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document-portal-fuse.c
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document-portal-fuse.c
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/*
* Copyright © 2018 Red Hat, Inc
* Copyright © 2023 GNOME Foundation Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Authors:
* Alexander Larsson <alexl@redhat.com>
* Hubert Figuière <hub@figuiere.net>
*/
#include "config.h"
#define FUSE_USE_VERSION 35
#include <glib-unix.h>
#include <fuse_lowlevel.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <assert.h>
#include <glib/gprintf.h>
#include <gio/gio.h>
#include <pthread.h>
#ifdef HAVE_SYS_STATFS_H
#include <sys/statfs.h>
#endif
#include <sys/types.h>
#ifdef HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
#ifdef HAVE_SYS_XATTR_H
#include <sys/xattr.h>
#endif
#ifdef HAVE_SYS_EXTATTR_H
#include <sys/extattr.h>
#endif
#include <sys/time.h>
#include <sys/resource.h>
#include "document-portal-fuse.h"
#include "document-store.h"
#include "src/xdp-utils.h"
#ifndef O_FSYNC
#define O_FSYNC O_SYNC
#endif
#ifndef ENODATA
#define ENODATA ENOATTR
#endif
#define XDP_XATTR_HOST_PATH "user.document-portal.host-path"
/* man listxattr:
* The list is the set of (null-terminated) names, one after the other.
*
* Example:
* user.name1\0system.name1\0user.name2\0
*
* We can statically define the string by doing this:
* XDP_XATTR_MY_ATTR "\0" XDP_XATTR_ANOTHER_ATTR
*/
#define XDP_XATTR_ATTRIBUTE_NAME_LIST XDP_XATTR_HOST_PATH
/* Inode ownership model
*
* The document portal exposes something as a filesystem that it
* doesn't have full control over. For instance at any point some
* other process can rename an exposed file on the real filesystem and
* we won't be told about this. This means that in general we always
* return 0 for the cacheable lifetimes of entries and file attributes.
* (Except for the virtual directories we have full control of, the
* section below only discusses real files).
*
* However, even though we don't have full control of the underlying
* filesystem the *kernel* has. This means we can use that to get
* the correct semantics.
*
* For example, assume that a directory is held open by a process
* (for example, it could be the CWD of the process). When we open
* the directory via a LOOKUP operation we return an inode to it,
* and, for as long as the kernel has this inode around (i.e. until it
* sent a FORGET message), it can send operations on this inode without
* looking it up again. For example, if the above process used a
* relative path.
*
* Now, consider the case where the app chdir():ed into the fuse
* directory, but after the backing directory was renamed outside
* the fuse filesystem. The fuse inode representation for the inode
* cannot be the directory name, because the expected semantics is
* that further relative pathnames from the app will still resolve
* to the same directory independent of its location in the tree.
*
* The way we do this is to keep a O_PATH file descriptor around for
* each underlying inode. This is represented by the XdpPhysicalInode
* type and we have a hashtable from backing dev+inode to a these
* so that we can use one fd per backing inode even when the file
* is visible in many places.
*
* Since we don't do any caching, each LOOKUP operation will do a
* statat() on the underlying filesystem. However, we then use the
* result of that to lookup (via backing dev+ino) the previous inode
* (as long as it still lives) if the backing file was unchanged.
*
* One problem with this approach is that the kernel tends to keep
* inodes alive for a very long time even if they are *only*
* referenced by the dcache (Directory Entry Cache) (even though we
* will not really use the dcache info due to the 0 valid time). This
* is unfortunate, because it means we will keep a lot of file
* descriptors open. But, we can not know if the kernel needs the inode
* for some non-dcache use so we can't close the file descriptors.
*
* To work around this we regularly emit entry invalidation calls
* to the kernel, which will make it forget the inodes that are
* only pinned by the dcache.
