| Message ID | 20241210-work-mount-rbtree-lockless-v1-5-338366b9bbe4@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fs: lockless mntns rbtree lookup | expand |
On Tue, 2024-12-10 at 21:58 +0100, Christian Brauner wrote: > Add a sample program illustrating how to list all mounts in all mount > namespaces. > > Signed-off-by: Christian Brauner <brauner@kernel.org> > --- > samples/vfs/.gitignore | 1 + > samples/vfs/Makefile | 2 +- > samples/vfs/test-list-all-mounts.c | 235 +++++++++++++++++++++++++++++++++++++ > 3 files changed, 237 insertions(+), 1 deletion(-) > > diff --git a/samples/vfs/.gitignore b/samples/vfs/.gitignore > index 79212d91285bca72b0ff85f28aaccd2e803ac092..8694dd17b318768b975ece5c7cd450c2cca67318 100644 > --- a/samples/vfs/.gitignore > +++ b/samples/vfs/.gitignore > @@ -1,3 +1,4 @@ > # SPDX-License-Identifier: GPL-2.0-only > /test-fsmount > +/test-list-all-mounts > /test-statx > diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile > index 6377a678134acf0d682151d751d2f5042dbf5e0a..301be72a52a0e376c7ebe235cc2058992919cc78 100644 > --- a/samples/vfs/Makefile > +++ b/samples/vfs/Makefile > @@ -1,4 +1,4 @@ > # SPDX-License-Identifier: GPL-2.0-only > -userprogs-always-y += test-fsmount test-statx > +userprogs-always-y += test-fsmount test-statx test-list-all-mounts > > There will be a minor merge conflict above vs. the new mountinfo program sitting in your tree. > > userccflags += -I usr/include > diff --git a/samples/vfs/test-list-all-mounts.c b/samples/vfs/test-list-all-mounts.c > new file mode 100644 > index 0000000000000000000000000000000000000000..f372d5aea4717fd1ab3d4b3f9af79316cd5dd3d3 > --- /dev/null > +++ b/samples/vfs/test-list-all-mounts.c > @@ -0,0 +1,235 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +// Copyright (c) 2024 Christian Brauner <brauner@kernel.org> > + > +#define _GNU_SOURCE > +#include <errno.h> > +#include <limits.h> > +#include <linux/types.h> > +#include <stdio.h> > +#include <sys/ioctl.h> > +#include <sys/syscall.h> > + > +#include "../../tools/testing/selftests/pidfd/pidfd.h" > + > +#define die_errno(format, ...) \ > + do { \ > + fprintf(stderr, "%m | %s: %d: %s: " format "\n", __FILE__, \ > + __LINE__, __func__, ##__VA_ARGS__); \ > + exit(EXIT_FAILURE); \ > + } while (0) > + > +/* Get the id for a mount namespace */ > +#define NS_GET_MNTNS_ID _IO(0xb7, 0x5) > +/* Get next mount namespace. */ > + > +struct mnt_ns_info { > + __u32 size; > + __u32 nr_mounts; > + __u64 mnt_ns_id; > +}; > + > +#define MNT_NS_INFO_SIZE_VER0 16 /* size of first published struct */ > + > +/* Get information about namespace. */ > +#define NS_MNT_GET_INFO _IOR(0xb7, 10, struct mnt_ns_info) > +/* Get next namespace. */ > +#define NS_MNT_GET_NEXT _IOR(0xb7, 11, struct mnt_ns_info) > +/* Get previous namespace. */ > +#define NS_MNT_GET_PREV _IOR(0xb7, 12, struct mnt_ns_info) > + > +#define PIDFD_GET_MNT_NAMESPACE _IO(0xFF, 3) > + > +#ifndef __NR_listmount > +#define __NR_listmount 458 > +#endif > + > +#ifndef __NR_statmount > +#define __NR_statmount 457 > +#endif > + > +/* @mask bits for statmount(2) */ > +#define STATMOUNT_SB_BASIC 0x00000001U /* Want/got sb_... */ > +#define STATMOUNT_MNT_BASIC 0x00000002U /* Want/got mnt_... */ > +#define STATMOUNT_PROPAGATE_FROM 0x00000004U /* Want/got propagate_from */ > +#define STATMOUNT_MNT_ROOT 0x00000008U /* Want/got mnt_root */ > +#define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */ > +#define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ > +#define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ > +#define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ > + > +#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */ > + > +struct statmount { > + __u32 size; > + __u32 mnt_opts; > + __u64 mask; > + __u32 sb_dev_major; > + __u32 sb_dev_minor; > + __u64 sb_magic; > + __u32 sb_flags; > + __u32 fs_type; > + __u64 mnt_id; > + __u64 mnt_parent_id; > + __u32 mnt_id_old; > + __u32 mnt_parent_id_old; > + __u64 mnt_attr; > + __u64 mnt_propagation; > + __u64 mnt_peer_group; > + __u64 mnt_master; > + __u64 propagate_from; > + __u32 