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Merge pull request #20513 from maribu/sys/vfs/atomic_utils
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sys/vfs: use atomic_utils rather C11 atomics
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@maribu
maribu authored Apr 16, 2024
2 parents 0391458 + 45c473d commit 48838f4
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Showing 3 changed files with 68 additions and 40 deletions.
10 changes: 1 addition & 9 deletions sys/include/vfs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -54,14 +54,6 @@
#define VFS_H

#include <stdint.h>
/* The stdatomic.h in GCC gives compilation errors with C++
* see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60932
*/
#ifdef __cplusplus
#include "c11_atomics_compat.hpp"
#else
#include <stdatomic.h> /* for atomic_int */
#endif
#include <sys/stat.h> /* for struct stat */
#include <sys/types.h> /* for off_t etc. */
#include <sys/statvfs.h> /* for struct statvfs */
Expand Down Expand Up @@ -383,7 +375,7 @@ struct vfs_mount_struct {
const vfs_file_system_t *fs; /**< The file system driver for the mount point */
const char *mount_point; /**< Mount point, e.g. "/mnt/cdrom" */
size_t mount_point_len; /**< Length of mount_point string (set by vfs_mount) */
atomic_int open_files; /**< Number of currently open files and directories */
uint16_t open_files; /**< Number of currently open files and directories */
void *private_data; /**< File system driver private data, implementation defined */
};

Expand Down
91 changes: 63 additions & 28 deletions sys/vfs/vfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,13 +23,16 @@
#include <fcntl.h> /* for O_ACCMODE, ..., fcntl */
#include <unistd.h> /* for STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO */

#include "atomic_utils.h"
#include "clist.h"
#include "compiler_hints.h"
#include "container.h"
#include "modules.h"
#include "vfs.h"
#include "mutex.h"
#include "thread.h"
#include "sched.h"
#include "clist.h"
#include "test_utils/expect.h"
#include "thread.h"
#include "vfs.h"

#define ENABLE_DEBUG 0
#include "debug.h"
Expand Down Expand Up @@ -295,7 +298,8 @@ int vfs_open(const char *name, int flags, mode_t mode)
if (fd < 0) {
DEBUG("vfs_open: _init_fd: ERR %d!\n", fd);
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return fd;
}
vfs_file_t *filp = &_vfs_open_files[fd];
Expand Down Expand Up @@ -425,7 +429,8 @@ int vfs_opendir(vfs_DIR *dirp, const char *dirname)
int res = dirp->d_op->opendir(dirp, rel_path);
if (res < 0) {
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
}
Expand Down Expand Up @@ -463,7 +468,8 @@ int vfs_closedir(vfs_DIR *dirp)
}
}
memset(dirp, 0, sizeof(*dirp));
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand Down Expand Up @@ -563,8 +569,9 @@ int vfs_umount(vfs_mount_t *mountp, bool force)
DEBUG("vfs_umount: invalid fs\n");
return -EINVAL;
}
DEBUG("vfs_umount: -> \"%s\" open=%d\n", mountp->mount_point, atomic_load(&mountp->open_files));
if (atomic_load(&mountp->open_files) > 0 && !force) {
DEBUG("vfs_umount: -> \"%s\" open=%u\n", mountp->mount_point,
(unsigned)atomic_load_u16(&mountp->open_files));
if (atomic_load_u16(&mountp->open_files) > 0 && !force) {
mutex_unlock(&_mount_mutex);
return -EBUSY;
}
Expand Down Expand Up @@ -610,7 +617,8 @@ int vfs_rename(const char *from_path, const char *to_path)
/* rename not supported */
DEBUG("vfs_rename: rename not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
const char *rel_to;
Expand All @@ -621,15 +629,18 @@ int vfs_rename(const char *from_path, const char *to_path)
/* No mount point maps to the requested file name */
DEBUG("vfs_rename: to: no matching mount\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}
if (mountp_to != mountp) {
/* The paths are on different file systems */
DEBUG("vfs_rename: from_path and to_path are on different mounts\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
atomic_fetch_sub(&mountp_to->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
before = atomic_fetch_sub_u16(&mountp_to->open_files, 1);
assume(before > 0);
return -EXDEV;
}
res = mountp->fs->fs_op->rename(mountp, rel_from, rel_to);
Expand All @@ -642,8 +653,10 @@ int vfs_rename(const char *from_path, const char *to_path)
DEBUG("\n");
}
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
atomic_fetch_sub(&mountp_to->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
before = atomic_fetch_sub_u16(&mountp_to->open_files, 1);
assume(before > 0);
return res;
}

