ANDROID: sdcardfs: Add sandbox

[GitHub/LineageOS/android_kernel_samsung_universal7580.git] / fs / sync.c

/*
 * High-level sync()-related operations
 */

#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/writeback.h>
#include <linux/syscalls.h>
#include <linux/linkage.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/backing-dev.h>
#include "internal.h"

#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
                        SYNC_FILE_RANGE_WAIT_AFTER)

/* Interruptible sync for Samsung Mobile Device */
#ifdef CONFIG_INTERRUPTIBLE_SYNC

#include <linux/workqueue.h>
#include <linux/suspend.h>
#include <linux/delay.h>

//#define CONFIG_INTR_SYNC_DEBUG

#ifdef CONFIG_INTR_SYNC_DEBUG
#define dbg_print       printk
#else
#define dbg_print(...)
#endif

enum {
        INTR_SYNC_STATE_IDLE = 0,
        INTR_SYNC_STATE_QUEUED,
        INTR_SYNC_STATE_RUNNING,
        INTR_SYNC_STATE_MAX
};

struct interruptible_sync_work {
        int id;
        int ret;
        unsigned int waiter;
        unsigned int state;
        unsigned long version;
        spinlock_t lock;
        struct completion done;
        struct work_struct work;
};

/* Initially, intr_sync_work has zero pending */
static struct interruptible_sync_work intr_sync_work[2];

/* Last work start time */
static atomic_t running_work_idx;

/* intr_sync_wq will be created when intr_sync() is called at first time.
 * And it is alive till system shutdown */
static struct workqueue_struct *intr_sync_wq;

/* It prevents double allocation of intr_sync_wq */
static DEFINE_MUTEX(intr_sync_wq_lock);

static inline struct interruptible_sync_work *INTR_SYNC_WORK(struct work_struct *work) 
{
        return container_of(work, struct interruptible_sync_work, work);
}

static void do_intr_sync(struct work_struct *work)
{
        struct interruptible_sync_work *sync_work = INTR_SYNC_WORK(work);
        int ret = 0;
        unsigned int waiter;

        spin_lock(&sync_work->lock);
        atomic_set(&running_work_idx, sync_work->id);
        sync_work->state = INTR_SYNC_STATE_RUNNING;
        waiter = sync_work->waiter;
        spin_unlock(&sync_work->lock);

        dbg_print("\nintr_sync: %s: call sys_sync on work[%d]-%ld\n",
                        __func__, sync_work->id, sync_work->version);

        /* if no one waits, do not call sync() */
        if (waiter) {
                ret = sys_sync();
                dbg_print("\nintr_sync: %s: done sys_sync on work[%d]-%ld\n",
                        __func__, sync_work->id, sync_work->version);
        } else {
                dbg_print("\nintr_sync: %s: cancel,no_wait on work[%d]-%ld\n",
                        __func__, sync_work->id, sync_work->version);
        }

        spin_lock(&sync_work->lock);
        sync_work->version++;
        sync_work->ret = ret;
        sync_work->state = INTR_SYNC_STATE_IDLE;
        complete_all(&sync_work->done);
        spin_unlock(&sync_work->lock);
}

/* wakeup functions that depend on PM facilities
 *
 * struct intr_wakeup_data  : wrapper structure for variables for PM
 *                            each thread has own instance of it
 * __prepare_wakeup_event() : prepare and check intr_wakeup_data
 * __check_wakeup_event()   : check wakeup-event with intr_wakeup_data
 */
struct intr_wakeup_data {
        unsigned int cnt;
};

static inline int __prepare_wakeup_event(struct intr_wakeup_data *wd)
{
        if (pm_get_wakeup_count(&wd->cnt, false))
                return 0;

        pr_info("intr_sync: detected wakeup events before sync\n");
        pm_print_active_wakeup_sources();
        return -EBUSY;
}

static inline  int __check_wakeup_event(struct intr_wakeup_data *wd)
{
        unsigned int cnt, no_inpr;

        no_inpr = pm_get_wakeup_count(&cnt, false);
        if (no_inpr && (cnt == wd->cnt))
                return 0;

        pr_info("intr_sync: detected wakeup events(no_inpr: %u cnt: %u->%u)\n",
                no_inpr, wd->cnt, cnt);
        pm_print_active_wakeup_sources();
        return -EBUSY;
}

