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ceph: remove the extra slashes in the server path

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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>
This commit is contained in:
Xiubo Li 2019-12-20 09:34:04 -05:00 committed by Ilya Dryomov
parent b38c9eb475
commit 4fbc0c711b
1 changed files with 102 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

122
fs/ceph/super.c
View File

@ -107,7 +107,6 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}
static int ceph_sync_fs(struct super_block *sb, int wait)
{
struct ceph_fs_client *fsc = ceph_sb_to_client(sb);
@ -211,7 +210,6 @@ 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 +230,15 @@ 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);
}
@ -461,6 +462,73 @@ 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;
const char *cur, *end;
char *buf, *p;
int len;
/* 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);
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return ERR_PTR(-ENOMEM);
end = path + len;
p = buf;
do {
cur = strchr(path, '/');
if (!cur)
cur = end;
len = cur - path;
/* including one '/' */
if (cur != end)
len += 1;
memcpy(p, path, len);
p += len;
while (cur <= end && *cur == '/')
cur++;
path = cur;
} while (path < end);
*p = '\0';
/*
* remove the last slash if there has and just to make sure that
* we will get something like "dir1/dir2"
*/
if (*(--p) == '/')
*p = '\0';
return buf;
}
static int compare_mount_options(struct ceph_mount_options *new_fsopt,
struct ceph_options *new_opt,
struct ceph_fs_client *fsc)
@ -468,6 +536,7 @@ 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);
@ -480,9 +549,21 @@ 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;
@ -788,7 +869,6 @@ static void destroy_caches(void)
ceph_fscache_unregister();
}
/*
* ceph_umount_begin - initiate forced umount. Tear down down the
* mount, skipping steps that may hang while waiting for server(s).
@ -868,9 +948,6 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
return root;
}
/*
* mount: join the ceph cluster, and open root directory.
*/
@ -885,7 +962,7 @@ 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;
@ -897,17 +974,22 @@ 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;