*/
#define NON_DOC_DIR_PERMS 0500
#define DOC_DIR_PERMS_FILE 0700
#define DOC_DIR_PERMS_DIR 0500
static GThread *fuse_thread = NULL;
static struct fuse_session *session = NULL;
G_LOCK_DEFINE (session);
static char *mount_path = NULL;
static pthread_t fuse_pthread = 0;
static uid_t my_uid;
static gid_t my_gid;
/* from libfuse */
#define FUSE_UNKNOWN_INO 0xffffffff
#define BY_APP_NAME "by-app"
typedef struct {
ino_t ino;
dev_t dev;
} DevIno;
typedef enum {
XDP_DOMAIN_ROOT,
XDP_DOMAIN_BY_APP,
XDP_DOMAIN_APP,
XDP_DOMAIN_DOCUMENT,
} XdpDomainType;
typedef struct _XdpDomain XdpDomain;
typedef struct _XdpInode XdpInode;
struct _XdpDomain {
gint ref_count; /* atomic */
XdpDomainType type;
XdpDomain *parent;
XdpInode *parent_inode; /* Inode of the parent domain (NULL for root) */
char *doc_id; /* NULL for root, by-app, app */
char *app_id; /* NULL for root, by-app, non-app id */
/* root: by docid
* app: by docid
* by_app: by app
* document: by physical
*/
GHashTable *inodes; /* Protected by domain_inodes */
/* Below only used for XDP_DOMAIN_DOCUMENT */
char *doc_path; /* path to the directory the files are in */
char *doc_file; /* != NULL for non-directory documents */
guint64 doc_dir_device;
guint64 doc_dir_inode;
guint32 doc_flags;
/* Below is mutable, protected by mutex */
GMutex tempfile_mutex;
GHashTable *tempfiles; /* Name -> physical */
};
static void xdp_domain_unref (XdpDomain *domain);
G_DEFINE_AUTOPTR_CLEANUP_FUNC (XdpDomain, xdp_domain_unref)
G_LOCK_DEFINE (domain_inodes);
typedef struct {
gint ref_count; /* atomic */
DevIno backing_devino;
int fd; /* O_PATH fd */
} XdpPhysicalInode;
static XdpPhysicalInode *xdp_physical_inode_ref (XdpPhysicalInode *inode);
static void xdp_physical_inode_unref (XdpPhysicalInode *inode);
G_DEFINE_AUTOPTR_CLEANUP_FUNC (XdpPhysicalInode, xdp_physical_inode_unref)
typedef struct {
gint ref_count; /* atomic */
char *name; /* This changes over time (i.e. in renames)
protected by domain->tempfile_mutex,
used as key in domain->tempfiles */
char *tempname; /* Real filename on disk.
This can be NULLed to avoid unlink at finalize */
XdpInode *inode;
} XdpTempfile;
static XdpTempfile *xdp_tempfile_ref (XdpTempfile *tempfile);
static void xdp_tempfile_unref (XdpTempfile *tempfile);
G_DEFINE_AUTOPTR_CLEANUP_FUNC (XdpTempfile, xdp_tempfile_unref)
struct _XdpInode {
guint64 ino;
gint ref_count; /* atomic, includes one ref if kernel_ref_count != 0 */
gint kernel_ref_count; /* atomic */
XdpDomain *domain;
/* The below are only used for XDP_DOMAIN_DOCUMENT inodes */
XdpPhysicalInode *physical;
/* The root of the domain, or NULL for the domain. We use this to
* keep the root document inode alive so that when the kernel
* forgets it and then looks it up we will not get a new inode and
* thus a new domain. */
XdpInode *domain_root_inode;
};
typedef struct {
int fd;
} XdpFile;
typedef struct {
DIR *dir;
struct dirent *entry;
off_t offset;
char *dirbuf;
gsize dirbuf_size;
} XdpDir;
XdpInode *root_inode;
XdpInode *by_app_inode;
typedef struct {
ino_t parent_ino;
char name[0];
} XdpInvalidateData;
static GList *invalidate_list;
G_LOCK_DEFINE (invalidate_list);
static XdpInode *xdp_inode_ref (XdpInode *inode);
static void xdp_inode_unref (XdpInode *inode);
/* Lookup by inode for verification */
