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>

2 files changed, 12 insertions, 15 deletions

diff --git a/mm/failslab.c b/mm/failslab.c
index 1ce58c201dc..0dd7b8fec71 100644
--- a/mm/failslab.c
+++ b/mm/failslab.c
@@ -34,23 +34,23 @@ __setup("failslab=", setup_failslab);
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 static int __init failslab_debugfs_init(void)
 {
+        struct dentry *dir;
         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
-        int err;
 
-        err = init_fault_attr_dentries(&failslab.attr, "failslab");
-        if (err)
-                return err;
+        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, failslab.attr.dir,
+        if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
                                 &failslab.ignore_gfp_wait))
                 goto fail;
-        if (!debugfs_create_bool("cache-filter", mode, failslab.attr.dir,
+        if (!debugfs_create_bool("cache-filter", mode, dir,
                                 &failslab.cache_filter))
                 goto fail;
 
         return 0;
 fail:
-        cleanup_fault_attr_dentries(&failslab.attr);
+        debugfs_remove_recursive(dir);
 
         return -ENOMEM;
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1dbcf8888f1..6e8ecb6e021 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1409,14 +1409,11 @@ static int __init fail_page_alloc_debugfs(void)
 {
         mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
         struct dentry *dir;
-        int err;
 
-        err = init_fault_attr_dentries(&fail_page_alloc.attr,
-                                       "fail_page_alloc");
-        if (err)
-                return err;
-
-        dir = fail_page_alloc.attr.dir;
+        dir = fault_create_debugfs_attr("fail_page_alloc", NULL,
+                                        &fail_page_alloc.attr);
+        if (IS_ERR(dir))
+                return PTR_ERR(dir);
 
         if (!debugfs_create_bool("ignore-gfp-wait", mode, dir,
                                 &fail_page_alloc.ignore_gfp_wait))
@@ -1430,7 +1427,7 @@ static int __init fail_page_alloc_debugfs(void)
 
         return 0;
 fail:
-        cleanup_fault_attr_dentries(&fail_page_alloc.attr);
+        debugfs_remove_recursive(dir);
 
         return -ENOMEM;
 }