[v2,15/28] fs: add is_userns_visible() helper
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Message ID 20200214183554.1133805-16-christian.brauner@ubuntu.com
State New
Headers show
  • user_namespace: introduce fsid mappings
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Commit Message

Christian Brauner Feb. 14, 2020, 6:35 p.m. UTC
Introduce a helper which makes it possible to detect fileystems whose
superblock is visible in multiple user namespace. This currently only
means proc and sys. Such filesystems usually have special semantics so their
behavior will not be changed with the introduction of fsid mappings.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
/* v2 */
 include/linux/fs.h | 5 +++++
 1 file changed, 5 insertions(+)

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diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3cd4fe6b845e..fdc8fb2d786b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3651,4 +3651,9 @@  static inline int inode_drain_writes(struct inode *inode)
 	return filemap_write_and_wait(inode->i_mapping);
+static inline bool is_userns_visible(unsigned long iflags)
+	return (iflags & SB_I_USERNS_VISIBLE);
 #endif /* _LINUX_FS_H */