static GHashTable *all_inodes; /* guint64 -> XdpInode */
static guint64 next_virtual_inode = FUSE_ROOT_ID; /* root is the first inode created, so it gets this */
G_LOCK_DEFINE (all_inodes);
G_DEFINE_AUTOPTR_CLEANUP_FUNC (XdpInode, xdp_inode_unref)
static int ensure_docdir_inode (XdpInode *parent,
int o_path_fd_in, /* Takes ownership */
struct fuse_entry_param *e,
XdpInode **inode_out);
static void queue_invalidate_dentry (XdpInode *parent, const char *name);
static gboolean
app_can_write_doc (PermissionDbEntry *entry, const char *app_id)
{
if (app_id == NULL)
return TRUE;
if (document_entry_has_permissions_by_app_id (entry, app_id, DOCUMENT_PERMISSION_FLAGS_WRITE))
return TRUE;
return FALSE;
}
static gboolean
app_can_see_doc (PermissionDbEntry *entry, const char *app_id)
{
if (app_id == NULL)
return TRUE;
if (document_entry_has_permissions_by_app_id (entry, app_id, DOCUMENT_PERMISSION_FLAGS_READ))
return TRUE;
return FALSE;
}
static char *
fd_to_path (int fd)
{
return g_strdup_printf ("/proc/self/fd/%d", fd);
}
static char *
open_flags_to_string (int flags)
{
GString *s;
const char *mode;
switch (flags & O_ACCMODE)
{
case O_RDONLY:
mode = "RDONLY";
break;
case O_WRONLY:
mode = "WRONLY";
break;
case O_RDWR:
default:
mode = "RDWR";
break;
}
s = g_string_new (mode);
if (flags & O_NONBLOCK)
g_string_append (s, ",NONBLOCK");
if (flags & O_APPEND)
g_string_append (s, ",APPEND");
if (flags & O_SYNC)
g_string_append (s, ",SYNC");
if (flags & O_ASYNC)
g_string_append (s, ",ASYNC");
if (flags & O_FSYNC)
g_string_append (s, ",FSYNC");
#ifdef O_DSYNC
if (flags & O_DSYNC)
g_string_append (s, ",DSYNC");
#endif
if (flags & O_CREAT)
g_string_append (s, ",CREAT");
if (flags & O_TRUNC)
g_string_append (s, ",TRUNC");
if (flags & O_EXCL)
g_string_append (s, ",EXCL");
if (flags & O_CLOEXEC)
g_string_append (s, ",CLOEXEC");
if (flags & O_DIRECT)
g_string_append (s, ",DIRECT");
#ifdef O_LARGEFILE
if (flags & O_LARGEFILE)
g_string_append (s, ",LARGEFILE");
#endif
#ifdef O_NOATIME
if (flags & O_NOATIME)
g_string_append (s, ",NOATIME");
#endif
if (flags & O_NOCTTY)
g_string_append (s, ",NOCTTY");
if (flags & O_PATH)
g_string_append (s, ",PATH");
#ifdef O_TMPFILE
if (flags & O_TMPFILE)
g_string_append (s, ",TMPFILE");
#endif
return g_string_free (s, FALSE);
}
static char *
setattr_flags_to_string (int flags)
{
GString *s = g_string_new ("");
if (flags & FUSE_SET_ATTR_MODE)
g_string_append (s, "MODE,");
if (flags & FUSE_SET_ATTR_UID)
g_string_append (s, "UID,");
if (flags & FUSE_SET_ATTR_GID)
g_string_append (s, "GID,");
if (flags & FUSE_SET_ATTR_SIZE)
g_string_append (s, "SIZE,");
if (flags & FUSE_SET_ATTR_ATIME)
g_string_append (s, "ATIME,");
if (flags & FUSE_SET_ATTR_MTIME)
g_string_append (s, "MTIME,");
if (flags & FUSE_SET_ATTR_ATIME_NOW)
g_string_append (s, "ATIME_NOW,");
if (flags & FUSE_SET_ATTR_MTIME_NOW)
g_string_append (s, "MTIME_NOW,");
/* Remove last comma */
if (s->len > 0)
g_string_truncate (s, s->len - 1);
return g_string_free (s, FALSE);
}
static char *
renameat2_flags_to_string (int flags)
{
#if HAVE_RENAMEAT2
GString *s = g_string_new ("");
if (flags & RENAME_EXCHANGE)
g_string_append (s, "EXCHANGE,");
if (flags & RENAME_NOREPLACE)
g_string_append (s, "NOREPLACE,");
