/* * 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; } EXPORT_SYMBOL(file_fsync); /** * 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_DSYNC) && !IS_SYNC(file->f_mapping->host)) return 0; return vfs_fsync_range(file, file->f_path.dentry, 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_DEFINE(sync_file_range)(int fd, loff_t offset, loff_t nbytes, unsigned int flags) { int ret; struct file *file; struct address_space *mapping; loff_t endbyte; /* inclusive */ int fput_needed; 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; file = fget_light(fd, &fput_needed); if (!file) goto out; i_mode = file->f_path.dentry->d_inode->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 = 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: fput_light(file, fput_needed); out: return ret; } #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS asmlinkage long SyS_sync_file_range(long fd, loff_t offset, loff_t nbytes, long flags) { return SYSC_sync_file_range((int) fd, offset, nbytes, (unsigned int) flags); } SYSCALL_ALIAS(sys_sync_file_range, SyS_sync_file_range); #endif /* It would be nice if people remember that not all the world's an i386 when they introduce new system calls */ SYSCALL_DEFINE(sync_file_range2)(int fd, unsigned int flags, loff_t offset, loff_t nbytes) { return sys_sync_file_range(fd, offset, nbytes, flags); } #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS asmlinkage long SyS_sync_file_range2(long fd, long flags, loff_t offset, loff_t nbytes) { return SYSC_sync_file_range2((int) fd, (unsigned int) flags, offset, nbytes); } SYSCALL_ALIAS(sys_sync_file_range2, SyS_sync_file_range2); #endif