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Message-ID: <20250804173228.1990317-3-paullawrence@google.com>
Date: Mon, 4 Aug 2025 10:32:28 -0700
From: Paul Lawrence <paullawrence@...gle.com>
To: amir73il@...il.com
Cc: bernd.schubert@...tmail.fm, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, miklos@...redi.hu, paullawrence@...gle.com
Subject: [PATCH 2/2] fuse: Add passthrough for mkdir and rmdir (WIP)
As proof of concept of setting a backing file at lookup, implement mkdir
and rmdir which work off the nodeid only and do not open the file.
Signed-off-by: Paul Lawrence <paullawrence@...gle.com>
---
fs/fuse/dir.c | 8 +++++++-
fs/fuse/fuse_i.h | 11 +++++++++--
fs/fuse/passthrough.c | 38 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/fuse.h | 2 ++
4 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c0bef93dd078..25d6929d600a 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -129,7 +129,7 @@ void fuse_invalidate_attr(struct inode *inode)
fuse_invalidate_attr_mask(inode, STATX_BASIC_STATS);
}
-static void fuse_dir_changed(struct inode *dir)
+void fuse_dir_changed(struct inode *dir)
{
fuse_invalidate_attr(dir);
inode_maybe_inc_iversion(dir, false);
@@ -951,6 +951,9 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
if (!fm->fc->dont_mask)
mode &= ~current_umask();
+ if (fuse_inode_passthrough_op(dir, FUSE_MKDIR))
+ return fuse_passthrough_mkdir(idmap, dir, entry, mode);
+
memset(&inarg, 0, sizeof(inarg));
inarg.mode = mode;
inarg.umask = current_umask();
@@ -1058,6 +1061,9 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
if (fuse_is_bad(dir))
return -EIO;
+ if (fuse_inode_passthrough_op(dir, FUSE_RMDIR))
+ return fuse_passthrough_rmdir(dir, entry);
+
args.opcode = FUSE_RMDIR;
args.nodeid = get_node_id(dir);
args.in_numargs = 2;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index aebd338751f1..d8df2d5a73ac 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1279,6 +1279,7 @@ void fuse_check_timeout(struct work_struct *work);
#define FUSE_STATX_MODSIZE (FUSE_STATX_MODIFY | STATX_SIZE)
void fuse_invalidate_attr(struct inode *inode);
+void fuse_dir_changed(struct inode *dir);
void fuse_invalidate_attr_mask(struct inode *inode, u32 mask);
void fuse_invalidate_entry_cache(struct dentry *entry);
@@ -1521,7 +1522,8 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
/* Passthrough operations for directories */
#define FUSE_PASSTHROUGH_DIR_OPS \
- (FUSE_PASSTHROUGH_OP_READDIR)
+ (FUSE_PASSTHROUGH_OP_READDIR | FUSE_PASSTHROUGH_OP_MKDIR | \
+ FUSE_PASSTHROUGH_OP_RMDIR)
/* Inode passthrough operations for backing file attached to inode */
#define FUSE_PASSTHROUGH_INODE_OPS \
@@ -1532,7 +1534,8 @@ void fuse_file_release(struct inode *inode, struct fuse_file *ff,
((map)->ops_mask & FUSE_PASSTHROUGH_OP(op))
#define FUSE_BACKING_MAP_VALID_OPS \
- (FUSE_PASSTHROUGH_RW_OPS | FUSE_PASSTHROUGH_INODE_OPS)
+ (FUSE_PASSTHROUGH_RW_OPS | FUSE_PASSTHROUGH_INODE_OPS |\
+ FUSE_PASSTHROUGH_DIR_OPS)
static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
{
@@ -1626,6 +1629,10 @@ ssize_t fuse_passthrough_getxattr(struct inode *inode, const char *name,
void *value, size_t size);
ssize_t fuse_passthrough_listxattr(struct dentry *entry, char *list,
size_t size);
+struct dentry *fuse_passthrough_mkdir(struct mnt_idmap *idmap,
+ struct inode *dir, struct dentry *entry,
+ umode_t mode);
+int fuse_passthrough_rmdir(struct inode *dir, struct dentry *entry);
#ifdef CONFIG_SYSCTL
extern int fuse_sysctl_register(void);
diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
index cee40e1c6e4a..acb06fbbd828 100644
--- a/fs/fuse/passthrough.c
+++ b/fs/fuse/passthrough.c
@@ -7,6 +7,7 @@
#include "fuse_i.h"
+#include "linux/namei.h"
#include <linux/file.h>
#include <linux/backing-file.h>
#include <linux/splice.h>
@@ -497,3 +498,40 @@ ssize_t fuse_passthrough_listxattr(struct dentry *entry, char *list,
revert_creds(old_cred);
return res;
}
+
+struct dentry *fuse_passthrough_mkdir(struct mnt_idmap *idmap,
+ struct inode *dir, struct dentry *entry,
+ umode_t mode)
+{
+ struct fuse_backing *fb = fuse_inode_backing(get_fuse_inode(dir));
+ struct dentry *backing_entry, *new_entry;
+ const struct cred *old_cred;
+
+ old_cred = override_creds(fb->cred);
+ backing_entry = lookup_one_unlocked(idmap, &entry->d_name,
+ fb->file->f_path.dentry);
+ new_entry = vfs_mkdir(idmap, fb->file->f_inode, backing_entry, mode);
+ d_drop(entry);
+ revert_creds(old_cred);
+ fuse_dir_changed(dir);
+ return new_entry;
+}
+
+int fuse_passthrough_rmdir(struct inode *dir, struct dentry *entry)
+{
+ int err;
+ struct dentry *backing_entry;
+ struct fuse_backing *fb = fuse_inode_backing(get_fuse_inode(dir));
+ const struct cred *old_cred;
+
+ old_cred = override_creds(fb->cred);
+ backing_entry = lookup_one_unlocked(&nop_mnt_idmap, &entry->d_name,
+ fb->file->f_path.dentry);
+ err = vfs_rmdir(&nop_mnt_idmap, fb->file->f_inode, backing_entry);
+ dput(backing_entry);
+ if (!err)
+ d_drop(entry);
+ revert_creds(old_cred);
+ return err;
+}
+
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 6dbb045c794d..8181d07b7bf1 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -1135,6 +1135,8 @@ struct fuse_backing_map {
#define FUSE_PASSTHROUGH_OP_STATX FUSE_PASSTHROUGH_OP(FUSE_STATX)
#define FUSE_PASSTHROUGH_OP_GETXATTR FUSE_PASSTHROUGH_OP(FUSE_GETXATTR)
#define FUSE_PASSTHROUGH_OP_LISTXATTR FUSE_PASSTHROUGH_OP(FUSE_LISTXATTR)
+#define FUSE_PASSTHROUGH_OP_MKDIR FUSE_PASSTHROUGH_OP(FUSE_MKDIR)
+#define FUSE_PASSTHROUGH_OP_RMDIR FUSE_PASSTHROUGH_OP(FUSE_RMDIR)
/* Device ioctls: */
#define FUSE_DEV_IOC_MAGIC 229
--
2.50.1.565.gc32cd1483b-goog
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