[RFC PATCH v4 11/36] fuse-bpf: Support file/dir open/close

Daniel Rosenberg
2024-03-29T01:54:24Z

This adds backing support for FUSE_OPEN, FUSE_OPENDIR, FUSE_CREATE,
FUSE_RELEASE, and FUSE_RELEASEDIR

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
fs/fuse/backing.c | 336 ++++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/dir.c | 3 +
fs/fuse/file.c | 62 +++++----
fs/fuse/fuse_i.h | 26 ++++
4 files changed, 404 insertions(+), 23 deletions(-)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index 4a22465ecdef..317a3adbbb3e 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -210,6 +210,342 @@ static void fuse_stat_to_attr(struct fuse_conn *fc, struct inode *inode,
attr->blksize = 1 << blkbits;
}

+struct fuse_open_args {
+ struct fuse_open_in in;
+ struct fuse_open_out out;
+};
+
+static int fuse_open_initialize_in(struct bpf_fuse_args *fa, struct fuse_open_args *args,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ args->in = (struct fuse_open_in) {
+ .flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY),
+ };
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(inode)->nodeid,
+ .opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN,
+ },
+ .in_numargs = 1,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->in),
+ .value = &args->in,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_open_initialize_out(struct bpf_fuse_args *fa, struct fuse_open_args *args,
+ struct inode *inode, struct file *file, bool isdir)
+{
+ args->out = (struct fuse_open_out) { 0 };
+
+ fa->out_numargs = 1;
+ fa->out_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->out),
+ .value = &args->out,
+ };
+
+ return 0;
+}
+
+static int fuse_open_backing(struct bpf_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(&nop_mnt_idmap,
+ 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 bpf_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 bpf_fuse_backing(inode, struct fuse_open_args, out,
+ fuse_open_initialize_in, fuse_open_initialize_out,
+ fuse_open_backing, fuse_open_finalize,
+ inode, file, isdir);
+}
+
+struct fuse_create_open_args {
+ struct fuse_create_in in;
+ struct fuse_buffer name;
+ struct fuse_entry_out entry_out;
+ struct fuse_open_out open_out;
+};
+
+static int fuse_create_open_initialize_in(struct bpf_fuse_args *fa, struct fuse_create_open_args *args,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ args->in = (struct fuse_create_in) {
+ .flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY),
+ .mode = mode,
+ };
+
+ args->name = (struct fuse_buffer) {
+ .data = (void *) entry->d_name.name,
+ .size = entry->d_name.len + 1,
+ .flags = BPF_FUSE_IMMUTABLE,
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_node_id(dir),
+ .opcode = FUSE_CREATE,
+ },
+ .in_numargs = 2,
+ .in_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->in),
+ .value = &args->in,
+ },
+ .in_args[1] = (struct bpf_fuse_arg) {
+ .is_buffer = true,
+ .buffer = &args->name,
+ },
+ };
+
+ return 0;
+}
+
+static int fuse_create_open_initialize_out(struct bpf_fuse_args *fa, struct fuse_create_open_args *args,
+ struct inode *dir, struct dentry *entry,
+ struct file *file, unsigned int flags, umode_t mode)
+{
+ args->entry_out = (struct fuse_entry_out) { 0 };
+ args->open_out = (struct fuse_open_out) { 0 };
+
+ fa->out_numargs = 2;
+ fa->out_args[0] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->entry_out),
+ .value = &args->entry_out,
+ };
+ fa->out_args[1] = (struct bpf_fuse_arg) {
+ .size = sizeof(args->open_out),
+ .value = &args->open_out,
+ };
+
+ 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 bpf_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(&nop_mnt_idmap, 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 (!inode) {
+ *out = -EIO;
+ goto out;
+ }
+
+ newent = d_splice_alias(inode, entry);
+ if (IS_ERR(newent)) {
+ *out = PTR_ERR(newent);
+ goto out;
+ }
+
+ inode = NULL;
+ entry = newent ? newent : entry;
+ *out = finish_open(file, entry, fuse_open_file_backing);
+
+out:
+ iput(inode);
+ path_put(&backing_path);
+ return *out;
+}
+
+static int fuse_create_open_finalize(struct bpf_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 bpf_fuse_backing(dir, struct fuse_create_open_args, 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 bpf_fuse_args *fa, struct fuse_release_in *fri,
+ struct inode *inode, struct fuse_file *ff)
+{
+ /* Always put backing file whatever bpf/userspace says */
+ fput(ff->backing_file);
+
+ *fri = (struct fuse_release_in) {
+ .fh = ff->fh,
+ };
+
+ *fa = (struct bpf_fuse_args) {
+ .info = (struct bpf_fuse_meta_info) {
+ .nodeid = get_fuse_inode(inode)->nodeid,
+ .opcode = S_ISDIR(inode->i_mode) ? FUSE_RELEASEDIR
+ : 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 bpf_fuse_args *fa, struct fuse_release_in *fri,
+ struct inode *inode, struct fuse_file *ff)
+{
+ return 0;
+}
+
+static int fuse_release_backing(struct bpf_fuse_args *fa, int *out,
+ struct inode *inode, struct fuse_file *ff)
+{
+ return 0;
+}
+
+static int fuse_release_finalize(struct bpf_fuse_args *fa, int *out,
+ struct inode *inode, struct fuse_file *ff)
+{
+ *out = 0;
+ return 0;
+}
+
+int fuse_bpf_release(int *out, struct inode *inode, struct fuse_file *ff)
+{
+ return bpf_fuse_backing(inode, struct fuse_release_in, out,
+ fuse_release_initialize_in, fuse_release_initialize_out,
+ fuse_release_backing, fuse_release_finalize,
+ inode, ff);
+}
+
+int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff)
+{
+ return bpf_fuse_backing(inode, struct fuse_release_in, out,
+ fuse_release_initialize_in, fuse_release_initialize_out,
+ fuse_release_backing, fuse_release_finalize, inode, ff);
+}
+
struct fuse_lseek_args {
struct fuse_lseek_in in;
struct fuse_lseek_out out;
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 8db6eb6a0848..09bb4c63fd71 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -736,6 +736,9 @@ 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)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 0ab882e1236a..c43f2d61c41a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -106,25 +106,35 @@ static void fuse_release_end(struct fuse_mount *fm, struct fuse_args *args,
kfree(ra);
}

