[PATCH 5.10 CANDIDATE 06/11] xfs: refactor xfs_file_fsync

Amir Goldstein
2022-06-17T10:07:38Z

From: Christoph Hellwig <hch@lst.de>

commit f22c7f87777361f94aa17f746fbadfa499248dc8 upstream.

[backported for dependency]

Factor out the log syncing logic into two helpers to make the code easier
to read and more maintainable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/xfs/xfs_file.c | 81 +++++++++++++++++++++++++++++------------------
1 file changed, 50 insertions(+), 31 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 5b0f93f73837..414d856e2e75 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -118,6 +118,54 @@ xfs_dir_fsync(
return xfs_log_force_inode(ip);
}

+static xfs_lsn_t
+xfs_fsync_lsn(
+ struct xfs_inode *ip,
+ bool datasync)
+{
+ if (!xfs_ipincount(ip))
+ return 0;
+ if (datasync && !(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
+ return 0;
+ return ip->i_itemp->ili_last_lsn;
+}
+
+/*
+ * All metadata updates are logged, which means that we just have to flush the
+ * log up to the latest LSN that touched the inode.
+ *
+ * If we have concurrent fsync/fdatasync() calls, we need them to all block on
+ * the log force before we clear the ili_fsync_fields field. This ensures that
+ * we don't get a racing sync operation that does not wait for the metadata to
+ * hit the journal before returning. If we race with clearing ili_fsync_fields,
+ * then all that will happen is the log force will do nothing as the lsn will
+ * already be on disk. We can't race with setting ili_fsync_fields because that
+ * is done under XFS_ILOCK_EXCL, and that can't happen because we hold the lock
+ * shared until after the ili_fsync_fields is cleared.
+ */
+static int
+xfs_fsync_flush_log(
+ struct xfs_inode *ip,
+ bool datasync,
+ int *log_flushed)
+{
+ int error = 0;
+ xfs_lsn_t lsn;
+
+ xfs_ilock(ip, XFS_ILOCK_SHARED);
+ lsn = xfs_fsync_lsn(ip, datasync);
+ if (lsn) {
+ error = xfs_log_force_lsn(ip->i_mount, lsn, XFS_LOG_SYNC,
+ log_flushed);
+
+ spin_lock(&ip->i_itemp->ili_lock);
+ ip->i_itemp->ili_fsync_fields = 0;
+ spin_unlock(&ip->i_itemp->ili_lock);
+ }
+ xfs_iunlock(ip, XFS_ILOCK_SHARED);
+ return error;
+}
+
STATIC int
xfs_file_fsync(
struct file *file,
@@ -125,13 +173,10 @@ xfs_file_fsync(
loff_t end,
int datasync)
{
- struct inode *inode = file->f_mapping->host;
- struct xfs_inode *ip = XFS_I(inode);
- struct xfs_inode_log_item *iip = ip->i_itemp;
+ struct xfs_inode *ip = XFS_I(file->f_mapping->host);
struct xfs_mount *mp = ip->i_mount;
int error = 0;
int log_flushed = 0;
- xfs_lsn_t lsn = 0;

trace_xfs_file_fsync(ip);

@@ -155,33 +200,7 @@ xfs_file_fsync(
else if (mp->m_logdev_targp != mp->m_ddev_targp)
xfs_blkdev_issue_flush(mp->m_ddev_targp);

- /*
- * All metadata updates are logged, which means that we just have to
- * flush the log up to the latest LSN that touched the inode. If we have
- * concurrent fsync/fdatasync() calls, we need them to all block on the
- * log force before we clear the ili_fsync_fields field. This ensures
- * that we don't get a racing sync operation that does not wait for the
- * metadata to hit the journal before returning. If we race with
- * clearing the ili_fsync_fields, then all that will happen is the log
- * force will do nothing as the lsn will already be on disk. We can't
- * race with setting ili_fsync_fields because that is done under
- * XFS_ILOCK_EXCL, and that can't happen because we hold the lock shared
- * until after the ili_fsync_fields is cleared.
- */
- xfs_ilock(ip, XFS_ILOCK_SHARED);
- if (xfs_ipincount(ip)) {
- if (!datasync ||
- (iip->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
- lsn = iip->ili_last_lsn;
- }
-
- if (lsn) {
- error = xfs_log_force_lsn(mp, lsn, XFS_LOG_SYNC, &log_flushed);
- spin_lock(&iip->ili_lock);
- iip->ili_fsync_fields = 0;
- spin_unlock(&iip->ili_lock);
- }
- xfs_iunlock(ip, XFS_ILOCK_SHARED);
+ error = xfs_fsync_flush_log(ip, datasync, &log_flushed);

/*
* If we only have a single device, and the log force about was
--
2.25.1