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Subject[patch 01/27] fs: cleanup files_lock
Lock tty_files with tty_mutex, provide helpers to manipulate the per-sb
files list, and unexport the files_lock spinlock.
---
drivers/char/pty.c | 6 +++-
drivers/char/tty_io.c | 39 +++++++++++++++++++--------
fs/file_table.c | 66 ++++++++++++++++++++++++++++++++++-------------
fs/open.c | 4 +-
fs/super.c | 39 ---------------------------
include/linux/fs.h | 8 ++---
security/selinux/hooks.c | 4 +-
7 files changed, 89 insertions(+), 77 deletions(-)

Index: linux-2.6/drivers/char/pty.c
===================================================================
--- linux-2.6.orig/drivers/char/pty.c
+++ linux-2.6/drivers/char/pty.c
@@ -662,7 +662,11 @@ static int __ptmx_open(struct inode *ino

set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
filp->private_data = tty;
- file_move(filp, &tty->tty_files);
+
+ mutex_lock(&tty_mutex);
+ file_list_del(filp);
+ list_add(&filp->f_u.fu_list, &tty->tty_files);
+ mutex_unlock(&tty_mutex);

retval = devpts_pty_new(inode, tty->link);
if (retval)
Index: linux-2.6/drivers/char/tty_io.c
===================================================================
--- linux-2.6.orig/drivers/char/tty_io.c
+++ linux-2.6/drivers/char/tty_io.c
@@ -229,17 +229,15 @@ int tty_paranoia_check(struct tty_struct
return 0;
}

-static int check_tty_count(struct tty_struct *tty, const char *routine)
+static int __check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
struct list_head *p;
int count = 0;

- file_list_lock();
list_for_each(p, &tty->tty_files) {
count++;
}
- file_list_unlock();
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count)
@@ -254,6 +252,19 @@ static int check_tty_count(struct tty_st
return 0;
}

+static int check_tty_count(struct tty_struct *tty, const char *routine)
+{
+ int ret = 0;
+
+#ifdef CHECK_TTY_COUNT
+ mutex_lock(&tty_mutex);
+ ret = __check_tty_count(tty, routine);
+ mutex_unlock(&tty_mutex);
+#endif
+
+ return ret;
+}
+
/**
* get_tty_driver - find device of a tty
* @dev_t: device identifier
@@ -543,6 +554,8 @@ static void do_tty_hangup(struct work_st
if (!tty)
return;

+ mutex_lock(&tty_mutex);
+
/* inuse_filps is protected by the single kernel lock */
lock_kernel();

@@ -553,8 +566,7 @@ static void do_tty_hangup(struct work_st
}
spin_unlock(&redirect_lock);

- check_tty_count(tty, "do_tty_hangup");
- file_list_lock();
+ __check_tty_count(tty, "do_tty_hangup");
/* 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)
@@ -565,7 +577,7 @@ static void do_tty_hangup(struct work_st
tty_fasync(-1, filp, 0); /* can't block */
filp->f_op = &hung_up_tty_fops;
}
- file_list_unlock();
+ mutex_unlock(&tty_mutex);
/*
* FIXME! What are the locking issues here? This may me overdoing
* things... This question is especially important now that we've
@@ -1467,9 +1479,9 @@ static void release_one_tty(struct kref
tty_driver_kref_put(driver);
module_put(driver->owner);

- file_list_lock();
+ mutex_lock(&tty_mutex);
list_del_init(&tty->tty_files);
- file_list_unlock();
+ mutex_unlock(&tty_mutex);

free_tty_struct(tty);
}
@@ -1678,7 +1690,8 @@ void tty_release_dev(struct file *filp)
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
- file_kill(filp);
+ BUG_ON(list_empty(&filp->f_u.fu_list));
+ list_del_init(&filp->f_u.fu_list);
filp->private_data = NULL;

/*
@@ -1836,8 +1849,12 @@ got_driver:
return PTR_ERR(tty);

filp->private_data = tty;
- file_move(filp, &tty->tty_files);
- check_tty_count(tty, "tty_open");
+ mutex_lock(&tty_mutex);
+ BUG_ON(list_empty(&filp->f_u.fu_list));
+ file_list_del(filp); /* __dentry_open has put it on the sb list */
+ list_add(&filp->f_u.fu_list, &tty->tty_files);
+ __check_tty_count(tty, "tty_open");
+ mutex_unlock(&tty_mutex);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
noctty = 1;
Index: linux-2.6/fs/file_table.c
===================================================================
--- linux-2.6.orig/fs/file_table.c
+++ linux-2.6/fs/file_table.c
@@ -30,8 +30,7 @@ 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;
@@ -285,7 +284,7 @@ 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_list_del(file);
if (file->f_mode & FMODE_WRITE)
drop_file_write_access(file);
file->f_path.dentry = NULL;
@@ -347,31 +346,29 @@ struct file *fget_light(unsigned int fd,
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_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_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);
}
}

