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/*
* High-level sync()-related operations
*/
#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/module.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/buffer_head.h>
#include "internal.h"
#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
SYNC_FILE_RANGE_WAIT_AFTER)
/*
* 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)
{
/*
* This should be safe, as we require bdi backing to actually
* write out data in the first place
*/
if (!sb->s_bdi)
return 0;
/* Avoid doing twice syncing and cache pruning for quota sync */
if (!wait) {
writeout_quota_sb(sb, -1);
writeback_inodes_sb(sb);
} else {
sync_quota_sb(sb, -1);
sync_inodes_sb(sb);
}
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);
/*
* Sync all the data for all the filesystems (called by sys_sync() and
* emergency sync)
*
* This operation is careful to avoid the livelock which could easily happen
* if two or more filesystems are being continuously dirtied. s_need_sync
* is used only here. We set it against all filesystems and then clear it as
* we sync them. So redirtied filesystems are skipped.
*
* But if process A is currently running sync_filesystems and then process B
* calls sync_filesystems as well, process B will set all the s_need_sync
* flags again, which will cause process A to resync everything. Fix that with
* a local mutex.
*/
static void sync_filesystems(int wait)
{
struct super_block *sb;
static DEFINE_MUTEX(mutex);
mutex_lock(&mutex); /* Could be down_interruptible */
spin_lock(&sb_lock);
list_for_each_entry(sb, &super_blocks, s_list)
sb->s_need_sync = 1;
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
if (!sb->s_need_sync)
continue;
sb->s_need_sync = 0;
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
if (!(sb->s_flags & MS_RDONLY) && sb->s_root && sb->s_bdi)
__sync_filesystem(sb, wait);
up_read(&sb->s_umount);
/* restart only when sb is no longer on the list */
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;
}
spin_unlock(&sb_lock);
mutex_unlock(&mutex);
}
/*
* sync everything. Start out by waking pdflush, because that writes back
* all queues in parallel.
*/
SYSCALL_DEFINE0(sync)
{
wakeup_flusher_threads(0);
sync_filesystems(0);
sync_filesystems(1);
if (unlikely(laptop_mode))
laptop_sync_completion();
return 0;
}
static void do_sync_work(struct work_struct *work)
{
/*
* Sync twice to reduce the possibility we skipped some inodes / pages
* because they were temporarily locked
*/
sync_filesystems(0);
sync_filesystems(0);
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);
}
}
/*
* Generic function to fsync a file.
*
* filp may be NULL if called via the msync of a vma.
*/
int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
struct inode * inode = dentry->d_inode;
struct super_block * sb;
int ret, err;
/* sync the inode to buffers */
ret = write_inode_now(inode, 0);
/* sync the superblock to buffers */
sb = inode->i_sb;
if (sb->s_dirt && sb->s_op->write_super)
sb->s_op->write_super(sb);
/* .. finally sync the buffers to disk */
err = sync_blockdev(sb->s_bdev);
if (!ret)
ret = err;
return ret;
}
/**
* vfs_fsync_range - helper to sync a range of data & metadata to disk
* @file: file to sync
* @dentry: dentry of @file
* @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.
*
* In case this function is called from nfsd @file may be %NULL and
* only @dentry is set. This can only happen when the filesystem
* implements the export_operations API.
*/
int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start,
loff_t end, int datasync)
{
const struct file_operations *fop;
struct address_space *mapping;
int err, ret;
/*
* Get mapping and operations from the file in case we have
* as file, or get the default values for them in case we
* don't have a struct file available. Damn nfsd..
*/
if (file) {
mapping = file->f_mapping;
fop = file->f_op;
} else {
mapping = dentry->d_inode->i_mapping;
fop = dentry->d_inode->i_fop;
}
if (!fop || !fop->fsync) {
ret = -EINVAL;
goto out;
}
ret = filemap_write_and_wait_range(mapping, start, end);
/*
* We need to protect against concurrent writers, which could cause
* livelocks in fsync_buffers_list().
*/
mutex_lock(&mapping->host->i_mutex);
err = fop->fsync(file, dentry, datasync);
if (!ret)
ret = err;
mutex_unlock(&mapping->host->i_mutex);
out:
return ret;
}
EXPORT_SYMBOL(vfs_fsync_range);
/**
* vfs_fsync - perform a fsync or fdatasync on a file
* @file: file to sync
* @dentry: dentry of @file
* @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.
*
* In case this function is called from nfsd @file may be %NULL and
* only @dentry is set. This can only happen when the filesystem
* implements the export_operations API.
*/
int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
{
return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync);
}
EXPORT_SYMBOL(vfs_fsync);
static int do_fsync(unsigned int fd, int datasync)
{
struct file *file;
int ret = -EBADF;
file = fget(fd);
if (file) {
ret = vfs_fsync(file, file->f_path.dentry, datasync);
fput(file);
}
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_SYNC) && !IS_SYNC(file->f_mapping->host))
return 0;
return vfs_fsync_range(file, file->f_path.dentry, pos,
pos + count - 1, 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
|