static void __free_fdtable(struct fdtable *fdt)
{
free_fdset(fdt->open_fds, fdt->max_fdset);
free_fdset(fdt->close_on_exec, fdt->max_fdset);
free_fd_array(fdt->fd, fdt->max_fds);
kfree(fdt);
}
void put_files_struct(struct files_struct *files)
{
if (atomic_dec_and_test(&files->count)) {
close_files(files);
/*
* Free the fd and fdset arrays if we expanded them.
*/
if (files->fd != &files->fd_array[0])
free_fd_array(files->fd, files->max_fds);
if (files->max_fdset > __FD_SETSIZE) {
free_fdset(files->open_fds, files->max_fdset);
free_fdset(files->close_on_exec, files->max_fdset);
}
kmem_cache_free(files_cachep, files);
}
}
static inline void __exit_files(struct task_struct *tsk)
{
struct files_struct * files = tsk->files;
if (files) {
tsk->files = NULL;
if (atomic_dec_and_test(&files->count)) {
close_files(files);
/*
* Free the fd and fdset arrays if we expanded them.
*/
if (files->fd != &files->fd_array[0])
free_fd_array(files->fd, files->max_fds);
if (files->max_fdset > __FD_SETSIZE) {
free_fdset(files->open_fds, files->max_fdset);
free_fdset(files->close_on_exec, files->max_fdset);
}
kmem_cache_free(files_cachep, files);
}
}
}
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
{
struct files_struct *oldf, *newf;
struct file **old_fds, **new_fds;
int open_files, size, i, error = 0, expand;
/*
* A background process may not have any files ...
*/
oldf = current->files;
if (!oldf)
goto out;
if (clone_flags & CLONE_FILES) {
atomic_inc(&oldf->count);
goto out;
}
/*
* Note: we may be using current for both targets (See exec.c)
* This works because we cache current->files (old) as oldf. Don't
* break this.
*/
tsk->files = NULL;
error = -ENOMEM;
newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
if (!newf)
goto out;
atomic_set(&newf->count, 1);
spin_lock_init(&newf->file_lock);
newf->next_fd = 0;
newf->max_fds = NR_OPEN_DEFAULT;
newf->max_fdset = __FD_SETSIZE;
newf->close_on_exec = &newf->close_on_exec_init;
newf->open_fds = &newf->open_fds_init;
newf->fd = &newf->fd_array[0];
spin_lock(&oldf->file_lock);
open_files = count_open_files(oldf, oldf->max_fdset);
expand = 0;
/*
* Check whether we need to allocate a larger fd array or fd set.
* Note: we're not a clone task, so the open count won't change.
*/
if (open_files > newf->max_fdset) {
newf->max_fdset = 0;
expand = 1;
}
if (open_files > newf->max_fds) {
newf->max_fds = 0;
expand = 1;
}
/* if the old fdset gets grown now, we'll only copy up to "size" fds */
if (expand) {
spin_unlock(&oldf->file_lock);
spin_lock(&newf->file_lock);
error = expand_files(newf, open_files-1);
spin_unlock(&newf->file_lock);
if (error < 0)
goto out_release;
spin_lock(&oldf->file_lock);
}
old_fds = oldf->fd;
new_fds = newf->fd;
memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
for (i = open_files; i != 0; i--) {
struct file *f = *old_fds++;
if (f) {
get_file(f);
} else {
/*
* The fd may be claimed in the fd bitmap but not yet
* instantiated in the files array if a sibling thread
* is partway through open(). So make sure that this
* fd is available to the new process.
*/
FD_CLR(open_files - i, newf->open_fds);
}
*new_fds++ = f;
}
spin_unlock(&oldf->file_lock);
/* compute the remainder to be cleared */
size = (newf->max_fds - open_files) * sizeof(struct file *);
/* This is long word aligned thus could use a optimized version */
memset(new_fds, 0, size);
if (newf->max_fdset > open_files) {
int left = (newf->max_fdset-open_files)/8;
int start = open_files / (8 * sizeof(unsigned long));
memset(&newf->open_fds->fds_bits[start], 0, left);
memset(&newf->close_on_exec->fds_bits[start], 0, left);
}
tsk->files = newf;
error = 0;
out:
return error;
out_release:
free_fdset (newf->close_on_exec, newf->max_fdset);
free_fdset (newf->open_fds, newf->max_fdset);
free_fd_array(newf->fd, newf->max_fds);
kmem_cache_free(files_cachep, newf);
goto out;
}
/*
* Allocate a new files structure and copy contents from the
* passed in files structure.
