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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>
This commit is contained in:
Nick Piggin 2010-08-18 04:37:35 +10:00 committed by Al Viro
parent b04f784e5d
commit ee2ffa0dfd
7 changed files with 48 additions and 42 deletions
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6
drivers/char/pty.c
View File

@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp)
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
filp->private_data = tty;
file_move(filp, &tty->tty_files);
file_sb_list_del(filp); /* __dentry_open has put it on the sb list */
spin_lock(&tty_files_lock);
list_add(&filp->f_u.fu_list, &tty->tty_files);
spin_unlock(&tty_files_lock);
retval = devpts_pty_new(inode, tty->link);
if (retval)

26
drivers/char/tty_io.c
View File

@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
DEFINE_MUTEX(tty_mutex);
EXPORT_SYMBOL(tty_mutex);
/* Spinlock to protect the tty->tty_files list */
DEFINE_SPINLOCK(tty_files_lock);
static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
ssize_t redirected_tty_write(struct file *, const char __user *,
@ -235,11 +238,11 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
struct list_head *p;
int count = 0;
file_list_lock();
spin_lock(&tty_files_lock);
list_for_each(p, &tty->tty_files) {
count++;
}
file_list_unlock();
spin_unlock(&tty_files_lock);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count)
@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty)
workqueue with the lock held */
check_tty_count(tty, "tty_hangup");
file_list_lock();
spin_lock(&tty_files_lock);
/* This breaks for file handles being sent over AF_UNIX sockets ? */
list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
if (filp->f_op->write == redirected_tty_write)
@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty)
__tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops;
}
file_list_unlock();
spin_unlock(&tty_files_lock);
tty_ldisc_hangup(tty);
@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work)
tty_driver_kref_put(driver);
module_put(driver->owner);
file_list_lock();
spin_lock(&tty_files_lock);
list_del_init(&tty->tty_files);
file_list_unlock();
spin_unlock(&tty_files_lock);
put_pid(tty->pgrp);
put_pid(tty->session);
@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp)
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
file_kill(filp);
spin_lock(&tty_files_lock);
BUG_ON(list_empty(&filp->f_u.fu_list));
list_del_init(&filp->f_u.fu_list);
spin_unlock(&tty_files_lock);
filp->private_data = NULL;
/*
@ -1840,7 +1846,11 @@ got_driver:
}
filp->private_data = tty;
file_move(filp, &tty->tty_files);
BUG_ON(list_empty(&filp->f_u.fu_list));
file_sb_list_del(filp); /* __dentry_open has put it on the sb list */
spin_lock(&tty_files_lock);
list_add(&filp->f_u.fu_list, &tty->tty_files);
spin_unlock(&tty_files_lock);
check_tty_count(tty, "tty_open");
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)

42
fs/file_table.c
View File

@ -32,8 +32,7 @@ struct files_stat_struct files_stat = {
.max_files = NR_FILE
};
/* public. Not pretty! */
__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
/* SLAB cache for file structures */
static struct kmem_cache *filp_cachep __read_mostly;
@ -249,7 +248,7 @@ static void __fput(struct file *file)
cdev_put(inode->i_cdev);
fops_put(file->f_op);
put_pid(file->f_owner.pid);
file_kill(file);
file_sb_list_del(file);
if (file->f_mode & FMODE_WRITE)
drop_file_write_access(file);
file->f_path.dentry = NULL;
@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed)
return file;
}
void put_filp(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
security_file_free(file);
file_kill(file);
file_sb_list_del(file);
file_free(file);
}
}
void file_move(struct file *file, struct list_head *list)
void file_sb_list_add(struct file *file, struct super_block *sb)
{
if (!list)
return;
file_list_lock();
list_move(&file->f_u.fu_list, list);
file_list_unlock();
spin_lock(&files_lock);
BUG_ON(!list_empty(&file->f_u.fu_list));
list_add(&file->f_u.fu_list, &sb->s_files);
spin_unlock(&files_lock);
}
void file_kill(struct file *file)
void file_sb_list_del(struct file *file)
{
if (!list_empty(&file->f_u.fu_list)) {
file_list_lock();
spin_lock(&files_lock);
list_del_init(&file->f_u.fu_list);
file_list_unlock();
spin_unlock(&files_lock);
}
}
@ -361,7 +358,7 @@ int fs_may_remount_ro(struct super_block *sb)
struct file *file;
/* Check that no files are currently opened for writing. */
file_list_lock();
spin_lock(&files_lock);
list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
struct inode *inode = file->f_path.dentry->d_inode;
@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb)
if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
goto too_bad;
}
file_list_unlock();
spin_unlock(&files_lock);
return 1; /* Tis' cool bro. */
too_bad:
file_list_unlock();
spin_unlock(&files_lock);
return 0;
}
@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb)
struct file *f;
retry:
file_list_lock();
spin_lock(&files_lock);
list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
struct vfsmount *mnt;
if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
@ -408,16 +405,13 @@ retry:
continue;
file_release_write(f);
mnt = mntget(f->f_path.mnt);
file_list_unlock();
/*
* This can sleep, so we can't hold
* the file_list_lock() spinlock.
*/
/* This can sleep, so we can't hold the spinlock. */
spin_unlock(&files_lock);
mnt_drop_write(mnt);
mntput(mnt);
goto retry;
}
file_list_unlock();
spin_unlock(&files_lock);
}
void __init files_init(unsigned long mempages)

4
fs/open.c
View File

@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_path.mnt = mnt;
f->f_pos = 0;
f->f_op = fops_get(inode->i_fop);
file_move(f, &inode->i_sb->s_files);
file_sb_list_add(f, inode->i_sb);
error = security_dentry_open(f, cred);
if (error)
@ -721,7 +721,7 @@ cleanup_all:
mnt_drop_write(mnt);
}
}
file_kill(f);
file_sb_list_del(f);
f->f_path.dentry = NULL;
f->f_path.mnt = NULL;
cleanup_file:

7
include/linux/fs.h
View File

@ -944,9 +944,6 @@ struct file {
unsigned long f_mnt_write_state;
#endif
};
extern spinlock_t files_lock;
#define file_list_lock() spin_lock(&files_lock);
#define file_list_unlock() spin_unlock(&files_lock);
#define get_file(x) atomic_long_inc(&(x)->f_count)
#define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1)
@ -2188,8 +2185,8 @@ static inline void insert_inode_hash(struct inode *inode) {
__insert_inode_hash(inode, inode->i_ino);
}
extern void file_move(struct file *f, struct list_head *list);
extern void file_kill(struct file *f);
extern void file_sb_list_add(struct file *f, struct super_block *sb);
extern void file_sb_list_del(struct file *f);
#ifdef CONFIG_BLOCK
extern void submit_bio(int, struct bio *);
extern int bdev_read_only(struct block_device *);

1
include/linux/tty.h
View File

@ -470,6 +470,7 @@ extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);
extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty);
extern struct mutex tty_mutex;
extern spinlock_t tty_files_lock;
extern void tty_write_unlock(struct tty_struct *tty);
extern int tty_write_lock(struct tty_struct *tty, int ndelay);

4
security/selinux/hooks.c
View File

@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
tty = get_current_tty();
if (tty) {
file_list_lock();
spin_lock(&tty_files_lock);
if (!list_empty(&tty->tty_files)) {
struct inode *inode;
@ -2186,7 +2186,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
drop_tty = 1;
}
}
file_list_unlock();
spin_unlock(&tty_files_lock);
tty_kref_put(tty);
}
/* Reset controlling tty. */