[RFC PATCH v2 11/21] fuse-bpf: Support file/dir open/close

Daniel Rosenberg
2022-11-22T02:18:00Z

fs/fuse/backing.c | 356 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dir.c | 8 ++
fs/fuse/file.c | 7 +
fs/fuse/fuse_i.h | 26 ++++
4 files changed, 397 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 51aadeb1b7dc..c8e95abc04aa 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -205,6 +205,362 @@ static void fuse_stat_to_attr(struct fuse_conn *fc, struct inode *inode,
attr->blksize = 1 << blkbits;
}

+struct fuse_open_io {
+ struct fuse_open_in foi;
+ struct fuse_open_out foo;
+};
+
+static int fuse_open_initialize_in(struct fuse_args *fa, struct fuse_open_io *foio,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ foio->foi = (struct fuse_open_in) {
+ .flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY),
+ };
+ *fa = (struct fuse_args) {
+ .nodeid = get_fuse_inode(inode)->nodeid,
+ .opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN,
+ .in_numargs = 1,
+ .in_args[0] = (struct fuse_in_arg) {
+ .size = sizeof(foio->foi),
+ .value = &foio->foi,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_open_initialize_out(struct fuse_args *fa, struct fuse_open_io *foio,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ foio->foo = (struct fuse_open_out) { 0 };
+
+ fa->out_numargs = 1;
+ fa->out_args[0] = (struct fuse_arg) {
+ .size = sizeof(foio->foo),
+ .value = &foio->foo,
+ };
+
+ return 0;
+}
+
+static int fuse_open_backing(struct fuse_args *fa, int *out,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ struct fuse_mount *fm = get_fuse_mount(inode);
+ const struct fuse_open_in *foi = fa->in_args[0].value;
+ struct fuse_file *ff;
+ int mask;
+ struct fuse_dentry *fd = get_fuse_dentry(file->f_path.dentry);
+ struct file *backing_file;
+
+ ff = fuse_file_alloc(fm);
+ if (!ff)
+ return -ENOMEM;
+ file->private_data = ff;
+
+ switch (foi->flags & O_ACCMODE) {
+ case O_RDONLY:
+ mask = MAY_READ;
+ break;
+
+ case O_WRONLY:
+ mask = MAY_WRITE;
+ break;
+
+ case O_RDWR:
+ mask = MAY_READ | MAY_WRITE;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ *out = inode_permission(&init_user_ns,
+ get_fuse_inode(inode)->backing_inode, mask);
+ if (*out)
+ return *out;
+
+ backing_file =
+ dentry_open(&fd->backing_path, foi->flags, current_cred());
+
+ if (IS_ERR(backing_file)) {
+ fuse_file_free(ff);
+ file->private_data = NULL;
+ return PTR_ERR(backing_file);
+ }
+ ff->backing_file = backing_file;
+
+ *out = 0;
+ return 0;
+}
+
+static int fuse_open_finalize(struct fuse_args *fa, int *out,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ struct fuse_file *ff = file->private_data;
+ struct fuse_open_out *foo = fa->out_args[0].value;
+
+ if (ff) {
+ ff->fh = foo->fh;
+ ff->nodeid = get_fuse_inode(inode)->nodeid;
+ }
+ return 0;
+}
+
+int fuse_bpf_open(int *out, struct inode *inode, struct file *file, bool isdir)
+{
+ return fuse_bpf_backing(inode, struct fuse_open_io, out,
+ fuse_open_initialize_in, fuse_open_initialize_out,
+ fuse_open_backing,
+ fuse_open_finalize,
+ inode, file, isdir);
+}
+
+struct fuse_create_open_io {
+ struct fuse_create_in fci;
+ struct fuse_entry_out feo;
+ struct fuse_open_out foo;
+};
+
+static int fuse_create_open_initialize_in(struct fuse_args *fa, struct fuse_create_open_io *fcoio,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ fcoio->fci = (struct fuse_create_in) {
+ .flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY),
+ .mode = mode,
+ };
+
+ *fa = (struct fuse_args) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_CREATE,
+ .in_numargs = 2,
+ .in_args[0] = (struct fuse_in_arg) {
+ .size = sizeof(fcoio->fci),
+ .value = &fcoio->fci,
+ },
+ .in_args[1] = (struct fuse_in_arg) {
+ .size = entry->d_name.len + 1,
+ .value = (void *) entry->d_name.name,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_create_open_initialize_out(struct fuse_args *fa, struct fuse_create_open_io *fcoio,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ fcoio->feo = (struct fuse_entry_out) { 0 };
+ fcoio->foo = (struct fuse_open_out) { 0 };
+
+ fa->out_numargs = 2;
+ fa->out_args[0] = (struct fuse_arg) {
+ .size = sizeof(fcoio->feo),
+ .value = &fcoio->feo,
+ };
+ fa->out_args[1] = (struct fuse_arg) {
+ .size = sizeof(fcoio->foo),
+ .value = &fcoio->foo,
+ };
+
+ return 0;
+}
+
+static int fuse_open_file_backing(struct inode *inode, struct file *file)
+{
+ struct fuse_mount *fm = get_fuse_mount(inode);
+ struct dentry *entry = file->f_path.dentry;
+ struct fuse_dentry *fuse_dentry = get_fuse_dentry(entry);
+ struct fuse_file *fuse_file;
+ struct file *backing_file;
+
+ fuse_file = fuse_file_alloc(fm);
+ if (!fuse_file)
+ return -ENOMEM;
+ file->private_data = fuse_file;
+
+ backing_file = dentry_open(&fuse_dentry->backing_path, file->f_flags,
+ current_cred());
+ if (IS_ERR(backing_file)) {
+ fuse_file_free(fuse_file);
