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Merge tag 'vfs-7.3-rc1.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Browse Source 
Pull vfs superblock updates from Christian Brauner:

 - Make it possible to share a block device between multiple
   filesystems.

   erofs can mount read-only blob devices shared between many
   superblocks, but because we only tracked a single superblock a
   freeze, thaw, removal or sync on such a device was never propagated
   to all the superblocks using it, and there was no way to find them.

   Add an efficient table to lookup all superblocks using a given block
   device.

 - A bunch of pre-existing fixes fell out of this work:

   A block-device freeze racing a btrfs device change could leave the
   whole filesystem stuck frozen. A bdev_freeze() issued by "dmsetup
   suspend" or an LVM snapshot resolves that holder to freeze the
   filesystem. and bdev_thaw() resolves it again to thaw. A freeze
   landing while btrfs is adding, removing or replacing a device freezes
   the filesystem. The membership change then drops that link. So the
   matching thaw could no longer find the superblock.

   Forbid freezing a device for the duration of a membership change,
   modelled on deny_write_access()/allow_write_access().

* tag 'vfs-7.3-rc1.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
  super: fix dying superblock warning messages
  block: reject block device inodes with i_rdev == 0 in lookup_bdev()
  selftests/filesystems: add ustat() coverage
  fs: look up the superblock via the device table in user_get_super()
  super: make fs_holder_ops private
  f2fs: open via dedicated fs bdev helpers
  erofs: open via dedicated fs bdev helpers
  fs: tolerate per-superblock freeze errors on shared devices
  fs: look up superblocks via the device table in fs_holder_ops
  ext4: open via dedicated fs bdev helpers
  btrfs: open via dedicated fs bdev helpers
  xfs: port to fs_bdev_file_open_by_path()
  fs: add dedicated block device open helpers for filesystems
  fs: maintain a global device-to-superblock table
  ocfs2: don't reset s_dev on dismount
  ext4: use anonymous devices for KUnit test superblocks
  fs, block: move blk_mode_t and fop_flags_t into <linux/types.h>
  super: take lock after last reference count
  super: convert s_count to refcount_t s_passive
  btrfs: deny freezing devices undergoing a replace
  ...
This commit is contained in:
Linus Torvalds
2026-08-17 13:57:04 -07:00
parent aaed66fadb 9ac8fd8312
commit 1781f0b3d7
27 changed files with 882 additions and 306 deletions
Download Patch File Download Diff File Expand all files Collapse all files
block/bdev.c
+99 -26
View File
@@ -304,7 +304,12 @@ int bdev_freeze(struct block_device *bdev)
mutex_lock(&bdev->bd_fsfreeze_mutex);
if (atomic_inc_return(&bdev->bd_fsfreeze_count) > 1) {
/* A device being removed from its filesystem refuses freezes. */
if (!atomic_inc_unless_negative(&bdev->bd_fsfreeze_count)) {
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return -EBUSY;
}
if (atomic_read(&bdev->bd_fsfreeze_count) > 1) {
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return 0;
}
@@ -340,18 +345,18 @@ int bdev_thaw(struct block_device *bdev)
mutex_lock(&bdev->bd_fsfreeze_mutex);
/*
* If this returns < 0 it means that @bd_fsfreeze_count was
* already 0 and no decrement was performed.
*/
nr_freeze = atomic_dec_if_positive(&bdev->bd_fsfreeze_count);
if (nr_freeze < 0)
/* <= 0: not frozen (0) or a freeze deny is held (< 0); leave it. */
nr_freeze = atomic_read(&bdev->bd_fsfreeze_count);
if (nr_freeze <= 0)
goto out;
error = 0;
if (nr_freeze > 0)
if (nr_freeze > 1) {
atomic_dec(&bdev->bd_fsfreeze_count);
goto out;
}
/* Keep the count positive across the thaw so a deny is refused. */
mutex_lock(&bdev->bd_holder_lock);
if (bdev->bd_holder_ops && bdev->bd_holder_ops->thaw) {
error = bdev->bd_holder_ops->thaw(bdev);
@@ -360,14 +365,52 @@ int bdev_thaw(struct block_device *bdev)
mutex_unlock(&bdev->bd_holder_lock);
}
if (error)
atomic_inc(&bdev->bd_fsfreeze_count);
if (!error)
atomic_dec(&bdev->bd_fsfreeze_count);
out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return error;
}
EXPORT_SYMBOL(bdev_thaw);
/**
* bdev_deny_freeze - make a block device unfreezable
* @bdev: block device
*
* Reserve @bdev against bdev_freeze() the way deny_write_access() reserves a
* file against writers. bd_fsfreeze_count is sign-encoded: > 0 counts active
* freezes, < 0 counts deniers, so a deny succeeds only while no freeze is in
* progress. While held, bdev_freeze() returns -EBUSY. Pair with
* bdev_allow_freeze().
*
* A filesystem removing, adding or replacing a member device denies freezes on
* it for the duration, so a claim a freeze walk might act on is never torn down
* behind the freezer's back. The deny is device-scoped, not (device,
* superblock)-scoped: a device shared by several superblocks is refused for all
* of them. No in-tree filesystem removes a shared claim from a live superblock.
*
* Return: 0, or -EBUSY if the device is currently frozen.
*/
int bdev_deny_freeze(struct block_device *bdev)
{
return atomic_dec_unless_positive(&bdev->bd_fsfreeze_count) ? 0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(bdev_deny_freeze);
/**
* bdev_allow_freeze - allow freezing a block device again
* @bdev: block device
*
* Undo one bdev_deny_freeze().
*/
void bdev_allow_freeze(struct block_device *bdev)
{
/* A deny must be held, i.e. the count must be negative. */
WARN_ON_ONCE(atomic_read(&bdev->bd_fsfreeze_count) >= 0);
atomic_inc(&bdev->bd_fsfreeze_count);
}
EXPORT_SYMBOL_GPL(bdev_allow_freeze);
/*
* pseudo-fs
*/
@@ -1152,6 +1195,39 @@ put_no_open:
blkdev_put_no_open(bdev);
}
/**
* bdev_yield_claim - give up the holder claim on an open block device
* @bdev_file: open block device
*
* Yield the holder and any write access for @bdev_file without closing it, so
* the caller can still act on the device - e.g. bdev_allow_freeze() it - before
* the final bdev_fput(). bdev_fput() yields too, so calling it afterwards is
* safe.
*/
void bdev_yield_claim(struct file *bdev_file)
{
struct block_device *bdev;
struct gendisk *disk;
if (!bdev_file->private_data)
return;
bdev = file_bdev(bdev_file);
disk = bdev->bd_disk;
mutex_lock(&disk->open_mutex);
bdev_yield_write_access(bdev_file);
bd_yield_claim(bdev_file);
/*
* Tell release we already gave up our hold on the
* device and if write restrictions are available that
* we already gave up write access to the device.
*/
bdev_file->private_data = BDEV_I(bdev_file->f_mapping->host);
mutex_unlock(&disk->open_mutex);
}
EXPORT_SYMBOL_GPL(bdev_yield_claim);
/**
* bdev_fput - yield claim to the block device and put the file
* @bdev_file: open block device
@@ -1165,22 +1241,7 @@ void bdev_fput(struct file *bdev_file)
if (WARN_ON_ONCE(bdev_file->f_op != &def_blk_fops))
return;
if (bdev_file->private_data) {
struct block_device *bdev = file_bdev(bdev_file);
struct gendisk *disk = bdev->bd_disk;
mutex_lock(&disk->open_mutex);
bdev_yield_write_access(bdev_file);
bd_yield_claim(bdev_file);
/*
* Tell release we already gave up our hold on the
* device and if write restrictions are available that
* we already gave up write access to the device.
*/
bdev_file->private_data = BDEV_I(bdev_file->f_mapping->host);
mutex_unlock(&disk->open_mutex);
}
bdev_yield_claim(bdev_file);
fput(bdev_file);
}
EXPORT_SYMBOL(bdev_fput);
@@ -1217,6 +1278,18 @@ int lookup_bdev(const char *pathname, dev_t *dev)
if (!may_open_dev(&path))
goto out_path_put;
/*
* Reject a block device inode with i_rdev == 0. A dev_t of 0 is
* never valid for a block device: no real block device driver
* registers major 0. Fake block device inodes (e.g. fuse with
* rootmode=S_IFBLK) can expose i_rdev == 0, and letting that
* propagate would confuse superblock lookup and trigger warnings
* in the device-to-superblock table (super_dev_register).
