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Subject[84/90] ext4: Wait for proper transaction commit on fsync
2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
(cherry picked from commit b436b9bef84de6893e86346d8fbf7104bc520645)

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>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/ext4/ext4.h | 7 +++++++
fs/ext4/ext4_jbd2.h | 13 +++++++++++++
fs/ext4/extents.c | 14 ++++++++++++--
fs/ext4/fsync.c | 46 +++++++++++++++++-----------------------------
fs/ext4/inode.c | 29 +++++++++++++++++++++++++++++
fs/ext4/super.c | 2 ++
fs/jbd2/journal.c | 1 +
7 files changed, 81 insertions(+), 31 deletions(-)

--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -700,6 +700,13 @@ struct ext4_inode_info {
struct list_head i_aio_dio_complete_list;
/* current io_end structure for async DIO write*/
ext4_io_end_t *cur_aio_dio;
+
+ /*
+ * Transactions that contain inode's metadata needed to complete
+ * fsync and fdatasync, respectively.
+ */
+ tid_t i_sync_tid;
+ tid_t i_datasync_tid;
};

/*
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -258,6 +258,19 @@ static inline int ext4_jbd2_file_inode(h
return 0;
}

+static inline void ext4_update_inode_fsync_trans(handle_t *handle,
+ struct inode *inode,
+ int datasync)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+
+ if (ext4_handle_valid(handle)) {
+ ei->i_sync_tid = handle->h_transaction->t_tid;
+ if (datasync)
+ ei->i_datasync_tid = handle->h_transaction->t_tid;
+ }
+}
+
/* super.c */
int ext4_force_commit(struct super_block *sb);

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3041,6 +3041,8 @@ ext4_ext_handle_uninitialized_extents(ha
if (flags == EXT4_GET_BLOCKS_DIO_CONVERT_EXT) {
ret = ext4_convert_unwritten_extents_dio(handle, inode,
path);
+ if (ret >= 0)
+ ext4_update_inode_fsync_trans(handle, inode, 1);
goto out2;
}
/* buffered IO case */
@@ -3068,6 +3070,8 @@ ext4_ext_handle_uninitialized_extents(ha
ret = ext4_ext_convert_to_initialized(handle, inode,
path, iblock,
max_blocks);
+ if (ret >= 0)
+ ext4_update_inode_fsync_trans(handle, inode, 1);
out:
if (ret <= 0) {
err = ret;
@@ -3306,10 +3310,16 @@ int ext4_ext_get_blocks(handle_t *handle
allocated = ext4_ext_get_actual_len(&newex);
set_buffer_new(bh_result);

- /* Cache only when it is _not_ an uninitialized extent */
- if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0)
+ /*
+ * Cache the extent and update transaction to commit on fdatasync only
+ * when it is _not_ an uninitialized extent.
+ */
+ if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
EXT4_EXT_CACHE_EXTENT);
+ ext4_update_inode_fsync_trans(handle, inode, 1);
+ } else
+ ext4_update_inode_fsync_trans(handle, inode, 0);
out:
if (allocated > max_blocks)
allocated = max_blocks;
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -51,25 +51,30 @@
int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
{
struct inode *inode = dentry->d_inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
- int err, ret = 0;
+ int ret;
+ tid_t commit_tid;

J_ASSERT(ext4_journal_current_handle() == NULL);

trace_ext4_sync_file(file, dentry, datasync);

+ if (inode->i_sb->s_flags & MS_RDONLY)
+ return 0;
+
ret = flush_aio_dio_completed_IO(inode);
if (ret < 0)
return ret;
+
+ if (!journal)
+ return simple_fsync(file, dentry, datasync);
+
/*
- * data=writeback:
+ * data=writeback,ordered:
* The caller's filemap_fdatawrite()/wait will sync the data.
- * sync_inode() will sync the metadata
- *
- * data=ordered:
- * The caller's filemap_fdatawrite() will write the data and
- * sync_inode() will write the inode if it is dirty. Then the caller's
- * filemap_fdatawait() will wait on the pages.
+ * 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).
@@ -82,27 +87,10 @@ int ext4_sync_file(struct file *file, st
if (ext4_should_journal_data(inode))
return ext4_force_commit(inode->i_sb);

