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authorLinus Torvalds <torvalds@linux-foundation.org>2022-08-08 11:10:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-08 11:10:02 -0700
commit2bd5d41e0e9d8e423a0bd446ee174584c8a495fe (patch)
tree720682607966689b7579344c5e8890f8bc8a6628 /fs/super.c
parent65512eb0e9e6308ca08110c88a9619a9e5a19aa9 (diff)
parent247861c325c2e4f5ad3c2f9a77ab9d85d15cbcfc (diff)
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Merge tag 'fuse-update-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse updates from Miklos Szeredi: - Fix an issue with reusing the bdi in case of block based filesystems - Allow root (in init namespace) to access fuse filesystems in user namespaces if expicitly enabled with a module param - Misc fixes * tag 'fuse-update-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: fuse: retire block-device-based superblock on force unmount vfs: function to prevent re-use of block-device-based superblocks virtio_fs: Modify format for virtio_fs_direct_access virtiofs: delete unused parameter for virtio_fs_cleanup_vqs fuse: Add module param for CAP_SYS_ADMIN access bypassing allow_other fuse: Remove the control interface for virtio-fs fuse: ioctl: translate ENOSYS fuse: limit nsec fuse: avoid unnecessary spinlock bump fuse: fix deadlock between atomic O_TRUNC and page invalidation fuse: write inode in fuse_release()
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c33
1 files changed, 31 insertions, 2 deletions
diff --git a/fs/super.c b/fs/super.c
index 4fca6657f442..734ed584a946 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -423,6 +423,35 @@ bool trylock_super(struct super_block *sb)
}
/**
+ * retire_super - prevents superblock from being reused
+ * @sb: superblock to retire
+ *
+ * The function marks superblock to be ignored in superblock test, which
+ * prevents it from being reused for any new mounts. If the superblock has
+ * a private bdi, it also unregisters it, but doesn't reduce the refcount
+ * of the superblock to prevent potential races. The refcount is reduced
+ * by generic_shutdown_super(). The function can not be called
+ * concurrently with generic_shutdown_super(). It is safe to call the
+ * function multiple times, subsequent calls have no effect.
+ *
+ * The marker will affect the re-use only for block-device-based
+ * superblocks. Other superblocks will still get marked if this function
+ * is used, but that will not affect their reusability.
+ */
+void retire_super(struct super_block *sb)
+{
+ WARN_ON(!sb->s_bdev);
+ down_write(&sb->s_umount);
+ if (sb->s_iflags & SB_I_PERSB_BDI) {
+ bdi_unregister(sb->s_bdi);
+ sb->s_iflags &= ~SB_I_PERSB_BDI;
+ }
+ sb->s_iflags |= SB_I_RETIRED;
+ up_write(&sb->s_umount);
+}
+EXPORT_SYMBOL(retire_super);
+
+/**
* generic_shutdown_super - common helper for ->kill_sb()
* @sb: superblock to kill
*
@@ -1216,7 +1245,7 @@ static int set_bdev_super_fc(struct super_block *s, struct fs_context *fc)
static int test_bdev_super_fc(struct super_block *s, struct fs_context *fc)
{
- return s->s_bdev == fc->sget_key;
+ return !(s->s_iflags & SB_I_RETIRED) && s->s_bdev == fc->sget_key;
}
/**
@@ -1309,7 +1338,7 @@ EXPORT_SYMBOL(get_tree_bdev);
static int test_bdev_super(struct super_block *s, void *data)
{
- return (void *)s->s_bdev == data;
+ return !(s->s_iflags & SB_I_RETIRED) && (void *)s->s_bdev == data;
}
struct dentry *mount_bdev(struct file_system_type *fs_type,