*/
error = -ENODEV;
if (!inode->i_rdev)
goto out_path_put;
*dev = inode->i_rdev;
error = 0;
out_path_put:
fs/btrfs/dev-replace.c
+58 -7
View File
@@ -247,8 +247,8 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
return -EINVAL;
}
bdev_file = bdev_file_open_by_path(device_path, BLK_OPEN_WRITE,
fs_info->sb, &fs_holder_ops);
/* Unfreezable for the whole replace; see btrfs_dev_replace_start(). */
bdev_file = btrfs_open_device_deny_freeze(device_path, fs_info->sb);
if (IS_ERR(bdev_file)) {
btrfs_err(fs_info, "target device %s is invalid!", device_path);
return PTR_ERR(bdev_file);
@@ -327,7 +327,8 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
return 0;
error:
bdev_fput(bdev_file);
/* Undo the open-time freeze deny. */
btrfs_release_device_allow_freeze(bdev_file);
return ret;
}
@@ -624,6 +625,15 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
if (ret)
return ret;
/* Deny the source before mark, so every 'leave' unwinds both denied. */
if (src_device->bdev) {
ret = bdev_deny_freeze(src_device->bdev);
if (ret) {
btrfs_destroy_dev_replace_tgtdev(tgt_device, true);
return ret;
}
}
ret = mark_block_group_to_copy(fs_info, src_device);
if (ret)
return ret;
@@ -708,7 +718,9 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
return ret;
leave:
btrfs_destroy_dev_replace_tgtdev(tgt_device);
if (src_device->bdev)
bdev_allow_freeze(src_device->bdev);
btrfs_destroy_dev_replace_tgtdev(tgt_device, true);
return ret;
}
@@ -889,6 +901,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
*/
ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
if (ret) {
/* Stays started/resumable; keep both denied. */
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
return ret;
}
@@ -902,6 +915,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
while (1) {
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
/* Stays started/resumable; keep both denied. */
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
return PTR_ERR(trans);
}
@@ -954,7 +968,10 @@ error:
mutex_unlock(&fs_devices->device_list_mutex);
btrfs_rm_dev_replace_blocked(fs_info);
if (tgt_device)
btrfs_destroy_dev_replace_tgtdev(tgt_device);
btrfs_destroy_dev_replace_tgtdev(tgt_device, true);
/* The source stays a member; re-allow freezing it. */
if (src_device->bdev)
bdev_allow_freeze(src_device->bdev);
btrfs_rm_dev_replace_unblocked(fs_info);
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
@@ -1027,6 +1044,8 @@ error:
mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
/* The target is now a member; the source is freed (allow + release). */
bdev_allow_freeze(tgt_device->bdev);
btrfs_rm_dev_replace_free_srcdev(src_device);
return 0;
@@ -1155,8 +1174,9 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
btrfs_dev_name(src_device), src_device->devid,
btrfs_dev_name(tgt_device));
/* A suspended replace never re-denied freezing; do not allow. */
if (tgt_device)
btrfs_destroy_dev_replace_tgtdev(tgt_device);
btrfs_destroy_dev_replace_tgtdev(tgt_device, false);
break;
default:
up_write(&dev_replace->rwsem);
@@ -1186,6 +1206,11 @@ void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
dev_replace->time_stopped = ktime_get_real_seconds();
dev_replace->item_needs_writeback = 1;
btrfs_info(fs_info, "suspending dev_replace for unmount");
/* Reopened freezable next mount; resume re-denies. */
if (dev_replace->srcdev && dev_replace->srcdev->bdev)
bdev_allow_freeze(dev_replace->srcdev->bdev);
if (dev_replace->tgtdev && dev_replace->tgtdev->bdev)
bdev_allow_freeze(dev_replace->tgtdev->bdev);
break;
}
@@ -1198,6 +1223,7 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
{
struct task_struct *task;
struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
int ret = 0;
down_write(&dev_replace->rwsem);
@@ -1241,8 +1267,33 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
return 0;
}
/* Re-deny for the resumed replace; stay suspended if frozen now. */
if (dev_replace->srcdev->bdev &&
bdev_deny_freeze(dev_replace->srcdev->bdev))
goto suspend;
if (bdev_deny_freeze(dev_replace->tgtdev->bdev)) {
if (dev_replace->srcdev->bdev)
bdev_allow_freeze(dev_replace->srcdev->bdev);
goto suspend;
}
task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");
return PTR_ERR_OR_ZERO(task);
if (IS_ERR(task)) {
bdev_allow_freeze(dev_replace->tgtdev->bdev);
if (dev_replace->srcdev->bdev)
bdev_allow_freeze(dev_replace->srcdev->bdev);
/* Undo the deny and suspend, but still fail the mount. */
ret = PTR_ERR(task);
goto suspend;
}
return 0;
suspend:
btrfs_exclop_finish(fs_info);
down_write(&dev_replace->rwsem);
dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
up_write(&dev_replace->rwsem);
return ret;
}
static int btrfs_dev_replace_kthread(void *data)
fs/btrfs/ioctl.c
+2 -2
View File
@@ -2629,7 +2629,7 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
err_drop:
mnt_drop_write_file(file);
if (bdev_file)
bdev_fput(bdev_file);
btrfs_release_device_allow_freeze(bdev_file);
out:
btrfs_put_dev_args_from_path(&args);
return ret;
@@ -2679,7 +2679,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
mnt_drop_write_file(file);
if (bdev_file)
bdev_fput(bdev_file);
btrfs_release_device_allow_freeze(bdev_file);
out:
btrfs_put_dev_args_from_path(&args);
return ret;
fs/btrfs/volumes.c
+89 -16
View File
@@ -481,7 +481,12 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder,
struct block_device *bdev;
int ret;
*bdev_file = bdev_file_open_by_path(device_path, flags, holder, &fs_holder_ops);
if (holder)
*bdev_file = fs_bdev_file_open_by_path(device_path, flags,
holder, holder);
else
*bdev_file = bdev_file_open_by_path(device_path, flags, NULL,
NULL);
if (IS_ERR(*bdev_file)) {
ret = PTR_ERR(*bdev_file);
@@ -496,7 +501,7 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder,
if (holder) {
ret = set_blocksize(*bdev_file, BTRFS_BDEV_BLOCKSIZE);
if (ret) {
bdev_fput(*bdev_file);
fs_bdev_file_release(*bdev_file, holder);
goto error;
}
}
@@ -504,7 +509,10 @@ btrfs_get_bdev_and_sb(const char *device_path, blk_mode_t flags, void *holder,
*disk_super = btrfs_read_disk_super(bdev, 0, false);
if (IS_ERR(*disk_super)) {
ret = PTR_ERR(*disk_super);
bdev_fput(*bdev_file);
if (holder)
fs_bdev_file_release(*bdev_file, holder);
else
bdev_fput(*bdev_file);
goto error;
}
@@ -728,7 +736,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices,
error_free_page:
btrfs_release_disk_super(disk_super);
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, holder);
return -EINVAL;
}
@@ -1088,7 +1096,7 @@ static void __btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices,
continue;
if (device->bdev_file) {
bdev_fput(device->bdev_file);
fs_bdev_file_release(device->bdev_file, device->bdev_file->private_data);
device->bdev = NULL;
device->bdev_file = NULL;
fs_devices->open_devices--;
@@ -1125,7 +1133,18 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices)
mutex_unlock(&uuid_mutex);
}
static void btrfs_close_bdev(struct btrfs_device *device)
/* Release a device that was made unfreezable for a membership change. */
void btrfs_release_device_allow_freeze(struct file *bdev_file)
{
struct super_block *sb = bdev_file->private_data;
/* Unregister before re-allowing (strand-safe); file still open (UAF-safe). */
fs_bdev_unregister(bdev_file, sb);
bdev_allow_freeze(file_bdev(bdev_file));
bdev_fput(bdev_file);
}
static void btrfs_close_bdev(struct btrfs_device *device, bool allow_freeze)
{
if (!device->bdev)
return;
@@ -1135,7 +1154,12 @@ static void btrfs_close_bdev(struct btrfs_device *device)
invalidate_bdev(device->bdev);
}
bdev_fput(device->bdev_file);
/* @allow_freeze undoes a replace-time deny; unmount-close was never denied. */
if (allow_freeze)
btrfs_release_device_allow_freeze(device->bdev_file);
else
fs_bdev_file_release(device->bdev_file,
device->bdev_file->private_data);
}
static void btrfs_close_one_device(struct btrfs_device *device)
@@ -1156,7 +1180,7 @@ static void btrfs_close_one_device(struct btrfs_device *device)
fs_devices->missing_devices--;
}
btrfs_close_bdev(device);
btrfs_close_bdev(device, false);
if (device->bdev) {
fs_devices->open_devices--;
device->bdev = NULL;
@@ -2382,6 +2406,13 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
fs_info->fs_devices->rw_devices == 1)
return BTRFS_ERROR_DEV_ONLY_WRITABLE;
/* Removal and freezing are mutually exclusive; refuse if frozen now. */
if (device->bdev) {
ret = bdev_deny_freeze(device->bdev);
if (ret)
return ret;
}
if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
mutex_lock(&fs_info->chunk_mutex);
list_del_init(&device->dev_alloc_list);
@@ -2408,6 +2439,8 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
device->devid, ret);
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
if (device->bdev)
bdev_allow_freeze(device->bdev);
return ret;
}
@@ -2499,6 +2532,8 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info,
return btrfs_commit_transaction(trans);
error_undo:
if (device->bdev)
bdev_allow_freeze(device->bdev);
if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
mutex_lock(&fs_info->chunk_mutex);
list_add(&device->dev_alloc_list,
@@ -2543,7 +2578,8 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev)
mutex_lock(&uuid_mutex);
btrfs_close_bdev(srcdev);
/* The source was made unfreezable for the replace; undo it. */
btrfs_close_bdev(srcdev, true);
synchronize_rcu();
btrfs_free_device(srcdev);
@@ -2564,7 +2600,8 @@ void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev)
mutex_unlock(&uuid_mutex);
}
void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev,
bool allow_freeze)
{
struct btrfs_fs_devices *fs_devices = tgtdev->fs_info->fs_devices;
@@ -2585,7 +2622,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev)
btrfs_scratch_superblocks(tgtdev->fs_info, tgtdev);
btrfs_close_bdev(tgtdev);
btrfs_close_bdev(tgtdev, allow_freeze);
synchronize_rcu();
btrfs_free_device(tgtdev);
}
@@ -2854,6 +2891,37 @@ next_slot:
return 0;
}
/*
* Open @path for @sb with freezing denied before the holder claim is published,
* so a racing bdev_freeze() can never reach a claim a device add or replace may
* still abort. The deny is taken on a throwaway non-holder probe open, then the
* holder is opened by the probe's dev_t. Balanced by the caller.