if (flags & RENAME_WHITEOUT)
g_string_append (s, "WHITEOUT,");
/* Remove last comma */
if (s->len > 0)
g_string_truncate (s, s->len - 1);
return g_string_free (s, FALSE);
#else
return g_strdup_printf ("%#x", flags);
#endif
}
static guint
devino_hash (gconstpointer key)
{
DevIno *devino = (DevIno *)key;
return (devino->ino >> 2) ^ devino->dev;
}
static gboolean
devino_equal (gconstpointer _a,
gconstpointer _b)
{
DevIno *a = (DevIno *)_a;
DevIno *b = (DevIno *)_b;
return a->ino == b->ino && a->dev == b->dev;
}
/* Lookup by physical backing devino */
static GHashTable *physical_inodes;
G_LOCK_DEFINE (physical_inodes);
/* Takes ownership of the o_path fd if passed in */
static XdpPhysicalInode *
ensure_physical_inode (dev_t dev, ino_t ino, int o_path_fd)
{
DevIno devino = {ino, dev};
XdpPhysicalInode *inode = NULL;
G_LOCK (physical_inodes);
inode = g_hash_table_lookup (physical_inodes, &devino);
if (inode != NULL)
{
inode = xdp_physical_inode_ref (inode);
close (o_path_fd);
}
else
{
/* Takes ownership of fd */
inode = g_new0 (XdpPhysicalInode, 1);
inode->ref_count = 1;
inode->fd = o_path_fd;
inode->backing_devino = devino;
g_hash_table_insert (physical_inodes, &inode->backing_devino, inode);
}
G_UNLOCK (physical_inodes);
return inode;
}
static XdpPhysicalInode *
xdp_physical_inode_ref (XdpPhysicalInode *inode)
{
g_atomic_int_inc (&inode->ref_count);
return inode;
}
static void
xdp_physical_inode_unref (XdpPhysicalInode *inode)
{
gint old_ref;
/* here we want to atomically do: if (ref_count>1) { ref_count--; return; } */
retry_atomic_decrement1:
old_ref = g_atomic_int_get (&inode->ref_count);
if (old_ref > 1)
{
if (!g_atomic_int_compare_and_exchange ((int *) &inode->ref_count, old_ref, old_ref - 1))
goto retry_atomic_decrement1;
}
else
{
if (old_ref <= 0)
{
g_warning ("Can't unref dead inode");
return;
}
/* Might be revived from physical_inodes hash by this time, so protect by lock */
G_LOCK (physical_inodes);
if (!g_atomic_int_compare_and_exchange ((int *) &inode->ref_count, old_ref, old_ref - 1))
{
G_UNLOCK (physical_inodes);
goto retry_atomic_decrement1;
}
g_hash_table_remove (physical_inodes, &inode->backing_devino);
G_UNLOCK (physical_inodes);
close (inode->fd);
g_free (inode);
}
}
static XdpDomain *
xdp_domain_ref (XdpDomain *domain)
{
g_atomic_int_inc (&domain->ref_count);
return domain;
}
static void
xdp_domain_unref (XdpDomain *domain)
{
if (g_atomic_int_dec_and_test (&domain->ref_count))
{
g_free (domain->doc_id);
g_free (domain->app_id);
g_free (domain->doc_path);
g_free (domain->doc_file);
if (domain->inodes)
g_assert (g_hash_table_size (domain->inodes) == 0);
g_clear_pointer (&domain->inodes, g_hash_table_unref);
g_clear_pointer (&domain->parent, xdp_domain_unref);
g_clear_pointer (&domain->parent_inode, xdp_inode_unref);
g_clear_pointer (&domain->tempfiles, g_hash_table_unref);
g_mutex_clear (&domain->tempfile_mutex);
g_free (domain);
}
}
static gboolean
xdp_domain_is_virtual_type (XdpDomain *domain)
{
return
domain->type == XDP_DOMAIN_ROOT ||
domain->type == XDP_DOMAIN_BY_APP ||
domain->type == XDP_DOMAIN_APP;
}
static XdpDomain *
_xdp_domain_new (XdpDomainType type)
{
XdpDomain *domain = g_new0 (XdpDomain, 1);
domain->ref_count = 1;
domain->type = type;
g_mutex_init (&domain->tempfile_mutex);
