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Commit 2dafe1c4d69345539735cca64250f2d4657bd057

Authored by Eric Sandeen
Committed by Linus Torvalds
1 parent ac2a659968
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

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>

Showing 1 changed file with 13 additions and 5 deletions Side-by-side Diff

... ... @@ -936,8 +936,9 @@
936 936  
937 937 /*
938 938 * recursively change the type of the mountpoint.
  939 + * noinline this do_mount helper to save do_mount stack space.
939 940 */
940   -static int do_change_type(struct nameidata *nd, int flag)
  941 +static noinline int do_change_type(struct nameidata *nd, int flag)
941 942 {
942 943 struct vfsmount *m, *mnt = nd->mnt;
943 944 int recurse = flag & MS_REC;
944 945  
... ... @@ -960,8 +961,10 @@
960 961  
961 962 /*
962 963 * do loopback mount.
  964 + * noinline this do_mount helper to save do_mount stack space.
963 965 */
964   -static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
  966 +static noinline int do_loopback(struct nameidata *nd, char *old_name,
  967 + int recurse)
965 968 {
966 969 struct nameidata old_nd;
967 970 struct vfsmount *mnt = NULL;
968 971  
... ... @@ -1010,8 +1013,9 @@
1010 1013 * change filesystem flags. dir should be a physical root of filesystem.
1011 1014 * If you've mounted a non-root directory somewhere and want to do remount
1012 1015 * on it - tough luck.
  1016 + * noinline this do_mount helper to save do_mount stack space.
1013 1017 */
1014   -static int do_remount(struct nameidata *nd, int flags, int mnt_flags,
  1018 +static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
1015 1019 void *data)
1016 1020 {
1017 1021 int err;
... ... @@ -1046,7 +1050,10 @@
1046 1050 return 0;
1047 1051 }
1048 1052  
1049   -static int do_move_mount(struct nameidata *nd, char *old_name)
  1053 +/*
  1054 + * noinline this do_mount helper to save do_mount stack space.
  1055 + */
  1056 +static noinline int do_move_mount(struct nameidata *nd, char *old_name)
1050 1057 {
1051 1058 struct nameidata old_nd, parent_nd;
1052 1059 struct vfsmount *p;
1053 1060  
... ... @@ -1121,8 +1128,9 @@
1121 1128 /*
1122 1129 * create a new mount for userspace and request it to be added into the
1123 1130 * namespace's tree
  1131 + * noinline this do_mount helper to save do_mount stack space.
1124 1132 */
1125   -static int do_new_mount(struct nameidata *nd, char *type, int flags,
  1133 +static noinline int do_new_mount(struct nameidata *nd, char *type, int flags,
1126 1134 int mnt_flags, char *name, void *data)
1127 1135 {
1128 1136 struct vfsmount *mnt;