-static void fuse_file_put(struct fuse_file *ff, bool sync, bool isdir)
+static void fuse_file_put(struct inode *inode, struct fuse_file *ff,
+ bool sync, bool isdir)
{
- if (refcount_dec_and_test(&ff->count)) {
- struct fuse_args *args = &ff->release_args->args;
+ struct fuse_args *args = &ff->release_args->args;
+#ifdef CONFIG_FUSE_BPF
+ int err;
+#endif
+ if (!refcount_dec_and_test(&ff->count))
+ return;

- if (isdir ? ff->fm->fc->no_opendir : ff->fm->fc->no_open) {
- /* Do nothing when client does not implement 'open' */
- fuse_release_end(ff->fm, args, 0);
- } else if (sync) {
- fuse_simple_request(ff->fm, args);
- fuse_release_end(ff->fm, args, 0);
- } else {
- args->end = fuse_release_end;
- if (fuse_simple_background(ff->fm, args,
- GFP_KERNEL | __GFP_NOFAIL))
- fuse_release_end(ff->fm, args, -ENOTCONN);
- }
- kfree(ff);
+#ifdef CONFIG_FUSE_BPF
+ if (fuse_bpf_releasedir(&err, inode, ff)) {
+ fuse_release_end(ff->fm, args, 0);
+ } else
+#endif
+
+ if (isdir ? ff->fm->fc->no_opendir : ff->fm->fc->no_open) {
+ /* Do nothing when client does not implement 'open' */
+ fuse_release_end(ff->fm, args, 0);
+ } else if (sync) {
+ fuse_simple_request(ff->fm, args);
+ fuse_release_end(ff->fm, args, 0);
+ } else {
+ args->end = fuse_release_end;
+ if (fuse_simple_background(ff->fm, args,
+ GFP_KERNEL | __GFP_NOFAIL))
+ fuse_release_end(ff->fm, args, -ENOTCONN);
}
+ kfree(ff);
}

struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
@@ -243,6 +253,9 @@ 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);

@@ -334,7 +347,7 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
* synchronous RELEASE is allowed (and desirable) in this case
* because the server can be trusted not to screw up.
*/
- fuse_file_put(ff, ff->fm->fc->destroy, isdir);
+ fuse_file_put(ra->inode, ff, ff->fm->fc->destroy, isdir);
}

void fuse_release_common(struct file *file, bool isdir)
@@ -374,7 +387,7 @@ void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff,
* iput(NULL) is a no-op and since the refcount is 1 and everything's
* synchronous, we are fine with not doing igrab() here"
*/
- fuse_file_put(ff, true, false);
+ fuse_file_put(&fi->inode, ff, true, false);
}
EXPORT_SYMBOL_GPL(fuse_sync_release);

@@ -930,8 +943,11 @@ static void fuse_readpages_end(struct fuse_mount *fm, struct fuse_args *args,
unlock_page(page);
put_page(page);
}
- if (ia->ff)
- fuse_file_put(ia->ff, false, false);
+ if (ia->ff) {
+ WARN_ON(!mapping);
+ fuse_file_put(mapping ? mapping->host : NULL, ia->ff,
+ false, false);
+ }

fuse_io_free(ia);
}
@@ -1673,7 +1689,7 @@ static void fuse_writepage_free(struct fuse_writepage_args *wpa)
__free_page(ap->pages[i]);

if (wpa->ia.ff)
- fuse_file_put(wpa->ia.ff, false, false);
+ fuse_file_put(wpa->inode, wpa->ia.ff, false, false);

kfree(ap->pages);
kfree(wpa);
@@ -1928,7 +1944,7 @@ int fuse_write_inode(struct inode *inode, struct writeback_control *wbc)
ff = __fuse_write_file_get(fi);
err = fuse_flush_times(inode, ff);
if (ff)
- fuse_file_put(ff, false, false);
+ fuse_file_put(inode, ff, false, false);

return err;
}
@@ -2326,7 +2342,7 @@ static int fuse_writepages(struct address_space *mapping,
fuse_writepages_send(&data);
}
if (data.ff)
- fuse_file_put(data.ff, false, false);
+ fuse_file_put(inode, data.ff, false, false);

kfree(data.orig_pages);
out:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7a6cebecd00f..a133010fde1c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1438,6 +1438,11 @@ 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 fuse_file *ff);
+int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff);
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);
@@ -1445,6 +1450,27 @@ 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;
--
2.44.0.478.gd926399ef9-goog