[PATCH] dup_fd() part 2

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>

1 files changed, 16 insertions, 8 deletions

diff --git a/fs/file.c b/fs/file.c
index 7dbadaaf00f0..6491b2b5bc38 100644
--- 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