*/
struct file *btrfs_open_device_deny_freeze(const char *path,
struct super_block *sb)
{
struct file *probe_file, *bdev_file;
int ret;
/* WRITE so bdev_file_open_by_path() rejects a read-only device. */
probe_file = bdev_file_open_by_path(path, BLK_OPEN_WRITE, NULL, NULL);
if (IS_ERR(probe_file))
return probe_file;
ret = bdev_deny_freeze(file_bdev(probe_file));
if (ret) {
bdev_fput(probe_file);
return ERR_PTR(ret);
}
bdev_file = fs_bdev_file_open_by_dev(file_bdev(probe_file)->bd_dev,
BLK_OPEN_WRITE, sb, sb);
if (IS_ERR(bdev_file))
bdev_allow_freeze(file_bdev(probe_file));
bdev_fput(probe_file);
return bdev_file;
}
int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path)
{
struct btrfs_root *root = fs_info->dev_root;
@@ -2872,8 +2940,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
if (sb_rdonly(sb) && !fs_devices->seeding)
return -EROFS;
bdev_file = bdev_file_open_by_path(device_path, BLK_OPEN_WRITE,
fs_info->sb, &fs_holder_ops);
/* Forbid freezing until the device is a committed member (or unwound). */
bdev_file = btrfs_open_device_deny_freeze(device_path, fs_info->sb);
if (IS_ERR(bdev_file))
return PTR_ERR(bdev_file);
@@ -3044,8 +3112,10 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
up_write(&sb->s_umount);
locked = false;
if (ret) /* transaction commit */
if (ret) { /* transaction commit */
bdev_allow_freeze(file_bdev(bdev_file));
return ret;
}
ret = btrfs_relocate_sys_chunks(fs_info);
if (ret < 0)
@@ -3053,8 +3123,10 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
"Failed to relocate sys chunks after device initialization. This can be fixed using the \"btrfs balance\" command.");
trans = btrfs_attach_transaction(root);
if (IS_ERR(trans)) {
if (PTR_ERR(trans) == -ENOENT)
if (PTR_ERR(trans) == -ENOENT) {
bdev_allow_freeze(file_bdev(bdev_file));
return 0;
}
ret = PTR_ERR(trans);
trans = NULL;
goto error_sysfs;
@@ -3074,6 +3146,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
/* Update ctime/mtime for blkid or udev */
update_dev_time(device_path);
bdev_allow_freeze(file_bdev(bdev_file));
return ret;
error_sysfs:
@@ -3103,7 +3176,7 @@ error_free_zone:
error_free_device:
btrfs_free_device(device);
error:
bdev_fput(bdev_file);
btrfs_release_device_allow_freeze(bdev_file);
if (locked) {
mutex_unlock(&uuid_mutex);
up_write(&sb->s_umount);
fs/btrfs/volumes.h
+5 -1
View File
@@ -744,6 +744,7 @@ int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
struct btrfs_device *btrfs_scan_one_device(const char *path, bool mount_arg_dev);
int btrfs_forget_devices(dev_t devt);
void btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
void btrfs_release_device_allow_freeze(struct file *bdev_file);
void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices);
void btrfs_assign_next_active_device(struct btrfs_device *device,
struct btrfs_device *this_dev);
@@ -768,6 +769,8 @@ struct btrfs_device *btrfs_find_device(const struct btrfs_fs_devices *fs_devices
const struct btrfs_dev_lookup_args *args);
int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *path);
struct file *btrfs_open_device_deny_freeze(const char *path,
struct super_block *sb);
int btrfs_balance(struct btrfs_fs_info *fs_info,
struct btrfs_balance_control *bctl,
struct btrfs_ioctl_balance_args *bargs);
@@ -788,7 +791,8 @@ int btrfs_init_writeback_bio_size(struct btrfs_fs_info *fs_info);
int btrfs_run_dev_stats(struct btrfs_trans_handle *trans);
void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev);
void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev);
void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev);
void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev,
bool allow_freeze);
unsigned long btrfs_full_stripe_len(struct btrfs_fs_info *fs_info,
u64 logical);
u64 btrfs_calc_stripe_length(const struct btrfs_chunk_map *map);
fs/cramfs/inode.c
+1 -1
View File
@@ -504,7 +504,7 @@ static void cramfs_kill_sb(struct super_block *sb)
sb->s_mtd = NULL;
} else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
sync_blockdev(sb->s_bdev);
bdev_fput(sb->s_bdev_file);
fs_bdev_file_release(sb->s_bdev_file, sb);
}
kfree(sbi);
}
fs/erofs/super.c
+23 -12
View File
@@ -147,8 +147,8 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
if (!sbi->devs->flatdev) {
file = erofs_is_fileio_mode(sbi) ?
filp_open(dif->path, O_RDONLY | O_LARGEFILE, 0) :
bdev_file_open_by_path(dif->path,
BLK_OPEN_READ, sb->s_type, NULL);
fs_bdev_file_open_by_path(dif->path,
BLK_OPEN_READ, sb->s_type, sb);
if (IS_ERR(file)) {
if (file == ERR_PTR(-ENOTBLK))
return -EINVAL;
@@ -790,28 +790,34 @@ static int erofs_fc_reconfigure(struct fs_context *fc)
static int erofs_release_device_info(int id, void *ptr, void *data)
{
struct super_block *sb = data;
struct erofs_device_info *dif = ptr;
fs_put_dax(dif->dax_dev, NULL);
if (dif->file)
fput(dif->file);
if (dif->file) {
if (S_ISBLK(file_inode(dif->file)->i_mode))
fs_bdev_file_release(dif->file, sb);
else
fput(dif->file);
}
kfree(dif->path);
kfree(dif);
return 0;
}
static void erofs_free_dev_context(struct erofs_dev_context *devs)
static void erofs_free_dev_context(struct erofs_dev_context *devs,
struct super_block *sb)
{
if (!devs)
return;
idr_for_each(&devs->tree, &erofs_release_device_info, NULL);
idr_for_each(&devs->tree, &erofs_release_device_info, sb);
idr_destroy(&devs->tree);
kfree(devs);
}
static void erofs_sb_free(struct erofs_sb_info *sbi)
static void erofs_sb_free(struct erofs_sb_info *sbi, struct super_block *sb)
{
erofs_free_dev_context(sbi->devs);
erofs_free_dev_context(sbi->devs, sb);
kfree_sensitive(sbi->domain_id);
if (sbi->dif0.file)
fput(sbi->dif0.file);
@@ -823,8 +829,13 @@ static void erofs_fc_free(struct fs_context *fc)
{
struct erofs_sb_info *sbi = fc->s_fs_info;
if (sbi) /* free here if an error occurs before transferring to sb */
erofs_sb_free(sbi);
/*
* Freed here only if an error occurs before the sb is set up; at that
* point no block-backed device has been claimed (that happens in
* fill_super), so the NULL sb never reaches fs_bdev_file_release().
