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Revision 3f9400981691f6845e5c22b962500742b80a5484 authored by Jeff Layton on 31 March 2015, 16:03:28 UTC, committed by Trond Myklebust on 23 April 2015, 18:42:27 UTC 
sunrpc: make debugfs file creation failure non-fatal
 
v2: gracefully handle the case where some dentry pointers end up NULL
    and be more dilligent about zeroing out dentry pointers

We currently have a problem that SELinux policy is being enforced when
creating debugfs files. If a debugfs file is created as a side effect of
doing some syscall, then that creation can fail if the SELinux policy
for that process prevents it.

This seems wrong. We don't do that for files under /proc, for instance,
so Bruce has proposed a patch to fix that.

While discussing that patch however, Greg K.H. stated:

    "No kernel code should care / fail if a debugfs function fails, so
     please fix up the sunrpc code first."

This patch converts all of the sunrpc debugfs setup code to be void
return functins, and the callers to not look for errors from those
functions.

This should allow rpc_clnt and rpc_xprt creation to work, even if the
kernel fails to create debugfs files for some reason.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
1 parent 5d05e54
Raw File
failslab.c 
#include <linux/fault-inject.h>
#include <linux/slab.h>

static struct {
	struct fault_attr attr;
	u32 ignore_gfp_wait;
	int cache_filter;
} failslab = {
	.attr = FAULT_ATTR_INITIALIZER,
	.ignore_gfp_wait = 1,
	.cache_filter = 0,
};

bool should_failslab(size_t size, gfp_t gfpflags, unsigned long cache_flags)
{
	if (gfpflags & __GFP_NOFAIL)
		return false;

        if (failslab.ignore_gfp_wait && (gfpflags & __GFP_WAIT))
		return false;

	if (failslab.cache_filter && !(cache_flags & SLAB_FAILSLAB))
		return false;

	return should_fail(&failslab.attr, size);
}

static int __init setup_failslab(char *str)
{
	return setup_fault_attr(&failslab.attr, str);
}
__setup("failslab=", setup_failslab);

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
static int __init failslab_debugfs_init(void)
{
	struct dentry *dir;
	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;

	dir = fault_create_debugfs_attr("failslab", NULL, &failslab.attr);
	if (IS_ERR(dir))
		return PTR_ERR(dir);

	if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
				&failslab.ignore_gfp_wait))
		goto fail;
	if (!debugfs_create_bool("cache-filter", mode, dir,
				&failslab.cache_filter))
		goto fail;

	return 0;
fail:
	debugfs_remove_recursive(dir);

	return -ENOMEM;
}

late_initcall(failslab_debugfs_init);

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
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