linux-stable.git/fs/fuse/dev.c, branch v6.10

fuse: clear FR_SENT when re-adding requests into pending list

2024-05-10T09:10:39+00:00

The following warning was reported by lee bruce:

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 8264 at fs/fuse/dev.c:300
  fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300
  Modules linked in:
  CPU: 0 PID: 8264 Comm: ab2 Not tainted 6.9.0-rc7
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
  RIP: 0010:fuse_request_end+0x685/0x7e0 fs/fuse/dev.c:300
  ......
  Call Trace:
  
  fuse_dev_do_read.constprop.0+0xd36/0x1dd0 fs/fuse/dev.c:1334
  fuse_dev_read+0x166/0x200 fs/fuse/dev.c:1367
  call_read_iter include/linux/fs.h:2104 [inline]
  new_sync_read fs/read_write.c:395 [inline]
  vfs_read+0x85b/0xba0 fs/read_write.c:476
  ksys_read+0x12f/0x260 fs/read_write.c:619
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xce/0x260 arch/x86/entry/common.c:83
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
  ......
  

The warning is due to the FUSE_NOTIFY_RESEND notify sent by the write()
syscall in the reproducer program and it happens as follows:

(1) calls fuse_dev_read() to read the INIT request
The read succeeds. During the read, bit FR_SENT will be set on the
request.
(2) calls fuse_dev_write() to send an USE_NOTIFY_RESEND notify
The resend notify will resend all processing requests, so the INIT
request is moved from processing list to pending list again.
(3) calls fuse_dev_read() with an invalid output address
fuse_dev_read() will try to copy the same INIT request to the output
address, but it will fail due to the invalid address, so the INIT
request is ended and triggers the warning in fuse_request_end().

Fix it by clearing FR_SENT when re-adding requests into pending list.

Acked-by: Miklos Szeredi 
Reported-by: xingwei lee 
Reported-by: yue sun 
Closes: https://lore.kernel.org/linux-fsdevel/58f13e47-4765-fce4-daf4-dffcc5ae2330@huaweicloud.com/T/#m091614e5ea2af403b259e7cea6a49e51b9ee07a7
Fixes: 760eac73f9f6 ("fuse: Introduce a new notification type for resend pending requests")
Signed-off-by: Hou Tao 
Signed-off-by: Miklos Szeredi

fuse: set FR_PENDING atomically in fuse_resend()

2024-05-10T09:10:12+00:00

When fuse_resend() moves the requests from processing lists to pending
list, it uses __set_bit() to set FR_PENDING bit in req->flags.

Using __set_bit() is not safe, because other functions may update
req->flags concurrently (e.g., request_wait_answer() may call
set_bit(FR_INTERRUPTED, &flags)).

Fix it by using set_bit() instead.

Fixes: 760eac73f9f6 ("fuse: Introduce a new notification type for resend pending requests")
Signed-off-by: Hou Tao 
Signed-off-by: Miklos Szeredi

fuse: Use the high bit of request ID for indicating resend requests

2024-03-06T08:56:35+00:00

Some FUSE daemons want to know if the received request is a resend
request. The high bit of the fuse request ID is utilized for indicating
this, enabling the receiver to perform appropriate handling.

The init flag "FUSE_HAS_RESEND" is added to indicate this feature.

Signed-off-by: Zhao Chen 
Signed-off-by: Miklos Szeredi

fuse: Introduce a new notification type for resend pending requests

2024-03-06T08:56:34+00:00

When a FUSE daemon panics and failover, we aim to minimize the impact on
applications by reusing the existing FUSE connection. During this process,
another daemon is employed to preserve the FUSE connection's file
descriptor. The new started FUSE Daemon will takeover the fd and continue
to provide service.

However, it is possible for some inflight requests to be lost and never
returned. As a result, applications awaiting replies would become stuck
forever. To address this, we can resend these pending requests to the
new started FUSE daemon.

This patch introduces a new notification type "FUSE_NOTIFY_RESEND", which
can trigger resending of the pending requests, ensuring they are properly
processed again.

Signed-off-by: Zhao Chen 
Signed-off-by: Miklos Szeredi

fuse: implement ioctls to manage backing files

2024-03-05T12:40:36+00:00

FUSE server calls the FUSE_DEV_IOC_BACKING_OPEN ioctl with a backing file
descriptor.  If the call succeeds, a backing file identifier is returned.

A later change will be using this backing file id in a reply to OPEN
request with the flag FOPEN_PASSTHROUGH to setup passthrough of file
operations on the open FUSE file to the backing file.

The FUSE server should call FUSE_DEV_IOC_BACKING_CLOSE ioctl to close the
backing file by its id.

This can be done at any time, but if an open reply with FOPEN_PASSTHROUGH
flag is still in progress, the open may fail if the backing file is
closed before the fuse file was opened.

Setting up backing files requires a server with CAP_SYS_ADMIN privileges.
For the backing file to be successfully setup, the backing file must
implement both read_iter and write_iter file operations.

The limitation on the level of filesystem stacking allowed for the
backing file is enforced before setting up the backing file.