*/
if (sbi)
erofs_sb_free(sbi, NULL);
}
static const struct fs_context_operations erofs_context_ops = {
@@ -878,7 +889,7 @@ static void erofs_kill_sb(struct super_block *sb)
kill_block_super(sb);
erofs_drop_internal_inodes(sbi);
fs_put_dax(sbi->dif0.dax_dev, NULL);
erofs_sb_free(sbi);
erofs_sb_free(sbi, sb);
sb->s_fs_info = NULL;
}
@@ -890,7 +901,7 @@ static void erofs_put_super(struct super_block *sb)
erofs_shrinker_unregister(sb);
erofs_xattr_prefixes_cleanup(sb);
erofs_drop_internal_inodes(sbi);
erofs_free_dev_context(sbi->devs);
erofs_free_dev_context(sbi->devs, sb);
sbi->devs = NULL;
}
fs/ext4/extents-test.c
+2 -7
View File
@@ -126,11 +126,6 @@ struct kunit_ext_test_param {
struct kunit_ext_data_state exp_data_state[3];
};
static void ext_kill_sb(struct super_block *sb)
{
generic_shutdown_super(sb);
}
static int ext_init_fs_context(struct fs_context *fc)
{
return 0;
@@ -138,13 +133,13 @@ static int ext_init_fs_context(struct fs_context *fc)
static int ext_set(struct super_block *sb, struct fs_context *fc)
{
return 0;
return set_anon_super_fc(sb, fc);
}
static struct file_system_type ext_fs_type = {
.name = "extents test",
.init_fs_context = ext_init_fs_context,
.kill_sb = ext_kill_sb,
.kill_sb = kill_anon_super,
};
static void extents_kunit_exit(struct kunit *test)
fs/ext4/mballoc-test.c
+2 -7
View File
@@ -59,11 +59,6 @@ static const struct super_operations mbt_sops = {
.free_inode = mbt_free_inode,
};
static void mbt_kill_sb(struct super_block *sb)
{
generic_shutdown_super(sb);
}
static int mbt_init_fs_context(struct fs_context *fc)
{
return 0;
@@ -72,7 +67,7 @@ static int mbt_init_fs_context(struct fs_context *fc)
static struct file_system_type mbt_fs_type = {
.name = "mballoc test",
.init_fs_context = mbt_init_fs_context,
.kill_sb = mbt_kill_sb,
.kill_sb = kill_anon_super,
};
static int mbt_mb_init(struct super_block *sb)
@@ -136,7 +131,7 @@ static void mbt_mb_release(struct super_block *sb)
static int mbt_set(struct super_block *sb, struct fs_context *fc)
{
return 0;
return set_anon_super_fc(sb, fc);
}
static struct super_block *mbt_ext4_alloc_super_block(void)
fs/ext4/super.c
+6 -6
View File
@@ -5797,7 +5797,7 @@ failed_mount:
brelse(sbi->s_sbh);
if (sbi->s_journal_bdev_file) {
invalidate_bdev(file_bdev(sbi->s_journal_bdev_file));
bdev_fput(sbi->s_journal_bdev_file);
fs_bdev_file_release(sbi->s_journal_bdev_file, sb);
}
out_fail:
invalidate_bdev(sb->s_bdev);
@@ -5981,9 +5981,9 @@ static struct file *ext4_get_journal_blkdev(struct super_block *sb,
struct ext4_super_block *es;
int errno;
bdev_file = bdev_file_open_by_dev(j_dev,
bdev_file = fs_bdev_file_open_by_dev(j_dev,
BLK_OPEN_READ | BLK_OPEN_WRITE | BLK_OPEN_RESTRICT_WRITES,
sb, &fs_holder_ops);
sb, sb);
if (IS_ERR(bdev_file)) {
ext4_msg(sb, KERN_ERR,
"failed to open journal device unknown-block(%u,%u) %pe",
@@ -6043,7 +6043,7 @@ static struct file *ext4_get_journal_blkdev(struct super_block *sb,
out_bh:
brelse(bh);
out_bdev:
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, sb);
return ERR_PTR(errno);
}
@@ -6082,7 +6082,7 @@ static journal_t *ext4_open_dev_journal(struct super_block *sb,
out_journal:
ext4_journal_destroy(EXT4_SB(sb), journal);
out_bdev:
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, sb);
return ERR_PTR(errno);
}
@@ -7499,7 +7499,7 @@ static void ext4_kill_sb(struct super_block *sb)
kill_block_super(sb);
if (bdev_file)
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, sb);
}
static struct file_system_type ext4_fs_type = {
fs/f2fs/super.c
+3 -3
View File
@@ -1971,7 +1971,7 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
for (i = 0; i < sbi->s_ndevs; i++) {
if (i > 0)
bdev_fput(FDEV(i).bdev_file);
fs_bdev_file_release(FDEV(i).bdev_file, sbi->sb);
#ifdef CONFIG_BLK_DEV_ZONED
kvfree(FDEV(i).blkz_seq);
#endif
@@ -4901,8 +4901,8 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
FDEV(i).end_blk = FDEV(i).start_blk +
SEGS_TO_BLKS(sbi,
FDEV(i).total_segments) - 1;
FDEV(i).bdev_file = bdev_file_open_by_path(
FDEV(i).path, mode, sbi->sb, NULL);
FDEV(i).bdev_file = fs_bdev_file_open_by_path(
FDEV(i).path, mode, sbi->sb, sbi->sb);
}
}
if (IS_ERR(FDEV(i).bdev_file))
fs/internal.h
+1
View File
@@ -137,6 +137,7 @@ extern int reconfigure_super(struct fs_context *);
extern bool super_trylock_shared(struct super_block *sb);
struct super_block *user_get_super(dev_t, bool excl);
void put_super(struct super_block *sb);
void __init super_dev_init(void);
extern bool mount_capable(struct fs_context *);
/*
fs/namespace.c
+2
View File
@@ -6270,6 +6270,8 @@ void __init mnt_init(void)
HASH_ZERO,
&mp_hash_shift, &mp_hash_mask, 0, 0);
super_dev_init();
kernfs_init();
err = sysfs_init();
fs/ocfs2/super.c
-1
View File
@@ -1882,7 +1882,6 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
ocfs2_delete_osb(osb);
kfree(osb);
sb->s_dev = 0;
sb->s_fs_info = NULL;
}
fs/romfs/super.c
+1 -1
View File
@@ -595,7 +595,7 @@ static void romfs_kill_sb(struct super_block *sb)
#ifdef CONFIG_ROMFS_ON_BLOCK
if (sb->s_bdev) {
sync_blockdev(sb->s_bdev);
bdev_fput(sb->s_bdev_file);
fs_bdev_file_release(sb->s_bdev_file, sb);
}
#endif
}
fs/super.c
+428 -196
View File
@@ -25,6 +25,7 @@
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/memcontrol.h>
#include <linux/rhashtable.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/writeback.h> /* for the emergency remount stuff */
@@ -103,7 +104,7 @@ static bool super_flags(const struct super_block *sb, unsigned int flags)
* creation will succeed and SB_BORN is set by vfs_get_tree() or we're
* woken and we'll see SB_DYING.
*
* The caller must have acquired a temporary reference on @sb->s_count.
* The caller must have acquired a temporary reference on @sb->s_passive.
*
* Return: The function returns true if SB_BORN was set and with
* s_umount held. The function returns false if SB_DYING was
@@ -287,6 +288,8 @@ static unsigned long super_cache_count(struct shrinker *shrink,
return total_objects;
}
static struct super_dev *super_dev_alloc(dev_t dev, struct super_block *sb);
static void destroy_super_work(struct work_struct *work)
{
struct super_block *s = container_of(work, struct super_block,
@@ -294,6 +297,8 @@ static void destroy_super_work(struct work_struct *work)
fsnotify_sb_free(s);
security_sb_free(s);
put_user_ns(s->s_user_ns);
/* Only an unregistered entry is still owned by the superblock. */
kfree(s->s_super_dev);
kfree(s->s_subtype);
for (int i = 0; i < SB_FREEZE_LEVELS; i++)
percpu_free_rwsem(&s->s_writers.rw_sem[i]);
@@ -382,7 +387,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
spin_lock_init(&s->s_inode_wblist_lock);
fserror_mount(s);
s->s_count = 1;
refcount_set(&s->s_passive, 1);
atomic_set(&s->s_active, 1);
mutex_init(&s->s_vfs_rename_mutex);
lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key);
@@ -407,6 +412,10 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
goto fail;
if (list_lru_init_memcg(&s->s_inode_lru, s->s_shrink))
goto fail;
s->s_super_dev = super_dev_alloc(0, s);
if (!s->s_super_dev)
goto fail;
s->s_min_writeback_pages = MIN_WRITEBACK_PAGES;
return s;
@@ -418,12 +427,17 @@ fail:
/* Superblock refcounting */
/*
* Drop a superblock's refcount. The caller must hold sb_lock.
* Drop a superblock's passive reference. Must be called WITHOUT sb_lock held;
* put_super() acquires sb_lock itself when the final reference is dropped.
