/* * linux/fs/ext4/fsync.c * * Copyright (C) 1993 Stephen Tweedie (sct@redhat.com) * from * Copyright (C) 1992 Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * from * linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds * * ext4fs fsync primitive * * Big-endian to little-endian byte-swapping/bitmaps by * David S. Miller (davem@caip.rutgers.edu), 1995 * * Removed unnecessary code duplication for little endian machines * and excessive __inline__s. * Andi Kleen, 1997 * * Major simplications and cleanup - we only need to do the metadata, because * we can depend on generic_block_fdatasync() to sync the data blocks. */ #include <linux/time.h> #include <linux/fs.h> #include <linux/sched.h> #include <linux/writeback.h> #include <linux/jbd2.h> #include <linux/blkdev.h> #include "ext4.h" #include "ext4_jbd2.h" #include <trace/events/ext4.h> static void dump_completed_IO(struct inode * inode) { #ifdef EXT4FS_DEBUG struct list_head *cur, *before, *after; ext4_io_end_t *io, *io0, *io1; unsigned long flags; if (list_empty(&EXT4_I(inode)->i_completed_io_list)){ ext4_debug("inode %lu completed_io list is empty\n", inode->i_ino); return; } ext4_debug("Dump inode %lu completed_io list \n", inode->i_ino); spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list){ cur = &io->list; before = cur->prev; io0 = container_of(before, ext4_io_end_t, list); after = cur->next; io1 = container_of(after, ext4_io_end_t, list); ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n", io, inode->i_ino, io0, io1); } spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags); #endif } /* * This function is called from ext4_sync_file(). * * When IO is completed, the work to convert unwritten extents to * written is queued on workqueue but may not get immediately * scheduled. When fsync is called, we need to ensure the * conversion is complete before fsync returns. * The inode keeps track of a list of pending/completed IO that * might needs to do the conversion. This function walks through * the list and convert the related unwritten extents for completed IO * to written. * The function return the number of pending IOs on success. */ extern int ext4_flush_completed_IO(struct inode *inode) { ext4_io_end_t *io; struct ext4_inode_info *ei = EXT4_I(inode); unsigned long flags; int ret = 0; int ret2 = 0; if (list_empty(&ei->i_completed_io_list)) return ret; dump_completed_IO(inode); spin_lock_irqsave(&ei->i_completed_io_lock, flags); while (!list_empty(&ei->i_completed_io_list)){ io = list_entry(ei->i_completed_io_list.next, ext4_io_end_t, list); /* * Calling ext4_end_io_nolock() to convert completed * IO to written. * * When ext4_sync_file() is called, run_queue() may already * about to flush the work corresponding to this io structure. * It will be upset if it founds the io structure related * to the work-to-be schedule is freed. * * Thus we need to keep the io structure still valid here after * conversion finished. The io structure has a flag to * avoid double converting from both fsync and background work * queue work. */ spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); ret = ext4_end_io_nolock(io); spin_lock_irqsave(&ei->i_completed_io_lock, flags); if (ret < 0) ret2 = ret; else list_del_init(&io->list); } spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); return (ret2 < 0) ? ret2 : 0; } /* * If we're not journaling and this is a just-created file, we have to * sync our parent directory (if it was freshly created) since * otherwise it will only be written by writeback, leaving a huge * window during which a crash may lose the file. This may apply for * the parent directory's parent as well, and so on recursively, if * they are also freshly created. */ static int ext4_sync_parent(struct inode *inode) { struct writeback_control wbc; struct dentry *dentry = NULL; int ret = 0; while (inode && ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) { ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY); dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias); if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode) break; inode = dentry->d_parent->d_inode; ret = sync_mapping_buffers(inode->i_mapping); if (ret) break; memset(&wbc, 0, sizeof(wbc)); wbc.sync_mode = WB_SYNC_ALL; wbc.nr_to_write = 0; /* only write out the inode */ ret = sync_inode(inode, &wbc); if (ret) break; } return ret; } /* * akpm: A new design for ext4_sync_file(). * * This is only called from sys_fsync(), sys_fdatasync() and sys_msync(). * There cannot be a transaction open by this task. * Another task could have dirtied this inode. Its data can be in any * state in the journalling system. * * What we do is just kick off a commit and wait on it. This will snapshot the * inode to disk. * * i_mutex lock is held when entering and exiting this function */ int ext4_sync_file(struct file *file, int datasync) { struct inode *inode = file->f_mapping->host; struct ext4_inode_info *ei = EXT4_I(inode); journal_t *journal = EXT4_SB(inode->i_sb)->s_journal; int ret; tid_t commit_tid; bool needs_barrier = false; J_ASSERT(ext4_journal_current_handle() == NULL); trace_ext4_sync_file_enter(file, datasync); if (inode->i_sb->s_flags & MS_RDONLY) return 0; ret = ext4_flush_completed_IO(inode); if (ret < 0) goto out; if (!journal) { ret = generic_file_fsync(file, datasync); if (!ret && !list_empty(&inode->i_dentry)) ret = ext4_sync_parent(inode); goto out; } /* * data=writeback,ordered: * The caller's filemap_fdatawrite()/wait will sync the data. * Metadata is in the journal, we wait for proper transaction to * commit here. * * data=journal: * filemap_fdatawrite won't do anything (the buffers are clean). * ext4_force_commit will write the file data into the journal and * will wait on that. * filemap_fdatawait() will encounter a ton of newly-dirtied pages * (they were dirtied by commit). But that's OK - the blocks are * safe in-journal, which is all fsync() needs to ensure. */ if (ext4_should_journal_data(inode)) { ret = ext4_force_commit(inode->i_sb); goto out; } commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; if (journal->j_flags & JBD2_BARRIER && !jbd2_trans_will_send_data_barrier(journal, commit_tid)) needs_barrier = true; jbd2_log_start_commit(journal, commit_tid); ret = jbd2_log_wait_commit(journal, commit_tid); if (needs_barrier) blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); out: trace_ext4_sync_file_exit(inode, ret); return ret; }