Signed-off-by: Alessio Balsini 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

fuse: factor out helper for FUSE_DEV_IOC_CLONE

2024-02-23T16:36:32+00:00

In preparation to adding more fuse dev ioctls.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

fuse_dev_ioctl(): switch to fdget()

2023-04-21T02:55:35+00:00

Reviewed-by: Christian Brauner 
Signed-off-by: Al Viro

fuse: fix all W=1 kernel-doc warnings

2023-01-26T16:10:58+00:00

Use correct function name in kernel-doc notation. (1)
Don't use "/**" to begin non-kernel-doc comments. (3)

Fixes these warnings:

fs/fuse/cuse.c:272: warning: expecting prototype for cuse_parse_dev_info(). Prototype was for cuse_parse_devinfo() instead
fs/fuse/dev.c:212: warning: expecting prototype for A new request is available, wake fiq(). Prototype was for fuse_dev_wake_and_unlock() instead
fs/fuse/dir.c:149: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * Mark the attributes as stale due to an atime change.  Avoid the invalidate if
fs/fuse/file.c:656: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 * In case of short read, the caller sets 'pos' to the position of

Signed-off-by: Randy Dunlap 
Signed-off-by: Miklos Szeredi

fuse: add request extension

2023-01-26T16:10:37+00:00

Will need to add supplementary groups to create messages, so add the
general concept of a request extension.  A request extension is appended to
the end of the main request.  It has a header indicating the size and type
of the extension.

The create security context (fuse_secctx_*) is similar to the generic
request extension, so include that as well in a backward compatible manner.

Add the total extension length to the request header.  The offset of the
extension block within the request can be calculated by:

  inh->len - inh->total_extlen * 8

Signed-off-by: Miklos Szeredi

Merge tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-12-14T03:29:45+00:00

Pull MM updates from Andrew Morton:

 - More userfaultfs work from Peter Xu

 - Several convert-to-folios series from Sidhartha Kumar and Huang Ying

 - Some filemap cleanups from Vishal Moola

 - David Hildenbrand added the ability to selftest anon memory COW
   handling

 - Some cpuset simplifications from Liu Shixin

 - Addition of vmalloc tracing support by Uladzislau Rezki

 - Some pagecache folioifications and simplifications from Matthew
   Wilcox

 - A pagemap cleanup from Kefeng Wang: we have VM_ACCESS_FLAGS, so use
   it

 - Miguel Ojeda contributed some cleanups for our use of the
   __no_sanitize_thread__ gcc keyword.

   This series should have been in the non-MM tree, my bad

 - Naoya Horiguchi improved the interaction between memory poisoning and
   memory section removal for huge pages

 - DAMON cleanups and tuneups from SeongJae Park

 - Tony Luck fixed the handling of COW faults against poisoned pages

 - Peter Xu utilized the PTE marker code for handling swapin errors

 - Hugh Dickins reworked compound page mapcount handling, simplifying it
   and making it more efficient

 - Removal of the autonuma savedwrite infrastructure from Nadav Amit and
   David Hildenbrand

 - zram support for multiple compression streams from Sergey Senozhatsky

 - David Hildenbrand reworked the GUP code's R/O long-term pinning so
   that drivers no longer need to use the FOLL_FORCE workaround which
   didn't work very well anyway

 - Mel Gorman altered the page allocator so that local IRQs can remnain
   enabled during per-cpu page allocations

 - Vishal Moola removed the try_to_release_page() wrapper

 - Stefan Roesch added some per-BDI sysfs tunables which are used to
   prevent network block devices from dirtying excessive amounts of
   pagecache

 - David Hildenbrand did some cleanup and repair work on KSM COW
   breaking

 - Nhat Pham and Johannes Weiner have implemented writeback in zswap's
   zsmalloc backend

 - Brian Foster has fixed a longstanding corner-case oddity in
   file[map]_write_and_wait_range()

 - sparse-vmemmap changes for MIPS, LoongArch and NIOS2 from Feiyang
   Chen

 - Shiyang Ruan has done some work on fsdax, to make its reflink mode
   work better under xfstests. Better, but still not perfect

 - Christoph Hellwig has removed the .writepage() method from several
   filesystems. They only need .writepages()

 - Yosry Ahmed wrote a series which fixes the memcg reclaim target
   beancounting

 - David Hildenbrand has fixed some of our MM selftests for 32-bit
   machines

 - Many singleton patches, as usual

* tag 'mm-stable-2022-12-13' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (313 commits)
  mm/hugetlb: set head flag before setting compound_order in __prep_compound_gigantic_folio
  mm: mmu_gather: allow more than one batch of delayed rmaps
  mm: fix typo in struct pglist_data code comment
  kmsan: fix memcpy tests
  mm: add cond_resched() in swapin_walk_pmd_entry()
  mm: do not show fs mm pc for VM_LOCKONFAULT pages
  selftests/vm: ksm_functional_tests: fixes for 32bit
  selftests/vm: cow: fix compile warning on 32bit
  selftests/vm: madv_populate: fix missing MADV_POPULATE_(READ|WRITE) definitions
  mm/gup_test: fix PIN_LONGTERM_TEST_READ with highmem
  mm,thp,rmap: fix races between updates of subpages_mapcount
  mm: memcg: fix swapcached stat accounting
  mm: add nodes= arg to memory.reclaim
  mm: disable top-tier fallback to reclaim on proactive reclaim
  selftests: cgroup: make sure reclaim target memcg is unprotected
  selftests: cgroup: refactor proactive reclaim code to reclaim_until()
  mm: memcg: fix stale protection of reclaim target memcg
  mm/mmap: properly unaccount memory on mas_preallocate() failure
  omfs: remove ->writepage
  jfs: remove ->writepage
  ...