linux-toradex.git/fs/fuse/dev.c, branch v5.19-rc7

fuse: remove reliance on bdi congestion

2022-03-22T22:57:00+00:00

The bdi congestion tracking in not widely used and will be removed.

Fuse is one of a small number of filesystems that uses it, setting both
the sync (read) and async (write) congestion flags at what it determines
are appropriate times.

The only remaining effect of the sync flag is to cause read-ahead to be
skipped.  The only remaining effect of the async flag is to cause (some)
WB_SYNC_NONE writes to be skipped.

So instead of setting the flags, change:

 - .readahead to stop when it has submitted all non-async pages for
   read.

 - .writepages to do nothing if WB_SYNC_NONE and the flag would be set

 - .writepage to return AOP_WRITEPAGE_ACTIVATE if WB_SYNC_NONE and the
   flag would be set.

The writepages change causes a behavioural change in that pageout() can
now return PAGE_ACTIVATE instead of PAGE_KEEP, so SetPageActive() will be
called on the page which (I think) will further delay the next attempt at
writeout.  This might be a good thing.

Link: https://lkml.kernel.org/r/164549983737.9187.2627117501000365074.stgit@noble.brown
Signed-off-by: NeilBrown 
Cc: Anna Schumaker 
Cc: Chao Yu 
Cc: Darrick J. Wong 
Cc: Ilya Dryomov 
Cc: Jaegeuk Kim 
Cc: Jan Kara 
Cc: Jeff Layton 
Cc: Jens Axboe 
Cc: Lars Ellenberg 
Cc: Miklos Szeredi 
Cc: Paolo Valente 
Cc: Philipp Reisner 
Cc: Ryusuke Konishi 
Cc: Trond Myklebust 
Cc: Wu Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fuse: fix pipe buffer lifetime for direct_io

2022-03-07T15:30:44+00:00

In FOPEN_DIRECT_IO mode, fuse_file_write_iter() calls
fuse_direct_write_iter(), which normally calls fuse_direct_io(), which then
imports the write buffer with fuse_get_user_pages(), which uses
iov_iter_get_pages() to grab references to userspace pages instead of
actually copying memory.

On the filesystem device side, these pages can then either be read to
userspace (via fuse_dev_read()), or splice()d over into a pipe using
fuse_dev_splice_read() as pipe buffers with &nosteal_pipe_buf_ops.

This is wrong because after fuse_dev_do_read() unlocks the FUSE request,
the userspace filesystem can mark the request as completed, causing write()
to return. At that point, the userspace filesystem should no longer have
access to the pipe buffer.

Fix by copying pages coming from the user address space to new pipe
buffers.

Reported-by: Jann Horn 
Fixes: c3021629a0d8 ("fuse: support splice() reading from fuse device")
Cc: 
Signed-off-by: Miklos Szeredi

fuse: release pipe buf after last use

2021-11-25T13:05:18+00:00

Checking buf->flags should be done before the pipe_buf_release() is called
on the pipe buffer, since releasing the buffer might modify the flags.

This is exactly what page_cache_pipe_buf_release() does, and which results
in the same VM_BUG_ON_PAGE(PageLRU(page)) that the original patch was
trying to fix.

Reported-by: Justin Forbes 
Fixes: 712a951025c0 ("fuse: fix page stealing")
Cc:  # v2.6.35
Signed-off-by: Miklos Szeredi

fuse: fix page stealing

2021-11-02T10:10:37+00:00

It is possible to trigger a crash by splicing anon pipe bufs to the fuse
device.

The reason for this is that anon_pipe_buf_release() will reuse buf->page if
the refcount is 1, but that page might have already been stolen and its
flags modified (e.g. PG_lru added).

This happens in the unlikely case of fuse_dev_splice_write() getting around
to calling pipe_buf_release() after a page has been stolen, added to the
page cache and removed from the page cache.

Fix by calling pipe_buf_release() right after the page was inserted into
the page cache.  In this case the page has an elevated refcount so any
release function will know that the page isn't reusable.

Reported-by: Frank Dinoff 
Link: https://lore.kernel.org/r/CAAmZXrsGg2xsP1CK+cbuEMumtrqdvD-NKnWzhNcvn71RV3c1yw@mail.gmail.com/
Fixes: dd3bb14f44a6 ("fuse: support splice() writing to fuse device")
Cc:  # v2.6.35
Signed-off-by: Miklos Szeredi

fuse: always invalidate attributes after writes

2021-10-28T07:45:32+00:00

Extend the fuse_write_update_attr() helper to invalidate cached attributes
after a write.

This has already been done in all cases except in fuse_notify_store(), so
this is mostly a cleanup.

fuse_direct_write_iter() calls fuse_direct_IO() which already calls
fuse_write_update_attr(), so don't repeat that again in the former.

Signed-off-by: Miklos Szeredi

fuse: rename fuse_write_update_size()

2021-10-28T07:45:32+00:00

This function already updates the attr_version in fuse_inode, regardless of
whether the size was changed or not.

Rename the helper to fuse_write_update_attr() to reflect the more generic
nature.

Signed-off-by: Miklos Szeredi

fuse: use kmap_local_page()

2021-10-22T15:03:01+00:00

Due to the introduction of kmap_local_*, the storage of slots used for
short-term mapping has changed from per-CPU to per-thread.  kmap_atomic()
disable preemption, while kmap_local_*() only disable migration.

There is no need to disable preemption in several kamp_atomic places used
in fuse.

Link: https://lwn.net/Articles/836144/
Signed-off-by: Peng Hao 
Signed-off-by: Miklos Szeredi

fuse: fix use after free in fuse_read_interrupt()

2021-08-04T11:22:58+00:00

There is a potential race between fuse_read_interrupt() and
fuse_request_end().

TASK1
  in fuse_read_interrupt(): delete req->intr_entry (while holding
  fiq->lock)

TASK2
  in fuse_request_end(): req->intr_entry is empty -> skip fiq->lock
  wake up TASK3

TASK3
  request is freed

TASK1
  in fuse_read_interrupt(): dereference req->in.h.unique ***BAM***


Fix by always grabbing fiq->lock if the request was ever interrupted
(FR_INTERRUPTED set) thereby serializing with concurrent
fuse_read_interrupt() calls.

FR_INTERRUPTED is set before the request is queued on fiq->interrupts.
Dequeing the request is done with list_del_init() but FR_INTERRUPTED is not
cleared in this case.

Reported-by: lijiazi 
Signed-off-by: Miklos Szeredi

virtiofs: Fix spelling mistakes

2021-06-22T07:15:36+00:00

Fix some spelling mistakes in comments:
refernce  ==> reference
happnes  ==> happens
threhold  ==> threshold
splitted  ==> split
mached  ==> matched

Signed-off-by: Zheng Yongjun 
Signed-off-by: Miklos Szeredi

fuse: reject internal errno

2021-06-22T07:15:35+00:00

Don't allow userspace to report errors that could be kernel-internal.

Reported-by: Anatoly Trosinenko 
Fixes: 334f485df85a ("[PATCH] FUSE - device functions")
Cc:  # v2.6.14
Signed-off-by: Miklos Szeredi