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Mon, 21 Nov 2022 18:16:14 -0800 (PST) Date: Mon, 21 Nov 2022 18:15:24 -0800 In-Reply-To: <20221122021536.1629178-1-drosen@google.com> Mime-Version: 1.0 References: <20221122021536.1629178-1-drosen@google.com> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog Message-ID: <20221122021536.1629178-10-drosen@google.com> Subject: [RFC PATCH v2 09/21] fuse-bpf: Add lseek support From: Daniel Rosenberg To: Miklos Szeredi Cc: Amir Goldstein , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, bpf@vger.kernel.org, kernel-team@android.com, Daniel Rosenberg , Paul Lawrence Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-State: RFC Signed-off-by: Daniel Rosenberg Signed-off-by: Paul Lawrence --- fs/fuse/backing.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++ fs/fuse/file.c | 3 ++ fs/fuse/fuse_i.h | 6 ++++ 3 files changed, 97 insertions(+) diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c index 8d862bc64acd..76f48872ed35 100644 --- a/fs/fuse/backing.c +++ b/fs/fuse/backing.c @@ -205,6 +205,94 @@ static void fuse_stat_to_attr(struct fuse_conn *fc, struct inode *inode, attr->blksize = 1 << blkbits; } +struct fuse_lseek_io { + struct fuse_lseek_in fli; + struct fuse_lseek_out flo; +}; + +static int fuse_lseek_initialize_in(struct fuse_args *fa, struct fuse_lseek_io *flio, + struct file *file, loff_t offset, int whence) +{ + struct fuse_file *fuse_file = file->private_data; + + flio->fli = (struct fuse_lseek_in) { + .fh = fuse_file->fh, + .offset = offset, + .whence = whence, + }; + + *fa = (struct fuse_args) { + .nodeid = get_node_id(file->f_inode), + .opcode = FUSE_LSEEK, + .in_numargs = 1, + .in_args[0].size = sizeof(flio->fli), + .in_args[0].value = &flio->fli, + }; + + return 0; +} + +static int fuse_lseek_initialize_out(struct fuse_args *fa, struct fuse_lseek_io *flio, + struct file *file, loff_t offset, int whence) +{ + fa->out_numargs = 1; + fa->out_args[0].size = sizeof(flio->flo); + fa->out_args[0].value = &flio->flo; + + return 0; +} + +static int fuse_lseek_backing(struct fuse_args *fa, loff_t *out, + struct file *file, loff_t offset, int whence) +{ + const struct fuse_lseek_in *fli = fa->in_args[0].value; + struct fuse_lseek_out *flo = fa->out_args[0].value; + struct fuse_file *fuse_file = file->private_data; + struct file *backing_file = fuse_file->backing_file; + + /* TODO: Handle changing of the file handle */ + if (offset == 0) { + if (whence == SEEK_CUR) { + flo->offset = file->f_pos; + *out = flo->offset; + return 0; + } + + if (whence == SEEK_SET) { + flo->offset = vfs_setpos(file, 0, 0); + *out = flo->offset; + return 0; + } + } + + inode_lock(file->f_inode); + backing_file->f_pos = file->f_pos; + *out = vfs_llseek(backing_file, fli->offset, fli->whence); + flo->offset = *out; + inode_unlock(file->f_inode); + return 0; +} + +static int fuse_lseek_finalize(struct fuse_args *fa, loff_t *out, + struct file *file, loff_t offset, int whence) +{ + struct fuse_lseek_out *flo = fa->out_args[0].value; + + if (!fa->error_in) + file->f_pos = flo->offset; + *out = flo->offset; + return 0; +} + +int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence) +{ + return fuse_bpf_backing(inode, struct fuse_lseek_io, out, + fuse_lseek_initialize_in, fuse_lseek_initialize_out, + fuse_lseek_backing, + fuse_lseek_finalize, + file, offset, whence); +} + ssize_t fuse_backing_mmap(struct file *file, struct vm_area_struct *vma) { int ret; diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 24fd4f33105c..e90b3e2d5452 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2704,6 +2704,9 @@ static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence) loff_t retval; struct inode *inode = file_inode(file); + if (fuse_bpf_lseek(&retval, inode, file, offset, whence)) + return retval; + switch (whence) { case SEEK_SET: case SEEK_CUR: diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 95d67afcff05..108c2ea15a49 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -1400,11 +1400,17 @@ int parse_fuse_bpf_entry(struct fuse_bpf_entry *fbe, int num_entries); #ifdef CONFIG_FUSE_BPF +int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence); int fuse_bpf_lookup(struct dentry **out, struct inode *dir, struct dentry *entry, unsigned int flags); int fuse_bpf_access(int *out, struct inode *inode, int mask); #else +static inline int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence) +{ + return 0; +} + static inline int fuse_bpf_lookup(struct dentry **out, struct inode *dir, struct dentry *entry, unsigned int flags) { return 0;