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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/file.c
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-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!
Diffstat (limited to 'fs/file.c')
-rw-r--r--fs/file.c254
1 files changed, 254 insertions, 0 deletions
diff --git a/fs/file.c b/fs/file.c
new file mode 100644
index 000000000000..92b5f25985d2
--- /dev/null
+++ b/fs/file.c
@@ -0,0 +1,254 @@
+/*
+ * linux/fs/file.c
+ *
+ * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
+ *
+ * Manage the dynamic fd arrays in the process files_struct.
+ */
+
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/time.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/file.h>
+#include <linux/bitops.h>
+
+
+/*
+ * Allocate an fd array, using kmalloc or vmalloc.
+ * Note: the array isn't cleared at allocation time.
+ */
+struct file ** alloc_fd_array(int num)
+{
+ struct file **new_fds;
+ int size = num * sizeof(struct file *);
+
+ if (size <= PAGE_SIZE)
+ new_fds = (struct file **) kmalloc(size, GFP_KERNEL);
+ else
+ new_fds = (struct file **) vmalloc(size);
+ return new_fds;
+}
+
+void free_fd_array(struct file **array, int num)
+{
+ int size = num * sizeof(struct file *);
+
+ if (!array) {
+ printk (KERN_ERR "free_fd_array: array = 0 (num = %d)\n", num);
+ return;
+ }
+
+ if (num <= NR_OPEN_DEFAULT) /* Don't free the embedded fd array! */
+ return;
+ else if (size <= PAGE_SIZE)
+ kfree(array);
+ else
+ vfree(array);
+}
+
+/*
+ * Expand the fd array in the files_struct. Called with the files
+ * spinlock held for write.
+ */
+
+static int expand_fd_array(struct files_struct *files, int nr)
+ __releases(files->file_lock)
+ __acquires(files->file_lock)
+{
+ 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;
+}
+
+/*
+ * Allocate an fdset array, using kmalloc or vmalloc.
+ * Note: the array isn't cleared at allocation time.
+ */
+fd_set * alloc_fdset(int num)
+{
+ fd_set *new_fdset;
+ int size = num / 8;
+
+ if (size <= PAGE_SIZE)
+ new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);
+ else
+ new_fdset = (fd_set *) vmalloc(size);
+ return new_fdset;
+}
+
+void free_fdset(fd_set *array, int num)
+{
+ int size = num / 8;
+
+ if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */
+ return;
+ else if (size <= PAGE_SIZE)
+ kfree(array);
+ else
+ vfree(array);
+}
+
+/*
+ * Expand the fdset in the files_struct. Called with the files spinlock
+ * held for write.
+ */
+static int expand_fdset(struct files_struct *files, int nr)
+ __releases(file->file_lock)
+ __acquires(file->file_lock)
+{
+ fd_set *new_openset = NULL, *new_execset = NULL;
+ int error, nfds = 0;
+
+ error = -EMFILE;
+ if (files->max_fdset >= NR_OPEN || nr >= NR_OPEN)
+ goto out;
+
+ nfds = files->max_fdset;
+ spin_unlock(&files->file_lock);
+
+ /* Expand to the max in easy steps */
+ do {
+ if (nfds < (PAGE_SIZE * 8))
+ nfds = PAGE_SIZE * 8;
+ else {
+ nfds = nfds * 2;
+ if (nfds > NR_OPEN)
+ nfds = NR_OPEN;
+ }
+ } while (nfds <= nr);
+
+ error = -ENOMEM;
+ new_openset = alloc_fdset(nfds);
+ new_execset = alloc_fdset(nfds);
+ spin_lock(&files->file_lock);
+ if (!new_openset || !new_execset)
+ goto out;
+
+ error = 0;
+
+ /* Copy the existing tables and install the new pointers */
+ if (nfds > files->max_fdset) {
+ int i = files->max_fdset / (sizeof(unsigned long) * 8);
+ int count = (nfds - files->max_fdset) / 8;
+
+ /*
+ * Don't copy the entire array if the current fdset is
+ * not yet initialised.
+ */
+ if (i) {
+ memcpy (new_openset, files->open_fds, files->max_fdset/8);
+ memcpy (new_execset, files->close_on_exec, files->max_fdset/8);
+ memset (&new_openset->fds_bits[i], 0, count);
+ memset (&new_execset->fds_bits[i], 0, count);
+ }
+
+ nfds = xchg(&files->max_fdset, nfds);
+ new_openset = xchg(&files->open_fds, new_openset);
+ new_execset = xchg(&files->close_on_exec, new_execset);
+ spin_unlock(&files->file_lock);
+ free_fdset (new_openset, nfds);
+ free_fdset (new_execset, nfds);
+ spin_lock(&files->file_lock);
+ return 0;
+ }
+ /* Somebody expanded the array while we slept ... */
+
+out:
+ spin_unlock(&files->file_lock);
+ if (new_openset)
+ free_fdset(new_openset, nfds);
+ if (new_execset)
+ free_fdset(new_execset, nfds);
+ spin_lock(&files->file_lock);
+ return error;
+}
+
+/*
+ * Expand files.
+ * Return <0 on error; 0 nothing done; 1 files expanded, we may have blocked.
+ * Should be called with the files->file_lock spinlock held for write.
+ */
+int expand_files(struct files_struct *files, int nr)
+{
+ int err, expand = 0;
+
+ if (nr >= files->max_fdset) {
+ expand = 1;
+ if ((err = expand_fdset(files, nr)))
+ goto out;
+ }
+ if (nr >= files->max_fds) {
+ expand = 1;
+ if ((err = expand_fd_array(files, nr)))
+ goto out;
+ }
+ err = expand;
+out:
+ return err;
+}