NFSv4: Fix up the documentation for nfs_do_refmount

[safe/jmp/linux-2.6] / fs / fs_struct.c

diff --git a/fs/fs_struct.c b/fs/fs_struct.c
index 36e0a12..eee0590 100644 (file)
--- a/fs/fs_struct.c
+++ b/fs/fs_struct.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/path.h>
 #include <linux/slab.h>
+#include <linux/fs_struct.h>
 
 /*
  * Replace the fs->{rootmnt,root} with {mnt,dentry}. Put the old values.
@@ -72,25 +73,27 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
                path_put(old_root);
 }
 
-void put_fs_struct(struct fs_struct *fs)
+void free_fs_struct(struct fs_struct *fs)
 {
-       /* No need to hold fs->lock if we are killing it */
-       if (atomic_dec_and_test(&fs->count)) {
-               path_put(&fs->root);
-               path_put(&fs->pwd);
-               kmem_cache_free(fs_cachep, fs);
-       }
+       path_put(&fs->root);
+       path_put(&fs->pwd);
+       kmem_cache_free(fs_cachep, fs);
 }
 
 void exit_fs(struct task_struct *tsk)
 {
-       struct fs_struct * fs = tsk->fs;
+       struct fs_struct *fs = tsk->fs;
 
        if (fs) {
+               int kill;
                task_lock(tsk);
+               write_lock(&fs->lock);
                tsk->fs = NULL;
+               kill = !--fs->users;
+               write_unlock(&fs->lock);
                task_unlock(tsk);
-               put_fs_struct(fs);
+               if (kill)
+                       free_fs_struct(fs);
        }
 }
 
@@ -99,7 +102,8 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
        struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
        /* We don't need to lock fs - think why ;-) */
        if (fs) {
-               atomic_set(&fs->count, 1);
+               fs->users = 1;
+               fs->in_exec = 0;
                rwlock_init(&fs->lock);
                fs->umask = old->umask;
                read_lock(&old->lock);
@@ -114,28 +118,60 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
 
 int unshare_fs_struct(void)
 {
-       struct fs_struct *fsp = copy_fs_struct(current->fs);
-       if (!fsp)
+       struct fs_struct *fs = current->fs;
+       struct fs_struct *new_fs = copy_fs_struct(fs);
+       int kill;
+
+       if (!new_fs)
                return -ENOMEM;
-       exit_fs(current);
-       current->fs = fsp;
+
+       task_lock(current);
+       write_lock(&fs->lock);
+       kill = !--fs->users;
+       current->fs = new_fs;
+       write_unlock(&fs->lock);
+       task_unlock(current);
+
+       if (kill)
+               free_fs_struct(fs);
+
        return 0;
 }
 EXPORT_SYMBOL_GPL(unshare_fs_struct);
 
+int current_umask(void)
+{
+       return current->fs->umask;
+}
+EXPORT_SYMBOL(current_umask);
+
 /* to be mentioned only in INIT_TASK */
 struct fs_struct init_fs = {
-       .count          = ATOMIC_INIT(1),
+       .users          = 1,
        .lock           = __RW_LOCK_UNLOCKED(init_fs.lock),
        .umask          = 0022,
 };
 
 void daemonize_fs_struct(void)
 {
-       struct fs_struct *fs;
+       struct fs_struct *fs = current->fs;
+
+       if (fs) {
+               int kill;
 
-       exit_fs(current);       /* current->fs->count--; */
-       fs = &init_fs;
-       current->fs = fs;
-       atomic_inc(&fs->count);
+               task_lock(current);
+
+               write_lock(&init_fs.lock);
+               init_fs.users++;
+               write_unlock(&init_fs.lock);
+
+               write_lock(&fs->lock);
+               current->fs = &init_fs;
+               kill = !--fs->users;
+               write_unlock(&fs->lock);
+
+               task_unlock(current);
+               if (kill)
+                       free_fs_struct(fs);
+       }
 }