- if (!journal)
- ret = sync_mapping_buffers(inode->i_mapping);
-
- if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
- goto out;
-
- /*
- * The VFS has written the file data. If the inode is unaltered
- * then we need not start a commit.
- */
- if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_ALL,
- .nr_to_write = 0, /* sys_fsync did this */
- };
- err = sync_inode(inode, &wbc);
- if (ret == 0)
- ret = err;
- }
-out:
- if (journal && (journal->j_flags & JBD2_BARRIER))
+ commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
+ if (jbd2_log_start_commit(journal, commit_tid))
+ jbd2_log_wait_commit(journal, commit_tid);
+ else if (journal->j_flags & JBD2_BARRIER)
blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
return ret;
}
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1026,6 +1026,8 @@ static int ext4_ind_get_blocks(handle_t
goto cleanup;

set_buffer_new(bh_result);
+
+ ext4_update_inode_fsync_trans(handle, inode, 1);
got_it:
map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
if (count > blocks_to_boundary)
@@ -4784,6 +4786,7 @@ struct inode *ext4_iget(struct super_blo
struct ext4_inode *raw_inode;
struct ext4_inode_info *ei;
struct inode *inode;
+ journal_t *journal = EXT4_SB(sb)->s_journal;
long ret;
int block;

@@ -4848,6 +4851,31 @@ struct inode *ext4_iget(struct super_blo
ei->i_data[block] = raw_inode->i_block[block];
INIT_LIST_HEAD(&ei->i_orphan);

+ /*
+ * Set transaction id's of transactions that have to be committed
+ * to finish f[data]sync. We set them to currently running transaction
+ * as we cannot be sure that the inode or some of its metadata isn't
+ * part of the transaction - the inode could have been reclaimed and
+ * now it is reread from disk.
+ */
+ if (journal) {
+ transaction_t *transaction;
+ tid_t tid;
+
+ spin_lock(&journal->j_state_lock);
+ if (journal->j_running_transaction)
+ transaction = journal->j_running_transaction;
+ else
+ transaction = journal->j_committing_transaction;
+ if (transaction)
+ tid = transaction->t_tid;
+ else
+ tid = journal->j_commit_sequence;
+ spin_unlock(&journal->j_state_lock);
+ ei->i_sync_tid = tid;
+ ei->i_datasync_tid = tid;
+ }
+
if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
@@ -5102,6 +5130,7 @@ static int ext4_do_update_inode(handle_t
err = rc;
ei->i_state &= ~EXT4_STATE_NEW;

+ ext4_update_inode_fsync_trans(handle, inode, 0);
out_brelse:
brelse(bh);
ext4_std_error(inode->i_sb, err);
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -713,6 +713,8 @@ static struct inode *ext4_alloc_inode(st
spin_lock_init(&(ei->i_block_reservation_lock));
INIT_LIST_HEAD(&ei->i_aio_dio_complete_list);
ei->cur_aio_dio = NULL;
+ ei->i_sync_tid = 0;
+ ei->i_datasync_tid = 0;

return &ei->vfs_inode;
}
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -78,6 +78,7 @@ EXPORT_SYMBOL(jbd2_journal_errno);
EXPORT_SYMBOL(jbd2_journal_ack_err);
EXPORT_SYMBOL(jbd2_journal_clear_err);
EXPORT_SYMBOL(jbd2_log_wait_commit);
+EXPORT_SYMBOL(jbd2_log_start_commit);
EXPORT_SYMBOL(jbd2_journal_start_commit);
EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
EXPORT_SYMBOL(jbd2_journal_wipe);



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