llapi_changelog_register(3)

LLAPI_CHANGELOG_REGISTER(3)

Lustre Library Functions

LLAPI_CHANGELOG_REGISTER(3)

NAME

llapi_changelog_register - Register changelog user on specific MDT device.

SYNOPSIS

#include <lustre/lustreapi.h>

int llapi_changelog_register(const char *mdtname, const char *username,
                    const char *usermask, char *regname, size_t reglen);

The function llapi_changelog_register() registers a changelog username using an optional application-specific identifier (e.g. 'audit') on the specified MDT device mdtname (e.g. lustrefs-MDT0000) with user-specific usermask, and returns the registered full consumer name regname with reglen length. The llapi_changelog_register() command must run on the MDS where the MDT is mounted as the root user for each mdtname in the filesystem to be monitored.

The username must be under CHANGELOG_USER_NAMELEN bytes in size, as this length includes a trailing NUL character. The name must start with a letter and only contain ASCII alphanumeric (isalnum(3)), dash '-', and underscore '_' characters.

The regname argument is a character array that should be long enough to hold the username plus the changelog user number, with reglen at least CHANGELOG_USER_NAMELEN_FULL bytes in size.

The usermask argument contains a comma- or '+' separated list of changelog record type names that should be activated while this user is registered.

RETURN VALUES

Return changelog user ID on success or a negative errno value on failure.

ERRORS

-EEXIST: Username already exists.
-EILSEQ: Mask is in a wrong format.
-EINVAL: MDT device name is invalid or not found.
-ENAMETOOLONG: The specified username is too long, shorten it.
-EOVERFLOW: The regname buffer is too small, increase its size and its corresponding reglen and/or shorten username.
-EPROTO: Assigned username is invalid.

EXAMPLE

To register a new changelog user on the specified MDT:

#include <lustre/lustreapi.h>
int main(int argc, char *argv[])
{
	char *mdtname = argv[1];  /* e.g. "testfs-MDT0000" */
	char *username = argv[2]; /* e.g. "audit" */
	char *usermask = argv[3]; /* e.g. "open,creat,renam,unlnk" */
	char regname[CHANGELOG_USER_NAMELEN_FULL];
	int rc;
	rc = llapi_changelog_register(mdtname, username, usermask,
	                              regname, sizeof(regname));
}

AVAILABILITY

llapi_changelog_register() is part of the lustre(7) user application interface library since release 2.18.0.