*/
static void __put_super(struct super_block *s)
void put_super(struct super_block *s)
{
if (!--s->s_count) {
if (refcount_dec_and_test(&s->s_passive)) {
spin_lock(&sb_lock);
list_del_init(&s->s_list);
spin_unlock(&sb_lock);
WARN_ON(s->s_dentry_lru.node);
WARN_ON(s->s_inode_lru.node);
WARN_ON(s->s_mounts);
@@ -431,18 +445,109 @@ static void __put_super(struct super_block *s)
}
}
/**
* put_super - drop a temporary reference to superblock
* @sb: superblock in question
*
* Drops a temporary reference, frees superblock if there's no
* references left.
*/
void put_super(struct super_block *sb)
struct super_dev {
dev_t sd_dev;
struct super_block *sd_sb;
refcount_t sd_ref;
struct rhlist_head sd_node;
struct rcu_head sd_rcu;
};
static struct rhltable super_dev_table;
static const struct rhashtable_params super_dev_params = {
.key_len = sizeof(dev_t),
.key_offset = offsetof(struct super_dev, sd_dev),
.head_offset = offsetof(struct super_dev, sd_node),
};
static struct super_dev *super_dev_alloc(dev_t dev, struct super_block *sb)
{
spin_lock(&sb_lock);
__put_super(sb);
spin_unlock(&sb_lock);
struct super_dev *fsd;
fsd = kzalloc_obj(*fsd);
if (!fsd)
return NULL;
fsd->sd_dev = dev;
fsd->sd_sb = sb;
refcount_set(&fsd->sd_ref, 1);
return fsd;
}
static void super_dev_put(struct super_dev *fsd)
{
/* Unlink only once unpinned, so a cursor never resumes from a removed node. */
if (fsd && refcount_dec_and_test(&fsd->sd_ref)) {
rhltable_remove(&super_dev_table, &fsd->sd_node, super_dev_params);
put_super(fsd->sd_sb);
kfree_rcu(fsd, sd_rcu);
}
}
void __init super_dev_init(void)
{
if (rhltable_init(&super_dev_table, &super_dev_params))
panic("VFS: Cannot initialise super_dev_table\n");
}
static int super_dev_insert(struct super_dev *fsd)
{
int err;
err = rhltable_insert(&super_dev_table, &fsd->sd_node, super_dev_params);
if (!err)
refcount_inc(&fsd->sd_sb->s_passive);
return err;
}
/* Register @sb under @sb->s_dev as the final fallible act of a set callback. */
static int super_dev_register(struct super_block *sb)
{
struct super_dev *fsd = sb->s_super_dev;
int err;
lockdep_assert_held(&sb_lock);
VFS_WARN_ON_ONCE(!sb->s_dev);
VFS_WARN_ON_ONCE(!fsd || fsd->sd_dev);
fsd->sd_dev = sb->s_dev;
err = super_dev_insert(fsd);
if (err)
fsd->sd_dev = 0;
return err;
}
static struct super_dev *super_dev_get(struct rhlist_head *pos)
{
struct super_dev *sb_dev;
for (; pos; pos = rcu_dereference_all(pos->next)) {
sb_dev = container_of(pos, struct super_dev, sd_node);
if (refcount_inc_not_zero(&sb_dev->sd_ref))
return sb_dev;
}
return NULL;
}
static struct super_dev *super_dev_first(dev_t dev)
{
struct super_dev *sb_dev;
rcu_read_lock();
sb_dev = super_dev_get(rhltable_lookup(&super_dev_table, &dev, super_dev_params));
rcu_read_unlock();
return sb_dev;
}
static struct super_dev *super_dev_next(struct super_dev *prev)
{
struct super_dev *sb_dev;
rcu_read_lock();
sb_dev = super_dev_get(rcu_dereference_all(prev->sd_node.next));
rcu_read_unlock();
super_dev_put(prev);
return sb_dev;
}
static void kill_super_notify(struct super_block *sb)
@@ -464,6 +569,12 @@ static void kill_super_notify(struct super_block *sb)
hlist_del_init(&sb->s_instances);
spin_unlock(&sb_lock);
/* Drop sget_fc()'s claim; a never-registered entry stays with the sb. */
if (sb->s_super_dev->sd_dev) {
super_dev_put(sb->s_super_dev);
sb->s_super_dev = NULL;
}
/*
* Let concurrent mounts know that this thing is really dead.
* We don't need @sb->s_umount here as every concurrent caller
@@ -493,11 +604,7 @@ void deactivate_locked_super(struct super_block *s)
kill_super_notify(s);
/*
* Since list_lru_destroy() may sleep, we cannot call it from
* put_super(), where we hold the sb_lock. Therefore we destroy
* the lru lists right now.
*/
/* list_lru_destroy() may sleep; put_super() callers may not. */
list_lru_destroy(&s->s_dentry_lru);
list_lru_destroy(&s->s_inode_lru);
@@ -544,7 +651,7 @@ static bool grab_super(struct super_block *sb)
{
bool locked;
sb->s_count++;
refcount_inc(&sb->s_passive);
spin_unlock(&sb_lock);
locked = super_lock_excl(sb);
if (locked) {
@@ -571,7 +678,7 @@ static bool grab_super(struct super_block *sb)
* lock held in read mode in case of success. On successful return,
* the caller must drop the s_umount lock when done.
*
* Note that unlike get_super() et.al. this one does *not* bump ->s_count.
* Note that unlike get_super() et.al. this one does *not* bump ->s_passive.
* The reason why it's safe is that we are OK with doing trylock instead
* of down_read(). There's a couple of places that are OK with that, but
* it's very much not a general-purpose interface.
@@ -778,6 +885,7 @@ retry:
}
if (!s) {
spin_unlock(&sb_lock);
s = alloc_super(fc->fs_type, fc->sb_flags, user_ns);
if (!s)
return ERR_PTR(-ENOMEM);
@@ -787,11 +895,13 @@ retry:
s->s_fs_info = fc->s_fs_info;
err = set(s, fc);
if (err) {
VFS_WARN_ON_ONCE(s->s_super_dev->sd_dev);
s->s_fs_info = NULL;
spin_unlock(&sb_lock);
destroy_unused_super(s);
return ERR_PTR(err);
}
VFS_WARN_ON_ONCE(!s->s_super_dev->sd_dev);
fc->s_fs_info = NULL;
s->s_type = fc->fs_type;
s->s_iflags |= fc->s_iflags;
@@ -866,14 +976,17 @@ static void __iterate_supers(void (*f)(struct super_block *, void *), void *arg,
struct super_block *sb, *p = NULL;
bool excl = flags & SUPER_ITER_EXCL;
guard(spinlock)(&sb_lock);
spin_lock(&sb_lock);
for (sb = first_super(flags);
!list_entry_is_head(sb, &super_blocks, s_list);
sb = next_super(sb, flags)) {
if (super_flags(sb, SB_DYING))
continue;
sb->s_count++;
if (!refcount_inc_not_zero(&sb->s_passive))
continue;
spin_unlock(&sb_lock);
if (flags & SUPER_ITER_UNLOCKED) {
@@ -883,13 +996,14 @@ static void __iterate_supers(void (*f)(struct super_block *, void *), void *arg,
super_unlock(sb, excl);
}
spin_lock(&sb_lock);
if (p)
__put_super(p);
put_super(p);
p = sb;
spin_lock(&sb_lock);
}
spin_unlock(&sb_lock);
if (p)
__put_super(p);
put_super(p);
}
void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
@@ -918,7 +1032,9 @@ void iterate_supers_type(struct file_system_type *type,
if (super_flags(sb, SB_DYING))
continue;
sb->s_count++;
if (!refcount_inc_not_zero(&sb->s_passive))
continue;
spin_unlock(&sb_lock);
locked = super_lock_shared(sb);
@@ -927,41 +1043,33 @@ void iterate_supers_type(struct file_system_type *type,
super_unlock_shared(sb);
}
spin_lock(&sb_lock);
if (p)
__put_super(p);
put_super(p);
p = sb;
spin_lock(&sb_lock);
}
if (p)
__put_super(p);
spin_unlock(&sb_lock);
if (p)
put_super(p);
}
EXPORT_SYMBOL(iterate_supers_type);
struct super_block *user_get_super(dev_t dev, bool excl)
{
struct super_block *sb;
struct super_dev *sb_dev;
spin_lock(&sb_lock);
list_for_each_entry(sb, &super_blocks, s_list) {
bool locked;
for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
struct super_block *sb = sb_dev->sd_sb;
if (sb->s_dev != dev)
if (!super_lock(sb, excl))
continue;
sb->s_count++;
spin_unlock(&sb_lock);
locked = super_lock(sb, excl);
if (locked)
return sb;
spin_lock(&sb_lock);
__put_super(sb);
break;
/* The pinned entry holds a passive reference, take our own. */
refcount_inc(&sb->s_passive);
super_dev_put(sb_dev);
return sb;
}
spin_unlock(&sb_lock);
return NULL;
}
@@ -1243,7 +1351,16 @@ EXPORT_SYMBOL(free_anon_bdev);
int set_anon_super(struct super_block *s, void *data)
{
return get_anon_bdev(&s->s_dev);
int error;
error = get_anon_bdev(&s->s_dev);
if (error)
return error;
error = super_dev_register(s);
if (error)
free_anon_bdev(s->s_dev);
return error;
}
EXPORT_SYMBOL(set_anon_super);
@@ -1329,7 +1446,7 @@ EXPORT_SYMBOL(get_tree_keyed);
static int set_bdev_super(struct super_block *s, void *data)
{
s->s_dev = *(dev_t *)data;
return 0;
return super_dev_register(s);
}
static int super_s_dev_set(struct super_block *s, struct fs_context *fc)
@@ -1371,197 +1488,313 @@ struct super_block *sget_dev(struct fs_context *fc, dev_t dev)
EXPORT_SYMBOL(sget_dev);
#ifdef CONFIG_BLOCK
/*
* Lock the superblock that is holder of the bdev. Returns the superblock
* pointer if we successfully locked the superblock and it is alive. Otherwise
* we return NULL and just unlock bdev->bd_holder_lock.