return domain;
}
static XdpDomain *
xdp_domain_new_root (void)
{
XdpDomain *domain = _xdp_domain_new (XDP_DOMAIN_ROOT);
domain->inodes = g_hash_table_new (g_str_hash, g_str_equal);
return domain;
}
static XdpDomain *
xdp_domain_new_by_app (XdpInode *root_inode)
{
XdpDomain *root_domain = root_inode->domain;
XdpDomain *domain = _xdp_domain_new (XDP_DOMAIN_BY_APP);
domain->parent = xdp_domain_ref (root_domain);
domain->parent_inode = xdp_inode_ref (root_inode);
domain->inodes = g_hash_table_new (g_str_hash, g_str_equal);
return domain;
}
static XdpDomain *
xdp_domain_new_app (XdpInode *parent_inode,
const char *app_id)
{
XdpDomain *parent = parent_inode->domain;
XdpDomain *domain = _xdp_domain_new (XDP_DOMAIN_APP);
domain->parent = xdp_domain_ref (parent);
domain->parent_inode = xdp_inode_ref (parent_inode);
domain->app_id = g_strdup (app_id);
domain->inodes = g_hash_table_new (g_str_hash, g_str_equal);
return domain;
}
static gboolean
xdp_document_domain_is_dir (XdpDomain *domain)
{
return (domain->doc_flags & DOCUMENT_ENTRY_FLAG_DIRECTORY) != 0;
}
static XdpDomain *
xdp_domain_new_document (XdpDomain *parent,
const char *doc_id,
PermissionDbEntry *doc_entry)
{
XdpDomain *domain = _xdp_domain_new (XDP_DOMAIN_DOCUMENT);
const char *db_path;
domain->parent = xdp_domain_ref (parent);
domain->doc_id = g_strdup (doc_id);
domain->app_id = g_strdup (parent->app_id);
domain->inodes = g_hash_table_new (g_direct_hash, g_direct_equal);
domain->doc_flags = document_entry_get_flags (doc_entry);
domain->doc_dir_device = document_entry_get_device (doc_entry);
domain->doc_dir_inode = document_entry_get_inode (doc_entry);
db_path = document_entry_get_path (doc_entry);
if (xdp_document_domain_is_dir (domain))
{
domain->doc_path = g_strdup (db_path);
domain->doc_file = g_path_get_basename (db_path);
}
else
{
domain->doc_path = g_path_get_dirname (db_path);
domain->doc_file = g_path_get_basename (db_path);
}
domain->tempfiles = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, (GDestroyNotify)xdp_tempfile_unref);
return domain;
}
static gboolean
xdp_document_domain_can_see (XdpDomain *domain)
{
if (domain->app_id != NULL)
{
g_autoptr(PermissionDbEntry) entry = xdp_lookup_doc (domain->doc_id);
if (entry == NULL ||
!app_can_see_doc (entry, domain->app_id))
return FALSE;
}
return TRUE;
}
static gboolean
xdp_document_domain_can_write (XdpDomain *domain)
{
if (domain->app_id != NULL)
{
g_autoptr(PermissionDbEntry) entry = xdp_lookup_doc (domain->doc_id);
if (entry == NULL ||
!app_can_write_doc (entry, domain->app_id))
return FALSE;
}
return TRUE;
}
static char **
xdp_domain_get_inode_keys_as_string (XdpDomain *domain)
{
char **res;
guint length, i;
g_assert (domain->type == XDP_DOMAIN_BY_APP);
G_LOCK (domain_inodes);
res = (char **)g_hash_table_get_keys_as_array (domain->inodes, &length);
for (i = 0; i < length; i++)
res[i] = g_strdup (res[i]);
G_UNLOCK (domain_inodes);
return res;
}
static XdpTempfile *
xdp_tempfile_ref (XdpTempfile *tempfile)
{
g_atomic_int_inc (&tempfile->ref_count);
return tempfile;
}
static XdpTempfile *
xdp_tempfile_new (XdpInode *inode,
const char *name,
const char *tempname)
{
XdpTempfile *tempfile = g_new0 (XdpTempfile, 1);
tempfile->ref_count = 1;
tempfile->inode = xdp_inode_ref (inode);