mnt_root; > + __u32 mnt_point; > + __u64 mnt_ns_id; > + __u64 __spare2[49]; > + char str[]; > +}; > + > +struct mnt_id_req { > + __u32 size; > + __u32 spare; > + __u64 mnt_id; > + __u64 param; > + __u64 mnt_ns_id; > +}; > + > +#define MNT_ID_REQ_SIZE_VER1 32 /* sizeof second published struct */ > + > +#define LSMT_ROOT 0xffffffffffffffff /* root mount */ > + > +static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask, > + struct statmount *stmnt, size_t bufsize, > + unsigned int flags) > +{ > + struct mnt_id_req req = { > + .size = MNT_ID_REQ_SIZE_VER1, > + .mnt_id = mnt_id, > + .param = mask, > + .mnt_ns_id = mnt_ns_id, > + }; > + > + return syscall(__NR_statmount, &req, stmnt, bufsize, flags); > +} > + > +static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id, > + __u64 mask, unsigned int flags) > +{ > + size_t bufsize = 1 << 15; > + struct statmount *stmnt = NULL, *tmp = NULL; > + int ret; > + > + for (;;) { > + tmp = realloc(stmnt, bufsize); > + if (!tmp) > + goto out; > + > + stmnt = tmp; > + ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags); > + if (!ret) > + return stmnt; > + > + if (errno != EOVERFLOW) > + goto out; > + > + bufsize <<= 1; > + if (bufsize >= UINT_MAX / 2) > + goto out; > + } > + > +out: > + free(stmnt); > + return NULL; > +} > + > +static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id, > + __u64 list[], size_t num, unsigned int flags) > +{ > + struct mnt_id_req req = { > + .size = MNT_ID_REQ_SIZE_VER1, > + .mnt_id = mnt_id, > + .param = last_mnt_id, > + .mnt_ns_id = mnt_ns_id, > + }; > + > + return syscall(__NR_listmount, &req, list, num, flags); > +} > + > +int main(int argc, char *argv[]) > +{ > +#define LISTMNT_BUFFER 10 > + __u64 list[LISTMNT_BUFFER], last_mnt_id = 0; > + int ret, pidfd, fd_mntns; > + struct mnt_ns_info info = {}; > + > + pidfd = sys_pidfd_open(getpid(), 0); > + if (pidfd < 0) > + die_errno("pidfd_open failed"); > + > + fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0); > + if (fd_mntns < 0) > + die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed"); > + > + ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info); > + if (ret < 0) > + die_errno("ioctl(NS_GET_MNTNS_ID) failed"); > + > + printf("Listing %u mounts for mount namespace %llu\n", > + info.nr_mounts, info.mnt_ns_id); > + for (;;) { > + ssize_t nr_mounts; > +next: > + nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id, > + info.mnt_ns_id, list, LISTMNT_BUFFER, > + 0); > + if (nr_mounts <= 0) { > + int fd_mntns_next; > + > + printf("Finished listing %u mounts for mount namespace %llu\n\n", > + info.nr_mounts, info.mnt_ns_id); > + fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info); > + if (fd_mntns_next < 0) { > + if (errno == ENOENT) { > + printf("Finished listing all mount namespaces\n"); > + exit(0); > + } > + die_errno("ioctl(NS_MNT_GET_NEXT) failed"); > + } > + close(fd_mntns); > + fd_mntns = fd_mntns_next; > + last_mnt_id = 0; > + printf("Listing %u mounts for mount namespace %llu\n", > + info.nr_mounts, info.mnt_ns_id); > + goto next; > + } > + > + for (size_t cur = 0; cur < nr_mounts; cur++) { > + struct statmount *stmnt; > + > + last_mnt_id = list[cur]; > + > + stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id, > + STATMOUNT_SB_BASIC | > + STATMOUNT_MNT_BASIC | > + STATMOUNT_MNT_ROOT | > + STATMOUNT_MNT_POINT | > + STATMOUNT_MNT_NS_ID | > + STATMOUNT_MNT_OPTS | > + STATMOUNT_FS_TYPE, 0); > + if (!stmnt) { > + printf("Failed to statmount(%llu) in mount namespace(%llu)\n", > + last_mnt_id, info.mnt_ns_id); > + continue; > + } > + > + printf("mnt_id:\t\t%llu\nmnt_parent_id:\t%llu\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n", > + stmnt->mnt_id, > + stmnt->mnt_parent_id, > + stmnt->str + stmnt->fs_type, > + stmnt->str + stmnt->mnt_root, > + stmnt->str + stmnt->mnt_point, > + stmnt->str + stmnt->mnt_opts); > + free(stmnt); > + } > + } > + > + exit(0); > +} > Note that this replicates a lot of the functionality of the "mountinfo" program. You could also extend that program with a different output format instead of adding a new one.
