On Tue, 2019-12-17 at 00:02 -0500, xiubli@xxxxxxxxxx wrote:
> From: Xiubo Li <xiubli@xxxxxxxxxx>
>
> When mounting if the server path has more than one slash continously,
> such as:
>
> 'mount.ceph 192.168.195.165:40176:/// /mnt/cephfs/'
>
> In the MDS server side the extra slashes of the server path will be
> treated as snap dir, and then we can get the following debug logs:
>
> <7>[ ...] ceph: mount opening path //
> <7>[ ...] ceph: open_root_inode opening '//'
> <7>[ ...] ceph: fill_trace 0000000059b8a3bc is_dentry 0 is_target 1
> <7>[ ...] ceph: alloc_inode 00000000dc4ca00b
> <7>[ ...] ceph: get_inode created new inode 00000000dc4ca00b 1.ffffffffffffffff ino 1
> <7>[ ...] ceph: get_inode on 1=1.ffffffffffffffff got 00000000dc4ca00b
>
> And then when creating any new file or directory under the mount
> point, we can get the following crash core dump:
>
> <4>[ ...] ------------[ cut here ]------------
> <2>[ ...] kernel BUG at fs/ceph/inode.c:1347!
> <4>[ ...] invalid opcode: 0000 [#1] SMP PTI
> <4>[ ...] CPU: 0 PID: 7 Comm: kworker/0:1 Tainted: G E 5.4.0-rc5+ #1
> <4>[ ...] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/19/2017
> <4>[ ...] Workqueue: ceph-msgr ceph_con_workfn [libceph]
> <4>[ ...] RIP: 0010:ceph_fill_trace+0x992/0xb30 [ceph]
> <4>[ ...] Code: ff 0f 0b 0f 0b 0f 0b 4c 89 fa 48 c7 c6 4d [...]
> <4>[ ...] RSP: 0018:ffffa23d40067c70 EFLAGS: 00010297
> <4>[ ...] RAX: fffffffffffffffe RBX: ffff8a229eb566c0 RCX: 0000000000000006
> <4>[ ...] RDX: 0000000000000000 RSI: 0000000000000092 RDI: ffff8a23aec17900
> <4>[ ...] RBP: ffff8a226bd91eb0 R08: 0000000000000001 R09: 0000000000000885
> <4>[ ...] R10: 000000000002dfd8 R11: ffff8a226bd95b30 R12: ffff8a239347e000
> <4>[ ...] R13: 0000000000000000 R14: ffff8a22fabeb000 R15: ffff8a2338b0c900
> <4>[ ...] FS: 0000000000000000(0000) GS:ffff8a23aec00000(0000) knlGS:0000000000000000
> <4>[ ...] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> <4>[ ...] CR2: 000055b479d92068 CR3: 00000003764f6004 CR4: 00000000003606f0
> <4>[ ...] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> <4>[ ...] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> <4>[ ...] Call Trace:
> <4>[ ...] dispatch+0x2ac/0x12b0 [ceph]
> <4>[ ...] ceph_con_workfn+0xd40/0x27c0 [libceph]
> <4>[ ...] process_one_work+0x1b0/0x350
> <4>[ ...] worker_thread+0x50/0x3b0
> <4>[ ...] kthread+0xfb/0x130
> <4>[ ...] ? process_one_work+0x350/0x350
> <4>[ ...] ? kthread_park+0x90/0x90
> <4>[ ...] ret_from_fork+0x35/0x40
> <4>[ ...] Modules linked in: ceph(E) libceph fscache [...]
> <4>[ ...] ---[ end trace ba883d8ccf9afcb0 ]---
> <4>[ ...] RIP: 0010:ceph_fill_trace+0x992/0xb30 [ceph]
> <4>[ ...] Code: ff 0f 0b 0f 0b 0f 0b 4c 89 fa 48 c7 c6 [...]
> <4>[ ...] RSP: 0018:ffffa23d40067c70 EFLAGS: 00010297
> <4>[ ...] RAX: fffffffffffffffe RBX: ffff8a229eb566c0 RCX: 0000000000000006
> <4>[ ...] RDX: 0000000000000000 RSI: 0000000000000092 RDI: ffff8a23aec17900
> <4>[ ...] RBP: ffff8a226bd91eb0 R08: 0000000000000001 R09: 0000000000000885
> <4>[ ...] R10: 000000000002dfd8 R11: ffff8a226bd95b30 R12: ffff8a239347e000
> <4>[ ...] R13: 0000000000000000 R14: ffff8a22fabeb000 R15: ffff8a2338b0c900
> <4>[ ...] FS: 0000000000000000(0000) GS:ffff8a23aec00000(0000) knlGS:0000000000000000
> <4>[ ...] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> <4>[ ...] CR2: 000055b479d92068 CR3: 00000003764f6004 CR4: 00000000003606f0
> <4>[ ...] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> <4>[ ...] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
> And we should ignore the extra slashes in the server path when mount
> opening in case users have added them by mistake.
>
> This will also help us to get an existing superblock if all the
> other options are the same, such as all the following server paths
> are treated as the same:
>
> 1) "//mydir1///mydir//"
> 2) "/mydir1/mydir"
> 3) "/mydir1/mydir/"
>
> The mount_options->server_path will always save the original string
> including the leading '/'.
>
> Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> ---
> fs/ceph/super.c | 108 +++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 93 insertions(+), 15 deletions(-)
>
> diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> index 6f33a265ccf1..9fe1bfac66a2 100644
> --- a/fs/ceph/super.c
> +++ b/fs/ceph/super.c
> @@ -211,7 +211,6 @@ struct ceph_parse_opts_ctx {
>
> /*
> * Parse the source parameter. Distinguish the server list from the path.
