[PATCH 16/17] lxc_fuse: Implement support for FUSE3
Plenty of projects switch from FUSE to FUSE3. This commit enables
libvirt to compile with newer fuse-3.1 which allows users to have
just one fuse package on their systems, allows us to set
O_CLOEXEC on the fuse session FD. In general, FUSE3 offers more
features, but apparently we don't need them right now. There is a
rewrite guide at [1] but I've took most inspiration from sshfs
[2].
1: https://github.com/libfuse/libfuse/releases/tag/fuse-3.0.0
2: https://github.com/libfuse/sshfs
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/lxc/lxc_fuse.c | 73 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 71 insertions(+), 2 deletions(-)
diff --git a/src/lxc/lxc_fuse.c b/src/lxc/lxc_fuse.c
index 181b05b605..802b2f5a1b 100644
--- a/src/lxc/lxc_fuse.c
+++ b/src/lxc/lxc_fuse.c
@@ -28,6 +28,9 @@
#if WITH_FUSE
# define FUSE_USE_VERSION 26
# include <fuse.h>
+# if FUSE_USE_VERSION >= 31
+# include <fuse_lowlevel.h>
+# endif
#endif
#include "lxc_fuse.h"
@@ -48,15 +51,19 @@ struct virLXCFuse {
virThread thread;
char *mountpoint;
struct fuse *fuse;
+# if FUSE_USE_VERSION < 31
struct fuse_chan *ch;
+# else
+ struct fuse_session *sess;
+# endif
virMutex lock;
};
static const char *fuse_meminfo_path = "/meminfo";
static int
-lxcProcGetattr(const char *path,
- struct stat *stbuf)
+lxcProcGetattrImpl(const char *path,
+ struct stat *stbuf)
{
g_autofree char *mempath = NULL;
struct stat sb;
@@ -90,6 +97,40 @@ lxcProcGetattr(const char *path,
return 0;
}
+# if FUSE_USE_VERSION >= 31
+static int
+lxcProcGetattr(const char *path,
+ struct stat *stbuf,
+ struct fuse_file_info *fi G_GNUC_UNUSED)
+{
+ return lxcProcGetattrImpl(path, stbuf);
+}
+# else
+static int lxcProcGetattr(const char *path, struct stat *stbuf)
+{
+ return lxcProcGetattrImpl(path, stbuf);
+}
+# endif
+
+# if FUSE_USE_VERSION >= 31
+static int
+lxcProcReaddir(const char *path,
+ void *buf,
+ fuse_fill_dir_t filler,
+ off_t offset G_GNUC_UNUSED,
+ struct fuse_file_info *fi G_GNUC_UNUSED,
+ enum fuse_readdir_flags unused_flags G_GNUC_UNUSED)
+{
+ if (STRNEQ(path, "/"))
+ return -ENOENT;
+
+ filler(buf, ".", NULL, 0, 0);
+ filler(buf, "..", NULL, 0, 0);
+ filler(buf, fuse_meminfo_path + 1, NULL, 0, 0);
+
+ return 0;
+}
+# else
static int
lxcProcReaddir(const char *path,
void *buf,
@@ -106,6 +147,7 @@ lxcProcReaddir(const char *path,
return 0;
}
+# endif
static int
lxcProcOpen(const char *path,
@@ -292,7 +334,11 @@ lxcFuseDestroy(struct virLXCFuse *fuse)
{
VIR_LOCK_GUARD lock = virLockGuardLock(&fuse->lock);
+# if FUSE_USE_VERSION >= 31
+ fuse_unmount(fuse->fuse);
+# else
fuse_unmount(fuse->mountpoint, fuse->ch);
+# endif
g_clear_pointer(&fuse->fuse, fuse_destroy);
}
@@ -335,6 +381,23 @@ lxcSetupFuse(struct virLXCFuse **f,
fuse_opt_add_arg(&args, "-ofsname=libvirt") == -1)
goto error;
+# if FUSE_USE_VERSION >= 31
+ fuse->fuse = fuse_new(&args, &lxcProcOper, sizeof(lxcProcOper),
fuse->def);
+ if (fuse->fuse == NULL)
+ goto error;
+
+ if (fuse_mount(fuse->fuse, fuse->mountpoint) < 0)
+ goto error;
+
+ fuse->sess = fuse_get_session(fuse->fuse);
+
+ if (virSetInherit(fuse_session_fd(fuse->sess), false) < 0) {
+ virReportSystemError(errno, "%s",
+ _("Cannot disable close-on-exec flag"));
+ goto error;
+ }
+
+# else
fuse->ch = fuse_mount(fuse->mountpoint, &args);
if (fuse->ch == NULL)
goto error;
@@ -344,6 +407,7 @@ lxcSetupFuse(struct virLXCFuse **f,
if (fuse->fuse == NULL) {
goto error;
}
+# endif
*f = g_steal_pointer(&fuse);
ret = 0;
@@ -352,8 +416,13 @@ lxcSetupFuse(struct virLXCFuse **f,
return ret;
error:
+# if FUSE_USE_VERSION < 31
if (fuse->ch)
fuse_unmount(fuse->mountpoint, fuse->ch);
+# else
+ fuse_unmount(fuse->fuse);
+ fuse_destroy(fuse->fuse);
+# endif
g_free(fuse->mountpoint);
virMutexDestroy(&fuse->lock);
goto cleanup;
--
2.34.1