/* Interruptible Sync
 *
 * intr_sync() is same function as sys_sync() except that it can wakeup.
 * It's possible because of inter_syncd workqueue.
 *
 * If system gets wakeup event while sync_work is running,
 * just return -EBUSY, otherwise 0.
 *
 * If intr_sync() is called again while sync_work is running, it will enqueue
 * idle sync_work to work_queue and wait the completion of it.
 * If there is not idle sync_work but queued one, it just increases waiter by 1,
 * and waits the completion of queued sync_work.
 *
 * If you want to know returned value of sys_sync(),
 * you can get it from the argument, sync_ret
 */

int intr_sync(int *sync_ret)
{
        int ret;
enqueue_sync_wait:
        /* If the workqueue exists, try to enqueue work and wait */
        if (likely(intr_sync_wq)) {
                struct interruptible_sync_work *sync_work;
                struct intr_wakeup_data wd;
                int work_idx;
                int work_ver;

find_idle:
                work_idx = !atomic_read(&running_work_idx);
                sync_work = &intr_sync_work[work_idx];

                /* Prepare intr_wakeup_data and check wakeup event:
                 * If a wakeup-event is detected, wake up right now
                 */
                if (__prepare_wakeup_event(&wd)) {
                        dbg_print("intr_sync: detect wakeup event "
                                "before waiting work[%d]\n", work_idx);
                        return -EBUSY;
                }

                dbg_print("\nintr_sync: try to wait work[%d]\n", work_idx);

                spin_lock(&sync_work->lock);
                work_ver = sync_work->version;
                if (sync_work->state == INTR_SYNC_STATE_RUNNING) {
                        spin_unlock(&sync_work->lock);
                        dbg_print("intr_sync: work[%d] is already running, "
                                "find idle work\n", work_idx);
                        goto find_idle;
                }

                sync_work->waiter++;
                if (sync_work->state == INTR_SYNC_STATE_IDLE) {
                        dbg_print("intr_sync: enqueue work[%d]\n", work_idx);
                        sync_work->state = INTR_SYNC_STATE_QUEUED;
                        INIT_COMPLETION(sync_work->done);
                        queue_work(intr_sync_wq, &sync_work->work);
                }
                spin_unlock(&sync_work->lock);
                
                do {
                        /* Check wakeup event first before waiting:
                         * If a wakeup-event is detected, wake up right now
                         */
                        if  (__check_wakeup_event(&wd)) {
                                spin_lock(&sync_work->lock);
                                sync_work->waiter--;
                                spin_unlock(&sync_work->lock);
                                dbg_print("intr_sync: detect wakeup event "
                                        "while waiting work[%d]\n", work_idx);
                                return -EBUSY;
                        }

//                      dbg_print("intr_sync: waiting work[%d]\n", work_idx);
                        /* Return 0 if timed out, or positive if completed. */
                        ret = wait_for_completion_io_timeout(
                                        &sync_work->done, HZ/10);
                        /* A work that we are waiting for has done. */
                        if ((ret > 0) || (sync_work->version != work_ver))
                                break;
//                      dbg_print("intr_sync: timeout work[%d]\n", work_idx);
                } while (1);

                spin_lock(&sync_work->lock);
                sync_work->waiter--;
                if (sync_ret)
                        *sync_ret = sync_work->ret;
                spin_unlock(&sync_work->lock);
                dbg_print("intr_sync: sync work[%d] is done with ret(%d)\n",
                                work_idx, sync_work->ret);
                return 0;
        }

