Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
254
fs/file.c
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254
fs/file.c
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/*
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* linux/fs/file.c
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*
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* Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
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*
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* Manage the dynamic fd arrays in the process files_struct.
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*/
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/time.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/file.h>
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#include <linux/bitops.h>
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/*
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* Allocate an fd array, using kmalloc or vmalloc.
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* Note: the array isn't cleared at allocation time.
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*/
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struct file ** alloc_fd_array(int num)
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{
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struct file **new_fds;
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int size = num * sizeof(struct file *);
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if (size <= PAGE_SIZE)
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new_fds = (struct file **) kmalloc(size, GFP_KERNEL);
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else
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new_fds = (struct file **) vmalloc(size);
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return new_fds;
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}
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void free_fd_array(struct file **array, int num)
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{
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int size = num * sizeof(struct file *);
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if (!array) {
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printk (KERN_ERR "free_fd_array: array = 0 (num = %d)\n", num);
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return;
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}
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if (num <= NR_OPEN_DEFAULT) /* Don't free the embedded fd array! */
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return;
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else if (size <= PAGE_SIZE)
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kfree(array);
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else
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vfree(array);
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}
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/*
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* Expand the fd array in the files_struct. Called with the files
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* spinlock held for write.
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*/
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static int expand_fd_array(struct files_struct *files, int nr)
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__releases(files->file_lock)
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__acquires(files->file_lock)
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{
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struct file **new_fds;
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int error, nfds;
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error = -EMFILE;
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if (files->max_fds >= NR_OPEN || nr >= NR_OPEN)
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goto out;
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nfds = files->max_fds;
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spin_unlock(&files->file_lock);
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/*
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* Expand to the max in easy steps, and keep expanding it until
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* we have enough for the requested fd array size.
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*/
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do {
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#if NR_OPEN_DEFAULT < 256
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if (nfds < 256)
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nfds = 256;
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else
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#endif
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if (nfds < (PAGE_SIZE / sizeof(struct file *)))
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nfds = PAGE_SIZE / sizeof(struct file *);
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else {
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nfds = nfds * 2;
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if (nfds > NR_OPEN)
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nfds = NR_OPEN;
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}
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} while (nfds <= nr);
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error = -ENOMEM;
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new_fds = alloc_fd_array(nfds);
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spin_lock(&files->file_lock);
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if (!new_fds)
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goto out;
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/* Copy the existing array and install the new pointer */
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if (nfds > files->max_fds) {
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struct file **old_fds;
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int i;
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old_fds = xchg(&files->fd, new_fds);
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i = xchg(&files->max_fds, nfds);
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/* Don't copy/clear the array if we are creating a new
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fd array for fork() */
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if (i) {
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memcpy(new_fds, old_fds, i * sizeof(struct file *));
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/* clear the remainder of the array */
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memset(&new_fds[i], 0,
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(nfds-i) * sizeof(struct file *));
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spin_unlock(&files->file_lock);
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free_fd_array(old_fds, i);
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spin_lock(&files->file_lock);
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}
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} else {
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/* Somebody expanded the array while we slept ... */
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spin_unlock(&files->file_lock);
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free_fd_array(new_fds, nfds);
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spin_lock(&files->file_lock);
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}
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error = 0;
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out:
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return error;
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}
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/*
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* Allocate an fdset array, using kmalloc or vmalloc.
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* Note: the array isn't cleared at allocation time.
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*/
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fd_set * alloc_fdset(int num)
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{
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fd_set *new_fdset;
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int size = num / 8;
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if (size <= PAGE_SIZE)
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new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);
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else
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new_fdset = (fd_set *) vmalloc(size);
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return new_fdset;
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}
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void free_fdset(fd_set *array, int num)
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{
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int size = num / 8;
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if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */
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return;
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else if (size <= PAGE_SIZE)
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kfree(array);
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else
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vfree(array);
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}
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/*
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* Expand the fdset in the files_struct. Called with the files spinlock
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* held for write.
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*/
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static int expand_fdset(struct files_struct *files, int nr)
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__releases(file->file_lock)
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__acquires(file->file_lock)
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{
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fd_set *new_openset = NULL, *new_execset = NULL;
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int error, nfds = 0;
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error = -EMFILE;
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if (files->max_fdset >= NR_OPEN || nr >= NR_OPEN)
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goto out;
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nfds = files->max_fdset;
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spin_unlock(&files->file_lock);
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/* Expand to the max in easy steps */
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do {
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if (nfds < (PAGE_SIZE * 8))
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nfds = PAGE_SIZE * 8;
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else {
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nfds = nfds * 2;
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if (nfds > NR_OPEN)
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nfds = NR_OPEN;
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}
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} while (nfds <= nr);
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error = -ENOMEM;
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new_openset = alloc_fdset(nfds);
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new_execset = alloc_fdset(nfds);
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spin_lock(&files->file_lock);
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if (!new_openset || !new_execset)
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goto out;
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error = 0;
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/* Copy the existing tables and install the new pointers */
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if (nfds > files->max_fdset) {
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int i = files->max_fdset / (sizeof(unsigned long) * 8);
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int count = (nfds - files->max_fdset) / 8;
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/*
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* Don't copy the entire array if the current fdset is
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* not yet initialised.
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*/
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if (i) {
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memcpy (new_openset, files->open_fds, files->max_fdset/8);
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memcpy (new_execset, files->close_on_exec, files->max_fdset/8);
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memset (&new_openset->fds_bits[i], 0, count);
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memset (&new_execset->fds_bits[i], 0, count);
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}
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nfds = xchg(&files->max_fdset, nfds);
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new_openset = xchg(&files->open_fds, new_openset);
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new_execset = xchg(&files->close_on_exec, new_execset);
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spin_unlock(&files->file_lock);
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free_fdset (new_openset, nfds);
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free_fdset (new_execset, nfds);
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spin_lock(&files->file_lock);
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return 0;
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}
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/* Somebody expanded the array while we slept ... */
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out:
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spin_unlock(&files->file_lock);
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if (new_openset)
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free_fdset(new_openset, nfds);
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if (new_execset)
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free_fdset(new_execset, nfds);
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spin_lock(&files->file_lock);
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return error;
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}
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/*
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* Expand files.
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* Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
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* Should be called with the files->file_lock spinlock held for write.
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*/
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int expand_files(struct files_struct *files, int nr)
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{
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int err, expand = 0;
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if (nr >= files->max_fdset) {
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expand = 1;
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if ((err = expand_fdset(files, nr)))
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goto out;
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}
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if (nr >= files->max_fds) {
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expand = 1;
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if ((err = expand_fd_array(files, nr)))
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goto out;
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}
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err = expand;
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out:
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return err;
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}
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