152 lines
4.3 KiB
C
Executable File
152 lines
4.3 KiB
C
Executable File
/*
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* linux/fs/ext4/fsync.c
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*
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* Copyright (C) 1993 Stephen Tweedie (sct@redhat.com)
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* from
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* Copyright (C) 1992 Remy Card (card@masi.ibp.fr)
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* Laboratoire MASI - Institut Blaise Pascal
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* Universite Pierre et Marie Curie (Paris VI)
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* from
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* linux/fs/minix/truncate.c Copyright (C) 1991, 1992 Linus Torvalds
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*
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* ext4fs fsync primitive
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*
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* Big-endian to little-endian byte-swapping/bitmaps by
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* David S. Miller (davem@caip.rutgers.edu), 1995
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*
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* Removed unnecessary code duplication for little endian machines
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* and excessive __inline__s.
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* Andi Kleen, 1997
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*
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* Major simplications and cleanup - we only need to do the metadata, because
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* we can depend on generic_block_fdatasync() to sync the data blocks.
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*/
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#include <linux/time.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/writeback.h>
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#include <linux/jbd2.h>
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#include <linux/blkdev.h>
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#include "ext4.h"
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#include "ext4_jbd2.h"
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#include <trace/events/ext4.h>
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/*
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* If we're not journaling and this is a just-created file, we have to
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* sync our parent directory (if it was freshly created) since
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* otherwise it will only be written by writeback, leaving a huge
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* window during which a crash may lose the file. This may apply for
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* the parent directory's parent as well, and so on recursively, if
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* they are also freshly created.
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*/
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static int ext4_sync_parent(struct inode *inode)
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{
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struct dentry *dentry = NULL;
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struct inode *next;
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int ret = 0;
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if (!ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY))
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return 0;
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inode = igrab(inode);
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while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
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ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
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dentry = d_find_any_alias(inode);
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if (!dentry)
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break;
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next = igrab(dentry->d_parent->d_inode);
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dput(dentry);
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if (!next)
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break;
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iput(inode);
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inode = next;
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ret = sync_mapping_buffers(inode->i_mapping);
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if (ret)
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break;
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ret = sync_inode_metadata(inode, 1);
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if (ret)
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break;
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}
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iput(inode);
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return ret;
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}
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/*
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* akpm: A new design for ext4_sync_file().
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*
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* This is only called from sys_fsync(), sys_fdatasync() and sys_msync().
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* There cannot be a transaction open by this task.
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* Another task could have dirtied this inode. Its data can be in any
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* state in the journalling system.
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*
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* What we do is just kick off a commit and wait on it. This will snapshot the
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* inode to disk.
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*/
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int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
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{
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struct inode *inode = file->f_mapping->host;
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struct ext4_inode_info *ei = EXT4_I(inode);
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journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
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int ret = 0, err;
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tid_t commit_tid;
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bool needs_barrier = false;
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J_ASSERT(ext4_journal_current_handle() == NULL);
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trace_ext4_sync_file_enter(file, datasync);
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if (inode->i_sb->s_flags & MS_RDONLY) {
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/* Make sure that we read updated s_mount_flags value */
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smp_rmb();
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if (EXT4_SB(inode->i_sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
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ret = -EROFS;
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goto out;
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}
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if (!journal) {
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ret = generic_file_fsync(file, start, end, datasync);
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if (!ret && !hlist_empty(&inode->i_dentry))
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ret = ext4_sync_parent(inode);
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goto out;
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}
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ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
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if (ret)
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return ret;
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/*
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* data=writeback,ordered:
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* The caller's filemap_fdatawrite()/wait will sync the data.
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* Metadata is in the journal, we wait for proper transaction to
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* commit here.
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*
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* data=journal:
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* filemap_fdatawrite won't do anything (the buffers are clean).
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* ext4_force_commit will write the file data into the journal and
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* will wait on that.
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* filemap_fdatawait() will encounter a ton of newly-dirtied pages
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* (they were dirtied by commit). But that's OK - the blocks are
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* safe in-journal, which is all fsync() needs to ensure.
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*/
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if (ext4_should_journal_data(inode)) {
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ret = ext4_force_commit(inode->i_sb);
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goto out;
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}
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commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
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if (journal->j_flags & JBD2_BARRIER &&
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!jbd2_trans_will_send_data_barrier(journal, commit_tid))
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needs_barrier = true;
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ret = jbd2_complete_transaction(journal, commit_tid);
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if (needs_barrier) {
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err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
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if (!ret)
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ret = err;
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}
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out:
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trace_ext4_sync_file_exit(inode, ret);
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return ret;
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}
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