#include <linux/lglock.h>
#include <linux/percpu_counter.h>
#include <linux/percpu.h>
+#include <linux/hardirq.h>
+#include <linux/task_work.h>
#include <linux/ima.h>
-#include <asm/atomic.h>
+#include <linux/atomic.h>
#include "internal.h"
.max_files = NR_FILE
};
-DECLARE_LGLOCK(files_lglock);
-DEFINE_LGLOCK(files_lglock);
+DEFINE_STATIC_LGLOCK(files_lglock);
/* SLAB cache for file structures */
static struct kmem_cache *filp_cachep __read_mostly;
static struct percpu_counter nr_files __cacheline_aligned_in_smp;
-static inline void file_free_rcu(struct rcu_head *head)
+static void file_free_rcu(struct rcu_head *head)
{
struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
#endif
/* Find an unused file structure and return a pointer to it.
- * Returns NULL, if there are no more free file structures or
- * we run out of memory.
+ * Returns an error pointer if some error happend e.g. we over file
+ * structures limit, run out of memory or operation is not permitted.
*
* Be very careful using this. You are responsible for
* getting write access to any mount that you might assign
{
const struct cred *cred = current_cred();
static long old_max;
- struct file * f;
+ struct file *f;
+ int error;
/*
* Privileged users can go above max_files
}
f = kmem_cache_zalloc(filp_cachep, GFP_KERNEL);
- if (f == NULL)
- goto fail;
+ if (unlikely(!f))
+ return ERR_PTR(-ENOMEM);
percpu_counter_inc(&nr_files);
f->f_cred = get_cred(cred);
- if (security_file_alloc(f))
- goto fail_sec;
+ error = security_file_alloc(f);
+ if (unlikely(error)) {
+ file_free(f);
+ return ERR_PTR(error);
+ }
INIT_LIST_HEAD(&f->f_u.fu_list);
atomic_long_set(&f->f_count, 1);
pr_info("VFS: file-max limit %lu reached\n", get_max_files());
old_max = get_nr_files();
}
- goto fail;
-
-fail_sec:
- file_free(f);
-fail:
- return NULL;
+ return ERR_PTR(-ENFILE);
}
/**
struct file *file;
file = get_empty_filp();
- if (!file)
- return NULL;
+ if (IS_ERR(file))
+ return file;
file->f_path = *path;
+ file->f_inode = path->dentry->d_inode;
file->f_mapping = path->dentry->d_inode->i_mapping;
file->f_mode = mode;
file->f_op = fop;
* to write to @file, along with access to write through
* its vfsmount.
*/
-void drop_file_write_access(struct file *file)
+static void drop_file_write_access(struct file *file)
{
struct vfsmount *mnt = file->f_path.mnt;
struct dentry *dentry = file->f_path.dentry;
return;
if (file_check_writeable(file) != 0)
return;
- mnt_drop_write(mnt);
+ __mnt_drop_write(mnt);
file_release_write(file);
}
-EXPORT_SYMBOL_GPL(drop_file_write_access);
/* the real guts of fput() - releasing the last reference to file
*/
if (file->f_op && file->f_op->fasync)
file->f_op->fasync(-1, file, 0);
}
+ ima_file_free(file);
if (file->f_op && file->f_op->release)
file->f_op->release(inode, file);
security_file_free(file);
- ima_file_free(file);
- if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL))
+ if (unlikely(S_ISCHR(inode->i_mode) && inode->i_cdev != NULL &&
+ !(file->f_mode & FMODE_PATH))) {
cdev_put(inode->i_cdev);
+ }
fops_put(file->f_op);
put_pid(file->f_owner.pid);
- file_sb_list_del(file);
if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
i_readcount_dec(inode);
if (file->f_mode & FMODE_WRITE)
drop_file_write_access(file);
file->f_path.dentry = NULL;
file->f_path.mnt = NULL;
+ file->f_inode = NULL;
file_free(file);
dput(dentry);
mntput(mnt);
}
-void fput(struct file *file)
+static DEFINE_SPINLOCK(delayed_fput_lock);
+static LIST_HEAD(delayed_fput_list);
+static void delayed_fput(struct work_struct *unused)
{
- if (atomic_long_dec_and_test(&file->f_count))
- __fput(file);
+ LIST_HEAD(head);
+ spin_lock_irq(&delayed_fput_lock);
+ list_splice_init(&delayed_fput_list, &head);
+ spin_unlock_irq(&delayed_fput_lock);
+ while (!list_empty(&head)) {
+ struct file *f = list_first_entry(&head, struct file, f_u.fu_list);
+ list_del_init(&f->f_u.fu_list);
+ __fput(f);
+ }
}
-EXPORT_SYMBOL(fput);
+static void ____fput(struct callback_head *work)
+{
+ __fput(container_of(work, struct file, f_u.fu_rcuhead));
+}
-struct file *fget(unsigned int fd)
+/*
+ * If kernel thread really needs to have the final fput() it has done
+ * to complete, call this. The only user right now is the boot - we
+ * *do* need to make sure our writes to binaries on initramfs has
+ * not left us with opened struct file waiting for __fput() - execve()
+ * won't work without that. Please, don't add more callers without
+ * very good reasons; in particular, never call that with locks
+ * held and never call that from a thread that might need to do
+ * some work on any kind of umount.