Expand All @@ -669,7 +682,8 @@ int vfs_unlink(const char *name)
/* unlink not supported */
DEBUG("vfs_unlink: unlink not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->unlink(mountp, rel_path);
Expand All @@ -682,7 +696,8 @@ int vfs_unlink(const char *name)
DEBUG("\n");
}
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand All @@ -706,7 +721,8 @@ int vfs_mkdir(const char *name, mode_t mode)
/* mkdir not supported */
DEBUG("vfs_mkdir: mkdir not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->mkdir(mountp, rel_path, mode);
Expand All @@ -719,7 +735,8 @@ int vfs_mkdir(const char *name, mode_t mode)
DEBUG("\n");
}
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand All @@ -743,7 +760,8 @@ int vfs_rmdir(const char *name)
/* rmdir not supported */
DEBUG("vfs_rmdir: rmdir not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EROFS;
}
res = mountp->fs->fs_op->rmdir(mountp, rel_path);
Expand All @@ -756,7 +774,8 @@ int vfs_rmdir(const char *name)
DEBUG("\n");
}
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand All @@ -780,13 +799,15 @@ int vfs_stat(const char *restrict path, struct stat *restrict buf)
/* stat not supported */
DEBUG("vfs_stat: stat not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EPERM;
}
memset(buf, 0, sizeof(*buf));
res = mountp->fs->fs_op->stat(mountp, rel_path, buf);
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand All @@ -810,13 +831,15 @@ int vfs_statvfs(const char *restrict path, struct statvfs *restrict buf)
/* statvfs not supported */
DEBUG("vfs_statvfs: statvfs not supported by fs!\n");
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return -EPERM;
}
memset(buf, 0, sizeof(*buf));
res = mountp->fs->fs_op->statvfs(mountp, rel_path, buf);
/* remember to decrement the open_files count */
atomic_fetch_sub(&mountp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&mountp->open_files, 1);
assume(before > 0);
return res;
}

Expand Down Expand Up @@ -954,14 +977,20 @@ bool vfs_iterate_mount_dirs(vfs_DIR *dir)
* we'd need to let go of it now to actually open the directory. This
* temporary count ensures that the file system will stick around for the
* directory open step that follows immediately */
atomic_fetch_add(&next->open_files, 1);
uint16_t before = atomic_fetch_add_u16(&next->open_files, 1);
/* We cannot use assume() here, an overflow could occur in absence of
* any bugs and should also be checked for in production code. We use
* expect() here, which was actually written for unit tests but works
* here as well */
expect(before < UINT16_MAX);

/* Ignoring errors, can't help with them */
vfs_closedir(dir);

int err = vfs_opendir(dir, next->mount_point);
/* No matter the success, the open_files lock has done its duty */
atomic_fetch_sub(&next->open_files, 1);
before = atomic_fetch_sub_u16(&next->open_files, 1);
assume(before > 0);

if (err != 0) {
DEBUG("vfs_iterate_mount opendir erred: vfs_opendir(\"%s\") = %d\n", next->mount_point, err);
Expand Down Expand Up @@ -1018,7 +1047,8 @@ static inline void _free_fd(int fd)
{
DEBUG("_free_fd: %d, pid=%d\n", fd, _vfs_open_files[fd].pid);
if (_vfs_open_files[fd].mp != NULL) {
atomic_fetch_sub(&_vfs_open_files[fd].mp->open_files, 1);
uint16_t before = atomic_fetch_sub_u16(&_vfs_open_files[fd].mp->open_files, 1);
assume(before > 0);
}
_vfs_open_files[fd].pid = KERNEL_PID_UNDEF;
}
Expand Down Expand Up @@ -1082,7 +1112,12 @@ static inline int _find_mount(vfs_mount_t **mountpp, const char *name, const cha
return -ENOENT;
}
/* Increment open files counter for this mount */
atomic_fetch_add(&mountp->open_files, 1);
uint16_t before = atomic_fetch_add_u16(&mountp->open_files, 1);
/* We cannot use assume() here, an overflow could occur in absence of
* any bugs and should also be checked for in production code. We use
* expect() here, which was actually written for unit tests but works
* here as well */
expect(before < UINT16_MAX);
mutex_unlock(&_mount_mutex);
*mountpp = mountp;

Expand Down
7 changes: 4 additions & 3 deletions tests/unittests/tests-vfs/tests-vfs-file-system-ops.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,12 @@
*/
#include <errno.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include "atomic_utils.h"
#include "embUnit/embUnit.h"

#include "vfs.h"
Expand Down Expand Up @@ -72,7 +72,7 @@ static void setup(void)
static void teardown(void)
{
vfs_umount(&_test_vfs_mount_null, false);
atomic_store(&_test_vfs_mount_null.open_files, 0);
atomic_store_u16(&_test_vfs_mount_null.open_files, 0);
}

static void test_vfs_null_fs_ops_mount(void)
Expand All @@ -96,7 +96,8 @@ static void test_vfs_null_fs_ops_umount(void)
static void test_vfs_null_fs_ops_umount__EBUSY(void)
{
TEST_ASSERT_EQUAL_INT(0, _test_vfs_fs_op_mount_res);
atomic_fetch_add(&_test_vfs_mount_null.open_files, 1);
uint16_t before = atomic_fetch_add_u16(&_test_vfs_mount_null.open_files, 1);
TEST_ASSERT(before < UINT16_MAX);
int res = vfs_umount(&_test_vfs_mount_null, false);
TEST_ASSERT_EQUAL_INT(-EBUSY, res);
/* force unmount */
Expand Down

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