tempfile->name = g_strdup (name);
tempfile->tempname = g_strdup (tempname);
return tempfile;
}
static void
xdp_tempfile_unref (XdpTempfile *tempfile)
{
if (g_atomic_int_dec_and_test (&tempfile->ref_count))
{
if (tempfile->tempname)
{
g_autofree char *temppath = g_build_filename (tempfile->inode->domain->doc_path, tempfile->tempname, NULL);
(void)unlink (temppath);
}
g_free (tempfile->name);
g_free (tempfile->tempname);
g_clear_pointer (&tempfile->inode, xdp_inode_unref);
g_free (tempfile);
}
}
static XdpInode *
_xdp_inode_new (void)
{
XdpInode *inode = g_new0 (XdpInode, 1);
inode->ref_count = 1;
inode->kernel_ref_count = 0;
return inode;
}
/* We try to create persistent inode number based on the backing
* device and inode numbers, as well as the doc/app id (since the same
* backing dev/ino should be different inodes in the fuse
* filesystem). We do this by hashing the data to generate a value.
* For non-physical files or accidental collisions we just pick a free
* number by incrementing.
*/
static guint64
generate_persistent_ino (DevIno *backing_devino,
const char *doc_id,
const char *app_id)
{
g_autoptr(GChecksum) checksum = g_checksum_new (G_CHECKSUM_MD5);
guchar digest[64];
gsize digest_len = 64;
guint64 res;
g_checksum_update (checksum, (guchar *)backing_devino, sizeof (DevIno));
if (doc_id)
g_checksum_update (checksum, (guchar *)doc_id, strlen (doc_id));
if (app_id)
g_checksum_update (checksum, (guchar *)app_id, strlen (app_id));
g_checksum_get_digest (checksum, digest, &digest_len);
res = *(guint64 *)digest;
if (res == FUSE_ROOT_ID || res == 0)
res = FUSE_ROOT_ID + 1;
return res;
}
/* takes ownership of fd */
static XdpInode *
xdp_inode_new (XdpDomain *domain,
XdpPhysicalInode *physical)
{
XdpInode *inode = _xdp_inode_new ();
inode->domain = xdp_domain_ref (domain);
guint64 persistent_ino, try_ino;
if (physical)
{
inode->physical = xdp_physical_inode_ref (physical);
persistent_ino = generate_persistent_ino (&physical->backing_devino,
domain->doc_id,
domain->app_id);
}
G_LOCK (all_inodes);
if (physical)
try_ino = persistent_ino;
else
try_ino = next_virtual_inode++;
if (g_hash_table_contains (all_inodes, &try_ino))
try_ino++;
inode->ino = try_ino;
g_hash_table_insert (all_inodes, &inode->ino, inode);
G_UNLOCK (all_inodes);
return inode;
}
static ino_t
xdp_inode_to_ino (XdpInode *inode)
{
return inode->ino;
}
/* This is called on kernel upcalls, so it *should* be guaranteed that the inode exists due to the kernel refs */
static XdpInode *
xdp_inode_from_ino (ino_t ino)
{
XdpInode *inode;
G_LOCK (all_inodes);
inode = g_hash_table_lookup (all_inodes, &ino);
G_UNLOCK (all_inodes);
g_assert (inode != NULL);
/* Its safe to ref it here because we know it exists outside the lock due to the kernel refs */
return xdp_inode_ref (inode);
}
static XdpInode *
xdp_inode_ref (XdpInode *inode)
{
g_atomic_int_inc (&inode->ref_count);
return inode;
}
static void
xdp_inode_unref (XdpInode *inode)
{
gint old_ref;
XdpDomain *domain;
/* here we want to atomically do: if (ref_count>1) { ref_count--; return; } */
retry_atomic_decrement1:
old_ref = g_atomic_int_get (&inode->ref_count);
if (old_ref > 1)
{
if (!g_atomic_int_compare_and_exchange ((int *) &inode->ref_count, old_ref, old_ref - 1))
