Commit ee2ffa0d authored by Nick Piggin's avatar Nick Piggin Committed by Al Viro

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: default avatarAndi Kleen <ak@linux.intel.com>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: default avatarNick Piggin <npiggin@kernel.dk>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b04f784e
...@@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp) ...@@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp)
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
filp->private_data = tty; 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); retval = devpts_pty_new(inode, tty->link);
if (retval) if (retval)
......
...@@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ ...@@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
DEFINE_MUTEX(tty_mutex); DEFINE_MUTEX(tty_mutex);
EXPORT_SYMBOL(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_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t tty_write(struct file *, const 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 *, 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) ...@@ -235,11 +238,11 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
struct list_head *p; struct list_head *p;
int count = 0; int count = 0;
file_list_lock(); spin_lock(&tty_files_lock);
list_for_each(p, &tty->tty_files) { list_for_each(p, &tty->tty_files) {
count++; count++;
} }
file_list_unlock(); spin_unlock(&tty_files_lock);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY && if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE && tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count) tty->link && tty->link->count)
...@@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty) ...@@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty)
workqueue with the lock held */ workqueue with the lock held */
check_tty_count(tty, "tty_hangup"); 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 ? */ /* This breaks for file handles being sent over AF_UNIX sockets ? */
list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
if (filp->f_op->write == redirected_tty_write) if (filp->f_op->write == redirected_tty_write)
...@@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty) ...@@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty)
__tty_fasync(-1, filp, 0); /* can't block */ __tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops; filp->f_op = &hung_up_tty_fops;
} }
file_list_unlock(); spin_unlock(&tty_files_lock);
tty_ldisc_hangup(tty); tty_ldisc_hangup(tty);
...@@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work) ...@@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work)
tty_driver_kref_put(driver); tty_driver_kref_put(driver);
module_put(driver->owner); module_put(driver->owner);
file_list_lock(); spin_lock(&tty_files_lock);
list_del_init(&tty->tty_files); list_del_init(&tty->tty_files);
file_list_unlock(); spin_unlock(&tty_files_lock);
put_pid(tty->pgrp); put_pid(tty->pgrp);
put_pid(tty->session); put_pid(tty->session);
...@@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp) ...@@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp)
* - do_tty_hangup no longer sees this file descriptor as * - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups. * 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; filp->private_data = NULL;
/* /*
...@@ -1840,7 +1846,11 @@ got_driver: ...@@ -1840,7 +1846,11 @@ got_driver:
} }
filp->private_data = tty; 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"); check_tty_count(tty, "tty_open");
if (tty->driver->type == TTY_DRIVER_TYPE_PTY && if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER) tty->driver->subtype == PTY_TYPE_MASTER)
......
...@@ -32,8 +32,7 @@ struct files_stat_struct files_stat = { ...@@ -32,8 +32,7 @@ struct files_stat_struct files_stat = {
.max_files = NR_FILE .max_files = NR_FILE
}; };
/* public. Not pretty! */ static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock);
/* SLAB cache for file structures */ /* SLAB cache for file structures */
static struct kmem_cache *filp_cachep __read_mostly; static struct kmem_cache *filp_cachep __read_mostly;
...@@ -249,7 +248,7 @@ static void __fput(struct file *file) ...@@ -249,7 +248,7 @@ static void __fput(struct file *file)
cdev_put(inode->i_cdev); cdev_put(inode->i_cdev);
fops_put(file->f_op); fops_put(file->f_op);
put_pid(file->f_owner.pid); put_pid(file->f_owner.pid);
file_kill(file); file_sb_list_del(file);
if (file->f_mode & FMODE_WRITE) if (file->f_mode & FMODE_WRITE)
drop_file_write_access(file); drop_file_write_access(file);
file->f_path.dentry = NULL; file->f_path.dentry = NULL;
...@@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed) ...@@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed)
return file; return file;
} }
void put_filp(struct file *file) void put_filp(struct file *file)
{ {
if (atomic_long_dec_and_test(&file->f_count)) { if (atomic_long_dec_and_test(&file->f_count)) {
security_file_free(file); security_file_free(file);
file_kill(file); file_sb_list_del(file);
file_free(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) spin_lock(&files_lock);
return; BUG_ON(!list_empty(&file->f_u.fu_list));
