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homed: always use quotactl_fd() if its available

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Let's always prefer quotactl_fd() when it's available and use quotactl()
only as as a fallback on old kernels.

This way we can operate on the fds we typically already have open, or if
needed we can open a new one, and use for multiple fs operation.

In the long run we should really focus on operating exclusively by fd
instead of by path, by device nor or otherwise. This gets us a step
closer to that.
This commit is contained in:
Lennart Poettering
2025-03-31 11:47:17 +02:00
parent da24983526
commit 5daca30b0f
9 changed files with 80 additions and 59 deletions
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16
src/home/homed-home.c
View File

@@ -25,7 +25,6 @@
#include "memfd-util.h"
#include "missing_magic.h"
#include "missing_mman.h"
#include "missing_syscall.h"
#include "mkdir.h"
#include "path-util.h"
#include "process-util.h"
@@ -2419,6 +2418,7 @@ static int home_get_disk_status_directory(
uint64_t disk_size = UINT64_MAX, disk_usage = UINT64_MAX, disk_free = UINT64_MAX,
disk_ceiling = UINT64_MAX, disk_floor = UINT64_MAX;
mode_t access_mode = MODE_INVALID;
_cleanup_close_ int fd = -EBADF;
statfs_f_type_t fstype = 0;
struct statfs sfs;
struct dqblk req;
@@ -2440,7 +2440,13 @@ static int home_get_disk_status_directory(
if (!path)
goto finish;
if (statfs(path, &sfs) < 0)
fd = open(path, O_CLOEXEC|O_RDONLY);
if (fd < 0) {
log_debug_errno(errno, "Failed to open '%s', ignoring: %m", path);
goto finish;
}
if (fstatfs(fd, &sfs) < 0)
log_debug_errno(errno, "Failed to statfs() %s, ignoring: %m", path);
else {
disk_free = sfs.f_bsize * sfs.f_bavail;
@@ -2454,13 +2460,13 @@ static int home_get_disk_status_directory(
if (IN_SET(h->record->storage, USER_CLASSIC, USER_DIRECTORY, USER_SUBVOLUME)) {
r = btrfs_is_subvol(path);
r = btrfs_is_subvol_fd(fd);
if (r < 0)
log_debug_errno(r, "Failed to determine whether %s is a btrfs subvolume: %m", path);
else if (r > 0) {
BtrfsQuotaInfo qi;
r = btrfs_subvol_get_subtree_quota(path, 0, &qi);
r = btrfs_subvol_get_subtree_quota_fd(fd, /* subvol_id= */ 0, &qi);
if (r < 0)
log_debug_errno(r, "Failed to query btrfs subtree quota, ignoring: %m");
else {
@@ -2493,7 +2499,7 @@ static int home_get_disk_status_directory(
}
if (IN_SET(h->record->storage, USER_CLASSIC, USER_DIRECTORY, USER_FSCRYPT)) {
r = quotactl_path(QCMD_FIXED(Q_GETQUOTA, USRQUOTA), path, h->uid, &req);
r = quotactl_fd_with_fallback(fd, QCMD_FIXED(Q_GETQUOTA, USRQUOTA), h->uid, &req);
if (r < 0) {
if (ERRNO_IS_NOT_SUPPORTED(r)) {
log_debug_errno(r, "No UID quota support on %s.", path);

13
src/home/homed-manager.c
View File

@@ -55,8 +55,8 @@
#include "user-record-util.h"
#include "user-record.h"
#include "user-util.h"
#include "varlink-io.systemd.service.h"
#include "varlink-io.systemd.UserDatabase.h"
#include "varlink-io.systemd.service.h"
#include "varlink-util.h"
/* Where to look for private/public keys that are used to sign the user records. We are not using
@@ -533,14 +533,15 @@ static int search_quota(uid_t uid, const char *exclude_quota_path) {
struct dqblk req;
struct stat st;
if (stat(where, &st) < 0) {
_cleanup_close_ int fd = open(where, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
if (fd < 0) {
log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno,
"Failed to stat %s, ignoring: %m", where);
"Failed to open '%s', ignoring: %m", where);
continue;
}
if (major(st.st_dev) == 0) {
log_debug("Directory %s is not on a real block device, not checking quota for UID use.", where);
if (fstat(fd, &st) < 0) {
log_error_errno(errno, "Failed to stat '%s', ignoring: %m", where);
continue;
}
@@ -559,7 +560,7 @@ static int search_quota(uid_t uid, const char *exclude_quota_path) {
previous_devno = st.st_dev;
r = quotactl_devnum(QCMD_FIXED(Q_GETQUOTA, USRQUOTA), st.st_dev, uid, &req);
r = quotactl_fd_with_fallback(fd, QCMD_FIXED(Q_GETQUOTA, USRQUOTA), uid, &req);
if (r < 0) {
if (ERRNO_IS_NOT_SUPPORTED(r))
log_debug_errno(r, "No UID quota support on %s, ignoring.", where);