> - * Internally we do not include the leading '/' in the path.
> *
> * The source will look like:
> * <server_spec>[,<server_spec>...]:[<path>]
> @@ -232,12 +231,15 @@ static int ceph_parse_source(struct fs_parameter *param, struct fs_context *fc)
>
> dev_name_end = strchr(dev_name, '/');
> if (dev_name_end) {
> - if (strlen(dev_name_end) > 1) {
> - kfree(fsopt->server_path);
> - fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
> - if (!fsopt->server_path)
> - return -ENOMEM;
> - }
> + kfree(fsopt->server_path);
> +
> + /*
> + * The server_path will include the whole chars from userland
> + * including the leading '/'.
> + */
> + fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
> + if (!fsopt->server_path)
> + return -ENOMEM;
> } else {
> dev_name_end = dev_name + strlen(dev_name);
> }
> @@ -459,6 +461,64 @@ static int strcmp_null(const char *s1, const char *s2)
> return strcmp(s1, s2);
> }
>
> +/**
> + * path_remove_extra_slash - Remove the extra slashes in the server path
> + * @server_path: the server path and could be NULL
> + *
> + * Return NULL if the path is NULL or only consists of "/", or a string
> + * without any extra slashes including the leading slash(es) and the
> + * slash(es) at the end of the server path, such as:
> + * "//dir1////dir2///" --> "dir1/dir2"
> + */
> +static char *path_remove_extra_slash(const char *server_path)
> +{
> + const char *path = server_path;
> + bool last_is_slash;
> + int i, j, len;
> + char *p;
> +
> + /* if the server path is omitted */
> + if (!path)
> + return NULL;
> +
> + /* remove all the leading slashes */
> + while (*path == '/')
> + path++;
> +
> + /* if the server path only consists of slashes */
> + if (*path == '\0')
> + return NULL;
> +
> + len = strlen(path);
> +
> + p = kmalloc(len, GFP_KERNEL);
> + if (!p)
> + return ERR_PTR(-ENOMEM);
> +
> + last_is_slash = false;
> + for (j = 0, i = 0; i < len; i++) {
> + if (path[i] == '/') {
> + if (last_is_slash)
> + continue;
> + last_is_slash = true;
> + } else {
> + last_is_slash = false;
> + }
> + p[j++] = path[i];
> + }
> +
Rather than walking through character by character, it might be better
to use strchr and the other string handling functions in
include/linux/string.h. Some arches have optimized string handling
routines that may perform better here.
> + /*
> + * remove the last slash if there has just to make sure that
> + * we will get "dir1/dir2"
> + */
> + if (p[j - 1] == '/')
> + j--;
> +
> + p[j] = '\0';
> +
> + return p;
> +}
> +
> static int compare_mount_options(struct ceph_mount_options *new_fsopt,
> struct ceph_options *new_opt,
> struct ceph_fs_client *fsc)
> @@ -466,6 +526,7 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt,
> struct ceph_mount_options *fsopt1 = new_fsopt;
> struct ceph_mount_options *fsopt2 = fsc->mount_options;
> int ofs = offsetof(struct ceph_mount_options, snapdir_name);
> + char *p1, *p2;
> int ret;
>
> ret = memcmp(fsopt1, fsopt2, ofs);
> @@ -478,9 +539,21 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt,
> ret = strcmp_null(fsopt1->mds_namespace, fsopt2->mds_namespace);
> if (ret)
> return ret;
> - ret = strcmp_null(fsopt1->server_path, fsopt2->server_path);
> +
> + p1 = path_remove_extra_slash(fsopt1->server_path);
> + if (IS_ERR(p1))
> + return PTR_ERR(p1);
> + p2 = path_remove_extra_slash(fsopt2->server_path);
> + if (IS_ERR(p2)) {
> + kfree(p1);
> + return PTR_ERR(p2);
> + }
> + ret = strcmp_null(p1, p2);
> + kfree(p1);
> + kfree(p2);
> if (ret)
> return ret;
> +
> ret = strcmp_null(fsopt1->fscache_uniq, fsopt2->fscache_uniq);
> if (ret)
> return ret;
> @@ -883,7 +956,7 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
> mutex_lock(&fsc->client->mount_mutex);
>
> if (!fsc->sb->s_root) {
> - const char *path;
> + const char *path, *p;
> err = __ceph_open_session(fsc->client, started);
> if (err < 0)
> goto out;
> @@ -895,17 +968,22 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
> goto out;
> }
>
> - if (!fsc->mount_options->server_path) {
> - path = "";
> - dout("mount opening path \\t\n");
> - } else {
> - path = fsc->mount_options->server_path + 1;
> - dout("mount opening path %s\n", path);
> + p = path_remove_extra_slash(fsc->mount_options->server_path);
> + if (IS_ERR(p)) {
> + err = PTR_ERR(p);
> + goto out;
> }
> + /* if the server path is omitted or just consists of '/' */
> + if (!p)
> + path = "";
> + else
> + path = p;
> + dout("mount opening path '%s'\n", path);
>
> ceph_fs_debugfs_init(fsc);
>
> root = open_root_dentry(fsc, path, started);
> + kfree(p);
> if (IS_ERR(root)) {
> err = PTR_ERR(root);
> goto out;
--
Jeff Layton <jlayton@xxxxxxxxxx>
