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| author | David Howells <dhowells@redhat.com> | 2018-11-02 00:33:31 +0100 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2019-03-20 23:49:06 +0100 |
| commit | 24dcb3d90a1f67fe08c68a004af37df059d74005 (patch) | |
| tree | 14f5bfaf1a0d7dcb56a1d2217d4ce13d1e447dea /arch/x86/entry | |
| parent | Make anon_inodes unconditional (diff) | |
| download | linux-24dcb3d90a1f67fe08c68a004af37df059d74005.tar.xz linux-24dcb3d90a1f67fe08c68a004af37df059d74005.zip | |
vfs: syscall: Add fsopen() to prepare for superblock creation
Provide an fsopen() system call that starts the process of preparing to
create a superblock that will then be mountable, using an fd as a context
handle. fsopen() is given the name of the filesystem that will be used:
int mfd = fsopen(const char *fsname, unsigned int flags);
where flags can be 0 or FSOPEN_CLOEXEC.
For example:
sfd = fsopen("ext4", FSOPEN_CLOEXEC);
fsconfig(sfd, FSCONFIG_SET_PATH, "source", "/dev/sda1", AT_FDCWD);
fsconfig(sfd, FSCONFIG_SET_FLAG, "noatime", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_FLAG, "acl", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_FLAG, "user_xattr", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_STRING, "sb", "1", 0);
fsconfig(sfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
fsinfo(sfd, NULL, ...); // query new superblock attributes
mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_RELATIME);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
sfd = fsopen("afs", -1);
fsconfig(fd, FSCONFIG_SET_STRING, "source",
"#grand.central.org:root.cell", 0);
fsconfig(fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
mfd = fsmount(sfd, 0, MS_NODEV);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
If an error is reported at any step, an error message may be available to be
read() back (ENODATA will be reported if there isn't an error available) in
the form:
"e <subsys>:<problem>"
"e SELinux:Mount on mountpoint not permitted"
Once fsmount() has been called, further fsconfig() calls will incur EBUSY,
even if the fsmount() fails. read() is still possible to retrieve error
information.
The fsopen() syscall creates a mount context and hangs it of the fd that it
returns.
Netlink is not used because it is optional and would make the core VFS
dependent on the networking layer and also potentially add network
namespace issues.
Note that, for the moment, the caller must have SYS_CAP_ADMIN to use
fsopen().
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 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/syscalls/syscall_32.tbl | 3 | ||||
| -rw-r--r-- | arch/x86/entry/syscalls/syscall_64.tbl | 1 |
2 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 0db9effb18d9..37fd1fc5396e 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -400,7 +400,8 @@ 386 i386 rseq sys_rseq __ia32_sys_rseq 387 i386 open_tree sys_open_tree __ia32_sys_open_tree 388 i386 move_mount sys_move_mount __ia32_sys_move_mount -# don't use numbers 389 through 392, add new calls at the end +389 i386 fsopen sys_fsopen __ia32_sys_fsopen +# don't use numbers 390 through 392, add new calls at the end 393 i386 semget sys_semget __ia32_sys_semget 394 i386 semctl sys_semctl __ia32_compat_sys_semctl 395 i386 shmget sys_shmget __ia32_sys_shmget diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index 0440f0eefa02..511608a21611 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -345,6 +345,7 @@ 334 common rseq __x64_sys_rseq 335 common open_tree __x64_sys_open_tree 336 common move_mount __x64_sys_move_mount +337 common fsopen __x64_sys_fsopen # don't use numbers 387 through 423, add new calls after the last # 'common' entry 424 common pidfd_send_signal __x64_sys_pidfd_send_signal |