*
* The function must be called with bdev->bd_holder_lock and releases it.
*/
static struct super_block *bdev_super_lock(struct block_device *bdev, bool excl)
__releases(&bdev->bd_holder_lock)
static int fs_super_freeze(struct super_block *sb)
{
struct super_block *sb = bdev->bd_holder;
bool locked;
if (sb->s_op->freeze_super)
return sb->s_op->freeze_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
return freeze_super(sb, FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
}
lockdep_assert_held(&bdev->bd_holder_lock);
lockdep_assert_not_held(&sb->s_umount);
lockdep_assert_not_held(&bdev->bd_disk->open_mutex);
/* Make sure sb doesn't go away from under us */
spin_lock(&sb_lock);
sb->s_count++;
spin_unlock(&sb_lock);
mutex_unlock(&bdev->bd_holder_lock);
locked = super_lock(sb, excl);
/*
* If the superblock wasn't already SB_DYING then we hold
* s_umount and can safely drop our temporary reference.
*/
put_super(sb);
if (!locked)
return NULL;
if (!sb->s_root || !(sb->s_flags & SB_ACTIVE)) {
super_unlock(sb, excl);
return NULL;
}
return sb;
static int fs_super_thaw(struct super_block *sb)
{
if (sb->s_op->thaw_super)
return sb->s_op->thaw_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
return thaw_super(sb, FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
}
static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise)
{
struct super_block *sb;
struct super_dev *sb_dev;
dev_t dev = bdev->bd_dev;
sb = bdev_super_lock(bdev, false);
if (!sb)
return;
mutex_unlock(&bdev->bd_holder_lock);
if (sb->s_op->remove_bdev) {
int ret;
for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
struct super_block *sb = sb_dev->sd_sb;
ret = sb->s_op->remove_bdev(sb, bdev);
if (!ret) {
super_unlock_shared(sb);
return;
if (!super_lock_shared(sb))
continue;
if (sb->s_root && (sb->s_flags & SB_ACTIVE)) {
if (!sb->s_op->remove_bdev ||
sb->s_op->remove_bdev(sb, bdev)) {
if (!surprise)
sync_filesystem(sb);
shrink_dcache_sb(sb);
evict_inodes(sb);
if (sb->s_op->shutdown)
sb->s_op->shutdown(sb);
}
}
/* Fallback to shutdown. */
super_unlock_shared(sb);
}
if (!surprise)
sync_filesystem(sb);
shrink_dcache_sb(sb);
evict_inodes(sb);
if (sb->s_op->shutdown)
sb->s_op->shutdown(sb);
super_unlock_shared(sb);
}
static void fs_bdev_sync(struct block_device *bdev)
{
struct super_block *sb;
struct super_dev *sb_dev;
dev_t dev = bdev->bd_dev;
sb = bdev_super_lock(bdev, false);
if (!sb)
return;
mutex_unlock(&bdev->bd_holder_lock);
sync_filesystem(sb);
super_unlock_shared(sb);
}
for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
struct super_block *sb = sb_dev->sd_sb;
static struct super_block *get_bdev_super(struct block_device *bdev)
{
bool active = false;
struct super_block *sb;
sb = bdev_super_lock(bdev, true);
if (sb) {
active = atomic_inc_not_zero(&sb->s_active);
super_unlock_excl(sb);
if (!super_lock_shared(sb))
continue;
if (sb->s_root && (sb->s_flags & SB_ACTIVE))
sync_filesystem(sb);
super_unlock_shared(sb);
}
if (!active)
return NULL;
return sb;
}
/**
* fs_bdev_freeze - freeze owning filesystem of block device
* fs_bdev_freeze - freeze every superblock using a block device
* @bdev: block device
*
* Freeze the filesystem that owns this block device if it is still
* active.
* Freeze each live superblock using @bdev. A superblock owning several block
* devices is frozen once per device and stays frozen until all are thawed; the
* block layer nests these freezes so the count stays balanced.
*
* A filesystem that owns multiple block devices may be frozen from each
* block device and won't be unfrozen until all block devices are
* unfrozen. Each block device can only freeze the filesystem once as we
* nest freezes for block devices in the block layer.
*
* Return: If the freeze was successful zero is returned. If the freeze
* failed a negative error code is returned.
* Return: 0, or the error from the one superblock on a single-fs device. When
* several superblocks share @bdev a per-superblock failure is swallowed
* (see below), but a sync_blockdev() failure is always reported.
*/
static int fs_bdev_freeze(struct block_device *bdev)
{
struct super_block *sb;
int error = 0;
dev_t dev = bdev->bd_dev;
struct super_dev *sb_dev;
unsigned int count = 0;
int error = 0, err;
lockdep_assert_held(&bdev->bd_fsfreeze_mutex);
sb = get_bdev_super(bdev);
if (!sb)
return -EINVAL;
mutex_unlock(&bdev->bd_holder_lock);
if (sb->s_op->freeze_super)
error = sb->s_op->freeze_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
else
error = freeze_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
if (!get_active_super(sb_dev->sd_sb))
continue;
err = fs_super_freeze(sb_dev->sd_sb);
if (err && !error)
error = err;
deactivate_super(sb_dev->sd_sb);
count++;
}
/*
* When several superblocks share the device, keep it frozen even if some
* of them failed to freeze and swallow the error: rolling the rest back
* via thaw_super() can fail too, so neither is a clear win. A single
* filesystem (count == 1) still reports its error.
*/
if (error && count > 1)
error = 0;
if (!error)
error = sync_blockdev(bdev);
deactivate_super(sb);
return error;
}
/**
* fs_bdev_thaw - thaw owning filesystem of block device
* fs_bdev_thaw - thaw every superblock using a block device
* @bdev: block device
*
* Thaw the filesystem that owns this block device.
* The counterpart to fs_bdev_freeze(): thaw each live superblock using @bdev.
* A zero return does not imply a superblock is fully unfrozen; it may have been
* frozen more than once (by the kernel or via another device).
*
* A filesystem that owns multiple block devices may be frozen from each
* block device and won't be unfrozen until all block devices are
* unfrozen. Each block device can only freeze the filesystem once as we
* nest freezes for block devices in the block layer.
*
* Return: If the thaw was successful zero is returned. If the thaw
* failed a negative error code is returned. If this function
* returns zero it doesn't mean that the filesystem is unfrozen
* as it may have been frozen multiple times (kernel may hold a
* freeze or might be frozen from other block devices).
* Return: 0, or the first error on a single-fs device; a shared device swallows
* per-superblock errors, as fs_bdev_freeze() does.
*/
static int fs_bdev_thaw(struct block_device *bdev)
{
struct super_block *sb;
int error;
dev_t dev = bdev->bd_dev;
struct super_dev *sb_dev;
unsigned int count = 0;
int error = 0, err;
lockdep_assert_held(&bdev->bd_fsfreeze_mutex);
/*
* The block device may have been frozen before it was claimed by a
* filesystem. Concurrently another process might try to mount that
* frozen block device and has temporarily claimed the block device for
* that purpose causing a concurrent fs_bdev_thaw() to end up here. The
* mounter is already about to abort mounting because they still saw an
* elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return
* NULL in that case.