goto retry_atomic_decrement1;
}
else
{
if (old_ref <= 0)
{
g_warning ("Can't unref dead inode");
return;
}
/* Might be revived from domain->inodes hash by this time, so protect by lock */
G_LOCK (domain_inodes);
if (!g_atomic_int_compare_and_exchange ((int *) &inode->ref_count, old_ref, old_ref - 1))
{
G_UNLOCK (domain_inodes);
goto retry_atomic_decrement1;
}
domain = inode->domain;
if (domain->type == XDP_DOMAIN_APP)
g_hash_table_remove (domain->parent->inodes, domain->app_id);
else if (domain->type == XDP_DOMAIN_DOCUMENT)
{
if (inode->physical)
{
g_hash_table_remove (domain->inodes, inode->physical);
}
else
g_hash_table_remove (domain->parent->inodes, domain->doc_id);
}
/* Run this under domain_inodes lock to avoid race condition in ensure_docdir_inode + xdp_inode_new
* where we don't want a domain->inode lookup to fail, but then an all_inode lookup to succeed
* when looking for an ino collision
*
* Note: After the domain->inodes removal and here we don't allow resurrection, but we may
* still race with an all_inodes lookup (e.g. in xdp_fuse_lookup_id_for_inode), which *is*
* allowed and it can read the inode fields (while the lock is held) as they are still valid.
**/
G_LOCK (all_inodes);
g_hash_table_remove (all_inodes, &inode->ino);
G_UNLOCK (all_inodes);
G_UNLOCK (domain_inodes);
/* By now we have no refs outstanding and no way to get at the inode, so free it */
g_clear_pointer (&inode->domain_root_inode, xdp_inode_unref);
g_clear_pointer (&inode->physical, xdp_physical_inode_unref);
xdp_domain_unref (inode->domain);
g_free (inode);
}
}
static XdpInode *
xdp_inode_kernel_ref (XdpInode *inode)
{
int old;
old = g_atomic_int_add (&inode->kernel_ref_count, 1);
if (old == 0)
xdp_inode_ref (inode);
return inode;
}
static void
xdp_inode_kernel_unref (XdpInode *inode, unsigned long count)
{
gint old_ref, new_ref;
retry_atomic_decrement1:
old_ref = g_atomic_int_get (&inode->kernel_ref_count);
if (old_ref < count)
{
g_warning ("Can't kernel_unref inode with no kernel refs");
return;
}
new_ref = old_ref - count;
if (!g_atomic_int_compare_and_exchange (&inode->kernel_ref_count, old_ref, new_ref))
goto retry_atomic_decrement1;
if (new_ref == 0)
xdp_inode_unref (inode);
}
static int
verify_doc_dir_devino (int dirfd, XdpDomain *doc_domain)
{
struct stat buf;
if (fstat (dirfd, &buf) != 0)
return -errno;
if (buf.st_ino != doc_domain->doc_dir_inode ||
buf.st_dev != doc_domain->doc_dir_device)
return -ENOENT;
return 0;
}
/* Only for toplevel dirs, not this is a bit weird for toplevel dir
inodes as it returns the dir itself which isn't really the dirfd
for that (nonphysical) inode */
static int
xdp_nonphysical_document_inode_opendir (XdpInode *inode)
{
XdpDomain *domain = inode->domain;
xdp_autofd int dirfd = -1;
int res;
g_assert (domain->type == XDP_DOMAIN_DOCUMENT);
g_assert (inode->physical == NULL);
dirfd = open (domain->doc_path, O_PATH | O_DIRECTORY);
if (dirfd < 0)
return -errno;
res = verify_doc_dir_devino (dirfd, domain);
if (res != 0)
return res;
return xdp_steal_fd (&dirfd);
}
static int
xdp_document_inode_ensure_dirfd (XdpInode *inode,
int *close_fd_out)
{
int close_fd;
g_assert (inode->domain->type == XDP_DOMAIN_DOCUMENT);
*close_fd_out = -1;
if (inode->physical)
return inode->physical->fd;
else