        /* check whether a workqueue exists or not under locked state.
         * Create new one if a workqueue is not created yet.
         */
        mutex_lock(&intr_sync_wq_lock);
        if (likely(!intr_sync_wq)) {
                intr_sync_work[0].id = 0;
                intr_sync_work[1].id = 1;
                INIT_WORK(&intr_sync_work[0].work, do_intr_sync);
                INIT_WORK(&intr_sync_work[1].work, do_intr_sync);
                spin_lock_init(&intr_sync_work[0].lock);
                spin_lock_init(&intr_sync_work[1].lock);
                init_completion(&intr_sync_work[0].done);
                init_completion(&intr_sync_work[1].done);
                intr_sync_wq = alloc_ordered_workqueue("intr_syncd", WQ_MEM_RECLAIM);
                dbg_print("\nintr_sync: try to allocate intr_sync_queue\n");
        }
        mutex_unlock(&intr_sync_wq_lock);

        /* try to enqueue work again if the workqueue is created successfully */
        if (likely(intr_sync_wq))
                goto enqueue_sync_wait;

        printk("\nintr_sync: allocation failed, just call sync()\n");
        ret = sys_sync();
        if (sync_ret)
                *sync_ret = ret;
        return 0;
}
#else /* CONFIG_INTERRUPTIBLE_SYNC */
int intr_sync(int *sync_ret)
{
        int ret = sys_sync();
        if (sync_ret)
                *sync_ret = ret;
        return 0;
}
#endif /* CONFIG_INTERRUPTIBLE_SYNC */

/*
 * Do the filesystem syncing work. For simple filesystems
 * writeback_inodes_sb(sb) just dirties buffers with inodes so we have to
 * submit IO for these buffers via __sync_blockdev(). This also speeds up the
 * wait == 1 case since in that case write_inode() functions do
 * sync_dirty_buffer() and thus effectively write one block at a time.
 */
static int __sync_filesystem(struct super_block *sb, int wait)
{
        if (wait)
                sync_inodes_sb(sb);
        else
                writeback_inodes_sb(sb, WB_REASON_SYNC);

        if (sb->s_op->sync_fs)
                sb->s_op->sync_fs(sb, wait);
        return __sync_blockdev(sb->s_bdev, wait);
}

/*
 * Write out and wait upon all dirty data associated with this
 * superblock.  Filesystem data as well as the underlying block
 * device.  Takes the superblock lock.
 */
int sync_filesystem(struct super_block *sb)
{
        int ret;

        /*
         * We need to be protected against the filesystem going from
         * r/o to r/w or vice versa.
         */
        WARN_ON(!rwsem_is_locked(&sb->s_umount));

        /*
         * No point in syncing out anything if the filesystem is read-only.
         */
        if (sb->s_flags & MS_RDONLY)
                return 0;

        ret = __sync_filesystem(sb, 0);
        if (ret < 0)
                return ret;
        return __sync_filesystem(sb, 1);
}
EXPORT_SYMBOL_GPL(sync_filesystem);

static void sync_inodes_one_sb(struct super_block *sb, void *arg)
{
        if (!(sb->s_flags & MS_RDONLY))
                sync_inodes_sb(sb);
}

static void sync_fs_one_sb(struct super_block *sb, void *arg)
{
        if (!(sb->s_flags & MS_RDONLY) && sb->s_op->sync_fs)
                sb->s_op->sync_fs(sb, *(int *)arg);
}

static void fdatawrite_one_bdev(struct block_device *bdev, void *arg)
{
        filemap_fdatawrite(bdev->bd_inode->i_mapping);
}

static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
{
        filemap_fdatawait(bdev->bd_inode->i_mapping);
}

