ceph: remove the extra slashes in the server path
It's possible to pass the mount helper a server path that has more than one contiguous slash character. For example: $ mount -t 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: ceph: mount opening path // ceph: open_root_inode opening '//' ceph: fill_trace 0000000059b8a3bc is_dentry 0 is_target 1 ceph: alloc_inode 00000000dc4ca00b ceph: get_inode created new inode 00000000dc4ca00b 1.ffffffffffffffff ino 1 ceph: get_inode on 1=1.ffffffffffffffff got 00000000dc4ca00b And then when creating any new file or directory under the mount point, we can hit the following BUG_ON in ceph_fill_trace(): BUG_ON(ceph_snap(dir) != dvino.snap); Have the client ignore the extra slashes in the server path when mounting. This will also canonicalize the path, so that identical mounts can be consilidated. 1) "//mydir1///mydir//" 2) "/mydir1/mydir" 3) "/mydir1/mydir/" Regardless of the internal treatment of these paths, the kernel still stores the original string including the leading '/' for presentation to userland. URL: https://tracker.ceph.com/issues/42771 Signed-off-by: Xiubo Li <xiubli@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Ilya Dryomov <idryomov@gmail.com>alistair/sensors
Xiubo Li
Ilya Dryomov
parent
b38c9eb475
commit
4fbc0c711b
122
fs/ceph/super.c
122
fs/ceph/super.c
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@ -107,7 +107,6 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf)
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return 0;
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}
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static int ceph_sync_fs(struct super_block *sb, int wait)
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{
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struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
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@ -211,7 +210,6 @@ struct ceph_parse_opts_ctx {
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/*
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* Parse the source parameter. Distinguish the server list from the path.
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* Internally we do not include the leading '/' in the path.
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*
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* The source will look like:
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* <server_spec>[,<server_spec>...]:[<path>]
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@ -232,12 +230,15 @@ static int ceph_parse_source(struct fs_parameter *param, struct fs_context *fc)
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dev_name_end = strchr(dev_name, '/');
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if (dev_name_end) {
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if (strlen(dev_name_end) > 1) {
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kfree(fsopt->server_path);
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fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
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if (!fsopt->server_path)
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return -ENOMEM;
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}
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kfree(fsopt->server_path);
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/*
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* The server_path will include the whole chars from userland
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* including the leading '/'.
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*/
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fsopt->server_path = kstrdup(dev_name_end, GFP_KERNEL);
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if (!fsopt->server_path)
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return -ENOMEM;
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} else {
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dev_name_end = dev_name + strlen(dev_name);
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}
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@ -461,6 +462,73 @@ static int strcmp_null(const char *s1, const char *s2)
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return strcmp(s1, s2);
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}
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/**
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* path_remove_extra_slash - Remove the extra slashes in the server path
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* @server_path: the server path and could be NULL
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*
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* Return NULL if the path is NULL or only consists of "/", or a string
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* without any extra slashes including the leading slash(es) and the
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* slash(es) at the end of the server path, such as:
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* "//dir1////dir2///" --> "dir1/dir2"
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*/
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static char *path_remove_extra_slash(const char *server_path)
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{
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const char *path = server_path;
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const char *cur, *end;
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char *buf, *p;
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int len;
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/* if the server path is omitted */
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if (!path)
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return NULL;
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/* remove all the leading slashes */
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while (*path == '/')
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path++;
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/* if the server path only consists of slashes */
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if (*path == '\0')
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return NULL;
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len = strlen(path);
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buf = kmalloc(len + 1, GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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end = path + len;
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p = buf;
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do {
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cur = strchr(path, '/');
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if (!cur)
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cur = end;
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len = cur - path;
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/* including one '/' */
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if (cur != end)
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len += 1;
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memcpy(p, path, len);
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p += len;
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while (cur <= end && *cur == '/')
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cur++;
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path = cur;
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} while (path < end);
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*p = '\0';
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/*
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* remove the last slash if there has and just to make sure that
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* we will get something like "dir1/dir2"
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*/
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if (*(--p) == '/')
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*p = '\0';
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return buf;
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}
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static int compare_mount_options(struct ceph_mount_options *new_fsopt,
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struct ceph_options *new_opt,
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struct ceph_fs_client *fsc)
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@ -468,6 +536,7 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt,
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struct ceph_mount_options *fsopt1 = new_fsopt;
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struct ceph_mount_options *fsopt2 = fsc->mount_options;
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int ofs = offsetof(struct ceph_mount_options, snapdir_name);
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char *p1, *p2;
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int ret;
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ret = memcmp(fsopt1, fsopt2, ofs);
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@ -480,9 +549,21 @@ static int compare_mount_options(struct ceph_mount_options *new_fsopt,
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ret = strcmp_null(fsopt1->mds_namespace, fsopt2->mds_namespace);
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if (ret)
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return ret;
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ret = strcmp_null(fsopt1->server_path, fsopt2->server_path);
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p1 = path_remove_extra_slash(fsopt1->server_path);
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if (IS_ERR(p1))
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return PTR_ERR(p1);
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p2 = path_remove_extra_slash(fsopt2->server_path);
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if (IS_ERR(p2)) {
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kfree(p1);
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return PTR_ERR(p2);
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}
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ret = strcmp_null(p1, p2);
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kfree(p1);
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kfree(p2);
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if (ret)
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return ret;
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ret = strcmp_null(fsopt1->fscache_uniq, fsopt2->fscache_uniq);
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if (ret)
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return ret;
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@ -788,7 +869,6 @@ static void destroy_caches(void)
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ceph_fscache_unregister();
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}
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/*
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* ceph_umount_begin - initiate forced umount. Tear down down the
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* mount, skipping steps that may hang while waiting for server(s).
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@ -868,9 +948,6 @@ out:
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return root;
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}
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/*
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* mount: join the ceph cluster, and open root directory.
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*/
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@ -885,7 +962,7 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
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mutex_lock(&fsc->client->mount_mutex);
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if (!fsc->sb->s_root) {
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const char *path;
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const char *path, *p;
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err = __ceph_open_session(fsc->client, started);
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if (err < 0)
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goto out;
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@ -897,17 +974,22 @@ static struct dentry *ceph_real_mount(struct ceph_fs_client *fsc,
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goto out;
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}
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if (!fsc->mount_options->server_path) {
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path = "";
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dout("mount opening path \\t\n");
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} else {
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path = fsc->mount_options->server_path + 1;
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dout("mount opening path %s\n", path);
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p = path_remove_extra_slash(fsc->mount_options->server_path);
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if (IS_ERR(p)) {
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err = PTR_ERR(p);
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goto out;
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}
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/* if the server path is omitted or just consists of '/' */
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if (!p)
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path = "";
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else
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path = p;
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dout("mount opening path '%s'\n", path);
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ceph_fs_debugfs_init(fsc);
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root = open_root_dentry(fsc, path, started);
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kfree(p);
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if (IS_ERR(root)) {
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err = PTR_ERR(root);
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goto out;
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