[PATCH] dup_fd() part 2
Al Viro [Fri, 9 May 2008 01:02:45 +0000 (21:02 -0400)]
use alloc_fdtable() instead of expand_files(), get rid of pointless
grabbing newf->file_lock, kill magic in copy_fdtable() that used to
be there only to skip copying when called from dup_fd().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/file.c

index 7dbadaa..6491b2b 100644 (file)
--- a/fs/file.c
+++ b/fs/file.c
@@ -119,8 +119,6 @@ static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
        unsigned int cpy, set;
 
        BUG_ON(nfdt->max_fds < ofdt->max_fds);
-       if (ofdt->max_fds == 0)
-               return;
 
        cpy = ofdt->max_fds * sizeof(struct file *);
        set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
@@ -327,14 +325,24 @@ struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
         * Note: we're not a clone task, so the open count won't change.
         */
        if (open_files > new_fdt->max_fds) {
-               new_fdt->max_fds = 0;
                spin_unlock(&oldf->file_lock);
-               spin_lock(&newf->file_lock);
-               *errorp = expand_files(newf, open_files-1);
-               spin_unlock(&newf->file_lock);
-               if (*errorp < 0)
+
+               new_fdt = alloc_fdtable(open_files - 1);
+               if (!new_fdt) {
+                       *errorp = -ENOMEM;
+                       goto out_release;
+               }
+
+               /* beyond sysctl_nr_open; nothing to do */
+               if (unlikely(new_fdt->max_fds < open_files)) {
+                       free_fdarr(new_fdt);
+                       free_fdset(new_fdt);
+                       kfree(new_fdt);
+                       *errorp = -EMFILE;
                        goto out_release;
-               new_fdt = files_fdtable(newf);
+               }
+               rcu_assign_pointer(files->fdt, new_fdt);
+
                /*
                 * Reacquire the oldf lock and a pointer to its fd table
                 * who knows it may have a new bigger fd table. We need