* errorp will be valid only when the returned files_struct is NULL.
*/
static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
{
struct files_struct *newf;
struct file **old_fds, **new_fds;
int open_files, size, i, expand;
struct fdtable *old_fdt, *new_fdt;
*errorp = -ENOMEM;
newf = alloc_files();
if (!newf)
goto out;
spin_lock(&oldf->file_lock);
old_fdt = files_fdtable(oldf);
new_fdt = files_fdtable(newf);
size = old_fdt->max_fdset;
open_files = count_open_files(old_fdt);
expand = 0;
/*
* Check whether we need to allocate a larger fd array or fd set.
* Note: we're not a clone task, so the open count won't change.
*/
if (open_files > new_fdt->max_fdset) {
new_fdt->max_fdset = 0;
expand = 1;
}
if (open_files > new_fdt->max_fds) {
new_fdt->max_fds = 0;
expand = 1;
}
/* if the old fdset gets grown now, we'll only copy up to "size" fds */
if (expand) {
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)
goto out_release;
new_fdt = files_fdtable(newf);
/*
* Reacquire the oldf lock and a pointer to its fd table
* who knows it may have a new bigger fd table. We need
* the latest pointer.
*/
spin_lock(&oldf->file_lock);
old_fdt = files_fdtable(oldf);
}
old_fds = old_fdt->fd;
new_fds = new_fdt->fd;
memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
for (i = open_files; i != 0; i--) {
struct file *f = *old_fds++;
if (f) {
get_file(f);
} else {
/*
* The fd may be claimed in the fd bitmap but not yet
* instantiated in the files array if a sibling thread
* is partway through open(). So make sure that this
* fd is available to the new process.
*/
FD_CLR(open_files - i, new_fdt->open_fds);
}
rcu_assign_pointer(*new_fds++, f);
}
spin_unlock(&oldf->file_lock);
/* compute the remainder to be cleared */
size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
/* This is long word aligned thus could use a optimized version */
memset(new_fds, 0, size);
if (new_fdt->max_fdset > open_files) {
int left = (new_fdt->max_fdset-open_files)/8;
int start = open_files / (8 * sizeof(unsigned long));
memset(&new_fdt->open_fds->fds_bits[start], 0, left);
memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
}
out:
return newf;
out_release:
free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
free_fd_array(new_fdt->fd, new_fdt->max_fds);
kmem_cache_free(files_cachep, newf);
return NULL;
}
int expand_fd_array(struct files_struct *files, int nr)
{
struct file **new_fds;
int error, nfds;
error = -EMFILE;
if (files->max_fds >= NR_OPEN || nr >= NR_OPEN)
goto out;
nfds = files->max_fds;
spin_unlock(&files->file_lock);
/*
* Expand to the max in easy steps, and keep expanding it until
* we have enough for the requested fd array size.
*/
do {
#if NR_OPEN_DEFAULT < 256
if (nfds < 256)
nfds = 256;
else
#endif
if (nfds < (PAGE_SIZE / sizeof(struct file *)))
nfds = PAGE_SIZE / sizeof(struct file *);
else {
nfds = nfds * 2;
if (nfds > NR_OPEN)
nfds = NR_OPEN;
}
} while (nfds <= nr);
error = -ENOMEM;
new_fds = alloc_fd_array(nfds);
spin_lock(&files->file_lock);
if (!new_fds)
goto out;
/* Copy the existing array and install the new pointer */
if (nfds > files->max_fds) {
struct file **old_fds;
int i;
old_fds = xchg(&files->fd, new_fds);
i = xchg(&files->max_fds, nfds);
/* Don't copy/clear the array if we are creating a new
fd array for fork() */
if (i) {
memcpy(new_fds, old_fds, i * sizeof(struct file *));
/* clear the remainder of the array */
memset(&new_fds[i], 0,
(nfds-i) * sizeof(struct file *));
spin_unlock(&files->file_lock);
free_fd_array(old_fds, i);
spin_lock(&files->file_lock);
}
} else {
/* Somebody expanded the array while we slept ... */
spin_unlock(&files->file_lock);
free_fd_array(new_fds, nfds);
spin_lock(&files->file_lock);
}
error = 0;
out:
return error;
}