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authorJoel Becker <joel.becker@oracle.com>2010-02-04 15:37:27 -0800
committerJoel Becker <joel.becker@oracle.com>2010-02-26 15:41:13 -0800
commit14a437c2b67aeee2a989a5d9c7e19094355d2fed (patch)
tree5fd3961361ed131bc7eb2ceded99ddba9a38449c /fs/ocfs2
parent399ff3a748cf4c8c853e96dd477153202636527b (diff)
ocfs2_dlmfs: Add capabilities parameter.
Over time, dlmfs has added some features that were not part of the initial ABI. Unfortunately, some of these features are not detectable via standard usage. For example, Linux's default poll always returns POLLIN, so there is no way for a caller of poll(2) to know when dlmfs added poll support. Instead, we provide this list of new capabilities. Capabilities is a read-only attribute. We do it as a module parameter so we can discover it whether dlmfs is built in, loaded, or even not loaded (via modinfo). The ABI features are local to this machine's dlmfs mount. This is distinct from the locking protocol, which is concerned with inter-node interaction. Signed-off-by: Joel Becker <joel.becker@oracle.com>
Diffstat (limited to 'fs/ocfs2')
-rw-r--r--fs/ocfs2/dlm/dlmfs.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
index 02bf17808bd..77d0df42fe0 100644
--- a/fs/ocfs2/dlm/dlmfs.c
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -81,6 +81,42 @@ static const struct dlm_protocol_version user_locking_protocol = {
.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
};
+
+/*
+ * These are the ABI capabilities of dlmfs.
+ *
+ * Over time, dlmfs has added some features that were not part of the
+ * initial ABI. Unfortunately, some of these features are not detectable
+ * via standard usage. For example, Linux's default poll always returns
+ * POLLIN, so there is no way for a caller of poll(2) to know when dlmfs
+ * added poll support. Instead, we provide this list of new capabilities.
+ *
+ * Capabilities is a read-only attribute. We do it as a module parameter
+ * so we can discover it whether dlmfs is built in, loaded, or even not
+ * loaded.
+ *
+ * The ABI features are local to this machine's dlmfs mount. This is
+ * distinct from the locking protocol, which is concerned with inter-node
+ * interaction.
+ */
+#define DLMFS_CAPABILITIES ""
+extern int param_set_dlmfs_capabilities(const char *val,
+ struct kernel_param *kp)
+{
+ printk(KERN_ERR "%s: readonly parameter\n", kp->name);
+ return -EINVAL;
+}
+static int param_get_dlmfs_capabilities(char *buffer,
+ struct kernel_param *kp)
+{
+ return strlcpy(buffer, DLMFS_CAPABILITIES,
+ strlen(DLMFS_CAPABILITIES) + 1);
+}
+module_param_call(capabilities, param_set_dlmfs_capabilities,
+ param_get_dlmfs_capabilities, NULL, 0444);
+MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
+
+
/*
* decodes a set of open flags into a valid lock level and a set of flags.
* returns < 0 if we have invalid flags