[PATCH] fs/namei.c: replace multiple current->fs by shortcut variable

Replace current->fs by fs helper variable to reduce some indirection
overhead and (at least at the moment, before the current_thread_info() %gs
PDA improvement is available) get rid of more costly current references.
Reduces fs/namei.o from 37786 to 37082 Bytes (704 Bytes saved).

[akpm@osdl.org: cleanup]
Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 47 insertions, 39 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 808e4ea2bb94..2892e68d3a86 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -518,18 +518,20 @@ static int __emul_lookup_dentry(const char *, struct nameidata *);
 static __always_inline int
 walk_init_root(const char *name, struct nameidata *nd)
 {
-        read_lock(&current->fs->lock);
-        if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
-                nd->mnt = mntget(current->fs->altrootmnt);
-                nd->dentry = dget(current->fs->altroot);
-                read_unlock(&current->fs->lock);
+        struct fs_struct *fs = current->fs;
+
+        read_lock(&fs->lock);
+        if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
+                nd->mnt = mntget(fs->altrootmnt);
+                nd->dentry = dget(fs->altroot);
+                read_unlock(&fs->lock);
                 if (__emul_lookup_dentry(name,nd))
                         return 0;
-                read_lock(&current->fs->lock);
+                read_lock(&fs->lock);
         }
-        nd->mnt = mntget(current->fs->rootmnt);
-        nd->dentry = dget(current->fs->root);
-        read_unlock(&current->fs->lock);
+        nd->mnt = mntget(fs->rootmnt);
+        nd->dentry = dget(fs->root);
+        read_unlock(&fs->lock);
         return 1;
 }
 
@@ -724,17 +726,19 @@ int follow_down(struct vfsmount **mnt, struct dentry **dentry)
 
 static __always_inline void follow_dotdot(struct nameidata *nd)
 {
+        struct fs_struct *fs = current->fs;
+
         while(1) {
                 struct vfsmount *parent;
                 struct dentry *old = nd->dentry;
 
-                read_lock(&current->fs->lock);
-                if (nd->dentry == current->fs->root &&
-                    nd->mnt == current->fs->rootmnt) {
-                        read_unlock(&current->fs->lock);
+                read_lock(&fs->lock);
+                if (nd->dentry == fs->root &&
+                    nd->mnt == fs->rootmnt) {
+                        read_unlock(&fs->lock);
                         break;
                 }
-                read_unlock(&current->fs->lock);
+                read_unlock(&fs->lock);
                 spin_lock(&dcache_lock);
                 if (nd->dentry != nd->mnt->mnt_root) {
                         nd->dentry = dget(nd->dentry->d_parent);
@@ -1042,15 +1046,17 @@ static int __emul_lookup_dentry(const char *name, struct nameidata *nd)
                 struct vfsmount *old_mnt = nd->mnt;
                 struct qstr last = nd->last;
                 int last_type = nd->last_type;
+                struct fs_struct *fs = current->fs;
+
                 /*
-                 * NAME was not found in alternate root or it's a directory.  Try to find
-                 * it in the normal root:
+                 * NAME was not found in alternate root or it's a directory.
+                 * Try to find it in the normal root:
                  */
                 nd->last_type = LAST_ROOT;
-                read_lock(&current->fs->lock);
-                nd->mnt = mntget(current->fs->rootmnt);
-                nd->dentry = dget(current->fs->root);
-                read_unlock(&current->fs->lock);
+                read_lock(&fs->lock);
+                nd->mnt = mntget(fs->rootmnt);
+                nd->dentry = dget(fs->root);
+                read_unlock(&fs->lock);
                 if (path_walk(name, nd) == 0) {
                         if (nd->dentry->d_inode) {
                                 dput(old_dentry);
@@ -1074,6 +1080,7 @@ void set_fs_altroot(void)
         struct vfsmount *mnt = NULL, *oldmnt;
         struct dentry *dentry = NULL, *olddentry;
         int err;
+        struct fs_struct *fs = current->fs;
 
         if (!emul)
                 goto set_it;
@@ -1083,12 +1090,12 @@ void set_fs_altroot(void)
                 dentry = nd.dentry;
         }
 set_it:
-        write_lock(&current->fs->lock);
-        oldmnt = current->fs->altrootmnt;
-        olddentry = current->fs->altroot;
-        current->fs->altrootmnt = mnt;
-        current->fs->altroot = dentry;
-        write_unlock(&current->fs->lock);
+        write_lock(&fs->lock);
+        oldmnt = fs->altrootmnt;
+        olddentry = fs->altroot;
+        fs->altrootmnt = mnt;
+        fs->altroot = dentry;
+        write_unlock(&fs->lock);
         if (olddentry) {
                 dput(olddentry);
                 mntput(oldmnt);
@@ -1102,29 +1109,30 @@ static int fastcall do_path_lookup(int dfd, const char *name,
         int retval = 0;
         int fput_needed;
         struct file *file;
+        struct fs_struct *fs = current->fs;
 
         nd->last_type = LAST_ROOT; /* if there are only slashes... */
         nd->flags = flags;
         nd->depth = 0;
 
         if (*name=='/') {
-                read_lock(&current->fs->lock);
-                if (current->fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
-                        nd->mnt = mntget(current->fs->altrootmnt);
-                        nd->dentry = dget(current->fs->altroot);
-                        read_unlock(&current->fs->lock);
+                read_lock(&fs->lock);
+                if (fs->altroot && !(nd->flags & LOOKUP_NOALT)) {
+                        nd->mnt = mntget(fs->altrootmnt);
+                        nd->dentry = dget(fs->altroot);
+                        read_unlock(&fs->lock);
                         if (__emul_lookup_dentry(name,nd))
                                 goto out; /* found in altroot */
-                        read_lock(&current->fs->lock);
+                        read_lock(&fs->lock);
                 }
-                nd->mnt = mntget(current->fs->rootmnt);
-                nd->dentry = dget(current->fs->root);
-                read_unlock(&current->fs->lock);
+                nd->mnt = mntget(fs->rootmnt);
+                nd->dentry = dget(fs->root);
+                read_unlock(&fs->lock);
         } else if (dfd == AT_FDCWD) {
-                read_lock(&current->fs->lock);
-                nd->mnt = mntget(current->fs->pwdmnt);
-                nd->dentry = dget(current->fs->pwd);
-                read_unlock(&current->fs->lock);
+                read_lock(&fs->lock);
+                nd->mnt = mntget(fs->pwdmnt);
+                nd->dentry = dget(fs->pwd);
+                read_unlock(&fs->lock);
         } else {
                 struct dentry *dentry;