file_list_lock(); list_add(&file->f_u.fu_list, &sb->s_files);
list_move(&file->f_u.fu_list, list); spin_unlock(&files_lock);
file_list_unlock();
} }
void file_kill(struct file *file) void file_sb_list_del(struct file *file)
{ {
if (!list_empty(&file->f_u.fu_list)) { if (!list_empty(&file->f_u.fu_list)) {
file_list_lock(); spin_lock(&files_lock);
list_del_init(&file->f_u.fu_list); 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) ...@@ -361,7 +358,7 @@ int fs_may_remount_ro(struct super_block *sb)
struct file *file; struct file *file;
/* Check that no files are currently opened for writing. */ /* 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) { list_for_each_entry(file, &sb->s_files, f_u.fu_list) {
struct inode *inode = file->f_path.dentry->d_inode; struct inode *inode = file->f_path.dentry->d_inode;
...@@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb) ...@@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb)
if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE))
goto too_bad; goto too_bad;
} }
file_list_unlock(); spin_unlock(&files_lock);
return 1; /* Tis' cool bro. */ return 1; /* Tis' cool bro. */
too_bad: too_bad:
file_list_unlock(); spin_unlock(&files_lock);
return 0; return 0;
} }
...@@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb) ...@@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb)
struct file *f; struct file *f;
retry: retry:
file_list_lock(); spin_lock(&files_lock);
list_for_each_entry(f, &sb->s_files, f_u.fu_list) { list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
struct vfsmount *mnt; struct vfsmount *mnt;
if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) if (!S_ISREG(f->f_path.dentry->d_inode->i_mode))
...@@ -408,16 +405,13 @@ retry: ...@@ -408,16 +405,13 @@ retry:
continue; continue;
file_release_write(f); file_release_write(f);
mnt = mntget(f->f_path.mnt); mnt = mntget(f->f_path.mnt);
file_list_unlock(); /* This can sleep, so we can't hold the spinlock. */
/* spin_unlock(&files_lock);
* This can sleep, so we can't hold
* the file_list_lock() spinlock.
*/
mnt_drop_write(mnt); mnt_drop_write(mnt);
mntput(mnt); mntput(mnt);
goto retry; goto retry;
} }
file_list_unlock(); spin_unlock(&files_lock);
} }
void __init files_init(unsigned long mempages) void __init files_init(unsigned long mempages)
......
...@@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, ...@@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
f->f_path.mnt = mnt; f->f_path.mnt = mnt;
f->f_pos = 0; f->f_pos = 0;
f->f_op = fops_get(inode->i_fop); 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); error = security_dentry_open(f, cred);
if (error) if (error)
...@@ -721,7 +721,7 @@ cleanup_all: ...@@ -721,7 +721,7 @@ cleanup_all:
mnt_drop_write(mnt); mnt_drop_write(mnt);
} }
} }
file_kill(f); file_sb_list_del(f);
f->f_path.dentry = NULL; f->f_path.dentry = NULL;
f->f_path.mnt = NULL; f->f_path.mnt = NULL;
cleanup_file: cleanup_file:
......
...@@ -944,9 +944,6 @@ struct file { ...@@ -944,9 +944,6 @@ struct file {
unsigned long f_mnt_write_state; unsigned long f_mnt_write_state;
#endif #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 get_file(x) atomic_long_inc(&(x)->f_count)
#define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1) #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) { ...@@ -2188,8 +2185,8 @@ static inline void insert_inode_hash(struct inode *inode) {
__insert_inode_hash(inode, inode->i_ino); __insert_inode_hash(inode, inode->i_ino);
} }
extern void file_move(struct file *f, struct list_head *list); extern void file_sb_list_add(struct file *f, struct super_block *sb);
extern void file_kill(struct file *f); extern void file_sb_list_del(struct file *f);
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
extern void submit_bio(int, struct bio *); extern void submit_bio(int, struct bio *);
extern int bdev_read_only(struct block_device *); extern int bdev_read_only(struct block_device *);
......
...@@ -470,6 +470,7 @@ extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty); ...@@ -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 tty_struct *tty_pair_get_pty(struct tty_struct *tty);
extern struct mutex tty_mutex; extern struct mutex tty_mutex;
extern spinlock_t tty_files_lock;
extern void tty_write_unlock(struct tty_struct *tty); extern void tty_write_unlock(struct tty_struct *tty);
extern int tty_write_lock(struct tty_struct *tty, int ndelay); extern int tty_write_lock(struct tty_struct *tty, int ndelay);
......
...@@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, ...@@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
tty = get_current_tty(); tty = get_current_tty();
if (tty) { if (tty) {
file_list_lock(); spin_lock(&tty_files_lock);
if (!list_empty(&tty->tty_files)) { if (!list_empty(&tty->tty_files)) {
struct inode *inode; struct inode *inode;
...@@ -2186,7 +2186,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, ...@@ -2186,7 +2186,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
drop_tty = 1; drop_tty = 1;
} }
} }
file_list_unlock(); spin_unlock(&tty_files_lock);
tty_kref_put(tty); tty_kref_put(tty);
} }
/* Reset controlling tty. */ /* Reset controlling tty. */
......
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