6
src/home/homework-directory.c
View File

@@ -153,7 +153,7 @@ int home_create_directory_or_subvolume(UserRecord *h, HomeSetup *setup, UserReco
/* Actually configure the quota. We also ignore errors here, but we do log
* about them loudly, to keep things discoverable even though we don't
* consider lacking quota support in kernel fatal. */
(void) home_update_quota_btrfs(h, d);
(void) home_update_quota_btrfs(h, /* fd= */ -EBADF, d);
}
break;
@@ -169,7 +169,7 @@ int home_create_directory_or_subvolume(UserRecord *h, HomeSetup *setup, UserReco
if (mkdir(d, 0700) < 0)
return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d);
(void) home_update_quota_classic(h, d);
(void) home_update_quota_classic(h, /* fd= */ -EBADF, d);
break;
default:
@@ -285,7 +285,7 @@ int home_resize_directory(
if (r < 0)
return r;
r = home_update_quota_auto(h, NULL);
r = home_update_quota_auto(h, setup->root_fd, /* path= */ NULL);
if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
return -ESOCKTNOSUPPORT; /* make recognizable */
if (r < 0)

2
src/home/homework-fscrypt.c
View File

@@ -628,7 +628,7 @@ int home_create_fscrypt(
nr++;
}
(void) home_update_quota_classic(h, temporary);
(void) home_update_quota_classic(h, setup->root_fd, temporary);
r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, h->uid, h->uid, &mount_fd);
if (r > 0)

57
src/home/homework-quota.c
View File

@@ -4,6 +4,7 @@
#include "blockdev-util.h"
#include "btrfs-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "format-util.h"
#include "homework-quota.h"
#include "missing_magic.h"
@@ -11,23 +12,32 @@
#include "stat-util.h"
#include "user-util.h"
int home_update_quota_btrfs(UserRecord *h, const char *path) {
int home_update_quota_btrfs(UserRecord *h, int fd, const char *path) {
int r;
assert(h);
assert(path);
_cleanup_close_ int _fd = -EBADF;
if (fd < 0) {
_fd = open(path, O_CLOEXEC|O_RDONLY);
if (_fd < 0)
return log_error_errno(errno, "Failed to open '%s': %m", path);
fd = _fd;
}
if (h->disk_size == UINT64_MAX)
return 0;
/* If the user wants quota, enable it */
r = btrfs_quota_enable(path, true);
r = btrfs_quota_enable_fd(fd, true);
if (r == -ENOTTY)
return log_error_errno(r, "No btrfs quota support on subvolume %s.", path);
if (r < 0)
return log_error_errno(r, "Failed to enable btrfs quota support on %s.", path);
r = btrfs_qgroup_set_limit(path, 0, h->disk_size);
r = btrfs_qgroup_set_limit_fd(fd, 0, h->disk_size);
if (r < 0)
return log_error_errno(r, "Failed to set disk quota on subvolume %s: %m", path);
@@ -36,25 +46,27 @@ int home_update_quota_btrfs(UserRecord *h, const char *path) {
return 0;
}
int home_update_quota_classic(UserRecord *h, const char *path) {
int home_update_quota_classic(UserRecord *h, int fd, const char *path) {
struct dqblk req;
dev_t devno;
int r;
assert(h);
assert(uid_is_valid(h->uid));
assert(path);
_cleanup_close_ int _fd = -EBADF;
if (fd < 0) {
_fd = open(path, O_CLOEXEC|O_RDONLY);
if (_fd < 0)
return log_error_errno(errno, "Failed to open '%s': %m", path);
fd = _fd;
}
if (h->disk_size == UINT64_MAX)
return 0;
r = get_block_device(path, &devno);
if (r < 0)
return log_error_errno(r, "Failed to determine block device of %s: %m", path);
if (devno == 0)
return log_error_errno(SYNTHETIC_ERRNO(ENODEV), "File system %s not backed by a block device.", path);
r = quotactl_devnum(QCMD_FIXED(Q_GETQUOTA, USRQUOTA), devno, h->uid, &req);
r = quotactl_fd_with_fallback(fd, QCMD_FIXED(Q_GETQUOTA, USRQUOTA), h->uid, &req);
if (r == -ESRCH)
zero(req);
else if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
@@ -70,7 +82,7 @@ int home_update_quota_classic(UserRecord *h, const char *path) {
req.dqb_valid = QIF_BLIMITS;
req.dqb_bsoftlimit = req.dqb_bhardlimit = h->disk_size / QIF_DQBLKSIZE;
r = quotactl_devnum(QCMD_FIXED(Q_SETQUOTA, USRQUOTA), devno, h->uid, &req);
r = quotactl_fd_with_fallback(fd, QCMD_FIXED(Q_SETQUOTA, USRQUOTA), h->uid, &req);
if (r == -ESRCH)
return log_error_errno(SYNTHETIC_ERRNO(ENOTTY), "UID quota not available on %s.", path);
if (r < 0)
@@ -81,7 +93,7 @@ int home_update_quota_classic(UserRecord *h, const char *path) {
return 0;
}
int home_update_quota_auto(UserRecord *h, const char *path) {
int home_update_quota_auto(UserRecord *h, int fd, const char *path) {
struct statfs sfs;
int r;
@@ -96,22 +108,31 @@ int home_update_quota_auto(UserRecord *h, const char *path) {
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Home record lacks image path.");
}
if (statfs(path, &sfs) < 0)
_cleanup_close_ int _fd = -EBADF;
if (fd < 0) {
_fd = open(path, O_CLOEXEC|O_RDONLY);
if (_fd < 0)
return log_error_errno(errno, "Failed to open '%s': %m", path);
fd = _fd;
}
if (fstatfs(fd, &sfs) < 0)
return log_error_errno(errno, "Failed to statfs() file system: %m");
if (is_fs_type(&sfs, XFS_SUPER_MAGIC) ||
is_fs_type(&sfs, EXT4_SUPER_MAGIC))
return home_update_quota_classic(h, path);
return home_update_quota_classic(h, fd, path);
if (is_fs_type(&sfs, BTRFS_SUPER_MAGIC)) {
r = btrfs_is_subvol(path);
r = btrfs_is_subvol_fd(fd);
if (r < 0)
return log_error_errno(r, "Failed to test if %s is a subvolume: %m", path);
if (r == 0)
return log_error_errno(SYNTHETIC_ERRNO(ENOTTY), "Directory %s is not a subvolume, cannot apply quota.", path);
return home_update_quota_btrfs(h, path);
return home_update_quota_btrfs(h, fd, path);
}
return log_error_errno(SYNTHETIC_ERRNO(ENOTTY), "Type of directory %s not known, cannot apply quota.", path);