+ */
+void flush_delayed_fput(void)
{
- struct file *file;
- struct files_struct *files = current->files;
-
- rcu_read_lock();
- file = fcheck_files(files, fd);
- if (file) {
- if (!atomic_long_inc_not_zero(&file->f_count)) {
- /* File object ref couldn't be taken */
- rcu_read_unlock();
- return NULL;
+ delayed_fput(NULL);
+}
+
+static DECLARE_WORK(delayed_fput_work, delayed_fput);
+
+void fput(struct file *file)
+{
+ if (atomic_long_dec_and_test(&file->f_count)) {
+ struct task_struct *task = current;
+ file_sb_list_del(file);
+ if (unlikely(in_interrupt() || task->flags & PF_KTHREAD)) {
+ unsigned long flags;
+ spin_lock_irqsave(&delayed_fput_lock, flags);
+ list_add(&file->f_u.fu_list, &delayed_fput_list);
+ schedule_work(&delayed_fput_work);
+ spin_unlock_irqrestore(&delayed_fput_lock, flags);
+ return;
}
+ init_task_work(&file->f_u.fu_rcuhead, ____fput);
+ task_work_add(task, &file->f_u.fu_rcuhead, true);
}
- rcu_read_unlock();
-
- return file;
}
-EXPORT_SYMBOL(fget);
-
/*
- * Lightweight file lookup - no refcnt increment if fd table isn't shared.
- *
- * You can use this instead of fget if you satisfy all of the following
- * conditions:
- * 1) You must call fput_light before exiting the syscall and returning control
- * to userspace (i.e. you cannot remember the returned struct file * after
- * returning to userspace).
- * 2) You must not call filp_close on the returned struct file * in between
- * calls to fget_light and fput_light.
- * 3) You must not clone the current task in between the calls to fget_light
- * and fput_light.
- *
- * The fput_needed flag returned by fget_light should be passed to the
- * corresponding fput_light.
+ * synchronous analog of fput(); for kernel threads that might be needed
+ * in some umount() (and thus can't use flush_delayed_fput() without
+ * risking deadlocks), need to wait for completion of __fput() and know
+ * for this specific struct file it won't involve anything that would
+ * need them. Use only if you really need it - at the very least,
+ * don't blindly convert fput() by kernel thread to that.
*/
-struct file *fget_light(unsigned int fd, int *fput_needed)
+void __fput_sync(struct file *file)
{
- struct file *file;
- struct files_struct *files = current->files;
-
- *fput_needed = 0;
- if (atomic_read(&files->count) == 1) {
- file = fcheck_files(files, fd);
- } else {
- rcu_read_lock();
- file = fcheck_files(files, fd);
- if (file) {
- if (atomic_long_inc_not_zero(&file->f_count))
- *fput_needed = 1;
- else
- /* Didn't get the reference, someone's freed */
- file = NULL;
- }
- rcu_read_unlock();
+ if (atomic_long_dec_and_test(&file->f_count)) {
+ struct task_struct *task = current;
+ file_sb_list_del(file);
+ BUG_ON(!(task->flags & PF_KTHREAD));
+ __fput(file);
}
-
- return file;
}
+EXPORT_SYMBOL(fput);
+
void put_filp(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
*/
void file_sb_list_add(struct file *file, struct super_block *sb)
{
- lg_local_lock(files_lglock);
+ lg_local_lock(&files_lglock);
__file_sb_list_add(file, sb);
- lg_local_unlock(files_lglock);
+ lg_local_unlock(&files_lglock);
}
/**
void file_sb_list_del(struct file *file)
{
if (!list_empty(&file->f_u.fu_list)) {
- lg_local_lock_cpu(files_lglock, file_list_cpu(file));
+ lg_local_lock_cpu(&files_lglock, file_list_cpu(file));
list_del_init(&file->f_u.fu_list);
- lg_local_unlock_cpu(files_lglock, file_list_cpu(file));
+ lg_local_unlock_cpu(&files_lglock, file_list_cpu(file));
}
}
#endif
-int fs_may_remount_ro(struct super_block *sb)
-{
- struct file *file;
- /* Check that no files are currently opened for writing. */
- lg_global_lock(files_lglock);
- do_file_list_for_each_entry(sb, file) {
- struct inode *inode = file->f_path.dentry->d_inode;
-
- /* File with pending delete? */
- if (inode->i_nlink == 0)
- goto too_bad;
-
- /* Writeable file? */
- if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
- goto too_bad;
- } while_file_list_for_each_entry;
- lg_global_unlock(files_lglock);
- return 1; /* Tis' cool bro. */
-too_bad:
- lg_global_unlock(files_lglock);
- return 0;
-}
-
/**
* mark_files_ro - mark all files read-only
* @sb: superblock in question
{
struct file *f;
-retry:
- lg_global_lock(files_lglock);
+ lg_global_lock(&files_lglock);
do_file_list_for_each_entry(sb, f) {
- struct vfsmount *mnt;
- if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
+ if (!S_ISREG(file_inode(f)->i_mode))
continue;
if (!file_count(f))
continue;
spin_unlock(&f->f_lock);
if (file_check_writeable(f) != 0)
continue;
+ __mnt_drop_write(f->f_path.mnt);
file_release_write(f);
- mnt = mntget(f->f_path.mnt);
- /* This can sleep, so we can't hold the spinlock. */
- lg_global_unlock(files_lglock);
- mnt_drop_write(mnt);
- mntput(mnt);
- goto retry;
} while_file_list_for_each_entry;
- lg_global_unlock(files_lglock);
+ lg_global_unlock(&files_lglock);
}
void __init files_init(unsigned long mempages)
n = (mempages * (PAGE_SIZE / 1024)) / 10;
files_stat.max_files = max_t(unsigned long, n, NR_FILE);
files_defer_init();
- lg_lock_init(files_lglock);
+ lg_lock_init(&files_lglock, "files_lglock");
percpu_counter_init(&nr_files, 0);
}
Code Review / linux-3.10.git / blobdiff