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authorAl Viro <viro@zeniv.linux.org.uk>2018-11-05 17:40:30 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2019-03-20 18:49:06 -0400
commita07b20004793d8926f78d63eb5980559f7813404 (patch)
tree08f7516cbd8ef036fac64b225fd480c2bec3758f /fs/internal.h
parent9e98c678c2d6ae3a17cb2de55d17f69dddaa231b (diff)
vfs: syscall: Add open_tree(2) to reference or clone a mount
open_tree(dfd, pathname, flags) Returns an O_PATH-opened file descriptor or an error. dfd and pathname specify the location to open, in usual fashion (see e.g. fstatat(2)). flags should be an OR of some of the following: * AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW - same meanings as usual * OPEN_TREE_CLOEXEC - make the resulting descriptor close-on-exec * OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE - instead of opening the location in question, create a detached mount tree matching the subtree rooted at location specified by dfd/pathname. With AT_RECURSIVE the entire subtree is cloned, without it - only the part within in the mount containing the location in question. In other words, the same as mount --rbind or mount --bind would've taken. The detached tree will be dissolved on the final close of obtained file. Creation of such detached trees requires the same capabilities as doing mount --bind. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-api@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/internal.h')
-rw-r--r--fs/internal.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/internal.h b/fs/internal.h
index 6a8b71643af4..f3a027c44758 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -94,6 +94,7 @@ extern int __mnt_want_write_file(struct file *);
extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
+extern void dissolve_on_fput(struct vfsmount *);
/*
* fs_struct.c
*/