* Manage the dynamic fd arrays in the process files_struct.
*/
+#include <linux/export.h>
#include <linux/fs.h>
#include <linux/mm.h>
+#include <linux/mmzone.h>
#include <linux/time.h>
+#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/file.h>
+#include <linux/fdtable.h>
#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
};
int sysctl_nr_open __read_mostly = 1024*1024;
+int sysctl_nr_open_min = BITS_PER_LONG;
+int sysctl_nr_open_max = 1024 * 1024; /* raised later */
/*
* We use this list to defer free fdtables that have vmalloced
*/
static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
-static inline void * alloc_fdmem(unsigned int size)
+static void *alloc_fdmem(size_t size)
{
- if (size <= PAGE_SIZE)
- return kmalloc(size, GFP_KERNEL);
- else
- return vmalloc(size);
+ /*
+ * Very large allocations can stress page reclaim, so fall back to
+ * vmalloc() if the allocation size will be considered "large" by the VM.
+ */
+ if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
+ void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
+ if (data != NULL)
+ return data;
+ }
+ return vmalloc(size);
}
-static inline void free_fdarr(struct fdtable *fdt)
+static void free_fdmem(void *ptr)
{
- if (fdt->max_fds <= (PAGE_SIZE / sizeof(struct file *)))
- kfree(fdt->fd);
- else
- vfree(fdt->fd);
+ is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr);
}
-static inline void free_fdset(struct fdtable *fdt)
+static void __free_fdtable(struct fdtable *fdt)
{
- if (fdt->max_fds <= (PAGE_SIZE * BITS_PER_BYTE / 2))
- kfree(fdt->open_fds);
- else
- vfree(fdt->open_fds);
+ free_fdmem(fdt->fd);
+ free_fdmem(fdt->open_fds);
+ kfree(fdt);
}
static void free_fdtable_work(struct work_struct *work)
spin_unlock_bh(&f->lock);
while(fdt) {
struct fdtable *next = fdt->next;
- vfree(fdt->fd);
- free_fdset(fdt);
- kfree(fdt);
+
+ __free_fdtable(fdt);
fdt = next;
}
}
container_of(fdt, struct files_struct, fdtab));
return;
}
- if (fdt->max_fds <= (PAGE_SIZE / sizeof(struct file *))) {
+ if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
kfree(fdt->fd);
kfree(fdt->open_fds);
kfree(fdt);
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 *);
static struct fdtable * alloc_fdtable(unsigned int nr)
{
struct fdtable *fdt;
- char *data;
+ void *data;
/*
* Figure out how many fds we actually want to support in this fdtable.
nr /= (1024 / sizeof(struct file *));
nr = roundup_pow_of_two(nr + 1);
nr *= (1024 / sizeof(struct file *));
- if (nr > sysctl_nr_open)
- nr = sysctl_nr_open;
+ /*
+ * Note that this can drive nr *below* what we had passed if sysctl_nr_open
+ * had been set lower between the check in expand_files() and here. Deal
+ * with that in caller, it's cheaper that way.
+ *
+ * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise
+ * bitmaps handling below becomes unpleasant, to put it mildly...
+ */
+ if (unlikely(nr > sysctl_nr_open))
+ nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
if (!fdt)
data = alloc_fdmem(nr * sizeof(struct file *));
if (!data)
goto out_fdt;
- fdt->fd = (struct file **)data;
- data = alloc_fdmem(max_t(unsigned int,
+ fdt->fd = data;
+
+ data = alloc_fdmem(max_t(size_t,
2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
if (!data)
goto out_arr;
- fdt->open_fds = (fd_set *)data;
+ fdt->open_fds = data;
data += nr / BITS_PER_BYTE;
- fdt->close_on_exec = (fd_set *)data;
- INIT_RCU_HEAD(&fdt->rcu);
+ fdt->close_on_exec = data;
fdt->next = NULL;
return fdt;
out_arr:
- free_fdarr(fdt);
+ free_fdmem(fdt->fd);
out_fdt:
kfree(fdt);
out:
spin_lock(&files->file_lock);
if (!new_fdt)
return -ENOMEM;
+ /*
+ * extremely unlikely race - sysctl_nr_open decreased between the check in
+ * caller and alloc_fdtable(). Cheaper to catch it here...