+ file->private_data = NULL;
+ return PTR_ERR(backing_file);
+ }
+ fuse_file->backing_file = backing_file;
+
+ return 0;
+}
+
+static int fuse_create_open_backing(struct fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ struct fuse_inode *dir_fuse_inode = get_fuse_inode(dir);
+ struct path backing_path;
+ struct inode *inode = NULL;
+ struct dentry *backing_parent;
+ struct dentry *newent;
+ const struct fuse_create_in *fci = fa->in_args[0].value;
+
+ get_fuse_backing_path(entry, &backing_path);
+ if (!backing_path.dentry)
+ return -EBADF;
+
+ if (IS_ERR(backing_path.dentry))
+ return PTR_ERR(backing_path.dentry);
+
+ if (d_really_is_positive(backing_path.dentry)) {
+ *out = -EIO;
+ goto out;
+ }
+
+ backing_parent = dget_parent(backing_path.dentry);
+ inode_lock_nested(dir_fuse_inode->backing_inode, I_MUTEX_PARENT);
+ *out = vfs_create(&init_user_ns, d_inode(backing_parent),
+ backing_path.dentry, fci->mode, true);
+ inode_unlock(d_inode(backing_parent));
+ dput(backing_parent);
+ if (*out)
+ goto out;
+
+ inode = fuse_iget_backing(dir->i_sb, 0, backing_path.dentry->d_inode);
+ if (IS_ERR(inode)) {
+ *out = PTR_ERR(inode);
+ goto out;
+ }
+
+ newent = d_splice_alias(inode, entry);
+ if (IS_ERR(newent)) {
+ *out = PTR_ERR(newent);
+ goto out;
+ }
+
+ entry = newent ? newent : entry;
+ *out = finish_open(file, entry, fuse_open_file_backing);
+
+out:
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_create_open_finalize(struct fuse_args *fa, int *out,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ struct fuse_file *ff = file->private_data;
+ struct fuse_inode *fi = get_fuse_inode(file->f_inode);
+ struct fuse_entry_out *feo = fa->out_args[0].value;
+ struct fuse_open_out *foo = fa->out_args[1].value;
+
+ if (fi)
+ fi->nodeid = feo->nodeid;
+ if (ff)
+ ff->fh = foo->fh;
+ return 0;
+}
+
+int fuse_bpf_create_open(int *out, struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ return fuse_bpf_backing(dir, struct fuse_create_open_io, out,
+ fuse_create_open_initialize_in,
+ fuse_create_open_initialize_out,
+ fuse_create_open_backing,
+ fuse_create_open_finalize,
+ dir, entry, file, flags, mode);
+}
+
+static int fuse_release_initialize_in(struct fuse_args *fa, struct fuse_release_in *fri,
+ struct inode *inode, struct file *file)
+{
+ struct fuse_file *fuse_file = file->private_data;
+
+ /* Always put backing file whatever bpf/userspace says */
+ fput(fuse_file->backing_file);
+
+ *fri = (struct fuse_release_in) {
+ .fh = ((struct fuse_file *)(file->private_data))->fh,
+ };
+
+ *fa = (struct fuse_args) {
+ .nodeid = get_fuse_inode(inode)->nodeid,
+ .opcode = FUSE_RELEASE,
+ .in_numargs = 1,
+ .in_args[0].size = sizeof(*fri),
+ .in_args[0].value = fri,
+ };
+
+ return 0;
+}
+
+static int fuse_release_initialize_out(struct fuse_args *fa, struct fuse_release_in *fri,
+ struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static int fuse_releasedir_initialize_in(struct fuse_args *fa,
+ struct fuse_release_in *fri,
+ struct inode *inode, struct file *file)
+{
+ struct fuse_file *fuse_file = file->private_data;
+
+ /* Always put backing file whatever bpf/userspace says */
+ fput(fuse_file->backing_file);
+
+ *fri = (struct fuse_release_in) {
+ .fh = ((struct fuse_file *)(file->private_data))->fh,
+ };
+
+ *fa = (struct fuse_args) {
+ .nodeid = get_fuse_inode(inode)->nodeid,
+ .opcode = FUSE_RELEASEDIR,
+ .in_numargs = 1,
+ .in_args[0].size = sizeof(*fri),
+ .in_args[0].value = fri,
+ };
+
+ return 0;
+}
+
+static int fuse_releasedir_initialize_out(struct fuse_args *fa,
+ struct fuse_release_in *fri,
+ struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static int fuse_release_backing(struct fuse_args *fa, int *out,
+ struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static int fuse_release_finalize(struct fuse_args *fa, int *out,
+ struct inode *inode, struct file *file)
+{
+ fuse_file_free(file->private_data);
+ *out = 0;
+ return 0;
+}
+
+int fuse_bpf_release(int *out, struct inode *inode, struct file *file)
+{
+ return fuse_bpf_backing(inode, struct fuse_release_in, out,
+ fuse_release_initialize_in, fuse_release_initialize_out,
+ fuse_release_backing, fuse_release_finalize,
+ inode, file);
+}
+
+int fuse_bpf_releasedir(int *out, struct inode *inode, struct file *file)
+{
+ return fuse_bpf_backing(inode, struct fuse_release_in, out,
+ fuse_releasedir_initialize_in, fuse_releasedir_initialize_out,
+ fuse_release_backing, fuse_release_finalize, inode, file);
+}
+
struct fuse_lseek_io {
struct fuse_lseek_in fli;
struct fuse_lseek_out flo;
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 4e19320889ed..e330a6af9ee7 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -635,6 +635,9 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
/* Userspace expects S_IFREG in create mode */
BUG_ON((mode & S_IFMT) != S_IFREG);