@@ -380,7 +377,7 @@ int fs_may_remount_ro(struct super_block
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;

@@ -392,13 +389,48 @@ int fs_may_remount_ro(struct super_block
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;
}

+/**
+ * mark_files_ro - mark all files read-only
+ * @sb: superblock in question
+ *
+ * All files are marked read-only. We don't care about pending
+ * delete files so this should be used in 'force' mode only.
+ */
+void mark_files_ro(struct super_block *sb)
+{
+ struct file *f;
+
+retry:
+ 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))
+ continue;
+ if (!file_count(f))
+ continue;
+ if (!(f->f_mode & FMODE_WRITE))
+ continue;
+ f->f_mode &= ~FMODE_WRITE;
+ if (file_check_writeable(f) != 0)
+ continue;
+ file_release_write(f);
+ mnt = mntget(f->f_path.mnt);
+ /* This can sleep, so we can't hold the spinlock. */
+ spin_unlock(&files_lock);
+ mnt_drop_write(mnt);
+ mntput(mnt);
+ goto retry;
+ }
+ spin_unlock(&files_lock);
+}
+
void __init files_init(unsigned long mempages)
{
int n;
Index: linux-2.6/fs/open.c
===================================================================
--- linux-2.6.orig/fs/open.c
+++ linux-2.6/fs/open.c
@@ -828,7 +828,7 @@ static struct file *__dentry_open(struct
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)
@@ -873,7 +873,7 @@ cleanup_all:
mnt_drop_write(mnt);
}
}
- file_kill(f);
+ file_list_del(f);
f->f_path.dentry = NULL;
f->f_path.mnt = NULL;
cleanup_file:
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -934,9 +934,6 @@ 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 file_count(x) atomic_long_read(&(x)->f_count)
@@ -2021,6 +2018,7 @@ extern const struct file_operations read
extern const struct file_operations write_pipefifo_fops;
extern const struct file_operations rdwr_pipefifo_fops;

+extern void mark_files_ro(struct super_block *sb);
extern int fs_may_remount_ro(struct super_block *);

#ifdef CONFIG_BLOCK
@@ -2172,8 +2170,8 @@ static inline void insert_inode_hash(str
}

extern struct file * get_empty_filp(void);
-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_list_del(struct file *f);
#ifdef CONFIG_BLOCK
struct bio;
extern void submit_bio(int, struct bio *);
Index: linux-2.6/fs/super.c
===================================================================
--- linux-2.6.orig/fs/super.c
+++ linux-2.6/fs/super.c
@@ -588,45 +588,6 @@ out:
}

/**
- * mark_files_ro - mark all files read-only
- * @sb: superblock in question
- *
- * All files are marked read-only. We don't care about pending
- * delete files so this should be used in 'force' mode only.
- */
-
-static void mark_files_ro(struct super_block *sb)
-{
- struct file *f;
-
-retry:
- file_list_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))
- continue;
- if (!file_count(f))
- continue;
- if (!(f->f_mode & FMODE_WRITE))
- continue;
- f->f_mode &= ~FMODE_WRITE;
- if (file_check_writeable(f) != 0)
- 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.
- */
- mnt_drop_write(mnt);
- mntput(mnt);
- goto retry;
- }
- file_list_unlock();
-}
-
-/**
* do_remount_sb - asks filesystem to change mount options.
* @sb: superblock in question
* @flags: numeric part of options
Index: linux-2.6/security/selinux/hooks.c
===================================================================
--- linux-2.6.orig/security/selinux/hooks.c
+++ linux-2.6/security/selinux/hooks.c
@@ -2244,7 +2244,7 @@ static inline void flush_unauthorized_fi

tty = get_current_tty();
if (tty) {
- file_list_lock();
+ mutex_lock(&tty_mutex);
if (!list_empty(&tty->tty_files)) {
struct inode *inode;

@@ -2260,7 +2260,7 @@ static inline void flush_unauthorized_fi
drop_tty = 1;
}
}
- file_list_unlock();
+ mutex_unlock(&tty_mutex);
tty_kref_put(tty);
}
/* Reset controlling tty. */



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