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We cannot rely on buffer dirty bits during fsync because pdflush can come before fsync is called and clear dirty bits without forcing a transaction commit. What we do is that we track which transaction has last changed the inode and which transaction last changed allocation and force it to disk on fsync. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
97 lines
2.8 KiB
C
97 lines
2.8 KiB
C
/*
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* linux/fs/ext3/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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* ext3fs 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/blkdev.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/jbd.h>
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#include <linux/ext3_fs.h>
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#include <linux/ext3_jbd.h>
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/*
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* akpm: A new design for ext3_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 ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
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{
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struct inode *inode = dentry->d_inode;
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struct ext3_inode_info *ei = EXT3_I(inode);
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journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;
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int ret = 0;
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tid_t commit_tid;
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if (inode->i_sb->s_flags & MS_RDONLY)
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return 0;
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J_ASSERT(ext3_journal_current_handle() == NULL);
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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 a proper transaction
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* to 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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* ext3_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 (ext3_should_journal_data(inode)) {
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ret = ext3_force_commit(inode->i_sb);
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goto out;
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}
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if (datasync)
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commit_tid = atomic_read(&ei->i_datasync_tid);
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else
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commit_tid = atomic_read(&ei->i_sync_tid);
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if (log_start_commit(journal, commit_tid)) {
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log_wait_commit(journal, commit_tid);
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goto out;
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}
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/*
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* In case we didn't commit a transaction, we have to flush
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* disk caches manually so that data really is on persistent
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* storage
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*/
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if (test_opt(inode->i_sb, BARRIER))
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blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
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out:
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return ret;
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}
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