[PATCH] merge locate_fd() and get_unused_fd()

	New primitive: alloc_fd(start, flags).  get_unused_fd() and
get_unused_fd_flags() become wrappers on top of it.

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

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 61d6251..2e40799 100644 (file)
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -49,73 +49,6 @@ static int get_close_on_exec(unsigned int fd)
        return res;
 }
 
-/*
- * locate_fd finds a free file descriptor in the open_fds fdset,
- * expanding the fd arrays if necessary.  Must be called with the
- * file_lock held for write.
- */
-
-static int locate_fd(unsigned int orig_start, int cloexec)
-{
-       struct files_struct *files = current->files;
-       unsigned int newfd;
-       unsigned int start;
-       int error;
-       struct fdtable *fdt;
-
-       spin_lock(&files->file_lock);
-repeat:
-       fdt = files_fdtable(files);
-       /*
-        * Someone might have closed fd's in the range
-        * orig_start..fdt->next_fd
-        */
-       start = orig_start;
-       if (start < files->next_fd)
-               start = files->next_fd;
-
-       newfd = start;
-       if (start < fdt->max_fds)
-               newfd = find_next_zero_bit(fdt->open_fds->fds_bits,
-                                          fdt->max_fds, start);
-
-       error = expand_files(files, newfd);
-       if (error < 0)
-               goto out;
-
-       /*
-        * If we needed to expand the fs array we
-        * might have blocked - try again.
-        */
-       if (error)
-               goto repeat;
-
-       if (start <= files->next_fd)
-               files->next_fd = newfd + 1;
-
-       FD_SET(newfd, fdt->open_fds);
-       if (cloexec)
-               FD_SET(newfd, fdt->close_on_exec);
-       else
-               FD_CLR(newfd, fdt->close_on_exec);
-       error = newfd;
-
-out:
-       spin_unlock(&files->file_lock);
-       return error;
-}
-
-static int dupfd(struct file *file, unsigned int start, int cloexec)
-{
-       int fd = locate_fd(start, cloexec);
-       if (fd >= 0)
-               fd_install(fd, file);
-       else
-               fput(file);
-
-       return fd;
-}
-
 asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
 {
        int err = -EBADF;
@@ -194,10 +127,15 @@ asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
 asmlinkage long sys_dup(unsigned int fildes)
 {
        int ret = -EBADF;
-       struct file * file = fget(fildes);
-
-       if (file)
-               ret = dupfd(file, 0, 0);
+       struct file *file = fget(fildes);
+
+       if (file) {
+               ret = get_unused_fd();
+               if (ret >= 0)
+                       fd_install(ret, file);
+               else
+                       fput(file);
+       }
        return ret;
 }
 
@@ -322,8 +260,11 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
        case F_DUPFD_CLOEXEC:
                if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
                        break;
-               get_file(filp);
-               err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC);
+               err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
+               if (err >= 0) {
+                       get_file(filp);
+                       fd_install(err, filp);
+               }
                break;
        case F_GETFD:
                err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;

diff --git a/fs/file.c b/fs/file.c
index d8773b1..f313314 100644 (file)
--- a/fs/file.c
+++ b/fs/file.c
@@ -6,6 +6,7 @@
  *  Manage the dynamic fd arrays in the process files_struct.
  */
 
+#include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/time.h>
@@ -432,3 +433,63 @@ struct files_struct init_files = {
        },
        .file_lock      = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
 };
+
+/*
+ * allocate a file descriptor, mark it busy.
+ */
+int alloc_fd(unsigned start, unsigned flags)
+{
+       struct files_struct *files = current->files;
+       unsigned int fd;
+       int error;
+       struct fdtable *fdt;
+
+       spin_lock(&files->file_lock);
+repeat:
+       fdt = files_fdtable(files);
+       fd = start;
+       if (fd < files->next_fd)
+               fd = files->next_fd;
+
+       if (fd < fdt->max_fds)
+               fd = find_next_zero_bit(fdt->open_fds->fds_bits,
+                                          fdt->max_fds, fd);
+
+       error = expand_files(files, fd);
+       if (error < 0)
+               goto out;
+
+       /*
+        * If we needed to expand the fs array we
+        * might have blocked - try again.
+        */
+       if (error)
+               goto repeat;
+
+       if (start <= files->next_fd)
+               files->next_fd = fd + 1;
+
+       FD_SET(fd, fdt->open_fds);
+       if (flags & O_CLOEXEC)
+               FD_SET(fd, fdt->close_on_exec);
+       else
+               FD_CLR(fd, fdt->close_on_exec);
+       error = fd;
+#if 1
+       /* Sanity check */
+       if (rcu_dereference(fdt->fd[fd]) != NULL) {
+               printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
+               rcu_assign_pointer(fdt->fd[fd], NULL);
+       }
+#endif
+
+out:
+       spin_unlock(&files->file_lock);
+       return error;
+}
+
+int get_unused_fd(void)
+{
+       return alloc_fd(0, 0);
+}
+EXPORT_SYMBOL(get_unused_fd);

diff --git a/fs/open.c b/fs/open.c
index 52647be..07da935 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -963,62 +963,6 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
 }
 EXPORT_SYMBOL(dentry_open);
 
-/*
- * Find an empty file descriptor entry, and mark it busy.
- */
-int get_unused_fd_flags(int flags)
-{
-       struct files_struct * files = current->files;
-       int fd, error;
-       struct fdtable *fdt;
-
-       spin_lock(&files->file_lock);
-
-repeat:
-       fdt = files_fdtable(files);
-       fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,
-                               files->next_fd);
-
-       /* Do we need to expand the fd array or fd set?  */
-       error = expand_files(files, fd);
-       if (error < 0)
-               goto out;
-
-       if (error) {
-               /*
-                * If we needed to expand the fs array we
-                * might have blocked - try again.
-                */
-               goto repeat;
-       }
-
-       FD_SET(fd, fdt->open_fds);
-       if (flags & O_CLOEXEC)
-               FD_SET(fd, fdt->close_on_exec);
-       else
-               FD_CLR(fd, fdt->close_on_exec);
-       files->next_fd = fd + 1;
-#if 1
-       /* Sanity check */
-       if (fdt->fd[fd] != NULL) {
-               printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
-               fdt->fd[fd] = NULL;
-       }
-#endif
-       error = fd;
-
-out:
-       spin_unlock(&files->file_lock);
-       return error;
-}
-
-int get_unused_fd(void)
-{
-       return get_unused_fd_flags(0);
-}
-
-EXPORT_SYMBOL(get_unused_fd);
-
 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
 {
        struct fdtable *fdt = files_fdtable(files);

diff --git a/include/linux/file.h b/include/linux/file.h
index 27c64bd..a20259e 100644 (file)
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -34,8 +34,9 @@ extern struct file *fget(unsigned int fd);
 extern struct file *fget_light(unsigned int fd, int *fput_needed);
 extern void set_close_on_exec(unsigned int fd, int flag);
 extern void put_filp(struct file *);
+extern int alloc_fd(unsigned start, unsigned flags);
 extern int get_unused_fd(void);
-extern int get_unused_fd_flags(int flags);
+#define get_unused_fd_flags(flags) alloc_fd(0, (flags))
 extern void put_unused_fd(unsigned int fd);
 
 extern void fd_install(unsigned int fd, struct file *file);