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authorJoel Becker <joel.becker@oracle.com>2010-02-04 18:37:27 -0500
committerJoel Becker <joel.becker@oracle.com>2010-02-26 18:41:13 -0500
commit14a437c2b67aeee2a989a5d9c7e19094355d2fed (patch)
tree5fd3961361ed131bc7eb2ceded99ddba9a38449c /fs
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')
-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 02bf17808bdc..77d0df42fe02 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 = {
81 .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR, 81 .pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
82}; 82};
83 83
84
85/*
86 * These are the ABI capabilities of dlmfs.
87 *
88 * Over time, dlmfs has added some features that were not part of the
89 * initial ABI. Unfortunately, some of these features are not detectable
90 * via standard usage. For example, Linux's default poll always returns
91 * POLLIN, so there is no way for a caller of poll(2) to know when dlmfs
92 * added poll support. Instead, we provide this list of new capabilities.
93 *
94 * Capabilities is a read-only attribute. We do it as a module parameter
95 * so we can discover it whether dlmfs is built in, loaded, or even not
96 * loaded.
97 *
98 * The ABI features are local to this machine's dlmfs mount. This is
99 * distinct from the locking protocol, which is concerned with inter-node
100 * interaction.
101 */
102#define DLMFS_CAPABILITIES ""
103extern int param_set_dlmfs_capabilities(const char *val,
104 struct kernel_param *kp)
105{
106 printk(KERN_ERR "%s: readonly parameter\n", kp->name);
107 return -EINVAL;
108}
109static int param_get_dlmfs_capabilities(char *buffer,
110 struct kernel_param *kp)
111{
112 return strlcpy(buffer, DLMFS_CAPABILITIES,
113 strlen(DLMFS_CAPABILITIES) + 1);
114}
115module_param_call(capabilities, param_set_dlmfs_capabilities,
116 param_get_dlmfs_capabilities, NULL, 0444);
117MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
118
119
84/* 120/*
85 * decodes a set of open flags into a valid lock level and a set of flags. 121 * decodes a set of open flags into a valid lock level and a set of flags.
86 * returns < 0 if we have invalid flags 122 * returns < 0 if we have invalid flags