Traditionally, we've allowed people to set leases on FUSE inodes. Some
FUSE drivers are effectively local filesystems and should be fine with
kernel-internal lease support. But others are backed by a network server
that may have multiple clients, or may be backed by something non-file
like entirely.
Have the filesytem driver to set a fuse_conn flag to indicate whether it
wants support for local, in-kernel leases. If the flag is unset (the
default), then setlease attempts will fail with -EINVAL, indicating that
leases aren't supported on that inode.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
This is only tested for compilation, but it's fairly straightforward.
Having the FUSE drivers opt-out of this support might be more
backward-compatible, but that is a bit more dangerous. I'd rather driver
maintainer consciously opt-in.
---
fs/fuse/file.c | 11 +++++++++++
fs/fuse/fuse_i.h | 3 +++
fs/fuse/inode.c | 4 +++-
include/uapi/linux/fuse.h | 1 +
4 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index a56e7bffd000..3d9aef376783 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -3298,6 +3298,16 @@ static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off,
return ret;
}
+static int fuse_setlease(struct file *file, int arg,
+ struct file_lease **flp, void **priv)
+{
+ struct fuse_conn *fc = get_fuse_conn(file_inode(file));
+
+ if (fc->local_leases)
+ return generic_setlease(file, arg, flp, priv);
+ return -EINVAL;
+}
+
static const struct file_operations fuse_file_operations = {
.llseek = fuse_file_llseek,
.read_iter = fuse_file_read_iter,
@@ -3317,6 +3327,7 @@ static const struct file_operations fuse_file_operations = {
.poll = fuse_file_poll,
.fallocate = fuse_file_fallocate,
.copy_file_range = fuse_copy_file_range,
+ .setlease = fuse_setlease,
};
static const struct address_space_operations fuse_file_aops = {
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b24084b60864..2909788bf69f 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -860,6 +860,9 @@ struct fuse_conn {
/** Passthrough support for read/write IO */
unsigned int passthrough:1;
+ /** Opt-in to local kernel lease support */
+ unsigned int local_leases:1;
+
/** Maximum stack depth for passthrough backing files */
int max_stack_depth;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 3a5d88878335..6958c7690e68 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1330,6 +1330,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
}
if (flags & FUSE_NO_EXPORT_SUPPORT)
fm->sb->s_export_op = &fuse_export_fid_operations;
+ if (flags & FUSE_LOCAL_LEASES)
+ fc->local_leases = 1;
} else {
ra_pages = fc->max_read / PAGE_SIZE;
fc->no_lock = 1;
@@ -1377,7 +1379,7 @@ void fuse_send_init(struct fuse_mount *fm)
FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_INIT_EXT |
FUSE_SECURITY_CTX | FUSE_CREATE_SUPP_GROUP |
FUSE_HAS_EXPIRE_ONLY | FUSE_DIRECT_IO_ALLOW_MMAP |
- FUSE_NO_EXPORT_SUPPORT | FUSE_HAS_RESEND;
+ FUSE_NO_EXPORT_SUPPORT | FUSE_HAS_RESEND | FUSE_LOCAL_LEASES;
#ifdef CONFIG_FUSE_DAX
if (fm->fc->dax)
flags |= FUSE_MAP_ALIGNMENT;
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index d08b99d60f6f..76322808159d 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -463,6 +463,7 @@ struct fuse_file_lock {
#define FUSE_PASSTHROUGH (1ULL << 37)
#define FUSE_NO_EXPORT_SUPPORT (1ULL << 38)
#define FUSE_HAS_RESEND (1ULL << 39)
+#define FUSE_LOCAL_LEASES (1ULL << 40)
/* Obsolete alias for FUSE_DIRECT_IO_ALLOW_MMAP */
#define FUSE_DIRECT_IO_RELAX FUSE_DIRECT_IO_ALLOW_MMAP
---
base-commit: 0a7b0acecea273c8816f4f5b0e189989470404cf
change-id: 20240319-setlease-ce31fb8777b0
Best regards,
--
Jeff Layton <jlayton@xxxxxxxxxx>