> Note that this replicates a lot of the functionality of the "mountinfo" > program. You could also extend that program with a different output > format instead of adding a new one. Fair. I'll see what I can do.
diff --git a/samples/vfs/.gitignore b/samples/vfs/.gitignore index 79212d91285bca72b0ff85f28aaccd2e803ac092..8694dd17b318768b975ece5c7cd450c2cca67318 100644 --- a/samples/vfs/.gitignore +++ b/samples/vfs/.gitignore @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0-only /test-fsmount +/test-list-all-mounts /test-statx diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile index 6377a678134acf0d682151d751d2f5042dbf5e0a..301be72a52a0e376c7ebe235cc2058992919cc78 100644 --- a/samples/vfs/Makefile +++ b/samples/vfs/Makefile @@ -1,4 +1,4 @@ # SPDX-License-Identifier: GPL-2.0-only -userprogs-always-y += test-fsmount test-statx +userprogs-always-y += test-fsmount test-statx test-list-all-mounts userccflags += -I usr/include diff --git a/samples/vfs/test-list-all-mounts.c b/samples/vfs/test-list-all-mounts.c new file mode 100644 index 0000000000000000000000000000000000000000..f372d5aea4717fd1ab3d4b3f9af79316cd5dd3d3 --- /dev/null +++ b/samples/vfs/test-list-all-mounts.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +// Copyright (c) 2024 Christian Brauner <brauner@kernel.org> + +#define _GNU_SOURCE +#include <errno.h> +#include <limits.h> +#include <linux/types.h> +#include <stdio.h> +#include <sys/ioctl.h> +#include <sys/syscall.h> + +#include "../../tools/testing/selftests/pidfd/pidfd.h" + +#define die_errno(format, ...) \ + do { \ + fprintf(stderr, "%m | %s: %d: %s: " format "\n", __FILE__, \ + __LINE__, __func__, ##__VA_ARGS__); \ + exit(EXIT_FAILURE); \ + } while (0) + +/* Get the id for a mount namespace */ +#define NS_GET_MNTNS_ID _IO(0xb7, 0x5) +/* Get next mount namespace. */ + +struct mnt_ns_info { + __u32 size; + __u32 nr_mounts; + __u64 mnt_ns_id; +}; + +#define MNT_NS_INFO_SIZE_VER0 16 /* size of first published struct */ + +/* Get information about namespace. */ +#define NS_MNT_GET_INFO _IOR(0xb7, 10, struct mnt_ns_info) +/* Get next namespace. */ +#define NS_MNT_GET_NEXT _IOR(0xb7, 11, struct mnt_ns_info) +/* Get previous namespace. */ +#define NS_MNT_GET_PREV _IOR(0xb7, 12, struct mnt_ns_info) + +#define PIDFD_GET_MNT_NAMESPACE _IO(0xFF, 3) + +#ifndef __NR_listmount +#define __NR_listmount 458 +#endif + +#ifndef __NR_statmount +#define __NR_statmount 457 +#endif + +/* @mask bits for statmount(2) */ +#define STATMOUNT_SB_BASIC 0x00000001U /* Want/got sb_... */ +#define STATMOUNT_MNT_BASIC 0x00000002U /* Want/got mnt_... */ +#define STATMOUNT_PROPAGATE_FROM 0x00000004U /* Want/got propagate_from */ +#define STATMOUNT_MNT_ROOT 0x00000008U /* Want/got mnt_root */ +#define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */ +#define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ +#define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ +#define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ + +#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */ + +struct statmount { + __u32 size; + __u32 mnt_opts; + __u64 mask; + __u32 sb_dev_major; + __u32 sb_dev_minor; + __u64 sb_magic; + __u32 sb_flags; + __u32 fs_type; + __u64 mnt_id; + __u64 mnt_parent_id; + __u32 mnt_id_old; + __u32 mnt_parent_id_old; + __u64 mnt_attr; + __u64 mnt_propagation; + __u64 mnt_peer_group; + __u64 mnt_master; + __u64 propagate_from; + __u32 mnt_root; + __u32 mnt_point; + __u64 mnt_ns_id; + __u64 __spare2[49]; + char str[]; +}; + +struct mnt_id_req { + __u32 size; + __u32 spare; + __u64 mnt_id; + __u64 param; + __u64 mnt_ns_id; +}; + +#define MNT_ID_REQ_SIZE_VER1 32 /* sizeof second published