6
src/home/homework-quota.h
View File

@@ -3,6 +3,6 @@
#include "user-record.h"
int home_update_quota_btrfs(UserRecord *h, const char *path);
int home_update_quota_classic(UserRecord *h, const char *path);
int home_update_quota_auto(UserRecord *h, const char *path);
int home_update_quota_btrfs(UserRecord *h, int fd, const char *path);
int home_update_quota_classic(UserRecord *h, int fd, const char *path);
int home_update_quota_auto(UserRecord *h, int fd, const char *path);

34
src/shared/quota-util.c
View File

@@ -1,42 +1,36 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <stdint.h>
#include <sys/quota.h>
#include <sys/stat.h>
#include "alloc-util.h"
#include "blockdev-util.h"
#include "device-util.h"
#include "errno-util.h"
#include "missing_syscall.h"
#include "quota-util.h"
int quotactl_devnum(int cmd, dev_t devnum, int id, void *addr) {
_cleanup_free_ char *devnode = NULL;
int quotactl_fd_with_fallback(int fd, int cmd, int id, void *addr) {
int r;
/* Like quotactl() but takes a dev_t instead of a path to a device node, and fixes caddr_t → void*,
* like we should, today */
/* Emulates quotactl_fd() on older kernels that lack it. (i.e. kernels < 5.14) */
r = devname_from_devnum(S_IFBLK, devnum, &devnode);
if (r < 0)
r = RET_NERRNO(quotactl_fd(fd, cmd, id, addr));
if (!ERRNO_IS_NEG_NOT_SUPPORTED(r))
return r;
if (quotactl(cmd, devnode, id, addr) < 0)
return -errno;
return 0;
}
int quotactl_path(int cmd, const char *path, int id, void *addr) {
dev_t devno;
int r;
/* Like quotactl() but takes a path to some fs object, and changes the backing file system. I.e. the
* argument shouldn't be a block device but a regular file system object */
r = get_block_device(path, &devno);
r = get_block_device_fd(fd, &devno);
if (r < 0)
return r;
if (devno == 0) /* Doesn't have a block device */
return -ENODEV;
return quotactl_devnum(cmd, devno, id, addr);
_cleanup_free_ char *devnode = NULL;
r = devname_from_devnum(S_IFBLK, devno, &devnode);
if (r < 0)
return r;
return RET_NERRNO(quotactl(cmd, devnode, id, addr));
}

3
src/shared/quota-util.h
View File

@@ -15,5 +15,4 @@ static inline int QCMD_FIXED(uint32_t cmd, uint32_t type) {
return (int) QCMD(cmd, type);
}
int quotactl_devnum(int cmd, dev_t devnum, int id, void *addr);
int quotactl_path(int cmd, const char *path, int id, void *addr);
int quotactl_fd_with_fallback(int fd, int cmd, int id, void *addr);

2
units/systemd-homed.service.in
View File

@@ -34,7 +34,7 @@ StateDirectory=systemd/home
CacheDirectory=systemd/home
SystemCallArchitectures=native
SystemCallErrorNumber=EPERM
SystemCallFilter=@system-service @mount quotactl
SystemCallFilter=@system-service @mount quotactl quotactl_fd
TimeoutStopSec=3min
{{SERVICE_WATCHDOG}}