reduce large do_mount stack usage with noinlines
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>
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1 changed files with 13 additions and 5 deletions
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@ -936,8 +936,9 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
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/*
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* recursively change the type of the mountpoint.
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* noinline this do_mount helper to save do_mount stack space.
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*/
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static int do_change_type(struct nameidata *nd, int flag)
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static noinline int do_change_type(struct nameidata *nd, int flag)
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{
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struct vfsmount *m, *mnt = nd->mnt;
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int recurse = flag & MS_REC;
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@ -960,8 +961,10 @@ static int do_change_type(struct nameidata *nd, int flag)
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/*
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* do loopback mount.
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* noinline this do_mount helper to save do_mount stack space.
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*/
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static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
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static noinline int do_loopback(struct nameidata *nd, char *old_name,
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int recurse)
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{
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struct nameidata old_nd;
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struct vfsmount *mnt = NULL;
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@ -1010,8 +1013,9 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
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* change filesystem flags. dir should be a physical root of filesystem.
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* If you've mounted a non-root directory somewhere and want to do remount
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* on it - tough luck.
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* noinline this do_mount helper to save do_mount stack space.
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*/
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static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
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static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
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void *data)
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{
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int err;
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@ -1046,7 +1050,10 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt)
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return 0;
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}
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static int do_move_mount(struct nameidata *nd, char *old_name)
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/*
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* noinline this do_mount helper to save do_mount stack space.
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*/
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static noinline int do_move_mount(struct nameidata *nd, char *old_name)
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{
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struct nameidata old_nd, parent_nd;
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struct vfsmount *p;
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@ -1121,8 +1128,9 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
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/*
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* create a new mount for userspace and request it to be added into the
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* namespace's tree
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* noinline this do_mount helper to save do_mount stack space.
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*/
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static int do_new_mount(struct nameidata *nd, char *type, int flags,
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static noinline int do_new_mount(struct nameidata *nd, char *type, int flags,
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int mnt_flags, char *name, void *data)
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{
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struct vfsmount *mnt;
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