[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>

diff --git a/fs/namei.c b/fs/namei.c
index 808e4ea2bb9413a446743fbcdf10caae8d0baf2f..2892e68d3a8647981e5aa7caf3c53e708584d4bf 100644 (file)
--- 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;