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autofs-5.0.9 - amd lookup add external mounts tracking functions
From: Ian Kent <raven@themaw.net>
Amd automounts can use what's called a sublink option. Using this
option a single containing mount can be specified and symlinks
that point to directories within the mount created instead of a
mount for every directory.
In some cases this can greatly reduce the number of mounts needed
for a map but complicates automounting when using an "in-place"
automounter such as autofs.
Clearly we can't perform the mount and create symlinks within it
so we must us a mount lookaside directory like amd. Those external
mounts also need to be managed.
This patch adds functions to maintain a list of these mounts (much
like a reference counter) so we know if an external mount is present
and if it's time to umount it.
---
include/mounts.h | 2 +
lib/mounts.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 134 insertions(+)
diff --git a/include/mounts.h b/include/mounts.h
index c2f92ec..3bef086 100644
--- a/include/mounts.h
+++ b/include/mounts.h
@@ -93,6 +93,8 @@ unsigned int get_kver_major(void);
unsigned int get_kver_minor(void);
char *make_options_string(char *path, int kernel_pipefd, const char *extra);
char *make_mnt_name_string(char *path);
+int ext_mount_add(struct list_head *, const char *);
+int ext_mount_remove(struct list_head *, const char *);
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);
diff --git a/lib/mounts.c b/lib/mounts.c
index 868dcb1..aea6691 100644
--- a/lib/mounts.c
+++ b/lib/mounts.c
@@ -46,6 +46,17 @@ static const char mnt_name_template[] = "automount(pid%u)";
static struct kernel_mod_version kver = {0, 0};
static const char kver_options_template[] = "fd=%d,pgrp=%u,minproto=3,maxproto=5";
+#define EXT_MOUNTS_HASH_SIZE 50
+
+struct ext_mount {
+ char *mountpoint;
+ struct list_head mount;
+ struct list_head mounts;
+};
+static struct list_head ext_mounts_hash[EXT_MOUNTS_HASH_SIZE];
+static unsigned int ext_mounts_hash_init_done = 0;
+static pthread_mutex_t ext_mount_hash_mutex = PTHREAD_MUTEX_INITIALIZER;
+
unsigned int linux_version_code(void)
{
struct utsname my_utsname;
@@ -422,6 +433,127 @@ char *make_mnt_name_string(char *path)
return mnt_name;
}
+static void ext_mounts_hash_init(void)
+{
+ int i;
+ for (i = 0; i < EXT_MOUNTS_HASH_SIZE; i++)
+ INIT_LIST_HEAD(&ext_mounts_hash[i]);
+ ext_mounts_hash_init_done = 1;
+}
+
+static struct ext_mount *ext_mount_lookup(const char *mountpoint)
+{
+ u_int32_t hval = hash(mountpoint, EXT_MOUNTS_HASH_SIZE);
+ struct list_head *p, *head;
+
+ if (!ext_mounts_hash_init_done)
+ ext_mounts_hash_init();
+
+ if (list_empty(&ext_mounts_hash[hval]))
+ return NULL;
+
+ head = &ext_mounts_hash[hval];
+ list_for_each(p, head) {
+ struct ext_mount *this = list_entry(p, struct ext_mount, mount);
+ if (!strcmp(this->mountpoint, mountpoint))
+ return this;
+ }
+ return NULL;
+}
+
+int ext_mount_add(struct list_head *entry, const char *path)
+{
+ struct ext_mount *em;
+ char *auto_dir;
+ u_int32_t hval;
+ int ret = 0;
+
+ /* Not a mount in the external mount directory */
+ auto_dir = conf_amd_get_auto_dir();
+ if (strncmp(path, auto_dir, strlen(auto_dir))) {
+ free(auto_dir);
+ return 0;
+ }
+ free(auto_dir);
+
+ pthread_mutex_lock(&ext_mount_hash_mutex);
+
+ em = ext_mount_lookup(path);
+ if (em) {
+ struct list_head *p, *head;
+ head = &em->mounts;
+ list_for_each(p, head) {
+ if (p == entry)
+ goto done;
+ }
+ list_add_tail(entry, &em->mounts);
+ ret = 1;
+ goto done;
+ }
+
+ em = malloc(sizeof(struct ext_mount));
+ if (!em) {
+ ret = -1;
+ goto done;
+ }
+
+ em->mountpoint = strdup(path);
+ if (!em->mountpoint) {
+ free(em);
+ ret = -1;
+ goto done;
+ }
+ INIT_LIST_HEAD(&em->mount);
+ INIT_LIST_HEAD(&em->mounts);
+
+ hval = hash(path, EXT_MOUNTS_HASH_SIZE);
+ list_add_tail(&em->mount, &ext_mounts_hash[hval]);
+
+ list_add_tail(entry, &em->mounts);
+
+ ret = 1;
+done:
+ pthread_mutex_unlock(&ext_mount_hash_mutex);
+ return ret;
+}
+
+int ext_mount_remove(struct list_head *entry, const char *path)
+{
+ struct ext_mount *em;
+ char *auto_dir;
+ int ret = 0;
+
+ /* Not a mount in the external mount directory */
+ auto_dir = conf_amd_get_auto_dir();
+ if (strncmp(path, auto_dir, strlen(auto_dir))) {
+ free(auto_dir);
+ return 0;
+ }
+ free(auto_dir);
+
+ pthread_mutex_lock(&ext_mount_hash_mutex);
+
+ em = ext_mount_lookup(path);
+ if (!em)
+ goto done;
+
+ list_del_init(entry);
+
+ if (!list_empty(&em->mounts))
+ goto done;
+ else {
+ list_del_init(&em->mount);
+ if (list_empty(&em->mount)) {
+ free(em->mountpoint);
+ free(em);
+ }
+ ret = 1;
+ }
+done:
+ pthread_mutex_unlock(&ext_mount_hash_mutex);
+ return ret;
+}
+
/*
* Get list of mounts under path in longest->shortest order
*/