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1b061d9247
We don't name our generic fsync implementations very well currently. The no-op implementation for in-memory filesystems currently is called simple_sync_file which doesn't make too much sense to start with, the the generic one for simple filesystems is called simple_fsync which can lead to some confusion. This patch renames the generic file fsync method to generic_file_fsync to match the other generic_file_* routines it is supposed to be used with, and the no-op implementation to noop_fsync to make it obvious what to expect. In addition add some documentation for both methods. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
138 lines
4.3 KiB
C
138 lines
4.3 KiB
C
/*
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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 void ext4_sync_parent(struct inode *inode)
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{
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struct dentry *dentry = NULL;
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while (inode && 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 = list_entry(inode->i_dentry.next,
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struct dentry, d_alias);
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if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)
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break;
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inode = dentry->d_parent->d_inode;
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sync_mapping_buffers(inode->i_mapping);
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}
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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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* i_mutex lock is held when entering and exiting this function
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*/
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int ext4_sync_file(struct file *file, 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;
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tid_t commit_tid;
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J_ASSERT(ext4_journal_current_handle() == NULL);
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trace_ext4_sync_file(file, datasync);
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if (inode->i_sb->s_flags & MS_RDONLY)
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return 0;
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ret = flush_completed_IO(inode);
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if (ret < 0)
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return ret;
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if (!journal) {
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ret = generic_file_fsync(file, datasync);
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if (!ret && !list_empty(&inode->i_dentry))
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ext4_sync_parent(inode);
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return ret;
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}
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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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return ext4_force_commit(inode->i_sb);
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commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
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if (jbd2_log_start_commit(journal, commit_tid)) {
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/*
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* When the journal is on a different device than the
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* fs data disk, we need to issue the barrier in
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* writeback mode. (In ordered mode, the jbd2 layer
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* will take care of issuing the barrier. In
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* data=journal, all of the data blocks are written to
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* the journal device.)
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*/
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if (ext4_should_writeback_data(inode) &&
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(journal->j_fs_dev != journal->j_dev) &&
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(journal->j_flags & JBD2_BARRIER))
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blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL,
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NULL, BLKDEV_IFL_WAIT);
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ret = jbd2_log_wait_commit(journal, commit_tid);
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} else if (journal->j_flags & JBD2_BARRIER)
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blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
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BLKDEV_IFL_WAIT);
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return ret;
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}
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