struct filename: use names_cachep only for getname() and friends

        Instances of struct filename come from names_cachep (via
__getname()).  That is done by getname_flags() and getname_kernel()
and these two are the main callers of __getname().  However, there are
other callers that simply want to allocate PATH_MAX bytes for uses that
have nothing to do with struct filename.

	We want saner allocation rules for long pathnames, so that struct
filename would *always* come from names_cachep, with the out-of-line
pathname getting kmalloc'ed.  For that we need to be able to change the
size of objects allocated by getname_flags()/getname_kernel().

	That requires the rest of __getname() users to stop using
names_cachep; we could explicitly switch all of those to kmalloc(),
but that would cause quite a bit of noise.  So the plan is to switch
getname_...() to new helpers and turn __getname() into a wrapper for
kmalloc().  Remaining __getname() users could be converted to explicit
kmalloc() at leisure, hopefully along with figuring out what size do
they really want - PATH_MAX is an overkill for some of them, used out
of laziness ("we have a convenient helper that does 4K allocations and
that's large enough, let's use it").

	As a side benefit, names_cachep is no longer used outside
of fs/namei.c, so we can move it there and be done with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/dcache.c b/fs/dcache.c
index dc2fff4811d15301e60d67848ea2aa6e926fa71b..cf865c12cdf931878568152f1ec6680bce578a65 100644 (file)
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3290,10 +3290,6 @@ static void __init dcache_init(void)
        runtime_const_init(ptr, dentry_hashtable);
 }
 
-/* SLAB cache for __getname() consumers */
-struct kmem_cache *names_cachep __ro_after_init;
-EXPORT_SYMBOL(names_cachep);
-
 void __init vfs_caches_init_early(void)
 {
        int i;
@@ -3307,9 +3303,7 @@ void __init vfs_caches_init_early(void)
 
 void __init vfs_caches_init(void)
 {
-       names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0,
-                       SLAB_HWCACHE_ALIGN|SLAB_PANIC, 0, PATH_MAX, NULL);
-
+       filename_init();
        dcache_init();
        inode_init();
        files_init();

diff --git a/fs/internal.h b/fs/internal.h
index 7267aa0926a156c04e737abe41a3b68d20eb8ce0..c7a34412399e2cc16c03c091b71b84494ed201e1 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -72,6 +72,8 @@ struct dentry *start_dirop(struct dentry *parent, struct qstr *name,
                           unsigned int lookup_flags);
 int lookup_noperm_common(struct qstr *qname, struct dentry *base);
 
+void __init filename_init(void);
+
 /*
  * namespace.c
  */

diff --git a/fs/namei.c b/fs/namei.c
index 953cd254216d12d5a3d528f4b6045810493b28ee..f0be36e257a715388683242dae186f4caf26e7d8 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -125,6 +125,25 @@
 
 #define EMBEDDED_NAME_MAX      (PATH_MAX - offsetof(struct filename, iname))
 
+/* SLAB cache for struct filename instances */
+static struct kmem_cache *names_cachep __ro_after_init;
+
+void __init filename_init(void)
+{
+       names_cachep = kmem_cache_create_usercopy("names_cache", PATH_MAX, 0,
+                       SLAB_HWCACHE_ALIGN|SLAB_PANIC, 0, PATH_MAX, NULL);
+}
+
+static inline struct filename *alloc_filename(void)
+{
+       return kmem_cache_alloc(names_cachep, GFP_KERNEL);
+}
+
+static inline void free_filename(struct filename *p)
+{
+       kmem_cache_free(names_cachep, p);
+}
+
 static inline void initname(struct filename *name)
 {
        name->aname = NULL;
@@ -164,7 +183,7 @@ getname_flags(const char __user *filename, int flags)
        char *kname;
        int len;
 
-       result = __getname();
+       result = alloc_filename();
        if (unlikely(!result))
                return ERR_PTR(-ENOMEM);
 
@@ -181,13 +200,13 @@ getname_flags(const char __user *filename, int flags)
         */
        if (unlikely(len <= 0)) {
                if (unlikely(len < 0)) {
-                       __putname(result);
+                       free_filename(result);
                        return ERR_PTR(len);
                }
 
                /* The empty path is special. */
                if (!(flags & LOOKUP_EMPTY)) {
-                       __putname(result);
+                       free_filename(result);
                        return ERR_PTR(-ENOENT);
                }
        }
@@ -201,7 +220,7 @@ getname_flags(const char __user *filename, int flags)
        if (unlikely(len == EMBEDDED_NAME_MAX)) {
                struct filename *p = getname_long(result, filename);
                if (IS_ERR(p)) {
-                       __putname(result);
+                       free_filename(result);
                        return p;
                }
                result = p;
@@ -242,7 +261,7 @@ struct filename *getname_kernel(const char * filename)
        struct filename *result;
        int len = strlen(filename) + 1;
 
-       result = __getname();
+       result = alloc_filename();
        if (unlikely(!result))
                return ERR_PTR(-ENOMEM);
 
@@ -254,13 +273,13 @@ struct filename *getname_kernel(const char * filename)
 
                tmp = kmalloc(size, GFP_KERNEL);
                if (unlikely(!tmp)) {
-                       __putname(result);
+                       free_filename(result);
                        return ERR_PTR(-ENOMEM);
                }
                tmp->name = (char *)result;
                result = tmp;
        } else {
-               __putname(result);
+               free_filename(result);
                return ERR_PTR(-ENAMETOOLONG);
        }
        memcpy((char *)result->name, filename, len);
@@ -287,10 +306,10 @@ void putname(struct filename *name)
        }
 
        if (unlikely(name->name != name->iname)) {
-               __putname(name->name);
+               free_filename((struct filename *)name->name);
                kfree(name);
        } else
-               __putname(name);
+               free_filename(name);
 }
 EXPORT_SYMBOL(putname);
 

diff --git a/include/linux/fs.h b/include/linux/fs.h
index abe9c95c4874137c463c1f8194c2f7c0d8cc295d..997d515bab322a2bf62834f7b2ad906bad156db8 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2539,10 +2539,8 @@ static inline int finish_open_simple(struct file *file, int error)
 extern void __init vfs_caches_init_early(void);
 extern void __init vfs_caches_init(void);
 
-extern struct kmem_cache *names_cachep;
-
-#define __getname()            kmem_cache_alloc(names_cachep, GFP_KERNEL)
-#define __putname(name)                kmem_cache_free(names_cachep, (void *)(name))
+#define __getname()            kmalloc(PATH_MAX, GFP_KERNEL)
+#define __putname(name)                kfree(name)
 
 void emergency_thaw_all(void);
 extern int sync_filesystem(struct super_block *);