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reduce large do_mount stack usage with noinlines

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do_mount() uses a whopping 616 bytes of stack on x86_64 in 2.6.24-mm1,
largely thanks to gcc inlining the various helper functions.

noinlining these can slim it down a lot; on my box this patch gets it down
to 168, which is mostly the struct nameidata nd; left on the stack.

These functions are called only as do_mount() helpers; none of them should
be in any path that would see a performance benefit from inlining...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Sandeen 2008-02-08 04:22:12 -08:00 committed by Linus Torvalds
parent ac2a659968
commit 2dafe1c4d6
1 changed files with 13 additions and 5 deletions
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18
fs/namespace.c
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@ -936,8 +936,9 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
/*
* recursively change the type of the mountpoint.
* noinline this do_mount helper to save do_mount stack space.
*/
static int do_change_type(struct nameidata *nd, int flag)
static noinline int do_change_type(struct nameidata *nd, int flag)
{
struct vfsmount *m, *mnt = nd->mnt;
int recurse = flag & MS_REC;
@ -960,8 +961,10 @@ static int do_change_type(struct nameidata *nd, int flag)
/*
* do loopback mount.
* noinline this do_mount helper to save do_mount stack space.
*/
static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
static noinline int do_loopback(struct nameidata *nd, char *old_name,
int recurse)
{
struct nameidata old_nd;
struct vfsmount *mnt = NULL;
@ -1010,8 +1013,9 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
* change filesystem flags. dir should be a physical root of filesystem.
* If you've mounted a non-root directory somewhere and want to do remount
* on it - tough luck.
* noinline this do_mount helper to save do_mount stack space.
*/
static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
void *data)
{
int err;
@ -1046,7 +1050,10 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt)
return 0;
}
static int do_move_mount(struct nameidata *nd, char *old_name)
/*
* noinline this do_mount helper to save do_mount stack space.
*/
static noinline int do_move_mount(struct nameidata *nd, char *old_name)
{
struct nameidata old_nd, parent_nd;
struct vfsmount *p;
@ -1121,8 +1128,9 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
/*
* create a new mount for userspace and request it to be added into the
* namespace's tree
* noinline this do_mount helper to save do_mount stack space.
*/
static int do_new_mount(struct nameidata *nd, char *type, int flags,
static noinline int do_new_mount(struct nameidata *nd, char *type, int flags,
int mnt_flags, char *name, void *data)
{
struct vfsmount *mnt;