fs: cleanup files_lock locking
fs: cleanup files_lock locking Lock tty_files with a new spinlock, tty_files_lock; provide helpers to manipulate the per-sb files list; unexport the files_lock spinlock. Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig <hch@infradead.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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b04f784e5d
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ee2ffa0dfd
7 changed files with 48 additions and 42 deletions
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@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp)
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set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
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filp->private_data = tty;
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file_move(filp, &tty->tty_files);
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file_sb_list_del(filp); /* __dentry_open has put it on the sb list */
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spin_lock(&tty_files_lock);
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list_add(&filp->f_u.fu_list, &tty->tty_files);
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spin_unlock(&tty_files_lock);
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retval = devpts_pty_new(inode, tty->link);
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if (retval)
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@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
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DEFINE_MUTEX(tty_mutex);
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EXPORT_SYMBOL(tty_mutex);
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/* Spinlock to protect the tty->tty_files list */
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DEFINE_SPINLOCK(tty_files_lock);
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static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
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static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
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ssize_t redirected_tty_write(struct file *, const char __user *,
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@ -235,11 +238,11 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
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struct list_head *p;
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int count = 0;
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file_list_lock();
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spin_lock(&tty_files_lock);
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list_for_each(p, &tty->tty_files) {
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count++;
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}
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file_list_unlock();
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spin_unlock(&tty_files_lock);
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if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
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tty->driver->subtype == PTY_TYPE_SLAVE &&
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tty->link && tty->link->count)
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@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty)
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workqueue with the lock held */
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check_tty_count(tty, "tty_hangup");
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file_list_lock();
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spin_lock(&tty_files_lock);
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/* This breaks for file handles being sent over AF_UNIX sockets ? */
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list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
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if (filp->f_op->write == redirected_tty_write)
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@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty)
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__tty_fasync(-1, filp, 0); /* can't block */
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filp->f_op = &hung_up_tty_fops;
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}
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file_list_unlock();
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spin_unlock(&tty_files_lock);
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tty_ldisc_hangup(tty);
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@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work)
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tty_driver_kref_put(driver);
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module_put(driver->owner);
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file_list_lock();
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spin_lock(&tty_files_lock);
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list_del_init(&tty->tty_files);
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file_list_unlock();
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spin_unlock(&tty_files_lock);
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put_pid(tty->pgrp);
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put_pid(tty->session);
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@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp)
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* - do_tty_hangup no longer sees this file descriptor as
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* something that needs to be handled for hangups.
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*/
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file_kill(filp);
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spin_lock(&tty_files_lock);
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BUG_ON(list_empty(&filp->f_u.fu_list));
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list_del_init(&filp->f_u.fu_list);
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spin_unlock(&tty_files_lock);
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filp->private_data = NULL;
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/*
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@ -1840,7 +1846,11 @@ static int tty_open(struct inode *inode, struct file *filp)
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}
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filp->private_data = tty;
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file_move(filp, &tty->tty_files);
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BUG_ON(list_empty(&filp->f_u.fu_list));
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file_sb_list_del(filp); /* __dentry_open has put it on the sb list */
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spin_lock(&tty_files_lock);
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list_add(&filp->f_u.fu_list, &tty->tty_files);
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spin_unlock(&tty_files_lock);
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check_tty_count(tty, "tty_open");
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if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
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tty->driver->subtype == PTY_TYPE_MASTER)
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@ -32,8 +32,7 @@ struct files_stat_struct files_stat = {
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.max_files = NR_FILE
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};
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/* public. Not pretty! */
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__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
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static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
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/* SLAB cache for file structures */
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static struct kmem_cache *filp_cachep __read_mostly;
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@ -249,7 +248,7 @@ static void __fput(struct file *file)
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cdev_put(inode->i_cdev);
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fops_put(file->f_op);
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put_pid(file->f_owner.pid);
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file_kill(file);
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file_sb_list_del(file);
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if (file->f_mode & FMODE_WRITE)
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drop_file_write_access(file);
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file->f_path.dentry = NULL;
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@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed)
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return file;
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}
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void put_filp(struct file *file)
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{
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if (atomic_long_dec_and_test(&file->f_count)) {
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security_file_free(file);
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file_kill(file);
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file_sb_list_del(file);
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file_free(file);
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}
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}
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void file_move(struct file *file, struct list_head *list)
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void file_sb_list_add(struct file *file, struct super_block *sb)
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{
