autofs-5.1.1 - improve scalability of direct mount path component

From: Jeff Mahoney <jeffm@suse.com>

With direct mounts, we want to avoid creating path components on
remote file systems unless that file system is the root file system.

The check boils down to allowing the mkdir if:
1/ If it's the root directory, or
2/ If it's not a remote file system, or
3/ If it's a remote file system that's the root file system

We can do that without parsing the mount table and can
improve startup time for all cases.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG           |    1 
 daemon/automount.c  |   56 +++++++++++++++++++++++++++++++++++++++-------------
 include/automount.h |    2 +
 include/mounts.h    |    1 
 lib/mounts.c        |   45 -----------------------------------------
 5 files changed, 45 insertions(+), 60 deletions(-)

--- autofs-5.0.7.orig/CHANGELOG
+++ autofs-5.0.7/CHANGELOG
@@ -245,6 +245,7 @@
 - use autofs_point to store expire timeout where possibe.
 - fix possible NULL derefernce.
 - fix work around sss startup delay.
+- improve scalability of direct mount path component.
 
 25/07/2012 autofs-5.0.7
 =======================
--- autofs-5.0.7.orig/daemon/automount.c
+++ autofs-5.0.7/daemon/automount.c
@@ -135,10 +135,25 @@ void set_thread_mount_request_log_id(str
 	}
 }
 
+static int is_remote_fstype(unsigned int fs_type)
+{
+	int ret = 0;
+	switch (fs_type) {
+	case SMB_SUPER_MAGIC:
+	case CIFS_MAGIC_NUMBER:
+	case NCP_SUPER_MAGIC:
+	case NFS_SUPER_MAGIC:
+		ret = 1;
+		break;
+	};
+	return ret;
+}
+
 static int do_mkdir(const char *parent, const char *path, mode_t mode)
 {
 	int status;
-	struct stat st;
+	mode_t mask;
+	struct stat st, root;
 	struct statfs fs;
 
 	/* If path exists we're done */
@@ -151,24 +166,37 @@ static int do_mkdir(const char *parent,
 	}
 
 	/*
-	 * If we're trying to create a directory within an autofs fs
-	 * or the path is contained in a localy mounted fs go ahead.
+	 * We don't want to create the path on a remote file system
+	 * unless it's the root file system.
+	 * An empty parent means it's the root directory and always ok.
 	 */
-	status = -1;
-	if (*parent)
+	if (*parent) {
 		status = statfs(parent, &fs);
-	if ((status != -1 && fs.f_type == (__SWORD_TYPE) AUTOFS_SUPER_MAGIC) ||
-	    contained_in_local_fs(path)) {
-		mode_t mask = umask(0022);
-		int ret = mkdir(path, mode);
-		(void) umask(mask);
-		if (ret == -1) {
-			errno = EACCES;
-			return 0;
+		if (status == -1)
+			goto fail;
+
+		if (is_remote_fstype(fs.f_type)) {
+			status = stat(parent, &st);
+			if (status == -1)
+				goto fail;
+
+			status = stat("/", &root);
+			if (status == -1)
+				goto fail;
+
+			if (st.st_dev != root.st_dev)
+				goto fail;
 		}
-		return 1;
 	}
 
+	mask = umask(0022);
+	status = mkdir(path, mode);
+	(void) umask(mask);
+	if (status == -1)
+		goto fail;
+
+	return 1;
+fail:
 	errno = EACCES;
 	return 0;
 }
--- autofs-5.0.7.orig/include/automount.h
+++ autofs-5.0.7/include/automount.h
@@ -75,6 +75,8 @@ int load_autofs4_module(void);
 #define AUTOFS_SUPER_MAGIC 0x00000187L
 #define SMB_SUPER_MAGIC    0x0000517BL
 #define CIFS_MAGIC_NUMBER  0xFF534D42L
+#define NCP_SUPER_MAGIC    0x0000564CL
+#define NFS_SUPER_MAGIC    0x00006969L
 
 #define ATTEMPT_ID_SIZE 24
 
--- autofs-5.0.7.orig/include/mounts.h
+++ autofs-5.0.7/include/mounts.h
@@ -101,7 +101,6 @@ int ext_mount_remove(struct list_head *,
 struct mnt_list *get_mnt_list(const char *table, const char *path, int include);
 struct mnt_list *reverse_mnt_list(struct mnt_list *list);
 void free_mnt_list(struct mnt_list *list);
-int contained_in_local_fs(const char *path);
 int is_mounted(const char *table, const char *path, unsigned int type);
 int has_fstab_option(const char *opt);
 void tree_free_mnt_tree(struct mnt_list *tree);
--- autofs-5.0.7.orig/lib/mounts.c
+++ autofs-5.0.7/lib/mounts.c
@@ -941,51 +941,6 @@ void free_mnt_list(struct mnt_list *list
 	}
 }
 
-int contained_in_local_fs(const char *path)
-{
-	struct mnt_list *mnts, *this;
-	size_t pathlen = strlen(path);
-	int ret;
-
-	if (!path || !pathlen || pathlen > PATH_MAX)
-		return 0;
-
-	mnts = get_mnt_list(_PATH_MOUNTED, "/", 1);
-	if (!mnts)
-		return 0;
-
-	ret = 0;
-
-	for (this = mnts; this != NULL; this = this->next) {
-		size_t len = strlen(this->path);
-
-		if (!strncmp(path, this->path, len)) {
-			if (len > 1 && pathlen > len && path[len] != '/')
-				continue;
-			else if (len == 1 && this->path[0] == '/') {
-				/*
-				 * always return true on rootfs, we don't
-				 * want to break diskless clients.
-				 */
-				ret = 1;
-			} else if (this->fs_name[0] == '/') {
-				if (strlen(this->fs_name) > 1) {
-					if (this->fs_name[1] != '/')
-						ret = 1;
-				} else
-					ret = 1;
-			} else if (!strncmp("LABEL=", this->fs_name, 6) ||
-				   !strncmp("UUID=", this->fs_name, 5))
-				ret = 1;
-			break;
-		}
-	}
-
-	free_mnt_list(mnts);
-
-	return ret;
-}
-
 static int table_is_mounted(const char *table, const char *path, unsigned int type)
 {
 	struct mntent *mnt;