*/
sb = get_bdev_super(bdev);
if (!sb)
return -EINVAL;
mutex_unlock(&bdev->bd_holder_lock);
if (sb->s_op->thaw_super)
error = sb->s_op->thaw_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
else
error = thaw_super(sb,
FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE, NULL);
deactivate_super(sb);
for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
if (!get_active_super(sb_dev->sd_sb))
continue;
err = fs_super_thaw(sb_dev->sd_sb);
if (err && !error)
error = err;
deactivate_super(sb_dev->sd_sb);
count++;
}
/* Shared device: swallow per-superblock errors, like fs_bdev_freeze(). */
if (error && count > 1)
error = 0;
return error;
}
const struct blk_holder_ops fs_holder_ops = {
static const struct blk_holder_ops fs_holder_ops = {
.mark_dead = fs_bdev_mark_dead,
.sync = fs_bdev_sync,
.freeze = fs_bdev_freeze,
.thaw = fs_bdev_thaw,
};
EXPORT_SYMBOL_GPL(fs_holder_ops);
static struct super_dev *super_dev_lookup(dev_t dev, struct super_block *sb)
{
struct super_dev *it;
struct rhlist_head *list, *pos;
RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious super_dev_lookup() usage");
VFS_WARN_ON_ONCE(!dev);
VFS_WARN_ON_ONCE(!sb);
list = rhltable_lookup(&super_dev_table, &dev, super_dev_params);
rhl_for_each_entry_rcu(it, pos, list, sd_node) {
if (it->sd_sb == sb)
return it;
}
return NULL;
}
static int fs_bdev_register(struct file *bdev_file, struct super_block *sb)
{
struct super_dev *sb_dev __free(kfree) = NULL;
dev_t dev = file_bdev(bdev_file)->bd_dev;
int err;
scoped_guard(rcu) {
sb_dev = super_dev_lookup(dev, sb);
if (sb_dev && refcount_inc_not_zero(&sb_dev->sd_ref)) {
retain_and_null_ptr(sb_dev);
return 0;
}
}
sb_dev = super_dev_alloc(dev, sb);
if (!sb_dev)
return -ENOMEM;
err = super_dev_insert(sb_dev);
if (err)
return err;
/* Publish the entry before reading the count; pairs with bdev_freeze(). */
smp_mb();
if (atomic_read(&file_bdev(bdev_file)->bd_fsfreeze_count) > 0) {
err = -EBUSY;
super_dev_put(sb_dev);
}
retain_and_null_ptr(sb_dev);
return err;
}
/**
* fs_bdev_file_open_by_dev - claim a block device on behalf of a superblock
* @dev: block device number
* @mode: open mode
* @holder: block-layer exclusivity token (a superblock, or the file_system_type
* when the device may be shared by several superblocks of that type)
* @sb: superblock to drive fs_holder_ops events for
*
* Open @dev with &fs_holder_ops and register that @sb uses it, so device
* removal/sync/freeze/thaw are propagated to @sb (and any other superblock
* sharing @dev). Must be paired with fs_bdev_file_release().
*
* Return: an opened block-device file or an ERR_PTR().
*/
struct file *fs_bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
struct super_block *sb)
{
struct file *bdev_file;
int err;
bdev_file = bdev_file_open_by_dev(dev, mode, holder, &fs_holder_ops);
if (IS_ERR(bdev_file))
return bdev_file;
err = fs_bdev_register(bdev_file, sb);
if (err) {
bdev_fput(bdev_file);
return ERR_PTR(err);
}
return bdev_file;
}
EXPORT_SYMBOL_GPL(fs_bdev_file_open_by_dev);
/**
* fs_bdev_file_open_by_path - claim a block device on behalf of a superblock
* @path: path to the block device
* @mode: open mode
* @holder: block-layer exclusivity token (a superblock, or the file_system_type
* when the device may be shared by several superblocks of that type)
* @sb: superblock to drive fs_holder_ops events for
*
* Open the block device at @path with &fs_holder_ops and register that @sb
* uses it, so device removal/sync/freeze/thaw are propagated to @sb (and any
* other superblock sharing the device). Must be paired with
* fs_bdev_file_release().
*
* Return: an opened block-device file or an ERR_PTR().
*/
struct file *fs_bdev_file_open_by_path(const char *path, blk_mode_t mode,
void *holder, struct super_block *sb)
{
struct file *bdev_file;
int err;
bdev_file = bdev_file_open_by_path(path, mode, holder, &fs_holder_ops);
if (IS_ERR(bdev_file))
return bdev_file;
err = fs_bdev_register(bdev_file, sb);
if (err) {
bdev_fput(bdev_file);
return ERR_PTR(err);
}
return bdev_file;
}
EXPORT_SYMBOL_GPL(fs_bdev_file_open_by_path);
/**
* fs_bdev_unregister - drop a superblock's claim on a block device
* @bdev_file: file returned by fs_bdev_file_open_by_{dev,path}()
* @sb: superblock the device was claimed for
*
* The inverse of fs_bdev_register(): drop one claim on the {dev, @sb} entry
* (the last claim unregisters it; a pinning cursor defers the actual unlink)
* without closing the device. A caller that must act on the still-open device
* between unregistering and closing - e.g. re-allow freezing one denied for a
* membership change - pairs this with bdev_fput(). fs_bdev_file_release() is
* the common unregister-and-close.
*/
void fs_bdev_unregister(struct file *bdev_file, struct super_block *sb)
{
dev_t dev = file_bdev(bdev_file)->bd_dev;
struct super_dev *sb_dev;
rcu_read_lock();
sb_dev = super_dev_lookup(dev, sb);
rcu_read_unlock();
super_dev_put(sb_dev);
}
EXPORT_SYMBOL_GPL(fs_bdev_unregister);
/**
* fs_bdev_file_release - release a block device claimed for a superblock
* @bdev_file: file returned by fs_bdev_file_open_by_{dev,path}()
* @sb: superblock the device was claimed for
*
* Unregister the {dev, @sb} entry, then close the block device.
*/
void fs_bdev_file_release(struct file *bdev_file, struct super_block *sb)
{
fs_bdev_unregister(bdev_file, sb);
bdev_fput(bdev_file);
}
EXPORT_SYMBOL_GPL(fs_bdev_file_release);
int setup_bdev_super(struct super_block *sb, int sb_flags,
struct fs_context *fc)
@@ -1570,7 +1803,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
struct file *bdev_file;
struct block_device *bdev;
bdev_file = bdev_file_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops);
bdev_file = fs_bdev_file_open_by_dev(sb->s_dev, mode, sb, sb);
if (IS_ERR(bdev_file)) {
if (fc)
errorf(fc, "%s: Can't open blockdev", fc->source);
@@ -1584,20 +1817,19 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
* writable from userspace even for a read-only block device.
*/
if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) {
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, sb);
return -EACCES;
}
/*
* It is enough to check bdev was not frozen before we set
* s_bdev as freezing will wait until SB_BORN is set.
*/
/* The sget_fc() entry is already published; pairs with bdev_freeze(). */
smp_mb();
if (atomic_read(&bdev->bd_fsfreeze_count) > 0) {
if (fc)
warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev);
bdev_fput(bdev_file);
fs_bdev_file_release(bdev_file, sb);
return -EBUSY;
}
spin_lock(&sb_lock);
sb->s_bdev_file = bdev_file;
sb->s_bdev = bdev;
@@ -1686,7 +1918,7 @@ void kill_block_super(struct super_block *sb)
generic_shutdown_super(sb);
if (bdev) {
sync_blockdev(bdev);
bdev_fput(sb->s_bdev_file);
fs_bdev_file_release(sb->s_bdev_file, sb);
}
}
@@ -2033,7 +2265,7 @@ int freeze_super(struct super_block *sb, enum freeze_holder who, const void *fre
int ret;
if (!super_lock_excl(sb)) {
WARN_ON_ONCE("Dying superblock while freezing!");
WARN_ONCE(1, "Dying superblock while freezing!");
return -EINVAL;
}
atomic_inc(&sb->s_active);
@@ -2197,7 +2429,7 @@ int thaw_super(struct super_block *sb, enum freeze_holder who,
const void *freeze_owner)
{
if (!super_lock_excl(sb)) {
WARN_ON_ONCE("Dying superblock while thawing!");
WARN_ONCE(1, "Dying superblock while thawing!");
return -EINVAL;
}
return thaw_super_locked(sb, who, freeze_owner);
fs/xfs/xfs_buf.c
+1 -1
View File
@@ -1631,7 +1631,7 @@ xfs_free_buftarg(
fs_put_dax(btp->bt_daxdev, btp->bt_mount);
/* the main block device is closed by kill_block_super */
if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
bdev_fput(btp->bt_file);
fs_bdev_file_release(btp->bt_file, btp->bt_mount->m_super);
kfree(btp);
}
fs/xfs/xfs_super.c
+5 -5
View File
@@ -400,8 +400,8 @@ xfs_blkdev_get(
blk_mode_t mode;
mode = sb_open_mode(mp->m_super->s_flags);
*bdev_filep = bdev_file_open_by_path(name, mode,
mp->m_super, &fs_holder_ops);
*bdev_filep = fs_bdev_file_open_by_path(name, mode,
mp->m_super, mp->m_super);
if (IS_ERR(*bdev_filep)) {
error = PTR_ERR(*bdev_filep);
*bdev_filep = NULL;
@@ -526,7 +526,7 @@ xfs_open_devices(
mp->m_logdev_targp = mp->m_ddev_targp;
/* Handle won't be used, drop it */
if (logdev_file)
bdev_fput(logdev_file);
fs_bdev_file_release(logdev_file, mp->m_super);
}
return 0;
@@ -541,10 +541,10 @@ xfs_open_devices(
mp->m_ddev_targp = NULL;
out_close_rtdev:
if (rtdev_file)
bdev_fput(rtdev_file);
fs_bdev_file_release(rtdev_file, mp->m_super);
out_close_logdev:
if (logdev_file)
bdev_fput(logdev_file);
fs_bdev_file_release(logdev_file, mp->m_super);
return error;
}
include/linux/blk_types.h
+1 -1
View File
@@ -66,7 +66,7 @@ struct block_device {
int bd_holders;
struct kobject *bd_holder_dir;
atomic_t bd_fsfreeze_count; /* number of freeze requests */
atomic_t bd_fsfreeze_count; /* >0 freeze requests, <0 freeze deniers */
struct mutex bd_fsfreeze_mutex; /* serialize freeze/thaw */
struct partition_meta_info *bd_meta_info;
include/linux/blkdev.h
+3 -9
View File
@@ -126,8 +126,6 @@ struct blk_integrity {
unsigned char pi_tuple_size;
};
typedef unsigned int __bitwise blk_mode_t;
/* open for reading */
#define BLK_OPEN_READ ((__force blk_mode_t)(1 << 0))
/* open for writing */
@@ -1770,13 +1768,6 @@ struct blk_holder_ops {
__releases(&bdev->bd_holder_lock);
};
/*
* For filesystems using @fs_holder_ops, the @holder argument passed to
* helpers used to open and claim block devices via
* bd_prepare_to_claim() must point to a superblock.