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if (!list)
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return;
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file_list_lock();
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list_move(&file->f_u.fu_list, list);
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file_list_unlock();
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spin_lock(&files_lock);
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BUG_ON(!list_empty(&file->f_u.fu_list));
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list_add(&file->f_u.fu_list, &sb->s_files);
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spin_unlock(&files_lock);
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}
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void file_kill(struct file *file)
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void file_sb_list_del(struct file *file)
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{
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if (!list_empty(&file->f_u.fu_list)) {
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file_list_lock();
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spin_lock(&files_lock);
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list_del_init(&file->f_u.fu_list);
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file_list_unlock();
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spin_unlock(&files_lock);
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}
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}
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@ -361,7 +358,7 @@ int fs_may_remount_ro(struct super_block *sb)
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struct file *file;
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/* Check that no files are currently opened for writing. */
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file_list_lock();
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spin_lock(&files_lock);
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list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
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struct inode *inode = file->f_path.dentry->d_inode;
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@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb)
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if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
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goto too_bad;
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}
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file_list_unlock();
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spin_unlock(&files_lock);
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return 1; /* Tis' cool bro. */
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too_bad:
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file_list_unlock();
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spin_unlock(&files_lock);
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return 0;
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}
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@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb)
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struct file *f;
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retry:
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file_list_lock();
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spin_lock(&files_lock);
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list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
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struct vfsmount *mnt;
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if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
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@ -408,16 +405,13 @@ void mark_files_ro(struct super_block *sb)
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continue;
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file_release_write(f);
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mnt = mntget(f->f_path.mnt);
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file_list_unlock();
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/*
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* This can sleep, so we can't hold
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* the file_list_lock() spinlock.
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*/
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/* This can sleep, so we can't hold the spinlock. */
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spin_unlock(&files_lock);
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mnt_drop_write(mnt);
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mntput(mnt);
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goto retry;
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}
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file_list_unlock();
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spin_unlock(&files_lock);
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}
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void __init files_init(unsigned long mempages)
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@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
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f->f_path.mnt = mnt;
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f->f_pos = 0;
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f->f_op = fops_get(inode->i_fop);
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file_move(f, &inode->i_sb->s_files);
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file_sb_list_add(f, inode->i_sb);
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error = security_dentry_open(f, cred);
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if (error)
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@ -721,7 +721,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
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mnt_drop_write(mnt);
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}
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}
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file_kill(f);
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file_sb_list_del(f);
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f->f_path.dentry = NULL;
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f->f_path.mnt = NULL;
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cleanup_file:
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@ -944,9 +944,6 @@ struct file {
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unsigned long f_mnt_write_state;
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#endif
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};
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extern spinlock_t files_lock;
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#define file_list_lock() spin_lock(&files_lock);
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#define file_list_unlock() spin_unlock(&files_lock);
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#define get_file(x) atomic_long_inc(&(x)->f_count)
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#define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1)
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@ -2188,8 +2185,8 @@ static inline void insert_inode_hash(struct inode *inode) {
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__insert_inode_hash(inode, inode->i_ino);
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}
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extern void file_move(struct file *f, struct list_head *list);
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extern void file_kill(struct file *f);
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extern void file_sb_list_add(struct file *f, struct super_block *sb);
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extern void file_sb_list_del(struct file *f);
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#ifdef CONFIG_BLOCK
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extern void submit_bio(int, struct bio *);
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extern int bdev_read_only(struct block_device *);
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@ -470,6 +470,7 @@ extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);
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extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty);
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extern struct mutex tty_mutex;
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extern spinlock_t tty_files_lock;
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extern void tty_write_unlock(struct tty_struct *tty);
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extern int tty_write_lock(struct tty_struct *tty, int ndelay);
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@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
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tty = get_current_tty();
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if (tty) {
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file_list_lock();
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spin_lock(&tty_files_lock);
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if (!list_empty(&tty->tty_files)) {
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struct inode *inode;
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drop_tty = 1;
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}
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}
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file_list_unlock();
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spin_unlock(&tty_files_lock);
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tty_kref_put(tty);
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}
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/* Reset controlling tty. */
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