fault-injection: add ability to export fault_attr in arbitrary directory

init_fault_attr_dentries() is used to export fault_attr via debugfs.
But it can only export it in debugfs root directory.

Per Forlin is working on mmc_fail_request which adds support to inject
data errors after a completed host transfer in MMC subsystem.

The fault_attr for mmc_fail_request should be defined per mmc host and
export it in debugfs directory per mmc host like
/sys/kernel/debug/mmc0/mmc_fail_request.

init_fault_attr_dentries() doesn't help for mmc_fail_request.  So this
introduces fault_create_debugfs_attr() which is able to create a
directory in the arbitrary directory and replace
init_fault_attr_dentries().

[akpm@linux-foundation.org: extraneous semicolon, per Randy]
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Per Forlin <per.forlin@linaro.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 13 deletions

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 2577b12..f193b77 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -197,21 +197,15 @@ static struct dentry *debugfs_create_atomic_t(const char *name, mode_t mode,
 	return debugfs_create_file(name, mode, parent, value, &fops_atomic_t);
 }
 
-void cleanup_fault_attr_dentries(struct fault_attr *attr)
-{
-	debugfs_remove_recursive(attr->dir);
-}
-
-int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
+struct dentry *fault_create_debugfs_attr(const char *name,
+			struct dentry *parent, struct fault_attr *attr)
 {
 	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
 	struct dentry *dir;
 
-	dir = debugfs_create_dir(name, NULL);
+	dir = debugfs_create_dir(name, parent);
 	if (!dir)
-		return -ENOMEM;
-
-	attr->dir = dir;
+		return ERR_PTR(-ENOMEM);
 
 	if (!debugfs_create_ul("probability", mode, dir, &attr->probability))
 		goto fail;
@@ -243,11 +237,11 @@ int init_fault_attr_dentries(struct fault_attr *attr, const char *name)
 
 #endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
 
-	return 0;
+	return dir;
 fail:
-	debugfs_remove_recursive(attr->dir);
+	debugfs_remove_recursive(dir);
 
-	return -ENOMEM;
+	return ERR_PTR(-ENOMEM);
 }
 
 #endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */