signed-off-by: Joanne Koong Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi

fuse: convert direct io to use folios

2024-11-05T10:14:32Z

Convert direct io requests to use folios instead of pages. No functional changes. Signed-off-by: Joanne Koong Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi

fuse: convert writebacks to use folios

2024-11-05T10:14:32Z

Convert writeback requests to use folios instead of pages. No functional changes. Signed-off-by: Joanne Koong Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi

fuse: convert writes (non-writeback) to use folios

2024-11-05T10:14:32Z

Convert non-writeback write requests to use folios instead of pages. No functional changes. Signed-off-by: Joanne Koong Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi

fuse: convert reads to use folios

2024-11-05T10:14:32Z

Convert read requests to use folios instead of pages. No functional changes. Signed-off-by: Joanne Koong Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi

fuse: use the folio based vmstat helpers

2024-10-25T15:05:50Z

In order to make it easier to switch to folios in the fuse_args_pages update the places where we update the vmstat counters for writeback to use the folio related helpers. On the inc side this is easy as we already have the folio, on the dec side we have to page_folio() the pages for now. Reviewed-by: Joanne Koong Signed-off-by: Josef Bacik Signed-off-by: Miklos Szeredi