kernel/linux.git/fs/fuse/inode.c, branch linux-6.0.y

fuse: retire block-device-based superblock on force unmount

2022-07-27T09:30:31+00:00

Force unmount of FUSE severes the connection with the user space, even if there are still open files. Subsequent remount tries to re-use the superblock held by the open files, which is meaningless in the FUSE case after disconnect - reused super block doesn't have userspace counterpart attached to it and is incapable of doing any IO. This patch adds the functionality only for the block-device-based supers, since the primary use case of the feature is to gracefully handle force unmount of external devices, mounted with FUSE. This can be further extended to cover all superblocks, if the need arises. Signed-off-by: Daniil Lunev Signed-off-by: Miklos Szeredi

fuse: limit nsec

2022-07-21T14:06:18+00:00

Limit nanoseconds to 0..999999999. Fixes: d8a5ba45457e ("[PATCH] FUSE - core") Cc: Signed-off-by: Miklos Szeredi

fs: allocate inode by using alloc_inode_sb()

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

The inode allocation is supposed to use alloc_inode_sb(), so convert kmem_cache_alloc() of all filesystems to alloc_inode_sb(). Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Theodore Ts'o [ext4] Acked-by: Roman Gushchin Cc: Alex Shi Cc: Anna Schumaker Cc: Chao Yu Cc: Dave Chinner Cc: Fam Zheng Cc: Jaegeuk Kim Cc: Johannes Weiner Cc: Kari Argillander Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Qi Zheng Cc: Shakeel Butt Cc: Trond Myklebust Cc: Vladimir Davydov Cc: Vlastimil Babka Cc: Wei Yang Cc: Xiongchun Duan Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fuse: move FUSE_SUPER_MAGIC definition to magic.h

2022-02-21T13:57:26+00:00

...to help userland apps that need to identify FUSE mounts. Signed-off-by: Jeff Layton Signed-off-by: Miklos Szeredi

fuse: mark inode DONT_CACHE when per inode DAX hint changes

2021-12-14T10:09:37+00:00

When the per inode DAX hint changes while the file is still *opened*, it is quite complicated and maybe fragile to dynamically change the DAX state. Hence mark the inode and corresponding dentries as DONE_CACHE once the per inode DAX hint changes, so that the inode instance will be evicted and freed as soon as possible once the file is closed and the last reference to the inode is put. And then when the file gets reopened next time, the new instantiated inode will reflect the new DAX state. In summary, when the per inode DAX hint changes for an *opened* file, the DAX state of the file won't be updated until this file is closed and reopened later. Signed-off-by: Jeffle Xu Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: negotiate per inode DAX in FUSE_INIT

2021-12-14T10:09:37+00:00

Among the FUSE_INIT phase, client shall advertise per inode DAX if it's mounted with "dax=inode". Then server is aware that client is in per inode DAX mode, and will construct per-inode DAX attribute accordingly. Server shall also advertise support for per inode DAX. If server doesn't support it while client is mounted with "dax=inode", client will silently fallback to "dax=never" since "dax=inode" is advisory only. Signed-off-by: Jeffle Xu Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: enable per inode DAX

2021-12-14T10:09:37+00:00

DAX may be limited in some specific situation. When the number of usable DAX windows is under watermark, the recalim routine will be triggered to reclaim some DAX windows. It may have a negative impact on the performance, since some processes may need to wait for DAX windows to be recalimed and reused then. To mitigate the performance degradation, the overall DAX window need to be expanded larger. However, simply expanding the DAX window may not be a good deal in some scenario. To maintain one DAX window chunk (i.e., 2MB in size), 32KB (512 * 64 bytes) memory footprint will be consumed for page descriptors inside guest, which is greater than the memory footprint if it uses guest page cache when DAX disabled. Thus it'd better disable DAX for those files smaller than 32KB, to reduce the demand for DAX window and thus avoid the unworthy memory overhead. Per inode DAX feature is introduced to address this issue, by offering a finer grained control for dax to users, trying to achieve a balance between performance and memory overhead. The FUSE_ATTR_DAX flag in FUSE_LOOKUP reply is used to indicate whether DAX should be enabled or not for corresponding file. Currently the state whether DAX is enabled or not for the file is initialized only when inode is instantiated. Signed-off-by: Jeffle Xu Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: make DAX mount option a tri-state

2021-12-14T10:09:36+00:00

We add 'always', 'never', and 'inode' (default). '-o dax' continues to operate the same which is equivalent to 'always'. The following behavior is consistent with that on ext4/xfs: - The default behavior (when neither '-o dax' nor '-o dax=always|never|inode' option is specified) is equal to 'inode' mode, while 'dax=inode' won't be printed among the mount option list. - The 'inode' mode is only advisory. It will silently fallback to 'never' mode if fuse server doesn't support that. Also noted that by the time of this commit, 'inode' mode is actually equal to 'always' mode, before the per inode DAX flag is introduced in the following patch. Signed-off-by: Jeffle Xu Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: send security context of inode on file

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

When a new inode is created, send its security context to server along with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). This gives server an opportunity to create new file and set security context (possibly atomically). In all the configurations it might not be possible to set context atomically. Like nfs and ceph, use security_dentry_init_security() to dermine security context of inode and send it with create, mkdir, mknod, and symlink requests. Following is the information sent to server. fuse_sectx_header, fuse_secctx, xattr_name, security_context - struct fuse_secctx_header This contains total number of security contexts being sent and total size of all the security contexts (including size of fuse_secctx_header). - struct fuse_secctx This contains size of security context which follows this structure. There is one fuse_secctx instance per security context. - xattr name string This string represents name of xattr which should be used while setting security context. - security context This is the actual security context whose size is specified in fuse_secctx struct. Also add the FUSE_SECURITY_CTX flag for the `flags` field of the fuse_init_out struct. When this flag is set the kernel will append the security context for a newly created inode to the request (create, mkdir, mknod, and symlink). The server is responsible for ensuring that the inode appears atomically (preferrably) with the requested security context. For example, If the server is using SELinux and backed by a "real" linux file system that supports extended attributes it can write the security context value to /proc/thread-self/attr/fscreate before making the syscall to create the inode. This patch is based on patch from Chirantan Ekbote Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi

fuse: extend init flags

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

FUSE_INIT flags are close to running out, so add another 32bits worth of space. Add FUSE_INIT_EXT flag to the old flags field in fuse_init_in. If this flag is set, then fuse_init_in is extended by 48bytes, in which a flags_hi field is allocated to contain the high 32bits of the flags. A flags_hi field is also added to fuse_init_out, allocated out of the remaining unused fields. Known userspace implementations of the fuse protocol have been checked to accept the extended FUSE_INIT request, but this might cause problems with other implementations. If that happens to be the case, the protocol negotiation will have to be extended with an extra initialization request roundtrip. Signed-off-by: Miklos Szeredi