struct */ + +#define LSMT_ROOT 0xffffffffffffffff /* root mount */ + +static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask, + struct statmount *stmnt, size_t bufsize, + unsigned int flags) +{ + struct mnt_id_req req = { + .size = MNT_ID_REQ_SIZE_VER1, + .mnt_id = mnt_id, + .param = mask, + .mnt_ns_id = mnt_ns_id, + }; + + return syscall(__NR_statmount, &req, stmnt, bufsize, flags); +} + +static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id, + __u64 mask, unsigned int flags) +{ + size_t bufsize = 1 << 15; + struct statmount *stmnt = NULL, *tmp = NULL; + int ret; + + for (;;) { + tmp = realloc(stmnt, bufsize); + if (!tmp) + goto out; + + stmnt = tmp; + ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags); + if (!ret) + return stmnt; + + if (errno != EOVERFLOW) + goto out; + + bufsize <<= 1; + if (bufsize >= UINT_MAX / 2) + goto out; + } + +out: + free(stmnt); + return NULL; +} + +static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id, + __u64 list[], size_t num, unsigned int flags) +{ + struct mnt_id_req req = { + .size = MNT_ID_REQ_SIZE_VER1, + .mnt_id = mnt_id, + .param = last_mnt_id, + .mnt_ns_id = mnt_ns_id, + }; + + return syscall(__NR_listmount, &req, list, num, flags); +} + +int main(int argc, char *argv[]) +{ +#define LISTMNT_BUFFER 10 + __u64 list[LISTMNT_BUFFER], last_mnt_id = 0; + int ret, pidfd, fd_mntns; + struct mnt_ns_info info = {}; + + pidfd = sys_pidfd_open(getpid(), 0); + if (pidfd < 0) + die_errno("pidfd_open failed"); + + fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0); + if (fd_mntns < 0) + die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed"); + + ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info); + if (ret < 0) + die_errno("ioctl(NS_GET_MNTNS_ID) failed"); + + printf("Listing %u mounts for mount namespace %llu\n", + info.nr_mounts, info.mnt_ns_id); + for (;;) { + ssize_t nr_mounts; +next: + nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id, + info.mnt_ns_id, list, LISTMNT_BUFFER, + 0); + if (nr_mounts <= 0) { + int fd_mntns_next; + + printf("Finished listing %u mounts for mount namespace %llu\n\n", + info.nr_mounts, info.mnt_ns_id); + fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info); + if (fd_mntns_next < 0) { + if (errno == ENOENT) { + printf("Finished listing all mount namespaces\n"); + exit(0); + } + die_errno("ioctl(NS_MNT_GET_NEXT) failed"); + } + close(fd_mntns); + fd_mntns = fd_mntns_next; + last_mnt_id = 0; + printf("Listing %u mounts for mount namespace %llu\n", + info.nr_mounts, info.mnt_ns_id); + goto next; + } + + for (size_t cur = 0; cur < nr_mounts; cur++) { + struct statmount *stmnt; + + last_mnt_id = list[cur]; + + stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id, + STATMOUNT_SB_BASIC | + STATMOUNT_MNT_BASIC | + STATMOUNT_MNT_ROOT | + STATMOUNT_MNT_POINT | + STATMOUNT_MNT_NS_ID | + STATMOUNT_MNT_OPTS | + STATMOUNT_FS_TYPE, 0); + if (!stmnt) { + printf("Failed to statmount(%llu) in mount namespace(%llu)\n", + last_mnt_id, info.mnt_ns_id); + continue; + } + + printf("mnt_id:\t\t%llu\nmnt_parent_id:\t%llu\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n\n", + stmnt->mnt_id, + stmnt->mnt_parent_id, + stmnt->str + stmnt->fs_type, + stmnt->str + stmnt->mnt_root, + stmnt->str + stmnt->mnt_point, + stmnt->str + stmnt->mnt_opts); + free(stmnt); + } + } + + exit(0); +}
Add a sample program illustrating how to list all mounts in all mount namespaces. Signed-off-by: Christian Brauner <brauner@kernel.org> --- samples/vfs/.gitignore | 1 + samples/vfs/Makefile | 2 +- samples/vfs/test-list-all-mounts.c | 235 +++++++++++++++++++++++++++++++++++++ 3 files changed, 237 insertions(+), 1 deletion(-)