+ if (fuse_bpf_create_open(&err, dir, entry, file, flags, mode))
+ return err;
+
forget = fuse_alloc_forget();
err = -ENOMEM;
if (!forget)
@@ -1554,6 +1557,11 @@ static int fuse_dir_open(struct inode *inode, struct file *file)

static int fuse_dir_release(struct inode *inode, struct file *file)
{
+ int err = 0;
+
+ if (fuse_bpf_releasedir(&err, inode, file))
+ return err;
+
fuse_release_common(file, true);

return 0;
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ab3cd43556e0..70a5bd5403ca 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -241,6 +241,9 @@ int fuse_open_common(struct inode *inode, struct file *file, bool isdir)
if (err)
return err;

+ if (fuse_bpf_open(&err, inode, file, isdir))
+ return err;
+
if (is_wb_truncate || dax_truncate)
inode_lock(inode);

@@ -349,6 +352,10 @@ static int fuse_open(struct inode *inode, struct file *file)
static int fuse_release(struct inode *inode, struct file *file)
{
struct fuse_conn *fc = get_fuse_conn(inode);
+ int err;
+
+ if (fuse_bpf_release(&err, inode, file))
+ return err;

/*
* Dirty pages might remain despite write_inode_now() call from
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 4351dbc7f10d..794b1a06079c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1400,6 +1400,11 @@ int parse_fuse_bpf_entry(struct fuse_bpf_entry *fbe, int num_entries);

#ifdef CONFIG_FUSE_BPF

+int fuse_bpf_open(int *err, struct inode *inode, struct file *file, bool isdir);
+int fuse_bpf_create_open(int *out, struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode);
+int fuse_bpf_release(int *out, struct inode *inode, struct file *file);
+int fuse_bpf_releasedir(int *out, struct inode *inode, struct file *file);
int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence);
int fuse_bpf_file_fallocate(int *out, struct inode *inode, struct file *file, int mode, loff_t offset, loff_t length);
int fuse_bpf_lookup(struct dentry **out, struct inode *dir, struct dentry *entry, unsigned int flags);
@@ -1407,6 +1412,27 @@ int fuse_bpf_access(int *out, struct inode *inode, int mask);

#else

+static inline int fuse_bpf_open(int *err, struct inode *inode, struct file *file, bool isdir)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_create_open(int *out, struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_release(int *out, struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
+static inline int fuse_bpf_releasedir(int *out, struct inode *inode, struct file *file)
+{
+ return 0;
+}
+
static inline int fuse_bpf_lseek(loff_t *out, struct inode *inode, struct file *file, loff_t offset, int whence)
{
return 0;
--
2.38.1.584.g0f3c55d4c2-goog