/*
 * Sync everything. We start by waking flusher threads so that most of
 * writeback runs on all devices in parallel. Then we sync all inodes reliably
 * which effectively also waits for all flusher threads to finish doing
 * writeback. At this point all data is on disk so metadata should be stable
 * and we tell filesystems to sync their metadata via ->sync_fs() calls.
 * Finally, we writeout all block devices because some filesystems (e.g. ext2)
 * just write metadata (such as inodes or bitmaps) to block device page cache
 * and do not sync it on their own in ->sync_fs().
 */
SYSCALL_DEFINE0(sync)
{
        int nowait = 0, wait = 1;

        wakeup_flusher_threads(0, WB_REASON_SYNC);
        iterate_supers(sync_inodes_one_sb, NULL);
        iterate_supers(sync_fs_one_sb, &nowait);
        iterate_supers(sync_fs_one_sb, &wait);
        iterate_bdevs(fdatawrite_one_bdev, NULL);
        iterate_bdevs(fdatawait_one_bdev, NULL);
        if (unlikely(laptop_mode))
                laptop_sync_completion();
        return 0;
}

static void do_sync_work(struct work_struct *work)
{
        int nowait = 0;

        /*
         * Sync twice to reduce the possibility we skipped some inodes / pages
         * because they were temporarily locked
         */
        iterate_supers(sync_inodes_one_sb, &nowait);
        iterate_supers(sync_fs_one_sb, &nowait);
        iterate_bdevs(fdatawrite_one_bdev, NULL);
        iterate_supers(sync_inodes_one_sb, &nowait);
        iterate_supers(sync_fs_one_sb, &nowait);
        iterate_bdevs(fdatawrite_one_bdev, NULL);
        printk("Emergency Sync complete\n");
        kfree(work);
}

void emergency_sync(void)
{
        struct work_struct *work;

        work = kmalloc(sizeof(*work), GFP_ATOMIC);
        if (work) {
                INIT_WORK(work, do_sync_work);
                schedule_work(work);
        }
}

/*
 * sync a single super
 */
SYSCALL_DEFINE1(syncfs, int, fd)
{
        struct fd f = fdget(fd);
        struct super_block *sb;
        int ret;

        if (!f.file)
                return -EBADF;
        sb = f.file->f_dentry->d_sb;

        down_read(&sb->s_umount);
        ret = sync_filesystem(sb);
        up_read(&sb->s_umount);

        fdput(f);
        return ret;
}

/**
 * vfs_fsync_range - helper to sync a range of data & metadata to disk
 * @file:               file to sync
 * @start:              offset in bytes of the beginning of data range to sync
 * @end:                offset in bytes of the end of data range (inclusive)
 * @datasync:           perform only datasync
 *
 * Write back data in range @start..@end and metadata for @file to disk.  If
 * @datasync is set only metadata needed to access modified file data is
 * written.
 */
int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
{
        if (!file->f_op || !file->f_op->fsync)
                return -EINVAL;
        return file->f_op->fsync(file, start, end, datasync);
}
EXPORT_SYMBOL(vfs_fsync_range);

/**
 * vfs_fsync - perform a fsync or fdatasync on a file
 * @file:               file to sync
 * @datasync:           only perform a fdatasync operation
 *
 * Write back data and metadata for @file to disk.  If @datasync is
 * set only metadata needed to access modified file data is written.
 */
int vfs_fsync(struct file *file, int datasync)
{
        return vfs_fsync_range(file, 0, LLONG_MAX, datasync);
}
EXPORT_SYMBOL(vfs_fsync);

static int do_fsync(unsigned int fd, int datasync)
{
        struct fd f = fdget(fd);
        int ret = -EBADF;

        if (f.file) {
                ret = vfs_fsync(f.file, datasync);
                fdput(f);
                inc_syscfs(current);
        }
        return ret;
}

SYSCALL_DEFINE1(fsync, unsigned int, fd)
{
        return do_fsync(fd, 0);
}

SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
{
        return do_fsync(fd, 1);
}

