kernel.git/fs/fuse/inode.c, branch linux-6.10.y

fuse: disable the combination of passthrough and writeback cache

2024-09-12T09:12:45Z

commit 3ab394b363c5fd14b231e335fb6746ddfb93aaaa upstream. Current design and handling of passthrough is without fuse caching and with that FUSE_WRITEBACK_CACHE is conflicting. Fixes: 7dc4e97a4f9a ("fuse: introduce FUSE_PASSTHROUGH capability") Cc: stable@kernel.org # v6.9 Signed-off-by: Bernd Schubert Acked-by: Amir Goldstein Reviewed-by: Josef Bacik Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

fuse: verify {g,u}id mount options correctly

2024-08-03T07:00:32Z

commit 525bd65aa759ec320af1dc06e114ed69733e9e23 upstream. As was done in 0200679fc795 ("tmpfs: verify {g,u}id mount options correctly") we need to validate that the requested uid and/or gid is representable in the filesystem's idmapping. Cribbing from the above commit log, The contract for {g,u}id mount options and {g,u}id values in general set from userspace has always been that they are translated according to the caller's idmapping. In so far, fuse has been doing the correct thing. But since fuse is mountable in unprivileged contexts it is also necessary to verify that the resulting {k,g}uid is representable in the namespace of the superblock. Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: stable@vger.kernel.org # 5.4+ Signed-off-by: Eric Sandeen Link: https://lore.kernel.org/r/8f07d45d-c806-484d-a2e3-7a2199df1cd2@redhat.com Reviewed-by: Christian Brauner Reviewed-by: Josef Bacik Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

fuse: fix wrong ff->iomode state changes from parallel dio write

2024-04-15T08:12:03Z

There is a confusion with fuse_file_uncached_io_{start,end} interface. These helpers do two things when called from passthrough open()/release(): 1. Take/drop negative refcount of fi->iocachectr (inode uncached io mode) 2. State change ff->iomode IOM_NONE <-> IOM_UNCACHED (file uncached open) The calls from parallel dio write path need to take a reference on fi->iocachectr, but they should not be changing ff->iomode state, because in this case, the fi->iocachectr reference does not stick around until file release(). Factor out helpers fuse_inode_uncached_io_{start,end}, to be used from parallel dio write path and rename fuse_file_*cached_io_{start,end} helpers to fuse_file_*cached_io_{open,release} to clarify the difference. Fixes: 205c1d802683 ("fuse: allow parallel dio writes with FUSE_DIRECT_IO_ALLOW_MMAP") Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

Merge tag 'fuse-update-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

2024-03-15T16:47:14Z

Pull fuse updates from Miklos Szeredi: - Add passthrough mode for regular file I/O. This allows performing read and write (also via memory maps) on a backing file without incurring the overhead of roundtrips to userspace. For now this is only allowed to privileged servers, but this limitation will go away in the future (Amir Goldstein) - Fix interaction of direct I/O mode with memory maps (Bernd Schubert) - Export filesystem tags through sysfs for virtiofs (Stefan Hajnoczi) - Allow resending queued requests for server crash recovery (Zhao Chen) - Misc fixes and cleanups * tag 'fuse-update-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (38 commits) fuse: get rid of ff->readdir.lock fuse: remove unneeded lock which protecting update of congestion_threshold fuse: Fix missing FOLL_PIN for direct-io fuse: remove an unnecessary if statement fuse: Track process write operations in both direct and writethrough modes fuse: Use the high bit of request ID for indicating resend requests fuse: Introduce a new notification type for resend pending requests fuse: add support for explicit export disabling fuse: __kuid_val/__kgid_val helpers in fuse_fill_attr_from_inode() fuse: fix typo for fuse_permission comment fuse: Convert fuse_writepage_locked to take a folio fuse: Remove fuse_writepage virtio_fs: remove duplicate check if queue is broken fuse: use FUSE_ROOT_ID in fuse_get_root_inode() fuse: don't unhash root fuse: fix root lookup with nonzero generation fuse: replace remaining make_bad_inode() with fuse_make_bad() virtiofs: drop __exit from virtio_fs_sysfs_exit() fuse: implement passthrough for mmap fuse: implement splice read/write passthrough ...

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

2024-03-06T08:56:35Z

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: add support for explicit export disabling

2024-03-06T08:56:34Z

open_by_handle_at(2) can fail with -ESTALE with a valid handle returned by a previous name_to_handle_at(2) for evicted fuse inodes, which is especially common when entry_valid_timeout is 0, e.g. when the fuse daemon is in "cache=none" mode. The time sequence is like: name_to_handle_at(2) # succeed evict fuse inode open_by_handle_at(2) # fail The root cause is that, with 0 entry_valid_timeout, the dput() called in name_to_handle_at(2) will trigger iput -> evict(), which will send FUSE_FORGET to the daemon. The following open_by_handle_at(2) will send a new FUSE_LOOKUP request upon inode cache miss since the previous inode eviction. Then the fuse daemon may fail the FUSE_LOOKUP request with -ENOENT as the cached metadata of the requested inode has already been cleaned up during the previous FUSE_FORGET. The returned -ENOENT is treated as -ESTALE when open_by_handle_at(2) returns. This confuses the application somehow, as open_by_handle_at(2) fails when the previous name_to_handle_at(2) succeeds. The returned errno is also confusing as the requested file is not deleted and already there. It is reasonable to fail name_to_handle_at(2) early in this case, after which the application can fallback to open(2) to access files. Since this issue typically appears when entry_valid_timeout is 0 which is configured by the fuse daemon, the fuse daemon is the right person to explicitly disable the export when required. Also considering FUSE_EXPORT_SUPPORT actually indicates the support for lookups of "." and "..", and there are existing fuse daemons supporting export without FUSE_EXPORT_SUPPORT set, for compatibility, we add a new INIT flag for such purpose. Reviewed-by: Amir Goldstein Signed-off-by: Jingbo Xu Signed-off-by: Miklos Szeredi

fuse: __kuid_val/__kgid_val helpers in fuse_fill_attr_from_inode()

2024-03-06T08:56:25Z

For the sake of consistency, let's use these helpers to extract {u,g}id_t values from k{u,g}id_t ones. There are no functional changes, just to make code cleaner. Signed-off-by: Alexander Mikhalitsyn Reviewed-by: Christian Brauner Signed-off-by: Miklos Szeredi

fuse: use FUSE_ROOT_ID in fuse_get_root_inode()

2024-03-05T12:40:43Z

...when calling fuse_iget(). Signed-off-by: Miklos Szeredi

fuse: don't unhash root

2024-03-05T12:40:43Z

The root inode is assumed to be always hashed. Do not unhash the root inode even if it is marked BAD. Fixes: 5d069dbe8aaf ("fuse: fix bad inode") Cc: # v5.11 Signed-off-by: Miklos Szeredi

fuse: implement ioctls to manage backing files

2024-03-05T12:40:36Z

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