+ */
+ if (unlikely(new_fdt->max_fds <= nr)) {
+ __free_fdtable(new_fdt);
+ return -EMFILE;
+ }
/*
* Check again since another task may have expanded the fd table while
* we dropped the lock
free_fdtable(cur_fdt);
} else {
/* Somebody else expanded, so undo our attempt */
- free_fdarr(new_fdt);
- free_fdset(new_fdt);
- kfree(new_fdt);
+ __free_fdtable(new_fdt);
}
return 1;
}
struct fdtable *fdt;
fdt = files_fdtable(files);
+
+ /*
+ * N.B. For clone tasks sharing a files structure, this test
+ * will limit the total number of files that can be opened.
+ */
+ if (nr >= rlimit(RLIMIT_NOFILE))
+ return -EMFILE;
+
/* Do we need to expand? */
if (nr < fdt->max_fds)
return 0;
+
/* Can we expand? */
if (nr >= sysctl_nr_open)
return -EMFILE;
return expand_fdtable(files, nr);
}
+static int count_open_files(struct fdtable *fdt)
+{
+ int size = fdt->max_fds;
+ int i;
+
+ /* Find the last open fd */
+ for (i = size / BITS_PER_LONG; i > 0; ) {
+ if (fdt->open_fds[--i])
+ break;
+ }
+ i = (i + 1) * BITS_PER_LONG;
+ return i;
+}
+
+/*
+ * 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.
+ */
+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;
+ struct fdtable *old_fdt, *new_fdt;
+
+ *errorp = -ENOMEM;
+ newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
+ if (!newf)
+ goto out;
+
+ atomic_set(&newf->count, 1);
+
+ spin_lock_init(&newf->file_lock);
+ newf->next_fd = 0;
+ new_fdt = &newf->fdtab;
+ new_fdt->max_fds = NR_OPEN_DEFAULT;
+ new_fdt->close_on_exec = newf->close_on_exec_init;
+ new_fdt->open_fds = newf->open_fds_init;
+ new_fdt->fd = &newf->fd_array[0];
+ new_fdt->next = NULL;
+
+ spin_lock(&oldf->file_lock);
+ old_fdt = files_fdtable(oldf);
+ open_files = count_open_files(old_fdt);
+
+ /*
+ * Check whether we need to allocate a larger fd array and fd set.
+ */
+ while (unlikely(open_files > new_fdt->max_fds)) {
+ spin_unlock(&oldf->file_lock);
+
+ if (new_fdt != &newf->fdtab)
+ __free_fdtable(new_fdt);
+
+ 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_fdtable(new_fdt);
+ *errorp = -EMFILE;
+ goto out_release;
+ }
+
+ /*
+ * 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);
+ open_files = count_open_files(old_fdt);
+ }
+
+ old_fds = old_fdt->fd;
+ new_fds = new_fdt->fd;
+
+ memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8);
+ memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, 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.
+ */
+ __clear_open_fd(open_files - i, new_fdt);
+ }
+ 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_fds > open_files) {
+ int left = (new_fdt->max_fds - open_files) / 8;
+ int start = open_files / BITS_PER_LONG;
+
+ memset(&new_fdt->open_fds[start], 0, left);
+ memset(&new_fdt->close_on_exec[start], 0, left);
+ }
+
+ rcu_assign_pointer(newf->fdt, new_fdt);
+
+ return newf;
+
+out_release:
+ kmem_cache_free(files_cachep, newf);
+out:
+ return NULL;
+}
+
static void __devinit fdtable_defer_list_init(int cpu)
{
struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
int i;
for_each_possible_cpu(i)
fdtable_defer_list_init(i);
+ sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
+ -BITS_PER_LONG;
+}
+
+struct files_struct init_files = {
+ .count = ATOMIC_INIT(1),
+ .fdt = &init_files.fdtab,
+ .fdtab = {
+ .max_fds = NR_OPEN_DEFAULT,
+ .fd = &init_files.fd_array[0],
+ .close_on_exec = init_files.close_on_exec_init,
+ .open_fds = init_files.open_fds_init,
+ },
+ .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, 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;
+
+ __set_open_fd(fd, fdt);
+ if (flags & O_CLOEXEC)
+ __set_close_on_exec(fd, fdt);
+ else
+ __clear_close_on_exec(fd, fdt);
+ error = fd;
+#if 1
+ /* Sanity check */
+ if (rcu_dereference_raw(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);
Code Review / linux-2.6.git / blobdiff