*/
extern const struct blk_holder_ops fs_holder_ops;
/*
* Return the correct open flags for blkdev_get_by_* for super block flags
* as stored in sb->s_flags.
@@ -1837,7 +1828,10 @@ static inline int early_lookup_bdev(const char *pathname, dev_t *dev)
int bdev_freeze(struct block_device *bdev);
int bdev_thaw(struct block_device *bdev);
int bdev_deny_freeze(struct block_device *bdev);
void bdev_allow_freeze(struct block_device *bdev);
void bdev_fput(struct file *bdev_file);
void bdev_yield_claim(struct file *bdev_file);
struct io_comp_batch {
struct rq_list req_list;
include/linux/fs.h
-2
View File
@@ -1916,8 +1916,6 @@ struct dir_context {
struct io_uring_cmd;
struct offset_ctx;
typedef unsigned int __bitwise fop_flags_t;
struct file_operations {
struct module *owner;
fop_flags_t fop_flags;
include/linux/fs/super.h
+8
View File
@@ -237,4 +237,12 @@ int thaw_super(struct super_block *super, enum freeze_holder who,
int sb_init_dio_done_wq(struct super_block *sb);
struct file;
struct file *fs_bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
struct super_block *sb);
struct file *fs_bdev_file_open_by_path(const char *path, blk_mode_t mode,
void *holder, struct super_block *sb);
void fs_bdev_unregister(struct file *bdev_file, struct super_block *sb);
void fs_bdev_file_release(struct file *bdev_file, struct super_block *sb);
#endif /* _LINUX_FS_SUPER_H */
include/linux/fs/super_types.h
+3 -1
View File
@@ -30,6 +30,7 @@ struct mount;
struct mtd_info;
struct quotactl_ops;
struct shrinker;
struct super_dev;
struct unicode_map;
struct user_namespace;
struct workqueue_struct;
@@ -132,6 +133,7 @@ struct super_operations {
struct super_block {
struct list_head s_list; /* Keep this first */
dev_t s_dev; /* search index; _not_ kdev_t */
struct super_dev *s_super_dev; /* sget_fc()'s device table claim */
unsigned char s_blocksize_bits;
unsigned long s_blocksize;
loff_t s_maxbytes; /* Max file size */
@@ -145,7 +147,7 @@ struct super_block {
unsigned long s_magic;
struct dentry *s_root;
struct rw_semaphore s_umount;
int s_count;
refcount_t s_passive;
atomic_t s_active;
#ifdef CONFIG_SECURITY
void *s_security;
include/linux/types.h
+2
View File
@@ -163,6 +163,8 @@ typedef u32 dma_addr_t;
typedef unsigned int __bitwise gfp_t;
typedef unsigned int __bitwise slab_flags_t;
typedef unsigned int __bitwise fmode_t;
typedef unsigned int __bitwise blk_mode_t;
typedef unsigned int __bitwise fop_flags_t;
#ifdef CONFIG_PHYS_ADDR_T_64BIT
typedef u64 phys_addr_t;
tools/testing/selftests/filesystems/.gitignore
+1
View File
@@ -6,3 +6,4 @@ file_stressor
anon_inode_test
kernfs_test
idmapped_tmpfile
ustat_test
tools/testing/selftests/filesystems/Makefile
+1 -1
View File
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
CFLAGS += $(KHDR_INCLUDES)
TEST_GEN_PROGS := devpts_pts file_stressor anon_inode_test kernfs_test fclog
TEST_GEN_PROGS := devpts_pts file_stressor anon_inode_test kernfs_test fclog ustat_test
TEST_GEN_PROGS += idmapped_tmpfile
TEST_GEN_PROGS_EXTENDED := dnotify_test
tools/testing/selftests/filesystems/ustat_test.c
+135
View File
@@ -0,0 +1,135 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Test ustat(2): looking up superblocks by device number.
*
* ustat() resolves a device number to a mounted superblock via
* user_get_super(). Check that the device number of a mounted tmpfs (an
* anonymous device) resolves, that it stops resolving once the filesystem
* is unmounted and that bogus device numbers report EINVAL.
*/
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <unistd.h>
#include "../kselftest_harness.h"
/* struct ustat is not exported through UAPI, mirror include/linux/types.h. */
struct ustat_buf {
int f_tfree;
unsigned long f_tinode;
char f_fname[6];
char f_fpack[6];
/* slack in case an architecture lays the struct out differently */
char pad[64];
};
#ifdef __NR_ustat
/*
* The kernel decodes @dev with new_decode_dev(), which matches the low 32
* bits of the st_dev encoding stat(2) returns for any major below 4096.
*/
static int sys_ustat(unsigned int dev, struct ustat_buf *buf)
{
return syscall(__NR_ustat, dev, buf);
}
static int write_string(const char *path, const char *string)
{
ssize_t len = strlen(string);
int fd;
fd = open(path, O_WRONLY);
if (fd < 0)
return -1;
if (write(fd, string, len) != len) {
close(fd);
return -1;
}
return close(fd);
}
/* Enter namespaces in which mounting a tmpfs instance is allowed. */
static int setup_namespaces(void)
{
uid_t uid = getuid();
gid_t gid = getgid();
char map[64];
if (unshare(CLONE_NEWNS | (uid ? CLONE_NEWUSER : 0)))
return -1;
if (uid) {
if (write_string("/proc/self/setgroups", "deny"))
return -1;
snprintf(map, sizeof(map), "0 %d 1", uid);
if (write_string("/proc/self/uid_map", map))
return -1;
snprintf(map, sizeof(map), "0 %d 1", gid);
if (write_string("/proc/self/gid_map", map))
return -1;
}
return mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL);
}
TEST(resolves_mounted_superblock)
{
char dir[] = "/tmp/ustat_test.XXXXXX";
struct ustat_buf ub;
struct stat st;
ASSERT_NE(NULL, mkdtemp(dir));
if (setup_namespaces()) {
rmdir(dir);
SKIP(return, "cannot set up namespaces: %s", strerror(errno));
}
ASSERT_EQ(0, mount("ustat_test", dir, "tmpfs", 0, NULL));
ASSERT_EQ(0, stat(dir, &st));
memset(&ub, 0xff, sizeof(ub));
ASSERT_EQ(0, sys_ustat(st.st_dev, &ub))
TH_LOG("ustat(%u): %s", (unsigned int)st.st_dev,
strerror(errno));
ASSERT_EQ(0, umount(dir));
/* The unmount removed the superblock, the device is gone. */
ASSERT_EQ(-1, sys_ustat(st.st_dev, &ub));
ASSERT_EQ(EINVAL, errno);
rmdir(dir);
}
TEST(bogus_device_numbers)
{
struct ustat_buf ub;
ASSERT_EQ(-1, sys_ustat(0, &ub));
ASSERT_EQ(EINVAL, errno);
/* major 4095, minor 1048575: nothing plausible lives there */
ASSERT_EQ(-1, sys_ustat((0xfffu << 8) | 0xffu | (0xfff00u << 12), &ub));
ASSERT_EQ(EINVAL, errno);
}
#else /* !__NR_ustat */
TEST(unsupported)
{
SKIP(return, "ustat(2) is not available on this architecture");
}
#endif /* __NR_ustat */
TEST_HARNESS_MAIN