/**
 * generic_write_sync - perform syncing after a write if file / inode is sync
 * @file:       file to which the write happened
 * @pos:        offset where the write started
 * @count:      length of the write
 *
 * This is just a simple wrapper about our general syncing function.
 */
int generic_write_sync(struct file *file, loff_t pos, loff_t count)
{
        if (!(file->f_flags & O_DSYNC) && !IS_SYNC(file->f_mapping->host))
                return 0;
        return vfs_fsync_range(file, pos, pos + count - 1,
                               (file->f_flags & __O_SYNC) ? 0 : 1);
}
EXPORT_SYMBOL(generic_write_sync);

/*
 * sys_sync_file_range() permits finely controlled syncing over a segment of
 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
 * zero then sys_sync_file_range() will operate from offset out to EOF.
 *
 * The flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range
 * before performing the write.
 *
 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
 * range which are not presently under writeback. Note that this may block for
 * significant periods due to exhaustion of disk request structures.
 *
 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
 * after performing the write.
 *
 * Useful combinations of the flag bits are:
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages
 * in the range which were dirty on entry to sys_sync_file_range() are placed
 * under writeout.  This is a start-write-for-data-integrity operation.
 *
 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which
 * are not presently under writeout.  This is an asynchronous flush-to-disk
 * operation.  Not suitable for data integrity operations.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for
 * completion of writeout of all pages in the range.  This will be used after an
 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait
 * for that operation to complete and to return the result.
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:
 * a traditional sync() operation.  This is a write-for-data-integrity operation
 * which will ensure that all pages in the range which were dirty on entry to
 * sys_sync_file_range() are committed to disk.
 *
 *
 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any
 * I/O errors or ENOSPC conditions and will return those to the caller, after
 * clearing the EIO and ENOSPC flags in the address_space.
 *
 * It should be noted that none of these operations write out the file's
 * metadata.  So unless the application is strictly performing overwrites of
 * already-instantiated disk blocks, there are no guarantees here that the data
 * will be available after a crash.
 */
SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
                                unsigned int, flags)
{
        int ret;
        struct fd f;
        struct address_space *mapping;
        loff_t endbyte;                 /* inclusive */
        umode_t i_mode;

        ret = -EINVAL;
        if (flags & ~VALID_FLAGS)
                goto out;

        endbyte = offset + nbytes;

        if ((s64)offset < 0)
                goto out;
        if ((s64)endbyte < 0)
                goto out;
        if (endbyte < offset)
                goto out;

        if (sizeof(pgoff_t) == 4) {
                if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
                        /*
                         * The range starts outside a 32 bit machine's
                         * pagecache addressing capabilities.  Let it "succeed"
                         */
                        ret = 0;
                        goto out;
                }
                if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {
                        /*
                         * Out to EOF
                         */
                        nbytes = 0;
                }
        }

        if (nbytes == 0)
                endbyte = LLONG_MAX;
        else
                endbyte--;              /* inclusive */

        ret = -EBADF;
        f = fdget(fd);
        if (!f.file)
                goto out;

        i_mode = file_inode(f.file)->i_mode;
        ret = -ESPIPE;
        if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&
                        !S_ISLNK(i_mode))
                goto out_put;

        mapping = f.file->f_mapping;
        if (!mapping) {
                ret = -EINVAL;
                goto out_put;
        }

        ret = 0;
        if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {
                ret = filemap_fdatawait_range(mapping, offset, endbyte);
                if (ret < 0)
                        goto out_put;
        }

        if (flags & SYNC_FILE_RANGE_WRITE) {
                ret = filemap_fdatawrite_range(mapping, offset, endbyte);
                if (ret < 0)
                        goto out_put;
        }

        if (flags & SYNC_FILE_RANGE_WAIT_AFTER)
                ret = filemap_fdatawait_range(mapping, offset, endbyte);

out_put:
        fdput(f);
out:
        return ret;
}

/* It would be nice if people remember that not all the world's an i386
   when they introduce new system calls */
SYSCALL_DEFINE4(sync_file_range2, int, fd, unsigned int, flags,
                                 loff_t, offset, loff_t, nbytes)
{
        return sys_sync_file_range(fd, offset, nbytes, flags);
}